Marine Ecology
Ecology is the study of the interrelationships 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.
9-1
Ocean Habitats
There are two major marine
provinces: the benthonic (bottom)
and the pelagic (water column).
• The benthonic 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
9-1
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.
9-2
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.
9-2
Classification of Organisms
The five major kingdoms in the
ocean are: Monera, Protista, Fungi,
Metaphyta and Metazoa.
• 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.
9-3
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.
9-4
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 nonliving 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.
9-4
Basic Ecology
• Hydrostatic pressure is the pressures
exerted by a column of water surrounding an
organism.
9-5
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).
9-5
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.
9-5
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.
9-5
Selective Adaptive Strategies
Intertidal benthonic 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.
• Benthonic communities also vary in response
to substrate (bottom material).