Interciencia  JAN- FEB 1991, VOL. 16 N9 I

Coral reefs are tropical and subtropical eco­systems that flourish at temperatures between 25 and 29 centi­grade in insular and continental platforms. Living coral cover and species diversity is highest where waters are clear due to low input of nutrients and fine sediments. Recent Caribbean coral reefs are about 5,000-12,000 years old and started de­veloping when insular and continental shelves drowned after the last glacial period (Adey, 1978). They are spread throughout the Wider Caribbean from the Gulf of Mexico south to Panama and Tobago and north to Bahamas and rep­resent 9% (1,000 km2) of the total area covered by these ecosystems in the world (Smith, 1978). Bermuda and northern Brazil (Recife) contain the northernmost and southernmost coral reefs, respective­ly, in the Atlantic Ocean. These regions are related biogeographicatly to Carib­bean reefs but are impoverished in terms of reef related species. Those reefs off Brazil exhibit relatively high endemicity (Margarida, 1982).

Coral reefs are highly susceptible to disturbance in relation to other nearshore ecosystems, such as mangrove forests and seagrass beds (Ogden and Gladfelter, 1983). This report should be viewed in the context of exten­sive coral bleaching events recently occurring throughout the Caribbean (Williams et a!.. 1987); Goenaga ci a!. (1989) ~. Bleaching is related to the expulsion (Goreau, 1964) and/or loss of pigmentation (Hoegh-Guldberg and Smith. 1988) of endodermal symbionts, known as zooxanthellae which, under normal conditions, contribute to the nu­trition and calcification of corals (Mus­catine and Cernichiari, 1969). Coral bleach when subject to environmental stresses. Although this event may not be directly linked to human activities (given its extension) it is reasonable to think that the probability of recovery di­minished where coral reefs are already subject to local stress. Sediment remov­al by coral reefs, for example, is highly dependent on the production of mucus in some coral species (Hubbard and Pockock. 1972). Mucus production, in turn, has been shown to be intimately re­lated to the activity of zooxanthellae ((Crossland et al., 1980). Coral reefs in many Caribbean islands are already stressed by increased sediment loads due to intense upland deforestation (e.g., Johannes, 1975).

Coral reef degradation (in terms of observable changes in the relative abundance of major benthic components resulting from human activi­ties is well known to be underway in Caribbean. It has been documented in Kingston, Jamaica (Head and Hent 1985), in Veracruz, Mexico (Tunr 1985), in Venezuela (Weiss and G dard, 1977), in Parque Nacional Cahta, Costa Rica (Cortés and Risk, 198 in the Puerto Rican southern and west coast (Goenaga, 1986; C. Goenaga, Vicente, R. Acevedo, J. Morelock, personal observations), in Lindberg Bay, Thomas (van Eepoel and Grigg, 19 van Eapoel ci a!., 1971; Grigg and Lepoel, 1970), in Boca Chica, Repüb Dominicana (Ceraldes and Bonnelly Calventi, 1977), in Colombia (Cubit aL, 1984) and elsewhere as mentioned below. Significant small spatial S( (i.e., 1 m2) changes in the community structure of nearshore, Puerto Rican coral reefs have occurred within the decade and are associated with mass mortalities of Diadema antillaruni (cente, 1987) although the ultimate collective agent remains unknown. The main objective of this report is to summarize the available published and non published information of the effects of pollution coral reefs of the Wider Caribbean. Examples from elsewhere are included whenever information from the Carib­bean is not available.



Socioeconomic Importance of Coral Reefs

Although coral reefs  are mainly known for their natural beauty and high biotic diversity, this is only a minor portion of what they represent to nations that possess them. Recently it has been suggested that their importance for the maintenance of life on Earth transcends national barriers as explained below. Following is a list of the socio­economic importance of coral reefs:

Production of Pharmacological Compounds

A large diversity of chemical compounds have resulted pos­sibly as a consequence of complex inter­actions between species in the coral reef. Some of these substances are highly active biocompoUnds whose applications in medical research are just now being discovered. These include antimicrobial, antileukemic, anticoagulant and cardio­active properties (Fenical, 1980; Rine­hart et al., 1981; Saim and Clark, 1982). Coral reef organisms have been used as tools in the elucidation of phyriological mechanisms (e.g., sea hare), (fertiliza­lion (e.g., sca urchin), regeneration and cell association (c.g,, sponges) arid mechanisms of drug action (e.g,, squids) (Angeles, 1981).


Prevention of Coastal Erosion  and Storm Damage

This is particularly im­portant for regions with low lying coastal plains. Coral reefs also contribute to the formation of sandy beaches and sheltered harbors.

The importance of the maintenance of healthy coral reef growth is accentuated in light of the observed sea level rise in the last decades (Etkins and Epstein, 1982; Gornitz ci a!.. 1982). Coastal erosion is likely to be felt more in areas where coral reefs are degenerated since large waves are capable of penetrat­ing more easily in the absence of these natural barriers (Cubit et a!., 1984). Areas with reduced tidal fluctuations are more likely to be affected.



Coral reefs are among the most productive habitats of the world (Lewis, 1977). Fisheries in the Caribbean can be defined, with few although sig­nificant exceptions (e.g., upwelling zones and shrimp fisheries), as coral reef fisheries (Munro, 1983). Reef fishery products are often the primary sourc: of dietary protein for coastal and island people. According to the Caribbean Fisheries Management Council (National Ocean and Atmospheric Administration, US. Department of Commerce) 59% of the total fisheries consumed in Puerto Rico and the Virgin Islands come from coral reefs. The fisheries potential of many Caribbean reefs has been impaired in the last decades partially due to overfishing (e.g., Appeldorn and Lindeman, 1985) and, possibly, to habitat degradation (e.g, Bouchon-Navsrro etal,1985).



Tourism on many Carib­bean islands is based on reef related activities and on the aesthetic and rec­reational value of reefs. Submarine trails in Trunk Bay, St. John, are utilized daily by hundreds of tourists. This type of development, however, requires close supervision and a parallel educational process about the fragility of component reef organisms.


Extraction o/ Atmospheric Carbon Dioxide

Coral reefs constitute about 0.17% of the world ocean area and about 15% of the shallow sea floor within the 0-30 m depth range (Smith, 1978). These ecosystems play an im­portant role in the marine carbon budget primarily through the deposition of aragonitic calcium carbonate. Surface tropical waters, which are stratified by a permanent thermocline, are supersatu­rated with respect to calcium carbonate. The inorganic transfer of atmospheric CO2 across the air-sea interface is, there­fore, limited. By extracting CaCO5, coral reef organisms provide a way of bringing more CO2 into the ocean system. Reported rates of CaCO3 deposition by coral reefs demonstrate that these ecosystems are an important buffer in the Earth’s CO2 cycle (Barnes ci a!., 1986).


Human Activities Affecting Coral Reefs

In general, coral reefs within the Wider Caribbean are threatened by pollution related to industry, domestic wastes and upland vegetation clearing. Rodriguez (1981), in a review of en­vironmental stress in coastal waters of the Wider Caribbean, pointed our that there is no widespread industrial pollu­tion there, apart from contamination by petroleum hydrocarbons. He added, how­ever, that severe, localized problems do occur and stressed that these problems threaten the development of economic activities which depend on a healthy marine environment. The largest in­dustrial concentrations occur along the coast of Venezuela, Colombia, Mexico, Cuba, the US Gulf States, Puerto Rico, Trinidad and Tobago, the Netherlands Antilles, the US Virgin Islands and Ja­maica. Industrial development in the Central American states, with the excep­tion of the San Pedro Sula area on the north coast of Honduras, is mainly along or oriented towards the Pacific coast rather than the Caribbean (Rodriguez, 1981).

Marine pollution caused by dumping domestic wastes into the ocean (Rodriguez, 1981), and upland vegetation clearing (i.e., be it for industry, urbanization or agriculture) without concern towards appropriate land conser­vation practices (Johannes, 1975) are two other activities, common to the whole region, that have a negative impact upon coral reefs. These are associated with all major cities in the area.

Other activities that are spatially and temporally restricted, al­though not necessarily insignificant, are:  mining of coral reefs, military activities, standing and walking over coral, ship grounding, anchoring, coral collecting, fishing with explosives and with bleach, dredging and thermal pollution. Of these, the first seven destroy reef structure directly while the last three modify the relative abundance of the living compo­nents. The effect of most of these have been documented for the wider Carib­bean and examples are given next.


A.  Oil Pollution

Many coral reef scien­tists have expressed their apprehension concerning the harmful effects of oil spills (e.g., Bak and Elgershuizen, 1976). Degradation of some Caribbean coral reefs have already been attributed to chronic oil pollution. Chavez el of. (1985), for example, noted that the reef biota at Cayo Arcas, a group of islands off Yucatan (Mexico) that hold an oil pumping station, has been subjected to considerable environmental stress. Specifi­cally, they attributed the disappearance of dense Acropore cervicornis thickets at this site to “activities related to the oil industry”.


Bak and Elgershuizen (1976) have suggested that the water soluble fraction of oils in seawater is more harmful to corals than their direct contact with oil. Riitzler and Sterrer (1970) suggested that corals escaped observable damage from an oil spill in Panama because they were continuously submerged. Detergents, however, can disperse oil and its toxic fractions into deeper waters affecting the biota that otherwise would not come in contact (Cerame.Vivas, 1969; Cintrdn, 1981). Nevertheless, direct field evidence of these effects are generally wanting.


Data from laboratory experiments show that colonies of the scleractinian, Madrocis mirobilis were more affected by mixtures of various crude oils and Shell dispersant (LTX type) than by either the crude oils or the dispersant separately (Elgershuizen and de Kruijf, 1976). These investigators hypothesized that the observed non ad­ditive effects were related to a higher solubility of the toxic oil fraction in sea water after emulsification by the dis­persant. Active ingestion of oil drops by corals do not occur and it is unlikely that oil is adsorbed to living coral tissue (Bak and Elgershuizen, 1976). Mucus pro­duced by corals, however, can trap drops of oil that may be incorporated into the reef food web via the mucus-eating fish and crustaceans (Elgershuizen a of,, 1975). Zooxanthellae from the Caribbean scieractinian Diploria strigoso exhibit re­duced photosynthesis after eight hour exposure to dispersed oil in concentra­tions of 19 ppm (Cook and Knap, 1983). Although recovery was rapid, long term effects were not looked at. Also, most of these experiments simulate the effect of episodic, acute oil spills. The effect of chronic, long term oil pollution remains unassessed to my knowledge.

Shinn (1972) observed that the scieractinian Monto.strea onnulo­ris can survive two hours total immersion in Louisiana crude oil and that Acroporo cervicornts, exposed for two hours to a mixture of seawater containing one part crude to 6-12 parts seawater, caused im­mediate retraction of polyps although recovery was complete after 24 hours. Based on these observations he remarked that “it would seem safe to conclude then that crude oil spills do not pose a signif­icant threat to Atlantic coral reefs”. However, as Johannes (1975) has noted, this statement is premature since Shinn reported no subsequent observations on these corals. Dodge et ol. (1985) deter­mined experimentally that corals treated with chemically dispersed oil at concen­trations of 20 ppm showed no depression in calcification. Once again, it is un­known whether long term impairment of vital functions, such as reproduction or maintenance, had occurred in individuals of these species. Also, Shinn’s own experi­ments illustrate the importance of in­terspecific response to oil. Evidence of pathological responses, including im­paired development of reproductive tis­sues, atrophy of mucous secretory cells and muscle bundles, has been observed in colonies of the shallow water Caribbean coral Manicina oreolata during exposure to water accommodated fractions of No. 2 fuel oil (Peters, et ol., 1981). This atrophy may help explain the decreased capacity of corals to recover from inju­ries after subject to oil pollution reported in Panami by Guzmán and Jackson (1989). Gooding (1971) also docu­mented an extensive destruction of reef associated biota, other than corals, by an oil spill in Wake Island.

Other effects of oil and the use of dispersants on coral reefs are the alteration of the physical properties of the reef surface (which inhibits larval settlement), the impairment of oxygen exchange across the air-water interface (Blumer, 1971; Kinsey, 1973) and the in­terruption of light penetration by surface oil films (Mergner, 1981). These have not been documented in the Caribbean.


B.   Oil Drilling Muds

In addition to the danger of oil spills, potentially detrimental ef­fects of drilling near coral reefs include the actual physical disturbances caused by anchoring, pipeline and drill rig con­struction, the resuspension of bottom sediment created by such activities shadowing by the rig platform and the discharge of drilling effluent which include sewage, deck drainage, produced formation water, produced sand, materials for treating wells, drill cuttings and drilling muds (Dodge and Szmant, press; Thompson and Bright, 1977). The effects of drilling muds are discussed below.

Drilling muds are introduced in the marine environment during offshore drilling operations. Then are discharged at low levels and occasionally in bulk (up to 2,000 barrels or 14 tons in a few hours) when the muds require renewal or on termination of drilling activities (Thompson cx of., 1980)

Drilling muds are varied in composition and those containing ferrochrome lignosulphonates and other additives such as diesel fuel, appear to be more toxic. Their effect on coral reefs have been recently reviewed by Dodg and Szmant (in press) - Their major conclusion is that more research is needed urgently on this subject.

Exposure to chromiolignosulphate drilling muds leads to the production of mucus as a “stress”  response in Porites divaricata, P. furcata P. astreoldes, Montostrea annulari, .Acropora cervicornis and Agoricia ogar cites (Thompson et of., 1980) and may be responsible for decreased growth rate after short term exposure, by M. annularis (Hudson and Robbin, l980~ Dodge (1982) suggested that lower calical relief in corals exposed to usedb drilling muds can result in decrease sediment-shedding capabilities which may remain effective for some time after the period of exposure in M. annularis.

Szmant ci a!. (1981) have further investigated the response of M. annularis to drilling muds. They found that the rates of calcification and respiration of this species decreased by 53% and 25%, respectively, after four weeks of exposure to 100 ppm drilling mud and 84% arid 40% after six weeks of exposuse. Gross photosynthesis was reduced by 36% after five weeks. Nitrate uptake rates decreased by 42% and 48% after four and six weeks while ammonium uptake decreased by 32% and 49% after five and six weeks of exposure. Colonies exposed to 100 ppm were not able to feed on zooplankton and several of the exper­imental colonies died before completion of the experiment.


C.  Siltation From Upland Vegetation Clearing

       Siltation of coral reefs results from upland vegetation clearing and is generally considered an important factor controlling coral reefs. It can limit coral reefs by: 1) increasing water turbidity (Jerlov, 1968) and, thus, af­fecting the photosynthetic output of zooxanthellae, 2) causing energy expen­diture in particle rejection (Lasker, 1980), 3) increasing the potential for hacterial infection (Ducklow and Mitchell, 1979; Peters, 1984), 4) abrasion (Wein, 1962; Slorr, 1964), 5) creaeing condi­tions unsuitable for larval settlement (Maragos, 1972), 6) reducing feeding periods (personal observations) and/or altering heterotrophic and autotrophic  feeding efficiencies (Dodge and Szmant, j in press), 7) affecting planktonic food  supply (Bak, 1978), and, 8) shifting the relative abundance of fish and promoting the survival of those that graze on the benthos (Galzin, 1981). The removaL of mangrove stands, generally accompanying upland deforestation on developed coastal areas, magnifies the problem of siltation.

These stands act as natural barriers for runoff due to precipitation. In the Puerto Rican southwestern coast it is not uncom­mon to observe large sediment plumes after heavy rains where the mangroves have been removed and replaced with stilt houses (personal observations).  These are located within the maritime zone and many dump raw sewage into the water.

Although coral reefs are known to occur under silt laden and/or eutropinc waters (Goenaga, 1988), it is unknown whether these are in the process of disappearing or whether the compo­nent biota is or will be capable of adapt­ing to these conditions. The available evidence suggests that at least some of the biotic components which depend more upon sunlight die in deeper, al­though are able to persist in shallower portions of reefs (Morelock et a!., 1979; Acevedo, 1986; Goenaga, 1988).



D. Sewage Discharge

Sewage discharge into coastal waters may affect coral reef communities by 1) causing nutrient enrich­ment and enhancing the growth of algae at the expense of corals (Marszatek, 1981), 2) depressing oxygen levels Wade a al., 1972), and 3) by introduc­ing toxic substances such as chlorine (cf. Muchmore and Epel, 1973). Coral morbidity and mortality under experi­mental conditions is apparently the result of competition for space with algae and light and not directly related to effluent toxicity (Marszalek, 1981). Sewage is known to stress reefs in Barbados, Cu­raçao, Florida Keys, Guadeloupe, Ja­maica, Martinique, St. Kilts and British and U.S. Virgin Islands (Rogers, 1985).

The classical example of the effects of eutrophication on coral reefs is Kaneohe Bay in Hawaii. Twenty six to ninety nine percent of the local coral reefs here were destroyed by over­growth of corals with the green alga Dictyosphaeria cavernosa due to cultural eutrophication (Maragos, 1972). Partial regeneration of the reef habitat has oc­curred six years after diversion of sewer discharges from the ocean (Maragos ci at, 1985). In Puerto Rico, coral reefs growing close to sanitary discharges also show proliferations of green algae, namely, Ulva sp., Enteromorpha sp. and Dictyosphaeria sp. (V. Vicente and C. Goenaga, personal observation). These tend to colonize corals from their bases eventually overgrowing them. Recent mass mortalities of the black sea urchin, Diadema antillarum, in the Caribbean make the situation worse. This urchin is a voracious omnivore that continually grazes on fleshy and filamentous algae covering the substrate.


E.  Dredging and Mining

                The impact of dredging on coral reef communities are of three basic types: 1) mechanical damage (re­sulting in breakage of coral and octo­coral colonies many of which subsequent­ly die), 2) sediment loading or siltation(i.e., rapid deposition of coarse silt and coastal waters may affect coral reef com- sand size sediments resulting from sedi­ment laden water leaking from the dredge pumps) resulting in burial and death of colonies, and, 3) increased turbidity re­sulting in loss of color, excessive mucus secretion or death in scieractinians. Also, waters over dredged areas have signifi­cantly more bacteria than neighboring seawater (Galzin, 1981). This seems related to the suspension of fine sand particles that are utilized as a substratum by the bacteria and may result in the elimination of certain benthic faunal and floral species and the proliferation of tolerant species. Galzin (1981) also found that sand dredging in Guadaloupe, French West Indies, resulted in a decline of the abundance of the fish fauna and a reduction of species equitability.

One effect of dredging that is usually ignored is the resuspension of toxic materials, such as heavy metals, into the water column. Metals may be detrimental to corals by impairing their physiological processes and possibly by weakening the structure of the aragonite skeleton (Howard and Brown, 1984).

Associated with dredg­ing operations are mining and smelting processes. Fiftysix large scale mining operations are reported in the Caribbean, all discharging effluent, with little regula­tion, into waters showing incomplete and slow mixing characteristics (Howard and Brown, 1984). Brown and Holley (1981) found slightly elevated levels of copper and zinc and relatively high concentra­tions of tin in the silt fraction of reef sediment near to a tin smelter at Ko Phuket, Thailand. It is not unreasonable to think that the same is occurring in the Caribbean.


F.  Thermal Pollution

Activities generating ther­mal pollution, mainly related to the energy industry, are known to be main­tained in the vicinity of Caribbean coral reefs. Although the effect of this type of pollution has not been documented for the Caribbean it is known that thermal effluent retard growth or cause mortality in scleractinians and also prevent larval recruitment into thermally enriched areas of reefs of Guam (Neudecker, 1981). Maximum ambient temperatures were found to be close to lethal temperatures for corals in Guam (Mayor, 1918), Mayor noted that the temperature at which the feeding reactions and normal metabolic processes cease are more signif­icant than death temperatures. For ex­ample, three species of coral ceased to feed at temperatures 1.5-3.0°C lower than theiç lethal temperatures. The effect of thermal stress has been thoroughly studied in Hawaii (Jokiel and Coles, 1977; Jokiel and Coles, in press).


G. Anchoring

Anchoring on top of coral reefs can represent considerable disruption to coral reef communities. Davis (1977), for example, estimated that this activity has damaged nearly 20% of staghorn communities in the fort Jefferson National Monument, Florida. Tilmant and Schmahl (1981) found a significant linear correlation of reef use and incidence of physical damage. Stand­ing and walking over coral and coral col­lecting can also ruin large portions of reefs (Goenaga, personal observations) Although this damage appears to be local­ized and inconsequential in the long run it may not be so, especially where usage is intense.

However, touristic sight­seeing of coral reefs, if well planned and with adequate supervision, seems to be highly compatible with the preservation of these ecosystems and can be highly productive in terms of education and in terms of the employment generated. The economy of many Caribbean islands depend to a large extent on external tourism. The promotion of this activity for internal tourism seems equally impor­tant since it is likely to create an awareness of this important natural resource on islanders.


H. Military Activities

Although military ma­neuvers near coral reefs are possibly not widely practiced in the Caribbean, an ex­ample from Vieques, off eastern Puerto Rico, will illustrate the results from this activity. It seems particularly important to discuss this activity given that several authors (see below) have stated that mili­tary activities are inoffensive to coral  reefs and this notion may be utilized to justify further maneuvers elsewhere.

In 1982, Antonius and Weiner concluded that the “military im­pact of the Viequen reefs was negligible when compared to natural damage caused by storm — generated wave action”. These conclusions are based on compari­sons made between the reefs from Vieques and those in the eastern coast of St. Croix (presumably not subject to military activities) with which they found no differences. A close look at their section on Materials and Methods, however, reveals that, in their work, “the emphasis was on shallow water com­munities”. It is widely known and has been extensively documented (e.g., Wood­ley a at, 1981; Graus a al., 1984; among many others) that damage to coral reefs by storms occurs mainly in shallow waters. It is at these depths that corals with the highest growth rates predominate (e.g., Acropora palinata and A. cervi­cornis). This is one reason why hurricanes have minimal long term effects on coral reefs (Graus a at, 1984). Deeper por­tions of coral reefs, where slower grow­ing, massive corals predominate, are not affected as heavily by storms. However, military activities do not discriminate be­tween shallow and deeper portions of the reef and bombs drop in shallow and in deep substrates affecting them equally. It seems reasonable, therefore, to question why did Antonius, a consultant for the U.S. Navy, did not investigate the deeper portions of the reefs in Vieques. The same critique applies to the work by Raymond and Dodge (1980).

In another work, Dodge (1981) also concluded that “...a general similarity between (bombing) ran and control stations..." in Vieques, together with “...quantitative coral abundance and diversity data of other namely, data by Antonius and Weint (1982) indicate a lack of anomalous and adverse sedimentation/turbidity cotu tions affecting coral on reefs near range area”. However, several commer must be made. Reef corals, as well other organisms, need energy for processes other than growth, namely reproduction and maintenance. The effet of the presence of the range on these two other processes were not assessed. Coral colony fragmentation, a process knowledged by Antonius and Wein (1982) and Dodge (1982) to occur Vieques, is, in fact, known to. monotastrea annularic, the very same spec utilized by Dodge (1981) in his study.

Aerial photographs eastern Vieques do show extensive cratering resulting from bombing activities on land as well as in the sea. Crater range in diameter from 5 to 13 m and larger effects extend beyond the extent of direct disruption (Rogers et al., 1978). The reefs are littered with artillery and  delivered exploded and unexploded ordnance (metal fragments, flare casings, parachutes) which have sustained extensive damage. Damage to reefs in Vieques has been categorized by Rogers et (1978) as follows: 1) damage by direct hits and by shock waves which sheer colonies near the site of impact, 2)damage due to abrasion by steel and rough fragments generated by the blasts, 3)damage by fragments that come to remain on top of living coral tissue, 4) fracturing and weakening of reef structure blasts and direct hits, 5) dislodgement of colonies which can be transported by heavy seas causing greater damage, 6) deposition of coarse sediments on top of living corals, 7) damage by flare parachutes which drape around soft and stony corals, and others.

Large numbers of unex­ploded ordnance in these reefs limit their future utilization as fishing and/or touristic centers. It is hard to estimate the costs involved in their restoration. We can barely hope that leaching substances from oxidizing and degenerating ordi­nance do not pollute marine life in these areas.


I  Ship Grounding

   Ship grounding in coral reefs can abrade, fracture or overturn reef biota and hull breakage can result in the spill of hazardous substances. Also, alteration of the hydrodynamic regime while the ship is grounded over the reef can generate sediment plumes that in­crease water turbidity and smother corals downcurrent. Direct damage by ship grounding is more localized than that of storms but may alter the reef contour and re1ief to a much greater extent (Smith, 1985).

Curtis (1985) described how portions of Molasses Reef, FLorida, was crushed and resembled a “graded roadbed covered with a veneer of coral­line debris” when the M/V WELLWOOD grounded. He found that the damage was significant but that it depended on depth, location and afflicted taxa.  Additional consequences of this grounding included damage by cable drag, propeller wash scour and shading. In Bermuda, ship groundings have obliterated topographical features of coral reefs creating flat, bar­ren areas with deposits of boulders and rubble and sparse surviving corals (Smith, p985). Damage to coral reefs by ship grounding has also occurred on other important marine reserves such as Mona  Island, Puerto Rico (H. Ferrer, G. Cin­tront and R. Martinez, Department of Natural Resources, Commonwealth of Puerto Rico, personal communication).


J.  Fishing with Bleach and Explosives

Fishing with bleach and With explosives occurs in the Caribbean although it is more generalized in the Indopacific. In the Caribbean fishing with bleach occurs in the islands of Antigua (Rogers, 1985) and Bahamas (Campbell, 1977), Explosives are used in Antigua, Bahamas, Barbados, Dominican Repub­lic, Grenada, Jamaica and St. Lucia (Rogers, 1985).

Bleach (sodium hypo­ch1orite) is applied to coral heads to drive commercially valuable species into range of spears and granges, Campbell (1977) correlated the use of this chemical with infection of coral by blue-green algae (Oscillaforia submembranacea), anaerooic bacterium (De.wlfovibrio sp.) and the aerobic bacterium Beggiaioa sp. He fur­ther suggested that most fish and many crustaceans, annelids and mollusks be­come scarce in bleached coral reefs a!though the evidence is mostly circum­stantial.


K.  Overfishing

The manner in which overfishing may affect coral reefs is un­certain but it is likely that the community structure is modified. For example, over-fishing of predator species in St. Croix was suggested to be the cause of unusual abundances of the echinoid Diadema aruillarum in 1973 (Ogden et aL 1973). Diadema anrillarum can locally over­graze bottom vegetation and corals and its abundance has been directly linked to the frequency of recruitment of coral reefs (Sammarco, 1980).



Capacity For Recovery


Denuded coral reef corn­munities can recover by regeneration of partially damaged coLonies or fragments or through recolonization by larval set­tlement. Factors which can influence coral recolonization include tbe extent of damage and its location, the availability of coral larvae, the requirement for a ‘conditioning” period of the substratum before corals can settle, the availability and diversity of microhabitats for set­tlements and survival, the role of grazers, and competition with other organisms such as algae and soft corals (Pearson, 1981).

The available evidence suggests that coral communities may re­cover from major natural disturbance after several decades but are likely to suf­fer irreversible changes from man-made disturbance (Weiss and Goddard, 1977). Full recovery from man-made distur­bances may be prolonged or prevented altogether because of permanent change to the environment or a continuation of chronic, low level disturbances (Pearson, 1981). In 1975 Johannes reviewed the known effects of pollution on coral reef communities. He pointed out that reef corals are central to the integrity of the reef community and when these are se­lectively killed, migration or death of much of the other reef fauna ensues. Ac­cordingly, the environmental tolerance of the reef communtty as a whole can­not exceed that of its corals.

At this point it is neces­sary to mention that non-structural coral communities have the same practical im­portance as coral reefs in terms of coastal protection, nutritional importance, and others. Coral communities differ from coral reefs essentially in the thickness of the biogenic framework. The former form thin veneers over preexisting struc­tures, such as cemented sand dunes, that drowned after sea level rose during the last glacial period. Coral reefs, in contrast, have a thicker framework which, to a larger extent, have been the product of biogenic (i.e., versus physicochemical) activity. Non-structural coral communi­ties give integrity to the underlying struc­ture and prevent its physical or chemical erosion and eventual destruction.

The importance of habi­tats neighboring coral reefs, such as seagrass beds and mangrove forests, has been stressed by Ogden and Zieman (1977). Seagrass beds are important feeding grounds for nocturnal feeding fishes, such as grunts and snappers, which shelter on reefs by day. When they return to the reef these fishes deposit organic compounds in the form of feces that become available to detritivores and are introduced to the reef food web. Mangroves provide nurseries for juve­niles of certain reef fish (chactodontids, scarids, lutjanids) and are also feeding grounds for fish that shelter on reefs; mangroves also introduce fixed nitrogen and organic detritus into the trophic system or reefs as do reef flats and seagrass beds. Consequently, damage to these neighboring communities can po­tentially have an effect on nearby coral reefs.





Based on this review some recommendations seem logical:


1)  Compile a detailed bibliography on the factors that contrib­ute to the degeneration of coral reefs on a world basis.

2) Based on the litera­ture, define parameters known to be re­lated to coral reef degeneration.

3) Monitor polluted and non polluted reef habitats to dif­ferentiate between natural and man-in­duced sources of variation.

4) Establish marine parks in coordination with affected local communities; fishing communities must have an active and principal role in the management of the park.

5)  Consider and study the possibility of restoring damaged areas.

6) Update coral reef inventories.



Although in many cases a causal nexus have not been shown conclusively, the correlation between unplanned development and coral reef degradation makes it hard to attribute the latter effect to causes other than the former. Stressed reef communities show drastic reduction in live coral cover, overgrowth by filamentous algae, erosion of physical framework and reduction of diversity of associated fish and inverte­brates. Reef degradation has already been shown to result in an increase in wave energy at beaches, beach erosion and massive sediment movements (Head and Hendry, 1985) not to mention the de­cline in the catch of edible species. Touristic development, of primordial im­portance to many Caribbean nations and in principle highly compatible with the preservation of coral reefs, rests upon the amenity value of the coast, and this, in turn, depends upon maintaining the natural ecology of the reefs and related environments.  In turn, we observe re­peatedly that developers are able to respond only to the short term advantage of lower economic cost by land clearing extensive coastal areas without concern for land conservation practices and in detriment of natural littoral and sublit­toral marine communities. Recent find­ings that coral reefs play a significant role in the carbon dioxide cycle magni­fies the importance of these ecosystems and puts them in a global perspective. The destruction of coral reefs, therefore, is no longer of national but of interna­tional interest.

     It is perhaps sad that statements related to the preservation of coral reefs more than a decade ago by Johannes (1975) are as timely as ever and acquire more significance today. Johannes stated that:  the allocation of money for coral reef research and man­agement is. - . very small in relation to the importance of these communities to man and... their vulnerability to pollu­tion.

"…environmental cri­ses (related to the destruction of coral reefs) develop faster than they can be completely assessed. In this context it is more important to make interim deci­sions in time than to make more sci­entifically satisfying decisions later” (i.e., after the ecosystem is irreversibly dam­aged).

And also more timely than ever, he adds about scientists that comfortably and cowardly sit over their data, knowledge and/or insights that “those who remain silent when their observations point to environmental decay are the undertaken of the environ­ment; environmental post mortems be­come their stock and trade.”





1. Other coral sicknesses have been studied recently by Peters (1914) and others.


2. This phenomenon may be related to human activities. Preliminary observations suggest that bleaching is related to higher than normal penetration of solar radiation into the sea (R. Armstrong, C. Goensga and V. Vicente, personal observations). This is consistent with the known fact that the thinning of the ozone layer, particularly in the poles but also in the tropics, results from the usage of chloroftuorocarbons and halons. This subject, however, is outside of the scope of this report.






II Florida’s Coral reefs Beautiful & Alive!

 Florida's coral reefs are alive with an abundance of fish, stony & soft corals, sponges, jellyfish, anemones, snails, crabs, lobsters, rays, sea turtles, and other sea life. Corals reefs are the most biologically diverse marine ecosystems in the world. Corals are delicate structures composed of millions of tiny slow-growing animals called polyps. It can take years for some corals to grow one inch.

 North America's only coral barrier reef lies about six miles offshore and parallels the Florida Keys, a 158-mile long string of islands, surrounded by mangrove forests and seagrass beds, which together form a fragile, interdependent ecosystem.

 Mangroves are saltwater-tolerant trees that provide a nesting area for birds. The submerged roots are a nursery and breeding ground for most of the marine life that migrates to the reef. Mangroves trap and produce nutrients for food and habitat, stabilize the shoreline, and filter land-based pollutants. 

 Seagrasses offer food and habitat for juvenile fish, crustaceans, and shellfish. They filter the water of sediments, release oxygen into the water and stabilize the bottom with their roots. 

      The Florida Keys National Marine Sanctuary 

   To protect this spectacular marine ecosystem, the Florida Keys  National Marine Sanctuary was created in 1990. It is 2,800 square   nautical miles, extends on both sides of the Florida Keys, and is the second largest marine sanctuary in the United States.

 A comprehensive management plan and a water quality protection program are being created for the new sanctuary in cooperation with the public, a citizen's advisory council and several federal, state, and local government agencies for implementation in 1994.

 For more information, contact:  

   Florida Keys National Marine Sanctuary Planning Office   9499 Overseas Highway       Marathon, FL 33050      (305)743-2437

 For more information on Refuges, contact the Refuge Manager at (305)872-2239.  

    Fragile & Endangered

 Coral, for all its sturdy appearance, is fragile and vulnerable. The millions of annual divers, snorkelers, and fishermen who visit the coral reef ecosystem threaten its very existence!

 The careless toss of an anchor can destroy years of coral growth in minutes. Even the lightest touch can damage sensitive coral polyps.

 Nutrients from sewage, fertilizers, stormwater run-off, and deteriorating Gulf waters reduce water quality, causing increased occurrence of coral diseases and algal blooms.

 Monofilament line and trash wrapped around delicate corals can smother or abrade coral and even break them. Trash can be deadly for birds, fish, and turtles that become entangled or mistake it for food and ingest it.

 Boats that stray into shallow waters may Prop dredge, uprooting seagrass beds and damaging nursery and breeding areas. The noisy approach of a boat or jetski can disturb nesting birds in the mangroves, exposing the eggs or nestlings to predators and the intense sun. Disturbance of shallow feeding grounds can lead to the starvation of birds.  


    What You Can Do to Protect the Coral Reef Ecosystem

     Tips for Divers & Snorkelers:

 What you do (or don't do) can make a difference to the survival of the Coral Reef Ecosystem:   

   Before booking a reef trip, check weather conditions; it's best not to go out in rough seas. Poor visibility, strong winds & waves reduce safe interaction at the reef.  Remember that even the lightest touch with hands or equipment can damage sensitive coral polyps.  Snorkelers should wear float-coats to allow gear adjustments without standing on the coral.  

    To avoid contact with the ocean bottom, divers should only use the weight needed and practice proper buoyancy control. Lifeless areas may support new growth, if left undisturbed. Avoid wearing gloves and touching or collecting marine life. Most tropical fish captured die within a year. Queen conch is a protected species.  Please don't feed the fish; it destroys their natural feeding habits.  Remember, it's illegal to harvest coral in Florida and buying it at local shops only depletes reefs elsewhere.  

       Snorkeling is an enjoyable way to see the coral reef. Be sure to wear a float coat to avoid standing, stepping on, or touching the fragile living  organisms.

        Tips for Boaters & Fishermen

 Dumping trash at sea is illegal; plastic bags and other debris can injure or kill marine animals. Try to retrieve fishing gear & equipment, especially monofilament line.   

   Accidental boat groundings damage the reef. Prop damage destroys shallow seagrass beds. Consult tide & navigational charts and steer clear of shallow areas. Remember, "Brown, brown, run aground. Blue, blue, sail on through."  Use reef mooring buoys or anchor in sandy areas away from coral and seagrasses so that anchor and chain do not damage the coral or seagrass beds.  Use sewage pump-out facilities, biodegradable bilge cleaner, and never discharge bilgewater at the reef.  

    Practice good seamanship and safe boating. Maintain safe distances from fishermen. Observe size & catch limits; release all fish you can't eat.  Avoid wildlife disturbance: stay 200 feet or more offshore; keep speed, noise, and wakes to a minimum near mangroves.  Camping, campfires, and collecting of any kind are prohibited on all National Wildlife Refuges. Personal watercraft & airboats are illegal in all National Parks and Wildlife Refuges in the Florida Keys.  

       Mangroves are home to nesting birds and other animals; maintain a safe distance offshore and bring your trash back to shore.

 Healthy seagrass beds are an important part of the coral reef ecosystem; avoid prop dredging by staying in marked channels and away from shallow areas.     

 REEF RELIEF is a Key West-based non-profit conservation organization dedicated to "Preserve and Protect the Living Coral Reef of the Florida Keys." Programs include reef mooring buoy maintenance, public education and operation of the Environmental Education Center in Key West, marine debris reduction and oversight of the threats to the reef.


How to Use Mooring Buoys

Reef mooring buoys have been installed at most heavily-visited coral reefs in the Florida Keys. Boaters are encouraged to hook up to the buoys because they eliminate the need to drop anchor on the fragile living coral reef. The buoys are provided at no cost to boaters as a public service by Reef Relief at Key West-area reefs and by the Florida Keys National Marine Sanctuary at Looe Key, Sombrero Reef, Islamorada and Key Largo reefs.

John Halas and Harold Hudson of the Key Largo National Marine Sanctuary (now part of the Florida Keys National Marine Sanctuary) designed the original eyebolt and buoy assembly in use at most Keys coral reefs. Buoy technology is developing and Reef Relief has designed the Big Boat Buoy to allow for use of the buoys by large vessels. The Manta Ray design has also been installed at Keys reefs in areas of rubble inappropriate for the single eye or Big Boat moorings. The buoyassembly above the ocean surface is uniform for all reef mooring buoys. The polypropylene pick-up lines are treated for resistance to the damaging rays of the sun and are easily removed for replacement when necessary. The buoy itself floats on the surface and is recognizable from a distance. A reef tract surrounded by buoys provides a warning to boaters that this is an area of shallow water.

" A few basic procedural steps should be taken when using a mooring buoy:

1.Slowly approach the buoy from down wind and/or down current.

   2.Smaller boats are encouraged to tie off to one another, thereby allowing larger vessels access to buoys. Remember, the larger the vessel, the more potential damage to the coral (if an anchor is used).

   3.All boats should put out extra scope by adding an extra line to create a horizontal pull on the eyebolt. Otherwise, the eyebolt will be pulled out. A good rule to remember is: if the buoy is pulled underwater, you must let out extra scope.

   4.Inspect the mooring buoy your boat is tied to -- you are still responsible for your vessel.

   5.Sailboats should not leave large sails up as steadying sails when on a buoy; this puts too much strain on the eyebolt.


If you choose not to use a mooring buoy, anchoring is only permitted in the sandy areas, NOT IN THE CORAL!

This is Florida State Law.     Presented by The SportFishing WebSite


III Reefs In Danger:    The State of Coral Reefs Around the World  

Coral reefs are among the world's most fragile and endangered ecosystems. Reefs off of 93 countries have been damaged by human activity, and unless the current trends are reversed, up to 70% of the world's coral reefs may be killed within our lifetime.  

Coral reefs are vital environmental and economic resources that give shelter to one quarter of all marine life. Destruction of coral reefs would mean the extinction of thousands of marine species and the elimination of a primary source of income, employment and food for millions of people. 

 Some of the most serious threats to coral reefs are:   

    Over-fishing and fishing with cyanide that upset the ecological balance of coral reefs and allow algae or coral predators to overrun the reefs. 

      Silt from deforestation that smothers coral reefs by blocking sunlight and preventing photosynthesis. 

      Coral mining and blast fishing that destroy coral reefs with explosives. 

      Untreated or improperly treated sewage that chokes coral reefs by promoting algae growth. 

      Runoff of pesticides, fertilizers and other chemicals that poison the reefs. 

          The United States, Japan, Australia, Jamaica, France, the United Kingdom,  the Philippines, and Sweden have launched an initiative to protect coral reefs in partnership with  other coral reef nations around the world, NGOs, international organizations, multilateral                    development banks, and private sector businesses.

 International Year of the Reef - 1997    

 Coral reefs around the world are being threatened by factors such as over-fishing, coastal development, runoff from agriculture and logging, high-impact tourism and many other causes. Concern about the state of the world's reefs has inspired scientists and environmental groups to accept the following challenges: 

                        planning and executing major programs of public

                        education and outreach about coral reefs and coral  reef destruction

                         assessing the conditions of coral reefs worldwide

                         collaborating with governments, local communities and other reef managers to develop and implement  plans for the sustainable use of irreplaceable reef resources 

 The International Year of the Reef (IYOR) 1997 has begun a major effort of assessment, education and collaboration. Scientists and volunteers from the worldwide diving community are involved in diagnosing the condition of representative reefs throughout the tropical seas. Aquariums, scientists, and conservation organizations are collaborating to produce a variety of courses, video tapes, brochures and other educational materials. Individual coral reef areas are creating or revising management plans for their coastal zones. With the involvement and financial support of governments, foundations and individuals, all these initiatives are being put into place to insure that the world's coral reefs are preserved for the future.



IV  Are storms killing coral?

 Tue Mar 7 2000 18:01 EST   Environmental News Network 

 Are huge dust storms from Africa's deserts   killing the coral in the Caribbean Sea?  

 "I've been watching this for about 40 years," said U.S. Geological Survey scientist Gene Shinn. "The years with high dust were the same years most of the coral were damaged."    "No one has gotten into looking at the potential health effects or what dust  does to the environment," said Shinn, a self-proclaimed "dust nut" who's  hoping to raise awareness and funds for his cause.    Coral reefs throughout the Caribbean have been plagued by algal infestation, disease and attrition since the 1970s. Beginning about the same time, scientists noticed that desertification in North Africa was moving sand and other particulate across the Atlantic Ocean.    Changes in climate send strong winds loaded with African dust, soil, and organisms westward over the Atlantic. Earlier this week, NASA's SeaWiFS satellite, which takes pictures of Earth from space, captured one of the largest dust storms ever recorded by the spacecraft.    The dust ball is full of bacteria, viruses and fungi that are deadly to coral,  according to Dick Barber of Duke University in North Carolina. It is also rich in iron, which fertilizes reef-choking algae, he said.   

Shinn believes algal infestation, coral bleaching and coral killers such as  "white band" and "black band" diseases are connected to the nearly two billion tons of dust that each year blow from North Africa to the Caribbean.    "After we looked around and noticed coral was dying all over the Caribbean, not just in Florida where we have sewage and other problems, I found some  literature on the Amazon rain forest," Shinn said. "In the late '80s and early  '90s, scientists determined that the African dust supplies most of the essential nutrients for the rain forest."   

The best evidence of Shinn's theory is Aspergillis, a fungus normally found in soil, that has devastated a particular species of coral. Since 1983, when Aspergillis first appeared, it has killed more than 90 percent of the Caribbean's sea fans. The same year — an exceptionally dusty one — Diadema sea  urchins drastically declined, which, in turn, triggered algal infestations in the  reefs.    Dust from Africa carries millions of spores similar to Aspergillis. "It's a veritable soup of stuff," he said.    Millions of dollars have been spent researching sedimentation, sewage, pollution, ship groundings, temperature and other coral enemies, Shinn noted.  But none of these potential killers explain why coral disease and algal infestation occur simultaneously throughout the Caribbean, especially in  remote areas with little human activity.  

 One theory blamed deforestation runoff on coral demise. Shinn blames dust balls. "We looked at the dust," said Shinn. "That would explain how it could be all around the Caribbean, even in areas with no forests around."    Understanding the relationship between African dust and the demise of coral reefs could redirect research efforts.    Shinn and colleagues are analyzing dust trapped in coral skeletons. The data will be compared with climate records and dust levels from key Caribbean collection sites.    New coral cores will be collected from Caribbean reefs in the Virgin Islands.  Older coral cores, stored at a St. Petersburg, Florida, laboratory, will be analyzed for any correlation with the new cores.    Other microbiologists will examine fresh dust collected in the Virgin Islands for fungal and bacterial spores.    "All I'm trying to do is make people aware because most don't even think of this," said Shinn. "And it does affect people's health, no doubt about it."     



From Science News, Vol. 142  11/14/92  p334  from reports from geological Society of America annual meeting

     Tiny marine organisms known as foraminifera exhibit damage similar to that observed in bleached corals, reports Pamela  Hallock, an oceanographer at the University of South Florida in St. Petersburg.

     Both foraminifera and coral play an important role in the global ecosystem.  As these organisms "are very important sources of organic matter and calcium carbonate production...such [bleaching] phenomena could affect the global carbon cycle and the oceanic food chain," Hallock says.  Foraminifera and coral filter carbon dioxide out of the atmosphere.  If their numbers decline, the atmospheric concentration of this greenhouse gas could potentially increase.

     Many foraminifera, like many coral, live in a symbiotic relationship with microorganisms that provide their hosts with not only nourishment, but also color (SN 12/8/90, p 364).  A host organism that has lost its symbiotic companion turns white, or bleaches, and its health declines.

     In the first documented study of bleaching foraminifera, Hallock examined four species of the genus Amphistegina collected from Florida reefs.  These species live on the loose rubble bottom in water approximately 20 meters deep.

     Hallock found that while most of the population appeared normal throughout  the winter months, bleaching began to occur and then increase during the spring of 1992.  Bleaching peaked in June and July, with 85 percent of the population showing total or partial loss of color.  

     While damaged foraminifera began to regain color as fall approached, the bleaching appears to have had severe effects on reproduction and adult mortality.  "There were very few juveniles in the population at a time when you would expect them to be [abundant]," Hallock says.

     In the laboratory, bleached foraminifera produce significantly fewer young, and up to 30 percent of these may be deformed or nonviable, the study shows.

     Laboratory studies indicate the bleaching can be induced by increasing the organisms' exposure to ultraviolet light.  Hallock speculates that the bleaching she observed may have resulted from a minute increase in ultraviolet exposure related to Mt. Pinatubo's eruption in 1991.


VI Coral Reefs To Be First Casualty Of CO2 Emissions

Coral reefs will become a casualty of the industrialized world's growing carbon dioxide emissions by the middle of the next century, according to a study published in the April 2 issue of the journal Science.

     Oceanic surface waters will become more acidic as they absorb carbon dioxide in increasing amounts from the atmosphere, say the study's co-authors, including the University of Chicago's David Archer. This rising acidity will in turn significantly interfere with the growth of coral reefs.

     "It's an irrevocable thing that we're doing to the planet," said Archer, Associate Professor in Geophysical Sciences at Chicago. "Seventy-five percent of carbon dioxide has a lifetime of hundreds of years in the atmosphere. But a smaller fraction, seven or eight percent, has a lifetime of hundreds of thousands of years."

     The Science article's six co-authors, led by Joan Kleypas of the National Center for Atmospheric Research in Boulder, Colo., predict the first direct detrimental effect of rising carbon dioxide to be the impact on the growth of coral reefs.

     In 1700, the concentration of carbon dioxide in the atmosphere was approximately 280 parts per million. Today, it is nearly 370 and rising as much as two parts per million each year.

     "It's almost going to double from the pre-industrial value some time in the next century. That's almost unavoidable," Archer said.

     Fossil-fuel combustion and deforestation both have contributed to rising atmospheric carbon dioxide. "There was a long, broad rise of carbon dioxide throughout the 19th century, which predates the use of coal and other fossil fuels," Archer said. "They call it 'the pioneer effect,' for when the New World forests were cut down."

     This increase in carbon dioxide adds to the greenhouse effect, which traps heat in the atmosphere, possibly leading to global warming. Warming trends during the last 10 years, whether from increased carbon dioxide emissions or natural climatic variation, have already caused bleaching of coral reefs.

     Corals normally live in symbiosis with algal plants, but warm temperatures upset the relationship. "For some reason that nobody really quite understands, when corals get stressed they spit out the plants," Archer said. When that happens, corals lose their color, changing from green or brown to white. "This effect of carbon dioxide acidifying the ocean is on top of this already well-known bleaching effect," Archer said.

     The findings are based on a series of studies showing that acidity interferes with the growth of coral reefs. One of the studies was conducted in Biosphere 2 near Tucson, Ariz., by Science article co-author Chris Langdon of Columbia University's Lahmont-Doherty Earth Observatory. Biosphere 2 is an enclosed glass and metal frame structure that houses Earth's ecosystems in miniature, including a 900,000-gallon research ocean.

     Coral reefs are mostly made of calcium carbonate. When carbon dioxide dissolves in water it makes carbonic acid, which causes calcium carbonate to deteriorate. Langdon and his colleagues observed a slowdown in coral reef growth when Biosphere 2 contained higher levels of carbon dioxide.

     A key element of the Science study was Archer's model of carbon movement from the ocean surface to the deepest sea floor. The model takes into account such factors as fluid dynamics, current velocity, water temperature, salinity and chemistry.

     "It's like the models they use to predict weather in the atmosphere, only this is down in the ocean," said Archer, whose work is supported by the David and Lucille Packard Foundation and the Petroleum Research Fund.

     Archer's model produced rising carbon dioxide levels that rise over the decades at the ocean surface where coral reefs grow. These areas are warmer than other parts of the ocean and therefore more buoyant and in more continuous contact with the atmosphere, he explained.

     Similar models are used to determine how much carbon is going into the ocean today. The burning of fossil fuels and deforestation combined release approximately seven billion metric tons (seven gigatons) of carbon into the atmosphere each year. The amount in the atmosphere is increasing by three gigatons each year. Ocean models predict that the ocean takes up another two gigatons annually. Scientists suspect that the remaining two gigatons might be fertilizing terrestrial plants and soil in the Northern Hemisphere.

     "The fate of that two gigatons is still rather mysterious," Archer said. - By Steven N. Koppes

[Contact: Steve Koppes]



Death Of Corals In Florida Keys A Warning


     The dying corals of the Florida Keys could be an early warning of tough times ahead for the planet's environment, Cornell University ecologists worry. The reason: Hundred-year-old corals are succumbing to diseases they previously survived.

     Increasing global temperatures and worsening pollution, the ecologists say, could place so much stress on ecosystems that organisms of all kinds will face new challenges.

     "When we see corals that have persisted for hundreds of years suddenly die from opportunistic infections, we have to wonder what has changed in their environment," says C. Drew Harvell, associate professor of ecology at Cornell.

     Harvell organized a session, "Diseases of the Ocean: A New Environmental Challenge," at the annual meeting of the American Association for the Advancement of Science (AAAS) in Anaheim, Calif. on Jan. 22 to bring together leading microbiologists, ecologists and pathologists to evaluate the environmental threats from disease in the ocean. Speaking in the session was Kiho Kim, a postdoctoral research associate with Harvell at Cornell, who reported on an unusual disease in Florida Keys corals.

     Kim said that monitoring of sea fan corals in the Keys, where up to 40 percent of sea fans are infected by a fungal disease and many have already died, suggests that lower water quality and higher ocean temperatures stress corals and increase their susceptibility to disease. He said the Florida findings support a growing consensus among scientists worldwide that as ocean ecosystems become degraded they will offer more favorable places for disease outbreaks and the emergence of new pathogens.

     "We didn't begin our study of sea fans to monitor death and destruction," Harvell said. "Originally, we were interested in the natural disease-resistance properties of corals, such as the anti-bacterial and anti-fungal chemicals they produce, because some of those compounds may be useful in human medicine. That disease resistance normally keeps a coral alive for hundreds of years, despite living in an ocean full of potential pathogens."

     She said Garrett Smith of the University of South Carolina at Aiken was responsible for tracing the sea fan disease to a common soil-dwelling fungus. A type of Aspergillus fungus, washed out to sea by land erosion, collects on the flexible fan-shaped surface of the corals and promotes an aspergillosis infection that first discolors and eventually causes lesions and tumors as it destroys some corals, the researchers said. Sea fans, which position themselves perpendicular to water currents, are especially vulnerable to any pathogenic organisms in the passing water, Harvell noted.

     "Somehow, a soil pathogen that was best known for infecting aged and immune-compromised humans has crossed the land-sea barrier," Harvell said. "Now, one of our jobs is to discover what has compromised the resistance of the corals at some sites. Although a significant number of sea fans have died at a few sites, at many locales they recover from infections, pointing to the success of their natural resistance."

     While coral disease is reported throughout the Caribbean, the reef ecosystems of the Florida Keys may be particularly vulnerable because they are close to what ecologists call "natural stressors," such as fluctuating water temperatures and substantial freshwater runoff, Harvell said. The situation has worsened in recent years, the Cornell ecologist observed, with multiple "anthropogenic stressors," such as eutrophication, siltation and other effects of intensive human use of the land and off-shore waters.

     "Then you have rising water temperatures of the oceans," Harvell added. "Whether you believe that global warming is a function of human activity and whether last year's El Niño was a symptom of global warming, the fact is that sea temperatures globally in 1998 were high. And 1998 was the worst year ever recorded globally for coral bleaching."

     Corals bleach (or lose their symbiotic algae) when stressed by high temperatures, Harvell explained, adding: "I think we have to question the relationship between temperature stresses and diseases of the oceans."

     Lately in the Florida Keys, coral death has been occurring so suddenly and rapidly that Harvell and Kim must monitor their research sites three times a year. Harvell credits the assistance of Cornell undergraduate researchers, including Alisa Alker, who dive from NOAA vessels and return to the laboratory to perform biological assays of coral samples.

     "With a very few exceptions, we know so little about the pathogenic organisms that are affecting the coral reefs," Harvell said. "We don't know if new diseases are emerging, if the hosts are becoming more susceptible or both. We need to identify these new diseases and we should do it now while we have the chance. Disease ecology is poorly understood in the ocean because diseases are like lightning strikes -- they hit unexpectedly, burn through a population, and then they are often gone."

     Harvell and Kim conduct their studies from the Keys Marine Laboratory in Long Key, with the assistance of Reef Relief in Key West. Their research is supported by the National Science Foundation, National Oceanic and Atmospheric Administration (NOAA) and the New England Bio Labs Foundation. - By Roger Segelken



   VII  Coral Killer Identified; Is Global Warming An Accomplice?

     The culprit responsible for killing sea-fan coral from the Florida Keys to San Salvador has been caught in the act and identified for the first time, according to researchers at the University of California, Berkeley, and their collaborators.

     The group reports in the July 9 issue of the journal Nature that a fungus called Aspergillus sydowii has been responsible for the mass destruction of this coral over the last 15 years.

     "Aspergillus sydowii is the fungus causing the disease that's killing them," said John W. Taylor, UC Berkeley professor of plant and microbial biology. "It's the same fungus throughout the West Indies."

     Taylor made the finding with David M. Geiser, a UC Berkeley postdoctoral researcher who now is a professor at Penn State; Kim B. Ritchie of the University of North Carolina, Chapel Hill; and Garriet W. Smith of the University of South Carolina-Aiken.

     The sea fan -- a type of animal life, as are all corals -- is an extremely important component of coral reefs, said Ritchie. It hosts many reef organisms and provides a refuge for reef fish.

     What is interesting about the attacking fungus Aspergillus sydowii, said Taylor, is that it has inhabited Caribbean waters for a very long time but appears to have begun killing coral on a large scale only recently.

     One explanation for this is that the fungus mutated in recent years to become more virulent. But more likely, the researchers said, the problem lies with the coral itself. They suspect that weakening of the sea-fan immune system or some other damage to the organism, possibly from changes in the environment, could be making the coral more vulnerable to infection. Thus, the marine creatures may no longer be able to fight off the fungus.

     The fungus was identified by genetic studies of DNA taken from infected corals. The studies, done at UC Berkeley from samples provided by researchers at the other two institutions, placed the pathogen solidly among other known samples of A. sydowii, a well-known fungus described in the scientific literature in 1913 but undoubtedly in existence much earlier.

     "It's a temptation when you see a new disease to think that you have a new organism," said Taylor, a fungi expert. "But that's not necessarily true." In this case, explained Taylor, it's a new disease from a well-known fungus.

     The proof is that healthy sea-fan colonies exposed to A. sydowii from diseased tissue also come down with sickness, the researchers found. Alarmingly, the incidence of the coral reef disease "is increasing at a pretty intense rate," said Ritchie. "The reasons for this are highly debated and range from global warming to human factors like pollution and land run-off."

     Generally, she said, "disease occurs most frequently in organisms that are stressed. If the sea fans are not healthy, that is an indication of trouble, and the reefs are certainly not healthy."

     Aspergillus fungi have been found not only in Caribbean waters, but in many other places including soil from Washington, D.C., dried Japanese fish and Mexican bee hives.

     A close relative of penicillium, the fungus is well adapted to conditions of high salt or other solutes, such as sugar. "If you open up a jelly jar in the refrigerator and there's mold on it," said Taylor, "chances are it's Aspergillus."

     Sea fans are made up of polyps -- small finger-like cylinders of tissue -- attached in a fan-like pattern to a central internal skeleton. Overlaid by the polyps, the inert skeleton supports all branches of a colony. The polyps produce blue-green spores for reproduction.

     "Sea-fan colonies can get up to a meter and a half (about five feet) or even larger, (but) these are really old colonies," said Ritchie. "The colonies that we used for the inoculation experiments in our Nature article were small -- around 20 centimeters (about eight inches)."

     Two species of sea fan, Gorgonia ventalin and Gorgonia flabellum, are found throughout the Caribbean, said Ritchie. Both are affected by the A. sydowii pathogen.

     Sea-fan disease has been reported in the Virgin Islands, Puerto Rico, the Bahamas, Mexico, Panama, Venezuela, the Florida Keys and many other coral reef locations. It can be recognized by a characteristic receding of the polyps, revealing the dead central skeleton, or core.

     "You can clearly see places where the coral has died," said Taylor. "Visually, the human parallel would be a skin infection like ringworm. A closer human parallel would be the Aspergillus fumigatus infection afflicting people undergoing bone marrow or organ transplants. Like A. sydowii, this fungus is not normally a pathogen, but when the patient's immune system is suppressed for the transplant, it becomes one."

     As for the coral, the researchers said not to look for any solutions soon. Even if there were a safe, effective cure to rescue the sea fans, which at the moment there doesn't appear to be, "I don't think it would be economically possible to treat sea fans in their natural environment," said Taylor.


     "We need to understand what is making the infection possible. If we're lucky, it may be some kind of pollution or something else we could prevent. But if it's something like rising ocean temperature, good luck." - Kathleen Scalise



VIII Florida’s Coral Reefs-Pamphlet-DEP


Coral reefs are specialized habitats that provide shelter, food and breed­ing sites for numerous plants and ani­mals. They form a breakwater for the adjacent coast, providing natural storm protection. They are very important to southeast Florida’s economy. Recreational and commercial fishing annually bring many millions of dollars to the state. The attractions of the coral reef com­munities contribute greatly to the total value of Florida’s fisheries.


Coral reef development occurs only in areas with specific environmental char­acteristics: a solid structure for the base; warm and predictable water tempera­tures; oceanic salinities; clear, transparent waters low in phosphate and nitrogen nutrients, and moderate wave action to disperse wastes and bring oxygen and plankton to the reef.


The tropical setting in Florida’s reefs attracts millions of visitors annually. In order to minimize human damage to the corals, everyone’s cooperation is needed. The reefs are well marked on navigation charts; if you are not famil­iar with the area, refer to the charts.


Every year careless boaters run aground, destroying coral colonies that are hun­dreds of years old. Seen from the sur­face, reefs have a unique golden-brown color. If you see brown, you may be about to run aground. Be cautious when anchoring your boat. Do not deploy the anchor directly in coral. Usually there are sandy areas close by; anchor in the sand. Many popular reefs off Key Largo and at Looe Key National Marine Sanc­tuary have special anchor buoys for moor­ing. In these areas, tie up to the buoys, rather than anchoring. Do not dispose of trash, bilge washings and other de­bris on or near the reefs!


Anglers should avoid shallow coral reefs when trolling. Hooks can scar and injure the coral, leaving it vulnerable to infection by microscopic organisms that can kill the animals. When fishing for lobster, avoid placing traps on reefs. Heavy traps break corals and damage the bottom when the traps are pulled.


When diving or snorkeling, look, but do not touch! Do not grasp, stand or sit on living coral. You may damage the coral and hurt yourself in the pro­cess. All coral is protected. It is against the law to collect, harvest or sell Florida corals in state and adjacent federal wa­ters.

Florida coral reefs, with whom we share the seas, are significant, unique natural resources. Be a responsible visitor— insure the continued vitality of Florida’s coral reefs.

Department of Environmental Protection Florida Marine Research Institute 100 Eighth Avenue, S.E.St. Petersburg, F1 33701 -5095



IX Crown-of-Thorns Starfish [Acanthaster planci ]

National Geographic March 1970 p527

Once they head down the windward side of the island, we’ll lose them,” the marine scientist shouted over the out­board’s roar. “It’s too rough out there for small boats.”

Sounds like a sheriff leading his posse af­ter a gang of outlaws, I thought, as we knifed along the northern coast of Guam. True, our quarry was “speeding” at only a few hundred feet a day, but otherwise the analogy fitted. For, in their way, the marauders we had come to kill were as dangerous as any human des­peradoes.. They were spine-covered, coral-killing starfish, and they were destroying the living reef that shelters Guam’s coastline from the continual pounding of the sea.

Rare nocturnal predators only a decade ago, these spiny multipedes have undergone a mysterious population explosion and now, by day as well as by night, menace coral reefs in widely scattered areas of the Pacific.

Casualty List Spans Half an Ocean

The prickly starfish, known commonly as the crown-of-thorns and scientifically as Acanthaster planci, eats the tiny coral polyps that create such reefs.  In a single day it can graze an area twice the size of its 6- to l2~inch central disk.

Acanthaster has killed more than 90 per­cent of the coral along 24 miles of Guam’s 100-mile coastline in two and a half years. It has also invaded 300 miles of Australia’s 1,250-mile-long Great Barrier Reel, the world’s most extensive example of the crea­tion of reels and islands by the flowerlike little polyps. The list of other coral areas under assault by starfish has doubled and trebled: Malaysia, New Guinea. Palau. Saipan. Truk, Fiji, Tahiti, the Tuamotus.

At last our scientist skipper, Dr. Richard H. Chesher of the University of Guam shut down the engines. “The starfish have killed most of the coral back to Piti Bay,” he said. “They’re now moving at more than 2,000 feet a week, looking for live reef.”

We strapped on scuba gear and started down. Each of us carried a special hypoder­mic syringe with which to inject a fatal dose of formaldehyde solution into our prey.

I soon spotted the sea stars sixty feet below me. Their dark multi-armed bodies stood out clearly against the pale sea floor. I could see scores of them traveling in a herd about ten yards wide and perhaps a hundred yards long. Their orderly formation reminded me of a parade moving to the cadence of a band. But I was sure that these starfish marched only to the beat of their own private drum.

I dropped down for a close look at one and was again reminded of the aptness of the name “crown-of-thorns.” Dozens of sharp spines jut out from each of the animal’s arms as well as from the central disk. Be­sides simple pricking power, these thorns can poison: injuries from them sometimes cause swelling. pain, and even nausea.

I drew my knife and flipped a two-foot­wde creature onto its back. Its underside was covered with tiny yellow tube feet which en­abled it to move in any direction.

Those tube feet, I soon discovered, function like suction cups. I lifted the star with my knife and tried to balance it on my under­water camera. It immediately wrapped its arms around the camera, enveloping every­thing but the strap. I used that to tow my living pincushion to the boat, where I had to use my knife again to break the grip of its arms and tube feet on the camera.

Spears Are the Answer on Small Atolls

Diver Mick Church bobbed to the surface. His air tank was empty, but he was full of predatory pride. He had killed 150 starfish with his formaldehyde gun.

“Man, I’ve never seen so many in one place before,” Mick gasped as he tried to catch his breath. “They were all over the place, moving as if they were playing follow-the-leader. It looked like a scene from a science-fiction movie—an invasion from inner space.”

“We can control the invasion here in Guam,” said Dr. Chesher as we stowed our gear. Not long ago our killer team destroyed 2,549 star­fish in four hours. The trouble is, people on most of the outlying islands don’t have all this equipment. We’ll have to teach them to col­lect the starfish on spears and bury them on land. Just stabbing them isn’t enough. A pierced star may not die. If you chop one in two, both halves may regenerate and become complete individuals.’

Driving home from the dock, Dr. Chesher told me that people living on low-lying Pacific islands face real danger as a result of the starfish’s depredations.

“When live coral is killed, reefs may break down,” he said. “Then storm waves might eventually eat away shorelines. But before this could happen, islanders might be forced to leave or starve. They get almost all their protein from the sea. Once the reefs die, food fish go too.”

The possibility that such a disaster might strike the Pacific Islands Trust Territory, ad­ministered by the United States, prompted the U. S. Department of the Interior to send out an international team of more than 60 scien­tists and divers to study the problem last summer. The project, managed by the Wes­tinghouse Ocean Research Laboratory of San Diego, California, was set up to survey the damage caused by Acanthaster.

      But the team also studied the animal’s behavior, particularly it’s eating habits. Dr. Ralph W. Brauer, of the Wrightsville Marine BioMedical Laboratory in North Carolina, collected starfish, which he kept in aquariums at the University of Guam, where he could observe them closely.

I accompanied Dr. Brauer and his two colleagues, David Barnes and Mike Jordan, on a collecting expedition to an infested reef along Guam’s western coast. In an outboard propelled rubber raft, loaded with diving equipment and large buckets for holding the starfish, we rode to a spot where I had seen starfish feeding a few days earlier. We located a cluster of the creatures, dropped anchor, and put on our gear.

          “Be careful when you handle these critters.” Dr. Brauer warned us. “I don’t want you to damage the animals or yourselves.  Watch out for their spines!”

We headed for the bottom. Here the seafloor was covered with coral heads of all shapes and sizes, Only a few Acanthaster were feeding on top of the heads.  Most of them were well hidden under the coral, to which they held firmly with their arms and tube feet. To remove the starfish, I used my knife with the care of a surgeon, heeding Dr. Brauers warnings as I worked.

Spines Can Cause Painful Wounds

The four of us shuttled back and forth between the raft and the coral heads on the bottom. On each trip up we brought one star­fish to the surface, put it in a bucket on the raft, and headed back down for another.

On Mikes last trip to the surface, he handed a starfish to David, who was in the raft. A spine brushed David’s finger. Light as the touch was, it gashed his skin.  David yelped. “Force the cut to bleed” Dr. Brauer told him, “get the stuff out of the wound. If you do it right away, you’ll have less pain later.”

When we released our starfish in glass walled tanks at the university, Dr. Brauer ran sea water over some living coral, filled a hypodermic syringe with the polyp flavored water, and squirted it under a starfish creeping up the glass wall.

Mistaking the coral taste for live coral, the starfish opened its mouth (located in the center of its underside) and everted its stomach. The fleshy digestive sac covered an area larger than a man’s palm.

Next Dr. Brauer placed a hungry starfish on a piece of living coral. Out came the

stomach. It spread over the coral polyps and its digestive juices began to dissolve them inside their limey shelters. After an hour, the polyps were reduced to semifluid shreds. Where colonies of colorful little animals had lived, there remained only a bleached white skeleton.

‘In a single night,” Dr. Brauer told me, ‘an adult starfish can clear off a coral head that might have taken fifty years to grow’.

Giant Tritons Prey on Stars

While such studies of the sea star’s habits may lead eventually to a means of controlling the present plague, some scientists are seeking more immediate solutions. Australian biolo­gists, concerned about the threat to the Great Barrier Reef, plan to attack the stars with armies of their natural enemies, giant tritons. They believe that man has upset the delicate ecological balance of the reef by collecting too many of these mollusks for their handsome spiral shells, permitting the stars to multiply abnormally

“1 have calculated that shell collectors took at least 100,000 tritons from the Great Barrier Reef between 1949 and 1959,” says Dr. Robert Endean of the University of Queensland. “We are trying to find out whether it’s possible to grow these animals on a special triton farm. If it is, we’ll seed them as adults along the Great Barrier Reef.”

Having once watched a giant triton devour an Acanthaster, I can vouch for its voracious­ness. The triton first located the star with its two tentacles. The threatened starfish tried to creep away, but its pursuer chased it across a coral head and caught it. The mollusk first seized the starfish, holding it between shell and foot, then began to tear it to shreds and eat it.  Several hours later, it ejected the spines.

If isolated or somehow contained within a given coral area, the crown-of-thorns soon curbs its own population explosion—at the cost of a totally dead reef. “.‘Acanthaster be­come so numerous they eat themselves out of house and home,” explained Richard Randall, an expert on the corals of the Marianas.

While I browsed through the dozens of coral-laden racks in his house on Guam. Mr. Randall pointed out that the devastation of a reef leads to starvation of the starfish—though only after it has led to the starvation of other reef creatures, and perhaps humans as well.

Man May Have Set Off the Plague

Can a reef recover from a starfish attack? Mr. Randall is trying to find out.

Coral regeneration is difficult because the porous skeleton of a ruined reef is soon covered with algae which prevent new growth. Within two or three days the white skeleton becomes a dismal gray, coated with fuzz or festooned with long green strands.

No single theory offered to date has ade­quately explained the starfish plague and its wide distribution. Some scientists speculate that the population explosion has no unusual cause but is only a natural periodic phenom­enon. Other theories seem valid for certain areas but not for others. Many Australian scientists are convinced that over-collection of giant tritons created the plague on the Great Barrier Reef. But lack of intensive shell collecting in remote island areas, now equally star-infested, indicates other causes as well as triton harvestine.

In his office at the University of Guam, Dr. Chesher told me that man might be responsible in another way for the invasion. ‘By killing coral in the process of blasting channels, or dynamiting for fish,” Dr. Chesher said, “he has perhaps altered the underwater environ­ment in favor of the sea-star’s survival”

Dr. Chesher explained that under normal conditions only a tiny percentage of the millions of eggs spawned by the female Acanthaster ever reach adulthood Many of the floating starfish larvae are devoured by living coral polyps.  But when an area of reef is killed by man, the vulnerable larvae can settle upon it and mature in safety.

Because there is usually living coral immediately adjacent to the dead reef, the young adults have a ready food source once they begin to eat polyps. As the adult starfish de­stroy even more of the reef, they enlarge the sanctuary for their young. The result of the reaction is a population explosion,

“Support for my hypothesis,” Dr. Chesher pointed out. “comes from the fact that infestations in Guam, Rota, and Ponape were first discovered near blasting or dredging sites.” Others have wondered whether the imbalance in reef life might have been caused by testing of nuclear weapons, or by pesticide

residues washed into the oceans from the land. 

Whatever the cause may prove to be, all the theories advanced so far—except that of natural periodic population growth—pointed to the activities of man. Whether by dredging or shell collecting, or pollution, this latest disturbance of the balance of nature seems be a further example of man’s disruption of his world.

            The END



X   The Florida Keys

Resource Guide by Mike Mullins  Hillsborough CC 1989


Over 200 emerald green islands make up the Florida Keys. They form a 180 mile long gentle limerock arc which curves from Biscayne bay in the north to the Dry Tortugas in the south west.

       To the west of this island arc are the nutrient rich, shallow waters of Florida Bay and the Gulf of Mexjco.  To the cast of the Keys are the blue-green transparent waters of the Atlantic Ocean.  Beneath the Atlantic's surface, from four to six miles from the islands lies the only living coral reef in the continental United States, the Florida Reef Tract.  A favorable combination of climatic and geological features has produced this unique ecosystem which is only endangered by the actions of man.



Although the Keys lie in the temperate zone about 70 miles north of the Tropic of Cancer, they have a tropical climate due to the warming effect of the Gulf Stream.  The temperature is also greatly influenced by the fact that the Keys are islands.  The surrounding water buffers the temperature keeping the islands warmer in the winter and cooler in the summer than a mainland location at similar latitude.  Rather than having four seasons like the rest of the country, the Keys have a winter with the average air temperature in the low 70's and a summer with average air temperatures in the low 80's.

       The Florida Keys has what geographers call a tropical wet-dry climate.  This differs from a tropical wet climate in two ways.  First, there is less total precipitation.  Second, the rainfall is more seasonal in character, with a distinct wet season and a distinct dry season each more than two months in duration.



                        J    F          m     A     m      J        J    A       S         0          N        D

          TEMP.             71   72       73   75   77      79      80    81       79      75           73         71

          PPT.                1.5    1.5    2.2  ,2.7   6.0     9.5     8.7   7.2        9.2        6.0        1.5        1.0

       The dry season runs from October to April and the wet season begins in May and extends through September.  Although this climatic pattern is fairly consistent throughout the Keys, occasional extreme weather conditions exist.  During the summer, afternoon thundershowers are a significant factor in the weather. 

A rising column of air is created each summer day as the land heats up faster than the surrounding water.  This rising air creates a localized low-pressure area over the islands.  The area of low pressure is filled by air rushing in across the water from both sides of the islands.  This air is filled with water vapor, which evaporates from the ocean surface more rapidly in the moving air.  As this moisture rich air arrives over the islands. it too rises.  This cycle creates a sea breeze.  As the water vapor rises. it begins to cool and condenses to form a cloud.  This cumulus cloud grows until it reaches cold air where the top flattens off forming a typical Florida thunderhead.  This cloud is rich in energy and produces locally severe winds, rains and lightning

       Another significant weather factor during the summer is the hurricane.  Tropical storms and hurricanes are a normal part of the summer in the Keys.  Even when they do not hit the islands directly, they can make a major contribution to the summer rainfall.  During historic times, several of these storms have had a major impact on the Keys.

         A hurricane in 1622 sank the fabled Nuestra Senora de Atocha near the Marques islands off the western end of the Keys.  In 1733 another hurricane scattered a Spanish treasure fleet along the reefs of the middle keys.  Many of these reefs were later marked by lighthouses so that ships could detect their location during storms.

           The most devastating storm to hit the keys in this century was the Labor Day hurricane of 1935.  It battered the Middle Keys with 200 mile an hour winds.  This storm left over 500 people dead in its wake including a large contingent of CCC workers who were killed when a rescue train was destroyed by high winds and waves.  A monument was erected on Islamorada as a memorial to those who died in the storm.  A second great storm, hurricane Donna in 1960, caused millions of dollars worth of property damage but thanks to advance warning, there was little loss of life.

          In the winter, cold fronts occasionally move down through the Keys from the mainland.  When this cold arctic air slides in under the warm, moisture rich tropical air, it can bring cold temperatures and set off heavy rainstorms.  A series of such fronts dropped 23.3 Inches of rain on Key West during December of 1980.  However, the Keys normally receive less rain during the winter months than the mainland to the north.


      Geologically, the Keys are a chain of small Iimerock islands witch average 3 to 4 feet above sea level in elevation.  The maximum natural elevation of 18 feet is found on Lignum Vitae Key.

          The keys are divided into two distinct types of islands, which differ in shapes, orientation, and the composition of their surface rocks.  The surface rocks of the upper Keys are composed of a collection of fossilized coral reefs known as the Key Largo Formation.  This large fossilized reef system first outcrops at the surface at Soldier Key in Biscayne Bay and extends southward through the Newfound Harbor Keys.  Beginning at Big Pine Key and extending to Key West the Key Largo Limestone dips under another limestone formation known as the Miami Oolite.  Both of these formations are marine in origin.

         The Key Largo Limestone Formation is the older of the two formations.  It is a collection of fossilized coral reefs which vary in thickness from 35 to 180 feet.  The ancient reef tract originated about 100,000 to 125,000 years ago during the geological epoch known as the Pleistocene.  During this period sea level fluctuated several hundred feet as water was taken lip into glaciers and then released again as the glaciers melted.

               The ancient reef system was wider than the present reef system. In places it extended up to five miles eastward to the edge of the continental shell Sea level at the time of its formation was approximately 20 feet higher than it is at present.  No islands existed to block the exchange of water between the Gulf of Mexico and the Atlantic.  Strong tides surged back and forth between the two bodies of water.

          The ancient Key Largo reef, which grew in this environment, was not much different in its composition of coral species than the present reef.  It was dominated by the massive types of reef forming corals.  The dominant species were common star coral (Montastera annularis), three species of brain coral (Diploria labyrinthiformis, D, clivosa, and D. strigosa) and several species of finger corals Porities sp.). These large corals were surrounded by smaller coral colonies,  shells and coraline algae.  A coral noticeably absent is staghorn coral (Acophora palmate).  While this coral was building reefs throughout the tropics, it was prevented from growing on the ancient Key Largo Reef Tract by the cold water that spilled out of the Gulf during the winter.

          Over time, the slow growing corals built a wide, nearly solid reef system about 150 miles long.  Before the system could became a completely solid reef, glacier formation began and sea level began to fall. The former reefs were exposed to the air and became a string of islands. As sea level continued to fall the ancient reef tract became a solid landmass which blocked the flow of water between. the Atlantic and the Gulf.

       At the end of the Pleistocene some 6,000 to 10,000 years ago. the last glaciers began to melt and sea level began to rise.  Most of the present day Florida Bay was a vast freshwater marsh, a southern extension of the everglades.  As the reef tract began to submerge, corals began to grow again on the old limerock foundation.  One of the fastest growing was elkhom coral.  This time its growth was protected from cold water by the landmass to the north.

           About 3.500 ago sea level rose to the point where Florida Bay was again flooded.  In the summer its nutrient rich water increased in salinity due to evaporation.  When this water spilled out of the passes between the newly formed islands, it killed many species of reef forming corals.  In the winter the shallow waters of Florida Bay became colder than the Atlantic.  Again this cold water flowing through the passes killed corals, especially the tropical elkhorn.  This explains why today elkhom is most abundant along the Atlantic side of Key Largo where it is protected by a very long landmass.

    Whereas the Key Largo Limestone was created by the actions of sea animals, the Miami Oolite had chemical origins. Ooids are small egg shaped spheres of calcium carbonate.  They are formed under ideal conditions in warm water seas.

        Ooid formation begins when the temperature of seawater reaches a level where calcium carbonate or lime can no longer stay in solution.  This chemical begins to take on solid form in the water.  It begins to collect around tiny grains of sediment, microscopic plants and animals or bacteria.  The calcium carbonate continues to collect in concentric layers until it reaches a mass which causes the tiny egg-like particle to sink to the bottom.  This process of ooid formation occurred over a large portion of south Florida during the Pleistocene.  It is still occurring today on the Bahama bank.

         At a time when sea level was higher, extensive areas of oolite ooze were deposited in the prehistoric Florida Bay and on top of both the northern and southern ends of the old Key Largo reef.  This occurred due to upwelling of cold water from the Atlantic into the warm shallow waters of Florida Bay.  This ooid sand collected into extensive underwater ridges which were eventually cut by tidal channels.  Over a long period of time this loose material was chemically cemented together to form the Miami oolite.  This rock now forms the cap rock over the Key Largo Limestone on both the South Florida coastal ridge and the lower Keys.

        Both the Miami Oolite and the Key Largo Limestone have been greatly affected by their exposure above sea level.  Some of the original limestone structure has been melted by the presence of tannic acids from the decay of plant leaves.  The paste-like material has acted as cement to attach together the individual particles and to fill in the spaces between individual coral heads.  At the same time, this acidic water has eroded portions of the limerock.  This process has created pits, holes and even large solution cavities in the rock.  These larger solution cavities form fresh water catch basins which serve as watering holes for terrestrial wildlife.

             Because of the orientation of the ancient reel the islands where the Key Largo Formations outcrops are long and thin.  Their general orientation is northeast to southwest.  The southern oolitic islands are much different in shape and orientation.  They are generally wider than the northern islands and their orientation is northwest to southeast.  The transition between these two types of islands is best noted on Big Pine Key where the big island is Miami Oolite in origin and the small string of islands which make up the New Found Harbor collection are made of Key Largo Limestone.

          The unique climate and geology of the Florida Keys has produced a great variety of biological communities.  Each of these communities has its own assemblage of plants and animals.  These organisms are well adapted to the environmental conditions present in the communities.

       The higher portions of the Key Largo limerock islands of the upper and middle Keys have been colonized by a variety of hardwood trees which are West Indian in origin.  These same habitats in the broad oolitic islands of the lower Keys are covered by Caribbean pine forests.  In the lower inland portions of these islands are freshwater solution hole communities.

       Surrounding most of the islands throughout the Keys are fringing mangrove forests.  In some places, the mangroves are absent, replaced by a rocky intertidal community.  In the shallow portions of Florida Bay the salt tolerant mangrove trees have produced their own land known as overwash islands.

       In the shallow water just beyond the edges of the mangrove community is found another community consisting of calcareous green algae growing on soft carbonate sand and mud.  As the water gets slightly deeper, the type of algae changes to a soft green variety mixed with several species of sea grasses.  With increased water depth, sponge and soft coral communities appear.

        Scattered in a line between the islands and the outer fringing reef communities are mounds of large corals known as patch reef communities.

        Of all the communities found in the Keys.  It is the outer reefs which attract so many people to the islands.  And, of all the organisms, it is this human species which will ultimately determine the ecology of this tropical paradise.


The islands of the Florida Keys are home to two fascinating terrestrial forest Communities, These forests provide a variety of habitats for an animal assemblage which includes a large number of rare and endangered species.

            Hammock is the name used to describe the rich, green, jungle-like growth which originally covered all of the high ground in the upper keys. This community is typically compose of less than a dozen species of tropical hardwood trees and several species of palm.  Almost all of these plants are of Caribbean Basin in origin.  Their seeds were transported to the emerging islands by water, wind and birds

           As is the case with manv tropical forests. the vegetation of the hammock community is divided into a series of layers.  The upper or canopy layer is dominated by giant mahogany, tamarind, poison wood.  Jamaican dogwood, mastic and  gumbo limbo trees.  The trees of the second layer include pigeon plum, black ironwood, and satinleaf.  The third layer is dominated by cat claw and Florida thatch palm.  The understory layer, closest to the ground, is made up of wild coffee, marlberry, coral bean, white stopper, coco plum, and seven-year apple.

      Growing in and on the trees are a variety of epiphytes including orchids, bromeliads, resurrection fem and Spanish moss.  Growing up from the ground into the trees are Virginia creeper, wild grape. nicker bean and cat briar vines.  A unique parasite of the hammock is the strangler fig.

       Among the abundant animal life of these tropical hammocks are several types of swallowtail butterflies. blue land crabs. several species of lizards, the Keys raccoon, and several endangered species, the keys tree snails, the Key Largo wood rat and Keys red rat snake.  Many of the trees found in these hammocks are well adapted to the Keys environment.

       The West Indian mahogany,  Swietenia mahagoni grows to between 50 and 60 feet in height. This tree grows well in thin soils,  limerock and brackish water conditions found in the  Keys.  The West Indian Mahogany has a thick crown of compound leaves with four to six leaflets.  The large seed pods contain winged seeds which are  similar in appearance to maples trees.  The wood of this  mahogany tree is heavv, close-grained, hard, strong and durable.  It has a deep, dark red-brown color which darkens with age.  This  beautiful wood is highly desirable for building and the mahogany tree has been cut since the coming of the Spanish.   As a result the Florida mahagony has been placed on the list of threatened species.

        The gumbo limbo, Bursera simaruba, is one of the largest growing trees of the hammock.  It can attain a girth of 10 ft. and a height of over 60 feet.  The bark of the gumbo limbo is a rich reddish green.  On mature trees it peels off in thin paper-like red sheets.

          The lignum vitae.  Guaiacum sancturyl now on the endangered species list. was once common enough in the keys hammocks to support a small commercial timber industry.  Its extremely hard, dense wood was used for the bearings of prop driven steam ships.

             The poison wood.  Metopium toxiferuril is one of the most common trees in the hammock. it is also one of the trees to avoid.  The sap and the black gum-like resin exuded when the bark is bruised are poisonous.  Contact with human skin causes a rash similar to that produced by poison ivy.  The poison wood is a pioneer plant and usually colonizes an area after a fire.

            The strangler fig, Ficus aurea. which can grow from a seed planted in the ground, often begins life as an epiphyte growing in the boot of a cabbage palm.  In time, it sends out a root which winds its way down the trunk of its host until it reaches the ground.  As the roots grow downward, a thick crown of glossy green leaves is produced.  Down from the spreading branches come a. large number of drop roots which support the increasingly dense foliage.  As it continues. to grow the fig slowly, but completely, kills its host.  '

             The trees of the hammock typically have shallow root systems due to the thin layer of black soil spread over the solid rock below.  Only a few of the roots penetrate through cracks in the rock to tap the freshwater lens below.  The hammock vegetation protects the soil from erosion and moderates the temperature in the hammock through evaporation of water through openings in their large leaves.

           The leaves which fall from these trees are decomposed by leafmold.  This contributes humus to the sterile sandy soil.  When the hammock vegetation is cleared, the soil nutrients are quickly lost and the land is largely unproductive.


Pine Rockland Forests


Growing on the large, Miami oolite covered islands of the lower keys is a forest which is quite different from the tropical hammock.  This forest is dominated by more xerophytic species.  The most common tree is the Caribbean or Cuban pine.  This small relative of the south Florida slash pine is the tree for which the Isle of Pines south of Cuba was named.  The existence of these pines growing in the thin sandy soils on Big Pine Key and other of the oolitic islands is an indicator of a supply of freshwater under the surface.

          The islands have an abundance of solution holes extending down from the surface into the water table.  These breaks in the rocks provide homes and habitats for a number of freshwater plant and animal species.  They also serve as water holes for animals such as the key deer and the rare white key raccoon.

         In addition to the pines. a number of other plants arc abundant in the pine rocklands.  These include saw palmetto, key thatch palm.  Florida thatch palm, yellow top, locust berry, prickly-pear cactus and wire grass.  All of these plants are tire resistant and survive the frequent lightning caused fires.

        The pine rocklands are the home of the diminutive key deer.  These animals are small subspecies of the Virginia white-tailed deer.  They are 20-32 inches high at the shoulder and weigh from 30 to 100 lbs.  The average size buck weighs about 65 lbs and the does are about 40.  The deer browse on palm seeds, grasses and mangrove leaves.

       The pine rocklands environment is an inviting one for building homes.  As a result, much of this habitat has been utilized for this purpose.  This has created a problem for the deer herd.  The development on the Islands have reduced their water supply and.their number to less than 250.  They are undernourished due to the junk food they receive from residents and tourists.  The little deer are attacked by loose dogs and feral pigs.  The fawns are frequently trapped in mosquito control ditches cut into the limerock many years ago.  But the largest killer of deer are cars.  Between 1980 and 1987, over 80% of the deer killed on Big Pine Key were hit by cars.



The term "Mangrove" is applied to a diverse group of tropical salt tolerant trees which are abundant in the Florida Keys.  These trees have been able to successfully occupy coastal environments where they have little or no competition from other species of plants.  In order to do this, the mangrove trees have had to cope with a number of problems including soft oxygen poor soil. periodic flooding of their root zones and a highly saline environment.


Types of Mangrove Trees

There are three species of mangroves found in Florida: the red, the black and the white.  The three are only distantly related.  Each belongs to a different family.

        The red mangrove is the most noticeable of the three.  It grows in the deepest water and its arching prop roots support the tree above the water as if it were walking on stilts.  Wart-like lenticels on these prop roots provide openings where oxygen can be taken in and pumped through the system to the underground roots growing in the anaerobic mud.  Since red mangroves grow close together, their roots form an impenetrable tangled network which slows down the movement of water underneath the trees.  This causes a deposition of sediment and traps an enormous collection of debris.  This build up of sediment and debris under the right conditions can create a thick layer of organic peat.


The leathery evergreen leaves of the red mangrove form a dense canopy which are highly efficient in converting sunlight to organic molecules.  Sprinkled in among the leaves are yellow and white flowers.  The red mangroves have an unusual reproductive adaptation enabling the seedling to survive in the watery environment.  The seed germinates from the fruit while it is still attached to the parent tree.  Many fruits with finger-like seedlings, often twelve or more inches in length, can be seen hanging in clusters.  When mature, the seedlings break free from the fruit and fail into the water.  Some may stick in the soft mud around the base of the parent tree and begin to grow.  Many more float around with the tide.  After floating in the water for a short period of time, the pointed end absorbs water and begins to sink.  When the seedling becomes grounded in the mud, roots are quickly produced from the pointed end and the seedling begins to put out leaves.

         In the keys, the black or honey mangrove usually forms a zone behind that of the red mangrove.  This tree takes its name from its dark scaly bark.  Black mangroves usually grow in soils that are exposed to the air at low tide but covered by high tide.  Where they seldom experience frost, as in the Keys, black mangroves can develop into large trees over 50 feet tall.  Their 2 to 4 inch long leaves are dark green above with silvery, hairy undersides.  In these leaves there are special glands that excrete salt extracted from the water taken in by the roots.  The salt often forms a white crust-like coating on their upper surface.  Black mangroves have small white flowers which produce abundant nectar used by bees.  They have no prop roots but their root system produces many slender upright aerating roots known as pneumatophores. They cover the muddy soil around the base of the tree and supply the root system with oxygen.

        Black mangrove seeds are the size and shape of very large lima beans.  They germinate as soon as they fall into the water.  The seedlings are smaller than the red mangrove seedlings so they are washed farther up into the forest by tides.  Here they become entangled in mats of detritus trapped by the mangrove roots and begin to grow.

         White mangroves grow in sandy soils at the upper edge of the intertidal zone.  Their round pale green leaves are notched at the tip and have a pair of salt excreting glands on either side of their petioles.  The white mangroves have small peg roots which help anchor them in the sandy soil.

        The small green seeds of the white mangroves begin to develop after they fall into the water.  Over time they turn brown and wrinkled.  Due to their small size, the white mangrove seeds are carried high in the swamp by the tide.  When the seeds are finally deposited in the strand line, they germinate.  The seedlings quickly put down roots and produce a pair of notched tip leaves.

        Above the normal high tide line grows a relative of the white mangrove the buttonwood or grey mangrove.  These trees get their name from their spherical berry-like fruits.  Like the white mangrove, the buttonwood has salt glands on its leaf petioles.  The buttonwood tree has a twisted trunk covered with a loose bark.  The bark is a favored grow site for epiphytes.

        On some of the lower keys, buttonwoods are found growing in depressions on the interior of the islands surrounded by hardwood hammock plants.  Early residents of the Keys used the wood of these trees to make charcoal.


Types of Mangrove Forests


Because of different conditions of tide, substrate, freshwater runoff, nutrients and exposure, a variety of types of mangrove forests exist throughout the world.  Two scientists,  Lugo and Snedaker, have develop d a classification system to help them talk about the various types of mangrove forests.  Several of these types of forests occur in The Florida Keys.  The following is a synopsis of four of these which can be found in the Florida Keys.

          Overwash mangrove islands are abundant along the Florida Keys and in Florida Bay.  The main characteristic of overwash mangrove islands is that they are flooded by the high tide daily.  These islands are dominated by the red mangrove and are the most marine" of the mangrove wetlands.  These islands in south Florida are subject to low intensities of wave action and variations in salinity and nutrient conditions.  These environmental differences are probably responsible for the higher leaf area, biomass and productivity of Florida overwash mangrove islands and for the high prop root density which may be an indicator of the velocity of water flow through the islands.  Mangrove overwash islands tend to show a zonation of red, black, and white mangroves as they increase in size.


Because of their isolation, mangrove overwash islands are an ideal habitat for the nests and roosts of coastal birds


Overwash mangrove islands:

1.     Are overwashed by daily Tides

2.   Have a high rate of organic export

3.  Are dominated by red mangroves


Fringing mangrove forests grow along the shorelines of the Florida Keys. They are frequently dominated by red mangroves.  The degree of structural development in this forest depends on the quality of soil and water and the intensity of wave action.  Fringing mangroves along coastlines are exposed to tides, fairly constant salinities, variable nutrient concentrations, little wave action, and reduced wind and salt spray.

        Fringing mangrove wetlands may intermix with basin mangroves behind them or may end abruptly at the top of a land berm.  If the shoreline is steep, white, black and/or buttonwood trees-may grow behind the red mangrove and be considered part of the fringing mangrove system.  On a gently sloping beach, the width of red mangroves may vary considerably.

         Like the overwash islands, fringing mangrove forests harbor extensive communities of plants and animals on their roots.  They also act as refuges for fish and other wildlife during periods of rough weather and heavy seas.  These fringing forests protect the shoreline from storm damage and export a great amount of organic detritus into the Coastal lagoons.

       Small areas of basin mangrove forests occur in the Florida Keys, primarly on the Florida Bay side of Key Largo.  These types of forests occur in depressions which may be surrounded on one side by a fringing  mangrove forest and the other by a hardwood hammock.  Thev are flushed by the tides but not always daily.  Their interiors are dominated by large black mangroves.

       Dwarf mangrove forests are the first mangrove areas encountered on the trip dowm U.S. 1 from Miami to Key Largo.  The trees in this forest are widely spaced and stunted, usually less than five feet tall.  Their diminutive size is the result of a combination of unfavorable environmental factors.


Ecological Value of Mangrove Forests


      Every part of the mangrove forest, from the roots to the top most branches, which may reach as high as 60 feet, provide shelter or food for a multitude of creatures.  These organisms range from tiny sand flies to large tarpon offshore.

      One of the birds that finds its home in the tree tops of the mangroves is the brown pelican.  The pelicans share their "rookeries" with egrets, herons, wood storks, ospreys, and cormorants.

         A host of other creatures make use of the mangroves to forage.  Racoons favor the coon oysters that live on the prop root of the red mangrove.  Spiders weave many webs to catch unsuspecting insects; snakes slither up the tree trunks after birds' eggs and nestlings; and cormorants dine chiefly on the fish in the nearby waters.  Fiddler crabs and their larger relatives the land crabs move out during the low tide to perform a large service.  They aerate the soil as they probe the sediment for food, thereby increasing the supply of oxygen to the trees that attract the creatures.

         However. when the tide comes in covering the roots and pneumatophores of the mangrove forest, it becomes part of a marine nursery.  The mangrove forest provides a place where young fish. as well as other organisms such as blue crabs, are protected from predators and competing species which are unable to enter the lower salinity water.  The young of herbivores and detritivores occur in hordes.  Oysters, barnacles, and sponges along with the ribbed mussels are found in great Quantities in the mangrove root zone.

              It is well documented that the mangrove forest plays an important role In the ecology of the Keys.  The food chains and webs which begin in this rich habitat extend all the way out to the reel.  They also serve as a nursery and spawning ground for many of the organisms which live in other key communities as adults.  Lastly they provide protection for the delicate terrestrial communities from all but the most severe storms.



       Coral reefs are marine communities built of calcium carbonate secreted by a primitive types of animals called coral polyps In addition to the polyps. certain red and green algae, polychaetes, mollusks and bryozoans all play a role in the construction of coral reefs.

           Coral reefs have been prominent features in the warm, shallow waters of the world ocean for over two billion years.  They flourish in clear near-shore waters where the average annual temperature is at least 23.0 C. and seldom falls below 18.0 C. This puts them in a band that lies between the Tropic of Cancer and the Tropic of Capricorn.  The warm water reduces the solubility of calcium carbonate and increases the ability of the corals to produce their skeletons.  In addition to temperature, light, salinity, immersion, sedimentation, and substrate are the major factors influencing reef development.

          Coral polyps are similar to small sea anemones.  They have a circle of tentacles surrounding single body opening which serves as both a mouth and an anus.  Their sac shaped bodies are composed of two cell layers and are internally divided into segments.

            Polyps are nocturnal predators which feed on microscopic animals called zooplankton.  They trap their prey with specialized cells located on their tentacles.  These expode when an animal brushes against them releasing threads which stab, entangle or stick to the prey.  The tentacles are also covered by cilia.  In some species, a thick mucus curtain is secreted from the tentacles.  Planktonic organisms become trapped in the mucus and the cilia transfer them from the tentacles to the mouth.  In most species, the cilia sweep back and forth keeping the polyp free of silt and sediment.

          The organisms which form the basic structure of today's coral reefs are known as hermatypic, or reef-building coral.  These reef-building corals are colonial animals that differ from other members of their phylum (Cnidaria) primarily by the fact that each individual coral animal, or polyp, secretes a calcareous skeletal cup around its soft body.  These delicate polyps can withdraw inside their rigid outer casing for protection.  This hard casing is one reason why corals are often thought of as rock rather than the animals they are.  In fact, the living polyps occupy only the upper few millimeters the massive limestone structures that their species have secreted and subsequently grown out of over the past millennia.

          Algae known at zooxanthellae are as important to reef development as are the coral polyps.  These tiny dinoflagellates in the genus Symbiodinium,live in the tissues of the hermatypic corals.  They have a mutualisuc relationship with the coral polyps.  The coral offers protection and nutrients to the zooxanthellae.  The zooxanthehae remove metabolic waste and provide nutrients and oxygen to the coral.  Zooxantheflae also aid in the calcification of the coral skeleton. It is only with the assistance of the zooxanthellae that the corals are able to form massive reefs.  Environmental factors such as increased turbidity, reduced light, and fresh water effect the health of the zooxanthellae and thus the health of the corals.

            In the waters of continental United States individual coral colonies are found are found as far north as North Carolina in the Atlantic and Cedar Key in the Gulf.  They are also found off the Texas coast.  None of these corals are reef-building coral.  The water is either too cool or too cloudy to support these tropical species and their zooxanthellae.  In the Florida Keys, the coral reefs reach their greatest level of development seaward of Key Largo.  This long island provides an extended zone of protection from cold water and turbidity.

           There are three types of coral reef communities commonly found in the Florida Keys.  Moving from land to sea, these communities are described as patch reefs, transitional reefs, and bank reefs.

             A typical outer bank reef community is composed of three sections.  The fore reef is composed of large heads of star (Montastrea), boulder and pillar coral.  These thrive in the turbulence created by the waves.  Behind the large colonies are found the branching elkhom coral and frequently a branching form of fire coral.  In the shallowest portion of the outer reefs a ridge of the coralline red algae forms the reef crest which breaks up the action of the waves and protects the back side of the reef. On back reef the more delicate staghorn coral grows.

        During storms, the reef crest takes a tremendous pounding.  A great deal of coral may be broken off during this process and, occasionally, new channels may be carved through the reef.  This creates a pattern called spur and groove.  The impact from hurricanes and the constant pounding of the waves produce large quantities of sand from the coral skeletons.

         Rising from the quiet lagoons behind the outer reefs is a different type of coral reef corrimunit3r called a patch reel Ms type of reef community is primarily composed of species of large brain corals overgrown in places by staghorn coral.  The patch reefs also support numerous species of soft corals called gargonians.

           In addition to corals, reefs are home to a large number of colorful and fascinating species.  Blue tangs.  Acanthurus coeruleus, and princess parrotfish, Scarus taeniopterus wander over the reef clipping or scraping algae from the reef surface.  Herbivorous damselflsh defend their reef-top territories while trumpetfish, Aulostomus maculates, search for prey among the coral heads and waving gorgonians.  Yellow goatflsh,  Mulloidichthys martinicus , probe the sandy bottoms in search of food and spotted drum, Equetus punctatus, lurk under overhanging ledges.

          Many symbiotic relationships exist between various species of reef fish.  Pilot fish, Naucrates, form commensal associations with large sharks.  Shrimpfish, Aeloiscus maintain a relationship with the sea urchin.  Centrechinus, and the man-of-war fish,  Nomeus, swims among the dangling tentacles of the Portuguese man-of-war, Physalia.

     As alreadv mentioned, hurricanes and tropical storms can devastate coral reefs.  Changes in water conditions can also take their toll.  Mass bleaching (loss of zooxanthellac or pigments) appears to be increasing in coral reef areas in both the Pacific and the Caribbean.  This may be related to an increase in temperature or salinity.  Bleaching could lead to a radical change in the ecology of many Keys coral reefs.




Marine grass flat communities occur both in Florida Bay and in Hawks channel, the large lagoon which separates the islands of the Florida Reef Tract from the offshore reefs.  The plants and animals who are found in this community live upon, around and under the sea grasses.  This community is divided into a variety habitats.


The Sea Grasses


        There are several types of flowering marine plants are found in the sea grass community of the Florida Keys.  These plants have evolved adaptations which allow them to exploit this rich marine habitat.  These include the broad. flatbladed turtle grass,  'Thallasia testudium, the narrow, flat-bladed shoal grass.  Halodule wrightii, the round-bladed manatee grass, Syringodium filifaorme,  and two species of star grass in the genus Halophilia.  These grasses intermix but in general shoal grass grows in the shallowest water, then comes manatee grass and turtle grass.  Star grass grows in waters with low light levels both inshore and offshore.  Overall, turtle grass is the dominant species.

      In the Keys, the sea grass community grows from near the low tide line to about 50 meters of water.  This luxurious growth is possible due to the protective action of the reefs which reduce the wave energy.

       Like many, land grasses, sea grasses have an underground stem known as rhizome.  These grow horizontally, occasionally sending up a cluster of leaves and sending down a bundle of roots.  The leaves of the grasses slow down the flow of water and cause a deposition of sediment.

      The marine grass flat is a diverse community of plants and animals.  The grass blades provide food for some organisms, refuge for many and a substrate for others.  Like wise the sediment around and under the grasses provides a habitat which is exploited by a number of organisms.


Epiphytic Organisms


The wide blades of the turtle grass and the smaller blades of manatee, shoal and star grasses provide a habitat for a variety of plants and animals.  In the Florida Keys, the ephiphytic plants primarily consist of corallne and filamentous red algal.  Scientists have discovered that these plants not onjly use the sea grasses as a habitat but also benefit from excess nutrients which are released from their leaves.  As a result, the gross productivity of these epiphytic plants may equal that of the sea grasses themselves.

The epiphytic animals found on sea grass leaves include both attached and mobile forms.  The attached forms such as forams, hydroids, anemones, sponges, and bryozoans.  These animals feed on both plankton and particulate detritus.

     The mobile fauna are primarily crustaceans such as shrimp, amphipods, and isopods.  These feed on the sea grass leaves as well as the other epiphytic Plants and animals.


Benthic Epifauna

       Like the epiphytic organisms, the epifauna have both sessile and mobile forms.The sessile or attached animals include soft corals, hard corals, anemones, sponges and tunicates.  Patches of finger corals. Porites porities, are frequently common in areas of the grass flats.  Most of these sessile organisms feed on plankton and detritus.

         The mobile epifauna are dominated by echinoderms.  Sea stars. brittle stars, sea urchins, sea biscuits. sand dollars and sea cucumbers are all abundant.  One echinoderm, the long-spined black urchin, Diadema antillarum, is a nocturnal feeder on sea grasses, but spends its days tucked into the nooks and crannies of coral reefs. This grazing pattern creates a zone of bare sand around the edges of the reefs.  This "halo" Is especially evident around patch reefs which are usually surrounded by grass beds.

          Another unusual group of echinoderms which are common in the sea grass beds are the sea cucumbers.  Unlike most echinoderms which are radially symmetrical, the sea cucumbers are built bilaterally.  The small ones resemble worms and the larger ones, which can stretch up to 3 ft. in length, resemble the vegetables for which they are named.  Sea cucumbers feed on benthic detritus using five tentacles which protrude from their mouths.

        The most common sea cucumber in the Key's sea grass community is the donkey dung, Holothuria mexicana.  Each one eats huge volumes of sand each day and digest out the organic detritus.  In its wake it leaves a collection of elongated whit fecal pellets about the size and shape of a human thumb.

       The mollusks are also well represented in the in the epifaunal habitat. The large edible queen conch,  Strombus gigas, from which the Key's natives take their nicknames, feeds on both epiphytes and benthic detritus. Th king helmet conch, Cassis tuberose, are active predators.  They primarily feed on echinoderms with the sea egg urchin, Tilpneustes ventricosus, being their favorite prey.

The crustaceans are a common component of the sea grass epibenthic community.  A variety of shrimp including grass, broken back, and commercial shrimp feed on epiphytes, infauna, and detritus.  The spider crab is a seldom seen resident of the marine grass flat community. 


        The first people to live in the Keys were the Pre Columbian Indians.  Anthropologist are not sure who these early groups Were but there evidence pointing to the Tequesta in the Upper Keys and the fierce Vescayno and Matecumbes Indians in the Lower Keys.  There is very little evidence of permanent villages in the Keys but these frequent visitors left behind middens filled with the bones of fish, shellfish, turtles and manatees.

        The natural resources harvested by the Indians were occasionally supplemented by supplies salvaged from the ships of the early Spanish explorers who fell victim to the treacherous coral reefs. ay the 1570's, when the Spanish began to explore the Keys, these early visitors had all but disappeared.

       These early Indians who the Spanish first encountered the Keys were replaced by the Calusa which ruled much of the west Florida coast south of Tampa bay.  This warrior tribe lived in the Keys in an uneasy coexistence with the Spanish, From time to time the Calusa villages were raided by the Spanish.  The young males were captured and taken as slaves to mine sites through the new world.  Perhaps worse than the Spanish were the old world diseases they brought, The Indians had no natural immunity to diseases like small pox and influenza.  Only a small remnanent of the Calusa tribe was found in the Keys when the Spanish were replaced by settlers from the Bahamas.

       The last Indians who visited the Keys were the Seminoles.  They raided Indian Key on August 7, 1840 in retaliation for bounty hunting of members of their tribe by a resident, Jacob Houseman.


           The Spanish explorer, Juan once de Leon discovered the Keys during his 1513 expedition.  With a dramatic flair he named them Los Martires,.the martyrs, because they appeared to have a twisted and tortured shape.  The Spanish interest in the islands was limited.  They logged out both hardwood and pine trees but did not establish any permanent settlements.  There wasn't any gold, there was very little fresh water and there were hordes of mosquitoes.  Their principal interest was in mapping the reefs which took a great toll on the Spanish treasure fleets.

     For several centuries the keys were used by a variety of pirates and wreckers who sometimes attacked Spanish shipping but who more frequently plundered ships that wrecked on the reefs.  Many of these were "conchs", They were descendents of Englishmen who settled Eleuthera and the Great Abaco Islands in the Bahamas.  These adventurers roamed throughout the Keys catching turtles, fish and occasionally a wrecked ship. The cargo they salvaged was sold in the port of Nassau.  In 1821, the Keys and the rest of Florida were ceded to the United Stated by Spain.  The conchs who wanted to continue as legal wreckers had to become citizens of the United States.   Many moved their families to the Keys, especially the newly founded town of Key West. 

        The Teal pirates, such as Blackbeard and his lueitenant Black Caesar, continued to prey on shipping.  The situation remained bad enough however, that in 1822 the United States Navy sent its West Indian Squadron of eight small shallow draught schooners under the command of Commodore David Porter.  This small determined group soon made the Keys an unsafe place to be a pirate.  One of these brave ships, the USS Alligator, went aground off Matecumbe Key on a reef which now bears its name.  The ship was blown up by its own crew to prevent it falling into pirate hands.

            Many former pirates turned to the practice of wrecking.  The salvaged cargo was taken to Key West where the proper value of the salvage was determined by a federal admiralty court.  From Key West' the wreckers roamed the length of the keys.  By rights, the first ship to put a line aboard a wrecked ship claimed the salvage rights.  Thus, the sight of a wreck on the reef set off a race for the prize.  Under the watchful eye of the federal government, the salvage of ships became a major industry.  By 1880, Key West was the largest and richest city in Florida.

        The Spanish name for Indian Key was Matanzas,  which in English means massacre.  This small island became important well beyond its size in the history of the Florida Keys.  With the regulation of the wrecking business in Key West, some of the wreckers set up their own headquarter at Indian Key.  This tiny eleven acre island was established as a town by Jacob Houseman, a northener who arrived in the Keys about the time they came under the control of the navy.  He set up a salvage station on Indian Key to avoid the rules and fees of Key West.  He was able to pull of this feat by having Indian Key made the county seat of Dade county rather than Monroe.  The island had warehouses, homes, a post office, wharfs and a resort hotel.

        The island was home to Dr. Henry Perrine, a physician who was also a botanist.    He imported many plants to the island, many from  Mexico.  He was especially interested in the Agave, or sisal plant  which grew well in the rocky soil and produced fibers which could be made into strong rope.

        By 1840, the town of Indian Key was home to over 55 permanent residents.  This was during the Seminole war and Jacob Houseman had used his influence to have the Florida Naval Squadron moved to a base at nearby Tea Table Key.  Secure in this protection and with greed in his heart, Houseman began negotiations with the government to pay him a $200 bounty fir each Seminole he could kill.  Before he could embark on this enterprise, the Seminoles hit first.

      On August 7, of 1846, the Indians took advantage of the fleet being away and attacked the island.  They burned most of the buildings and killed sixteen of the residents including Dr. Perrine who tried to plead with them to stop the attack.  Many of the people including Dr. Perrine's family and Houseman survived by hiding in the water filled cisterns underneath their burning houses.

       In, 1832 when Indian Key was just beginning as a town it was visited by a budding birder and artist John James Audubon.  He continued on to Key Vaca, Key West and the Dry Tortugas.  Audubon identified many new species of birds, but like many 19th century naturalists, he killed a large number of birds in order to study and paint them.

        Where as the wreckers of the Keys found the reefs an aid to profit the owners of the wrecked ships did not.  They demanded that the federal government provide navigation aids to make the passage along the Keys safer.  A string of light ships were anchored along the reefs, but there were they were insufficient.  Their lights were weak and they  were frequently either blown off the reef or wrecked themselves during storms.  From 1850 to 1880 a string of seven steel light houses were built on the most dangerous reefs.  These' employed a unique construction.  A series of steel piles were screwed into the bed rock of the reefs.  The lighthouse was then attached to these structures.  The spider leg support allowed storm waves to pass through the lighthouse with out doing much damage.

     At the close of the War Between the States in 1865, the key played a part in history.  They were the pipeline through which Judith P. Benjamin, the Confederate Secretary of State was smuggled to safety in the Bahamas.  Fort Jefferson, on the Dry Tortugas served as a prison for Dr. Samuel Mudd, a physician who had set the broken leg of John Wilkes Booth, the assassin of President Lincoln.

          The Keys Have been the home of many entrepheurs.  Plantations which grew pineapples, tomatoes and coconuts briefly flourished throughout the Kevs. Most of the failed due to poor soil, mosquitoes, hurricanes or a combination there of.

             In the 1880's Vincent Ybor established a cigar industry in Key West.  This flourished until the factories were heavily damaged by a hurricane in the early 1900's.

         Around the turn of the century sponging became important in the Keys.  The rich sponge beds provided a high yield cash crop.  They were harvested from boats with three pronged hooks and glass bottom buckets.  Financial problems created by World War I and finally the sponge blight finished the industry in the 20's and it moved to Tarpon Springs.

        In 1904, Henry Flagler, president of the Florida East Coast Railroad realized the economic advantage of having a railhead close to the Panama Canal and only 90 miles from Cuba.  He gave to go ahead to extend his railroad south from the farming community of Homestead.  Thus was born "the railroad that went to sea.' Work progressed slowly but steadily until 1909 when a devastating hurricane ripped up over 40 miles of tracks and embankment in the upper keys.  This almost stopped the construction, but engineers studied the damage and realized they had closed too many natural channels between the islands.  The removed many-of these causeways and replaced them with concrete bridges.

       In March of 1926, bond sales were approved by the voters to begin construction of an overseas highway linking Key West to the mainland.  On many of the islands, the road paralleled the railroad.  After the killer hurricane of 1935, the road replaced the railroad using most of its existing bridges.




 1  State Of Coral Reefs in Carlos Goenaga                        name..........................................pd........

1.How old is the recent Caribbean Coral Reef System?

2.  That “Coral reefs are highly susceptible to disturbance in relation to other nearshore ecosystems  Is this fact or opinion?  Where could you check this statement?

3What is an endodermal symbiont?

4.  List 5 socioeconomic importance’s of coral reefs and give an example of each.

5.  How are reefs a buffer for the CO2 cycle?

6.  What 3 human activities threaten Caribbean reefs?  How do they occur?

7.  What part of oil is the most harmful to corals?

8.  How does upland clearing effect coral reef?

9.  How does sewage discharge effect coral reefs?

10.  The statement on page 16-G. Anchoring  Standing and walking over coral and coral collecting can also ruin large portions of the reefs..”is this fact or opinion and explain.

11.  What type of damage was observed from military activities on the reef?

12.  Where is this place?

13.  How can overfishing---fish, not coral, effect the reefs?
14.  Can these coral reefs recover...explain.

15.  Summarize the 6 recommendations the author makes.

16.  The discovery of what about coral has made the destruction of reefs an international interest?





  Questions...Coral Readings

2a Floridas Coral reefs beautiful and alive

1.  What is the most diverse marine ecosystem in the world?

2.  Where do you find North Americas only coral reef?

3.  Where, when and why was the florida keys National Marine Sanctuary formed?

4.  What human effect can harm corals?

5.  What is meant by prop-dredge?

6.  What is the saying for boaters around reefs?

7. What is the uses and benefits of a mooring buoy?

2b Reefs in Danger

8.  How much of the reefs may be killed in our lifetime?

9. List the serious threats to the reef.

10. What is IYOR...when was it and what was done?

3 Are Storms Killing Coral?

1. How much dust is blowing from North Africa to the Caribbean each year?

2. List how this dust can harm the corals?

3. What organisms may benefit from this dust?

4. What is found in the dust?

5. How is the dust tracked?

4 Bleaching Damage

11.  What animals play a large role in taking CO2 out of the atmosphere?

12.  What species was studied?

13.  When did bleaching peak?

14.  What were effects of bleached foraminifera?

15.  What did Hallock speculate caused the bleaching?


5a  1st Casulaty of CO2 Emissions   Name.................................................pd....

16.  How much has the CO2 levels risen since 1700?

17. What has lead to this increase?

18.  What happens when corals are stressed?

19.  What is this result known as?

20.  Where did they discover how acidity interfered with the growth of coral reefs?

21.  What is this acidity effect on corals?

22.  What happens to the 2 gigatons of CO2 a year?

5b Death of corals in Keys a warning

23.  Why are corals suddenly getting diseases?

24.  What causes sea fan disease?

5c  Coral Killer Identified

25. Why is the sea fan important?

26. Give 2 reasons the seafan is now getting this disease?

27. What 2 species of seafans are found in the keys?

28. What attiude does the author take if the cause is found to be from pollution?    Rising sea temperature?




6  Reading  Starfish Threaten Pacific Reefs  


Read the statements carefully.  If it is stated in the article, put TRUE...if not, put False.  Refer to these statements for part 2 as well.


..........1.  Coral-killing starfish are destroying living reefs that shelter coastlines from continual pounding of the sea.

...........2.  Acanthaster planci  may be used to control a population explosion that threatens coral reefs.

...........3. Scientists are following the spread of the crown-of-thorn starfish.

............4.  A major tactic in dealing with the crown-of-thorns starfish involves hunting and killing the animals by man.

............5.  Dead reefs pose few problems to the islands they surround.

...........6.  Shell collectors took at least 100,000 tritons from the Great Barrier Reef between 1949 and 1959.

............7.  Blasting for channels and channel dredging kills the coral animals.

..........8.  Animal populations in nature tend to fluctuate.

..........9.  Pollution may have an effect on corAl reef growth.

Science deals with causes and effects.  Effects are visable things brought about by a cause.  They are the results.  The cause produces the effect.  Most of the true statements above are either cause or effect statements.  Select the cause and effect statements and put the number below the proper heading.

A.  Causes         


 11. _________

12. ________      

B.  Effects


14. _________     


Causes listed above should be testable using scientific method  (causes could be formulated as an hypothesis).  Read the statements below releating to the details and authors interpretations drawn from the selection and write the number of the causes (from the 1st part) the statement is designed to test.

..........16.  Austrailian biologists are raising tritons for future release as adults along the Great Barrier Reef.

..........17.  Marine Biologists in Guam and Rota weekly study the coral reefs adjacent to new yacht harbor channels.

..........18.  Scientists in Tonga, an island which has not been affected by the crown-of-thorns starfish outbreak, are studying the ecology of coral reefs





7 The Florida Keys.......Questions to go with the Resource Guide Handout  Name.................................................pd....

1.  What causes the keys to have a tropical climate?

2.  How does a tropical wet-dry climate differ from a tropical wet climate?

3.  When is the dry season in the keys?

4.  How do the afternoon summer thundershowers form?

5.  Describe the most devastating hurricane that ever hit the keys?

6.  What is the highest natural elevation in the Keys?  What is the average?

7.  What are the two distinct types of islands found in the Keys and describe the differences between them?

8.  Describe the different types of trees throughout the Keys.

9.  What is the existence of slash pines growing an indicator of?

10.  What problems do mangrove trees have to cope with?

11.  What are the three species of mangroves in the Keys?

12.  Distinguish between these species.

13.  What is a pneumatophore.

14.  What is an overwash mangrove island?

15.  List 3 functions of the fringing mangrove forests.

16.  What organisms play a role in the construction of the reef?

17.  What environmental factors are bad for the zooxanthellae?

18.  Why do the reefs off Key Largo reach their greatest level of development?

19.  Name the three types of reef communities  commonly found in the Keys.

20.  What types of coral are located on the fore reef?

21.  Which is more delicate, staghorne or elkhorn coral?

22.  What is a gargonian and where are they usually found?

23.  Name 3 fish found living in a symbiotic relationship with another organism?

24.  What may be bringing about mass bleaching?

25.  What is the most dominant species of sea grass?

26.  What causes the zone of bare sand around edges of reefs?

27.  How do fish use the grass flat community?

28.  What happened on Aug. 7, 1840?

29.  What was the principle interest the Spanish had in the Keys?

30.  What strange practice became a major industry in the Keys?

31.  How did Jacob Houseman avoid the salvage rules and fees of Key West?

32.  How were the lighthouses constructed over the reefs?

33.  What mistake had the engineers building the railroad made when the 1st hurricane destroyed part of it in 1909?

34.  What replaced the railroad in 1935 after the hurricane?

35.  Who built the railroad?