Introduction to
Oceanography
Marine Ecology
-Adaptations and diversity-
Ecology 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.
In Ocean Habitats, there are two major marine provinces:
the benthic (bottom) and the pelagic (water column).
• The benthic environment is divided by depth into the: Intertidal
zone, Sublittoral zone, Bathyal zone, Abyssal zone, and the
Hadal zone
• The pelagic environment is divided into the Neritic Zone and the
Oceanic Zone
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Ocean Habitats
The ocean can also be divided into zones based upon
depth of light penetration.
• 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.
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Classification of Organisms
In 1735 Linnaeus developed the taxonomic
classification used in zoology.
• The categories are from largest to smallest: Kingdom, Phylum,
Class, Order, Family, Genus and Species.
• The name of a species consists of the genus name combined
with a trivial name.
• The genus name begins with a capital.
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Classification of Organisms
The five major kingdoms in the ocean are: Monera,
Protista, Fungi, Metaphyta and Metazoa (Animalia).
• Monera are the bacteria and blue-green algae.
• Protista are single-celled organisms with a nucleus.
• Fungi are abundant in the intertidal zone and are important in
decomposition.
• Metaphyta are the plants that grow attached to the sea floor.
• Metazoa include all multicellular animals in the ocean.
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Classification of Lifestyle
Marine organisms can also be classified by lifestyle.
• Plankton are the organisms which float in the water and have
no ability to propel themselves against a current.
• They can be divided into phytoplankton (plants) and zooplankton (animals).
• Nekton are active swimmers and include marine fish, reptiles,
mammals, birds and others.
• Benthos are the organisms which live on the bottom (epifauna)
or within the bottom sediments (infauna).
• Some organisms cross from one lifestyle to another during
their life, being pelagic early in life and benthonic later.
Foraminifera
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Basic Ecology
Environmental factors in the marine environment include:
temperature, salinity, pressure, nutrients, dissolved gases,
currents, light, suspended sediments, substrate (bottom
material), river inflow, tides and waves.
• Ecosystem is the total environment including the biota (all
living organisms) and non-living physical and chemical aspects.
– Temperature can control distribution, degree of activity and reproduction of
an organism.
– Salinity can control the distribution of organisms and force them to migrate
in response to changes in salinity.
– Hydrostatic pressure is the pressures exerted by a column of water
surrounding an organism.
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Selective Adaptive Strategies
More than 90% of marine plants are algae and most
are unicellular and microscopic.
• To photosynthesize (produce organic material from inorganic
matter and sunlight) plants must remain within the photic zone.
• Diatoms are single cells enclosed in a siliceous frustrule (shell)
that is shaped as a pillbox.
• Dinoflagellates are single cells with two whip-like tails
(flagella).
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Selective Adaptive Strategies
Zooplankton include the copepods and foraminifera.
• Copepods are small herbivores (plant-eating organisms) that
filter diatoms from the water.
• Foraminifera are single-celled, microscopic organisms which
build shells of calcium carbonate.
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Selective Adaptive Strategies
The morphology of fish has evolved to allow them to
move through the water easily.
• The fish’s body must overcome three types of drag (resistance):
Surface drag, Form drag, and Turbulent drag.
• Speed is dependent upon body length, beat frequency, and the
aspect ratio of the caudal fin.
• Aspect ratio is the ratio of the square of the caudal fin height to
caudal fin area:
AR = (Caudal Fin Height)2/Caudal Fin Area
• There are three basic body forms, each adapted to a different
life style.
• There is a strong correlation between predation success and
body form.
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Selective Adaptive Strategies
Intertidal benthic communities generally display vertical
zonation that parallels sea level.
• Zonation reflects the amount of time the area is submerged and
the ability of the organism to survive the stress of exposure.
• Benthic communities also vary in response to substrate (bottom
material).