Download Notes - Marine Ecology

MARINE ECOLOGY TERMS
Ecology - study of the relationship
of living organisms (biota) to the
environment (abiotic or non-living
part)
Each organism is structurally, chemically or behavioral adapted
for a particular habitat (place) and occupies a particular niche
(job).
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Major marine habitats are divided into 2 groups:
1. Pelagic Zone - photic zone
containing plankton (floaters) and
nekton (swimmers)
a. neritic - coastal areas
b. oceanic - open water
2. Benthic Zone - substrate on the margins or basins
a. aphotic - 90% dark area of open water
b. abyssal - deep bottom of the ocean floor
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These habitats are occupied by five levels of biota:
1. Individual - ONE plant or animal of a species
a. plankton - organisms that can not
make a forward motion against a
current
(1) phytoplankton - photosynthetic
primary producers
(2) zooplankton - primary consumers
b. nekton: swimming animals
ex. fish, mammals, birds, reptiles
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c. benthos - bottom dwellers
(1) epifauna - walk on the
substrate
ex. crabs
(2) infauna - live in the
substrate
ex. worms
d. demersal - hover, swim or rest
ex. flounder, skate, rays
e. sessile - attached
ex. barnacles, sponges
NOAA
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2. Populations - 2 or more individuals of the same species who
must compete for mates, food, light, and space because they
occupy the same niche and habitat.
DNA studies are used to identify which individuals are part of a
population. Population density is the number of individuals divided
by the size of the habitat.
Density is affected by geography, seasonal factors, pollution,
and birth-death ratio based on the number of adults.
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3. Communities - 2 or more
populations occupying different
niches in the same habitat.
photo credit: Florida Keys National Marine Sanctuary
Community living has an advantage by reducing competition,
increasing variety and diversity. The general niches are:
a. producers - phytoplankton, start the food chains
b. consumers – eat others - herbivores, carnivores, omnivores
c. decomposers - scavengers, break down organic
compounds into nutrients for producers
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Communities age in a process called Biological Succession.
Dr. James P. McVey, NOAA Sea Grant Program
a. Pioneer - first populations move into a habitat such as the
polychaete worm pictured here.
b. Juvenile - young populations; simple food chains
c. Mature - older communities with complex food webs,
stable populations are those where natality = mortality
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LS2.B
LS2.C
SEP :
2,4,8
CCC:
1,2,4,5,6,7
4. Ecosystems have 2 or more communities whose life style is
related to a unique habitat.
Ex: coral reefs, polar seas
Changes in the components will have unpredictable effects, but
ecosystems have remarkable ways of restoration.
5. The biosphere is composed
of many ecosystems,
exhibiting great diversity, that
are related by the
interdependence of living
things.
NOAA
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Ecosystem Energy
In ecosystems, energy is cycled through these niches:
autotrophs - produce
food by photosynthesis
heterotrophs - consume
autotrophs and other
heterotrophs
decomposers rearrange organic materials
into nutrients for autotrophs
The amount of energy available to support life or the largest
population that can be sustained by the available resources
is called the carrying capacity.
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Food chains represent the steps in transferring energy through the
ecosystem. Complex and integrated food chains are called food
webs.
A keystone species is the critical biomass in an ecosystem
because the food web is built around that particular organism.
Energy can be represented by trophic pyramids that compare the
number of organisms in a population, or the weight (biomass) of
organisms, or the productivity (energy calories).
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Generally, only 10% of the energy is passed on to the next higher
level.
Why does the amount of energy change if energy is never created
or destroyed?
1. It can be converted into unusable forms such as heat or for an
organisms’ respiration, metabolism, and predation.
2. Not all parts of an organism
have food value or provide
calories. ex: bones, scales
USDA
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The amount of energy available is calculated as net productivity or
primary productivity.
Primary productivity of the ocean is 22-28 billion tons of
carbohydrates (mostly glucose).
Gross productivity - respiration = net productivity given in units
of g/m2/yr.
Respiration is the amount of energy used at each level to maintain
life (estimated at 90% of the available calories).
If one trophic level has 100,000 calories available, only 10,000
can potentially be transferred to the next trophic level.
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phytoplankton
krill
baleen whale
The more levels in the ecosystem pyramid the less energy is
available in a useable form at the next higher level.
Shorter food chains are more efficient. The reason the ocean can
support the tremendous expense of endothermic (warm-blooded)
mammals is because they eat low on the food chain.
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