is the study of the inter-relationships between the physical and biological
aspects of the environment. It is the study of how organisms adapt to their
environment and in turn alter it.
ecology is the branch of ecology dealing with the interdependence of all
organisms living in the ocean, in shallow coastal waters, and on the seashore.
Classification of Organisms
horizontal: neritic |
(top) / euphotic (good)
(middle) / disphotic (low)
(deep) / aphotic (without)
Divisions of the Marine Environment
marine environment for all organisms consists of non-living, abiotic factors
and living, biotic factors
abiotic factors include all the physical, chemical and geological variables
that have a bearing on the type of life that can exist in an area. Included
to air. nutrient supply
factors regulating the distribution and
abundance of organisms in the ocean.
influence of physical and chemical
parameters on organisms in the various ecosystems that constitute the ocean.
An ecosystem includes both the living
(biotic) and non-living (abiotic) portions of the environment.
coral reefs, the North Pacific Gyre.
Hydrostatic pressure is the pressure
caused by the height of water.
It is a function of the density of water
and the total height of the water column.
Pressure generally increases at a rate of
1 atm per 10 m of water.
enormous in the deep sea yet animals live
Animals do not contain gases.
However, mesopelagic fish have gas-filled
swim bladders to help maintain neutral buoyancy
to move rapidly between depths
pressure change could cause bladder
The distribution of species closely
follows the shape of isotherms.
controls rates of chemical reactions and
thus metabolic rates, growth rates, feeding rates, etc.
Temperature tolerance varies tremendously
among marine organisms.
Young stages are generally less tolerant
of large changes.
e.g., eggs and young of the California
sardine cannot survive below 13 oC.
Temperature may indirectly effect a species due to a
direct effect on its predator.
This is exemplified by the
interrela-tionship of clams, crabs, and temperature in Casco Bay, ME.
Many of the elements used for growth.
Salinity tolerance is also important in
Salinity fluctuates most in coastal
waters due to shifts in river flow.
that are mobile can migrate offshore if they cannot tolerate a certain
salinity, but attached organisms must cope with the changes or die.
oysters, and barnacles manage to survive by closing their shells.
molecules move from high to low concentrations
internal fluids of marine organisms also
chemical gradient - salts inside the body
relative to the surrounding seawater
salts will diffuse from an area of high
concentration to low concentration.
uptake and the elimination of waste products.
Diffusion is also the mechanism by which
water molecules pass through cell membranes.
This is called osmosis.
The biotic factors are the interactions
among living organisms.
Two major divisions in the marine world.
zone...waters of the world and
Benthic zone..the ocean bottom.
pelagic zone include the productive coastal waters..neritic zone
deep waters of the open ocean..oceanic zone.
division in the pelagic zone is related to light penetration..the photic and
benthic zone extends from the seashore to the deepest parts of the sea.
that makes up the bottom is the substratum and the organisms living there
are the benthos.
16.7% of Earths animals are marine
2% inhabit pelagic environment (most of the
oceans are cold and dark)
98% are benthic!
uncover parts of this zone and the area uncovered is the intertidal zone, above
is the supratidal zone, affected by salt spray but not covered by sea water.
Below the intertidal zone is the subtidal zone..submerged and extending
elevation and slope determines the length of time its exposed.
affects organisms living there because some are restricted to zones according
to their adaptations to this type of zone (intertidal etc.).
Classification of Organisms
biota based on lifestyle.
Plankton are weak swimmers, and are known
as drifters, unable to counteract currents.
Nekton are active swimmers capable of
world include the
drifting organisms...plankton and
comprise the large and small organisms that drift or float while tides and
currents move them through the water.
plankton do have a limited ability to move and can migrate vertically through
the water from day to night.
drifters can photosynthesize while others are consumers..
is very important as it occupies the first two or three links in the marine
Nekton use fins, jets of water, strong flippers, flukes and flippers to swim
through the water.
living in pelagic waters also put up with changes in salinity, temperature etc.
and inhabit the coastal areas etc. which fit their adaptations.
withstand large changes (eury-- prefix) and narrow tolerance (steno))
Epiflora or epifauna live on the sea
Infauna live in the sea bottom.
Benthic plants are restricted to shallow
waters - why?
Benthic animals occur everywhere from
shallow depths to the deep sea.
zones include the surface waters of the coastal areas called the neritic
zone and the waters of the ocean called the epipelagic zone.
open ocean is less productive than the neritic zone which contains plant
plankton, fish larva, invertebrate larva that will eventually end up near the
open ocean is divided into zones depending on the amount of light it
receives...from the epipelagic layer to the mesopelagic zone
200-1000m in which daytime inhabitants migrate upwards during the night,
bringing back nutrients and some exhibit bioluminescence (light producing
organs called photophores).
The ocean can also be divided into zones based upon depth of light
The photic zone is the depth where light
is sufficient for photosynthesis.
The dysphotic zone is where illumination
is too weak for photosynthesis.
The aphotic zone receives no light from
the surface because it is all absorbed by the water above.
deep sea layers bathypelagic 1000-4000m and the abyssopelagic
zone (below 4000m) have limited food supplies although bacteria have been found
that can make their own food.
Ecosystems (or ecological systems) are systems of communities
in a large geographical area.
In order for an ecosystem
to be successful, four things are required:
.An energy source
capable of capturing this energy in the form of organic molecules
material must be available to all other organisms
Cycling of nutrients must occur between the
abiotic and biotic portions of the system
vEnergy transfer is
accomplished in a series of steps by groups of organisms known as autotrophs,
heterotrophs, and decomposers.
vEach level on the
pyramid represents a trophic level.
absorb sunlight energy and transfer inorganic mineral nutrients into organic
autotrophs of the marine environment include algae and flowering plants and in
the deep sea are chemosynthetic bacteria that harness inorganic chemical energy
to build organic matter
NUTRITION..supply food molecules to organisms that can't absorb sunlight.
Consumers that must rely on primary producers as a source of
energy stored in the organic molecules is passed to consumers in a series of
steps of eating and being eaten and is known as a food chain.
step represents a trophic level and the complex food chains within a community
interconnect and is known as a food web.
The final trophic level that connects consumer to producer is that of the
live on dead plant and animal material and the waste products excreted by
The nutritional activity of these replenish nutrients that are essential
ingredients for primary production.
dead and partially decayed plant and animal tissue and organic wastes from the
food chain are DETRITUS.
contains an enormous amount of energy and nutrients.
Many filter/deposit feeding animals use detritus as food.
decompose detritus completing the cycle.
TRANSFERS IN MARINE ENVIRONMENTS
Primary producers usually outnumber consumers and at each succeeding step of
the food chain the numbers decrease.
numerical relationship is called the pyramid of numbers. (base as opposed to
The energy pyramid is the
energy distribution at each trophic level as it passes from producers through
Some energy is lost as
it passes to the next level because
consumers don't usually consume the entire organism
energy is used to capture food
organisms used energy during their metabolism
energy is lost as heat.
only 10% will pass on to the next level. (The shorter the better..)
on dead plants and animals that they have NOT killed...crabs ripping chunks of
flesh from fish on the beach are scavengers.
Most scavengers consume detritus rather than flesh and deep sea animals can
feed on both.
Each chain or part of the
web serves to link phytoplankton to larger pelagic animals through the
eat phytoplankton while carnivorus zooplankton occupy the third level as
If the organism resides primarily in or
on the substrate and doesn't swim or drift for extended periods as an adult it
is considered benthic.
either burrow , crawl, walk, (motile) or are sessile..permanently affixed to
the substrate or each other.
on the bottom are epifauna and living within are infauna. The substrate could
be a source of food.
Demersal organisms, such
as flounder alternate between swimming and resting on the bottom.
plankton,are the important primary food producers in the pelagic environment.
The animal members of
the plankton are the zooplankton which range from bacteria size to 15m
Phytoplankton are the
trees of the sea which float near the surface to make the most of the sunlight
Two forms of
phytoplankton, dinoflagellates and diatoms are particularly important as
founders in the planktonic food webs because most of the animal life in the
oceans depend on these.
dinoflagellates are usually found in warmer waters, and the diatoms are usually
more abundant in cooler waters.
coccolithophores and silicoflagellates are also abundant as well as blue-green
algae (in certain locations it can become the dominant) and green algae but
usually in the coastal water (some are in the open ocean as findings of
chlorophyll b indicate.
adaptations which deal with methods of keeping them in the upper zones to stay
in the sunlight..
retards sinking, structure...
Shape/structure of the
diatoms effects sinking rate and
storing droplets of oil in the cytoplasm
Blooms Although unknown,
the availability of nutrients, amount of vertical mixing, salinity, density,
temperature, and depth of water affect phytoplankton growth rates.
Blooms called red tides
have occurred in almost all oceans.
Red tides usually refer
to the discoloration of the waters as a result of the absorption of light by
pigmentation in planktonic organisms.
red water usually results from actions of non-toxic organisms and the term red
tide is inadequate when used with reference to PSP (paralytic shellfish
poisoning) and toxic dinoflagellates will not always discolor the water (too
few) but may be numerous enough to toxify shellfish.
But evidence that PSP may
be increasing in intensity and spreading to new areas is surfacing.
About 60 species of
dinoflagellates may color offshore waters however only 6 have been shown to
produce toxic substances.
Some toxins, saxitoxin,
is 50x more poisonous than curare (used by SA Indians)
Repeated cell divisions
as result of long period of dry weather following a violent storm which stirs
up bottom sediments, reach concentrations of 25,000 dinoflagellates /ml of
phytoplankton bloom in the ocean and produce a bluish-green light.
Phosphorescent Bay in
Puerto Rico contains high concentrations of bioluminescent phytoplankton
throughout the year.
One type, Noctiluca
sp., by disturbing water, passing of
boat, wave breaking, initiates bioluminescence.
gal and range in size from single cell to jellyfish.
Almost any animal phylum
can be found wandering through the sea but the most common are Copepods (95%).
Two types of
zooplankton....Holoplankton or permanent members of the community and temporary
residents called Meroplankton.
Holoplankton have evolved
efficient means of remaining adrift...special appendages, droplets of oil and
wax, tread water, jelly-like layer, gas-filled float.
A majority of inverts and many vertebrates have planktonic stages (meroplankton).
Drifting eggs and larva of fish, crabs, barnacles, worms, clams, snails,
sponges, lobsters, etc.
use the water mass to feed and disperse their planktonic young to new habitats.
The reproductive cycles
often coincide with maximum concentrations of food and favorable currents.
EX. polar oceans, spring
phytoplankton bloom triggers increases in zooplankton coinciding with migration
patterns of whales, seals and penguins.
refers to Copepods and other zooplankton moving up toward the surface to feed
in the evening responding to the changing light reducing predation during the
day because they are in deeper layers.
This varies among
species but light, shadows and pigments of phytoplankton (color) helps
zooplankton locate food.
Thus buoyancy, mobility,
vertical migration, and chemical sensing enables Copepods to search open water
for concentrations of food.
Trophic levels in zooplankton
communities-- Energy incorporated in organic molecules by marine plants flows
to the zooplankton community in a complex series of interconnected food chains.
Nekton Free swimming
organisms equipped to direct their movements through the sea including
cephalopods, fishes, marine mammals, sea turtles and marine birds.
Many are at the top of
the trophic levels either as carnivores or herbivores without natural
Swimming allows escape or
movement toward food and methods of locomotion are very diverse, from jets of
water, flippers, large tail fins and flukes.
Planktivorous nekton are
animals that feed directly on plankton such as baleen whales and some fish.
Herbivorous Nekton are
ones that feed on large seaweeds and sea grasses (turtles and manatees)
Carnivorous Nekton are
the dominant carnivorous animals of the pelagic environment and generally these
animals migrate great distances in search of food.
Food production occurs
mainly through Photosynthesis.
It is measured and
called Primary food production which will occur in the photic zone as
phytoplankton manufacture organic matter during photosynthesis.
The primary productivity
varies seasonally and geographically.
measured as g of Carbon/m2/year. (Long Island
Sound 500g, Antarctica. 2-400g etc.)
seems that the more vertical mixing that occurs in an area, the higher the
primary production is because in the tropics where there is little vertical
mixing, their Primary Productivity is low because of the depletion of nutrients
in the surface waters.
productivity decreases as depth increases as there is less light and less
pigments in algae enable them to make the most of the little light that does
get to them.
boundary where the food production (photosynthesis) is balanced out by the rate
of respiration (the use of the food) is called the compensation depth.
metabolize droplets of diatom oil to liquid waxes and fats which can be used as
long-term energy reserves. (waxes; long/fats short).
is these waxes and oils that get used for blubber when the Copepods/krill are
fed on by marine birds and mammals.
food chains are also secondary when decaying material enter the detritus chain
as decaying materials, wastes, pieces of animal tissue.
swarms of Copepods feeding on diatoms excrete packets of partially digested
matter called fecal pellets.
pellets usually aren't eaten by other pelagic organisms and provide food for
bacteria when they settle as well as a host of detritus feeders on the bottom
(transfer of energy from the top to the bottom)
there is a loss of energy to the grazers, many consumers are adapted to feed on
detritus thereby returning energy to the food chains.
bacteria can break down chitin which represents an enormous source of organic
bacteria play a big role in making sure the billions of tons of chitin produced
in the marine environment each year get broken down and their nutrients are
returned to the primary food makers.
close nutritional relationship between two different species...
both benefit and parasitism
benefits at hosts expense.
Population Cycles ..density or numbers
of individuals depends on
1. natality or rate of
production of new organisms and
mortality..rate of death in a population.
to be stable the two must be in equilibrium but under favorable conditions,
populations can increase numbers (can be seasonal and geographical) but this
also increases mortality because of decreased food supply and living space and
mortality is greater, then the population decreases.
conditions depend on
high concentration of nutrient rich water,
rapid cycling of materials by decomposers,
high numbers or rapid turnover of producer organisms
nutrients including nitrate, phosphate, silicon, potassium, magnesium, copper,
dioxide needed for outer glass covering of diatoms and forms internal
structural parts of sponges, K and NO4 and PO4 needed in plant proteins, lipids
and carbohydrates during photosynthesis.
nutrients can be considered a limiting factor as well as pH temp. light , depth
salinity nesting sites and predation.