Marine
Ecology
vEcology
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.
Marine
Ecology
vMarine
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
by Environment
v
horizontal: neritic |
oceanic
v
vertical:
epipelagic
(top) / euphotic (good)
mesopelagic
(middle) / disphotic (low)
bathypelagic
(deep) / aphotic (without)
abyssopelagic
(bottomless)
Divisions of the Marine Environment
Marine
Ecology
vThe
marine environment for all organisms consists of non-living, abiotic factors
and living, biotic factors
Marine
Ecology
vAbiotic The
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
are: water
v
Light dissolved
gases
vpressure temperature
vtides pH
vcurrents salinity
vWaves substratum
vexposure
to air. nutrient supply
Basic Ecology
v
factors regulating the distribution and
abundance of organisms in the ocean.
v
influence of physical and chemical
parameters on organisms in the various ecosystems that constitute the ocean.
v
An ecosystem includes both the living
(biotic) and non-living (abiotic) portions of the environment.
e.g.,
coral reefs, the North Pacific Gyre.
Hydrostatic Pressure
v
Hydrostatic pressure is the pressure
caused by the height of water.
v
It is a function of the density of water
and the total height of the water column.
v
Pressure generally increases at a rate of
1 atm per 10 m of water.
Hydrostatic Pressure
(Cont.)
v
enormous in the deep sea yet animals live
there.
v
Animals do not contain gases.
v
However, mesopelagic fish have gas-filled
swim bladders to help maintain neutral buoyancy
unable
to move rapidly between depths
pressure change could cause bladder
explode.
Temperature
v
The distribution of species closely
follows the shape of isotherms.
Temperature
Figure 9-10
v
controls rates of chemical reactions and
thus metabolic rates, growth rates, feeding rates, etc.
Temperature
(Cont.)
v
Temperature tolerance varies tremendously
among marine organisms.
v
Young stages are generally less tolerant
of large changes.
v
e.g., eggs and young of the California
sardine cannot survive below 13 oC.
Temperature
Figure 9-11
v
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.
Salinity
v
Many of the elements used for growth.
v
Salinity tolerance is also important in
limiting distribution.
Salinity
(Cont.)
v
Salinity fluctuates most in coastal
waters due to shifts in river flow.
Organisms
that are mobile can migrate offshore if they cannot tolerate a certain
salinity, but attached organisms must cope with the changes or die.
clams,
oysters, and barnacles manage to survive by closing their shells.
Diffusion:
molecules move from high to low concentrations
Diffusion
v
internal fluids of marine organisms also
contain salts
v
chemical gradient - salts inside the body
relative to the surrounding seawater
v
salts will diffuse from an area of high
concentration to low concentration.
nutrient
uptake and the elimination of waste products.
Diffusion
(Cont.)
v
Diffusion is also the mechanism by which
water molecules pass through cell membranes.
This is called osmosis.
Diffusion/Osmoregulation
Marine
Ecology
vBiotic
The biotic factors are the interactions
among living organisms.
Marine
Ecology
vZonation
Two major divisions in the marine world.
vPelagic
zone...waters of the world and
v
Benthic zone..the ocean bottom.
Marine
Ecology
vThe
pelagic zone include the productive coastal waters..neritic zone
vand
deep waters of the open ocean..oceanic zone.
vAnother
division in the pelagic zone is related to light penetration..the photic and
aphotic zones..
Marine
Ecology
vThe
benthic zone extends from the seashore to the deepest parts of the sea.
vThe material
that makes up the bottom is the substratum and the organisms living there
are the benthos.
Distribution of
Marine Lifestyles
v
16.7% of Earths animals are marine
v
2% inhabit pelagic environment (most of the
oceans are cold and dark)
v
98% are benthic!
Marine
Ecology
vTides
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.
v
Below the intertidal zone is the subtidal zone..submerged and extending
seaward.
vThe
elevation and slope determines the length of time its exposed.
Marine
Ecology
vThis
affects organisms living there because some are restricted to zones according
to their adaptations to this type of zone (intertidal etc.).
Classification of Organisms
by Lifestyle
v
biota based on lifestyle.
plankton
(floaters)
nekton
(swimmers)
benthos
(bottom dwellers)
Plankton
v
Plankton are weak swimmers, and are known
as drifters, unable to counteract currents.
Phytoplankton
(plants)
Zooplankton
(animals)
Nekton
v
Nekton are active swimmers capable of
counteracting currents
Fish
Squids
Reptiles
Birds
Mammals
Marine
Ecology
•Distribution
•Pelagic
world include the
•
drifting organisms...plankton and
•the
swimmers...nekton.
Marine
Ecology
•Plankton
comprise the large and small organisms that drift or float while tides and
currents move them through the water.
•Most
plankton do have a limited ability to move and can migrate vertically through
the water from day to night.
•Some
drifters can photosynthesize while others are consumers..
Marine
Ecology
•Plankton
is very important as it occupies the first two or three links in the marine
food chains.
•
Nekton use fins, jets of water, strong flippers, flukes and flippers to swim
through the water.
Marine
Ecology
vOrganisms
living in pelagic waters also put up with changes in salinity, temperature etc.
and inhabit the coastal areas etc. which fit their adaptations.
v(can
withstand large changes (eury-- prefix) and narrow tolerance (steno))
Benthos
v
Epiflora or epifauna live on the sea
bottom.
v
Infauna live in the sea bottom.
v
Benthic plants are restricted to shallow
waters - why?
v
Benthic animals occur everywhere from
shallow depths to the deep sea.
Marine
Ecology
vOther
zones include the surface waters of the coastal areas called the neritic
zone and the waters of the ocean called the epipelagic zone.
vThe
open ocean is less productive than the neritic zone which contains plant
plankton, fish larva, invertebrate larva that will eventually end up near the
coast.
Marine
Ecology
vThe
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
penetration.
v
The photic zone is the depth where light
is sufficient for photosynthesis.
v
The dysphotic zone is where illumination
is too weak for photosynthesis.
v
The aphotic zone receives no light from
the surface because it is all absorbed by the water above.
Marine
Ecology
vThe
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.
Marine Ecosystems
v
Ecosystems
v
Ecosystems (or ecological systems) are systems of communities
in a large geographical area.
v
In order for an ecosystem
to be successful, four things are required:
Marine Ecosystems
.An energy source
Organisms
capable of capturing this energy in the form of organic molecules
.Organic
material must be available to all other organisms
Cycling of nutrients must occur between the
abiotic and biotic portions of the system
Marine
Ecology
vTROPHIC (FEEDING)
RELATIONSHIPS
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.
Marine
Ecology
vAutotrophs
absorb sunlight energy and transfer inorganic mineral nutrients into organic
molecules.
vThe
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
Marine
Ecology
vAUTOTROPHIC
NUTRITION..supply food molecules to organisms that can't absorb sunlight.
vHETEROTROPHS
Consumers that must rely on primary producers as a source of
energy...heterotrophic nutrition.
Marine
Ecology
vThe
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.
vEach
step represents a trophic level and the complex food chains within a community
interconnect and is known as a food web.
Marine
Ecology
vDECOMPOSERS--
The final trophic level that connects consumer to producer is that of the
decomposers.
vThey
live on dead plant and animal material and the waste products excreted by
living things.
v
The nutritional activity of these replenish nutrients that are essential
ingredients for primary production.
Marine
Ecology
vThe
dead and partially decayed plant and animal tissue and organic wastes from the
food chain are DETRITUS.
vThis
contains an enormous amount of energy and nutrients.
v
Many filter/deposit feeding animals use detritus as food.
vSaprophytes
decompose detritus completing the cycle.
Marine
Ecology
vENERGY
TRANSFERS IN MARINE ENVIRONMENTS
v
Primary producers usually outnumber consumers and at each succeeding step of
the food chain the numbers decrease.
vThe
numerical relationship is called the pyramid of numbers. (base as opposed to
each step.)
Marine
Ecology
The energy pyramid is the
energy distribution at each trophic level as it passes from producers through
the consumers.
Some energy is lost as
it passes to the next level because
..
Marine
Ecology
•(a)
consumers don't usually consume the entire organism
•(b)
energy is used to capture food
•(c)
organisms used energy during their metabolism
v(d)
energy is lost as heat.
Marine
Ecology
vGenerally
only 10% will pass on to the next level. (The shorter the better..)
Marine
Ecology
•Scavengers..feed
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.
Marine
Ecology
Each chain or part of the
web serves to link phytoplankton to larger pelagic animals through the
zooplankton.
Herbivorus zooplankton
eat phytoplankton while carnivorus zooplankton occupy the third level as
secondary consumers.
Marine
Ecology
•Benthic
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.
•They
either burrow , crawl, walk, (motile) or are sessile..permanently affixed to
the substrate or each other.
•Living
on the bottom are epifauna and living within are infauna. The substrate could
be a source of food.
Marine
Ecology
Demersal organisms, such
as flounder alternate between swimming and resting on the bottom.
Marine
Ecology
PLANKTON
Phytoplankton, plant
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
jellyfish.
Phytoplankton are the
trees of the sea which float near the surface to make the most of the sunlight
for photosynthesis
Marine
Ecology
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.
The
dinoflagellates are usually found in warmer waters, and the diatoms are usually
more abundant in cooler waters.
Marine
Ecology
Other plankton,
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.
Marine
Ecology
Phytoplankton have
adaptations which deal with methods of keeping them in the upper zones to stay
in the sunlight..
Size...small sizes
retards sinking, structure...
Shape/structure of the
diatoms effects sinking rate and
Density...decrease by
storing droplets of oil in the cytoplasm
Marine
Ecology
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.
Marine
Ecology
Red tides usually refer
to the discoloration of the waters as a result of the absorption of light by
pigmentation in planktonic organisms.
The
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.
Marine
Ecology
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)
Marine
Ecology
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
water.
Marine
Ecology
Bioluminescent
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.
Marine
Ecology
Zooplankton..500,000 per
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.
Marine
Ecology
Holoplankton have evolved
efficient means of remaining adrift...special appendages, droplets of oil and
wax, tread water, jelly-like layer, gas-filled float.
Marine
Ecology
.
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.
They
use the water mass to feed and disperse their planktonic young to new habitats.
Marine
Ecology
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.
Marine
Ecology
Vertical migrations
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.
Marine
Ecology
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.
Marine
Ecology
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
predators..except man.
Swimming allows escape or
movement toward food and methods of locomotion are very diverse, from jets of
water, flippers, large tail fins and flukes.
Marine
Ecology
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.
Marine
Ecology
Production
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.
It is
measured as g of Carbon/m2/year. (Long Island
Sound 500g, Antarctica. 2-400g etc.)
Marine
Ecology
It
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.
Marine
Ecology
Primary
productivity decreases as depth increases as there is less light and less
photosynthesis.
Accessory
pigments in algae enable them to make the most of the little light that does
get to them.
The
boundary where the food production (photosynthesis) is balanced out by the rate
of respiration (the use of the food) is called the compensation depth.
Marine
Ecology
Copepods
metabolize droplets of diatom oil to liquid waxes and fats which can be used as
long-term energy reserves. (waxes; long/fats short).
It
is these waxes and oils that get used for blubber when the Copepods/krill are
fed on by marine birds and mammals.
Marine
Ecology
Detritus
food chains are also secondary when decaying material enter the detritus chain
as decaying materials, wastes, pieces of animal tissue.
The
swarms of Copepods feeding on diatoms excrete packets of partially digested
matter called fecal pellets.
Marine
Ecology
These
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)
Marine
Ecology
While
there is a loss of energy to the grazers, many consumers are adapted to feed on
detritus thereby returning energy to the food chains.
Chitonolytic
bacteria can break down chitin which represents an enormous source of organic
carbon.
TK
9/16/2002
Marine
Ecology
These
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.
Marine
Ecology
•Symbiotic...refers to
close nutritional relationship between two different species...
•commensalism-
one benefits
•mutualism
both benefit and parasitism
•one
benefits at hosts expense.
Marine
Ecology
•Population Cycles
..density or numbers
of individuals depends on
•1. natality or rate of
production of new organisms and
•2.
mortality..rate of death in a population.
Marine
Ecology
•Now
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
increased predation.
•If
mortality is greater, then the population decreases.
Marine
Ecology
•These favorable
conditions depend on
•1.
high concentration of nutrient rich water,
•2.
rapid cycling of materials by decomposers,
•3.
high numbers or rapid turnover of producer organisms
•4.
Light
•5.
nutrients including nitrate, phosphate, silicon, potassium, magnesium, copper,
iron.
Marine
Ecology
•Silicon
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.
•The
nutrients can be considered a limiting factor as well as pH temp. light , depth
salinity nesting sites and predation.