Download Marine Environments

Marine Life Zones
The place an organism “calls
home” is known as its habitat.
Everything that surrounds an
organism’s habitat is called its
environment.
Biotic versus Abiotic
All the living (biological)
components of an environment
are called the Biotic Factors.
All of the nonliving (physical and
chemical) components of an
environment are called the
Abiotic Factors.
Causes of Zonation
• Physical factors: Tidal action on the shore
and the different tolerances of the
organisms to increasing exposure to the
air.
• Biological factors: competition, predation,
grazing and larval settlement.
• Competition: space is limited in the
intertidal; larvae of animals like barnacles
may settle on all three zones, they can be
killed by other species/organisms
outgrowing, crushing, or uplifting them.
• Predation: other organisms are
consumed by predators, and thus they
compete for control of the community.
• Grazing: affects algal zonation, species
diversity, patchiness, and succession;
influences upper limits of algal
distribution.
• Larval recruitment: highly variable in time
and space due to water
conditions/weather, adult reproduction;
thus can alter community structure on a
seasonal or year-to-year basis.
Organisms that live in the littoral
(intertidal) zone must be able to
cope with emersion, even if it
means giving up characteristics that
are advantageous below the tide.
Emersion = being exposed to the air.
Immersion = being underwater.
Substrate
The material on or in which an
organism lives is called the
substrate.
The most familiar communities
are the sandy beach and rocky
shore environments.
Composed of a loose sediment
the is easily shifted by wind and
waves.
Organisms that live buried in the
sand are called infauna
Zonation is easily recognized
when observing a typically
sandy beach.
• Supratidal
Zone
Sometimes called
the supralittoral
zone
This is the area
above high tide
Intertidal Zone
Sometimes called
the littorial zone.
This is the area
between the hightide mark and
low-tide mark.
Subtidal Zone
Sometimes called
the sublittoral
zone.
The area
between the lowtide mark and the
open ocean.
ROCKY SHORE
Community
Generally occur on
steep coasts without
large amounts of
sediment (West Coast
of America).
Usually formed from uplifts due to
active margins or when ice melts
away allowing the coast to rise.
Rocky Intertidal
Zones
Rocky Intertidal
Zones
• the upper intertidal or supralittoral
zone where conditions are nearly as
terrestrial as they are marine;
–the area is wetted infrequently by
extremely high tides and splash from
breaking waves is sparsely inhabited
by marine organisms.
• the middle intertidal or littoral zone,
which is sufficiently inundated by tides
and waves;
–has an abundance of plant nutrients,
oxygen, and planktonic food because of
the wave action which mixes the water
well and helps mix atmospheric gases
into the water.
• barnacle and mussel patches in the
middle intertidal algal zonation on
intertidal rocks.
• the lower intertidal or infralittoral zone,
which is submerged most of the time and
is characterized by numerous seaweeds
that provide a protective canopy of wet
blades over much of the zone
– the organisms that live here are tolerate only
to brief exposures to air.
– brown, red, and a few species of green algae
provide the canopy and tufts of filamentous
brown and red algae carpet many of the
rocks.
– anemones, snails, sea spiders, nudibranchs,
hydroids, sea stars, sea urchins, brittle stars,
and sea cucumbers are the common animals
in this zone.
Exposure at Low Tide
Most rocky intertidal organisms live
right on the rock’s surface, they are
called epifauna. Some can move
about but most are sessile and stay
put.
This places them under enormous
physical stress when exposed to the
elements.
Exposure at Low Tide
Marine animals tend to dry out, or
desiccate, when left out of water.
To survive they either run and
hide or clamp up.
Survival Methods:
The run and hide method
The clamp up method
Most important physical force
acting on the bottom
communities is turbulence or
wave action; turbulence keeps
the inshore waters from
becoming stratified and wave
action re-suspends particles of
the substrate .
Power of the Sea
When the tide is high a new set of
problems arise.
Waves expend large quantities of
energy and transfer it to anything
they come into contact with.
Power of the Sea
Coping with Wave Shock
Sessile organisms
anchor themselves
firmly to the rocks.
Seaweeds use
holdfasts, barnacles
use a glue so strong
that companies today
are still trying to
duplicate it.
Waves
As waves approach the shore they
touch the bottom and begin to
slow down.
They almost never approach the
shore straight on due to the
coriolis effect.
As a result one end reaches the
shallow water before the other
causing bending.
Bending
This means that one end travels faster
than the other and results in a
bending of a wave, called refraction.
As a result of bending there is a
tremendous variation in intensity of
wave impact, or wave shock.
Neritic Zone – This zone lies
above the continental shelf
and is shallow. Deep-sea
fishing occurs in this zone due
to its high productivity.
Pelagic Zone – This zone of
the ocean covers the entire
ocean above the bottom of the
sea.
Oceanic Zone – includes most
of the open ocean. The upper
part receives light and is
called the Photic zone.
The aphotic zone does not
receive light and begins about
200m deep.
Benthic Zone – the deepest
part of the ocean also called
the basin or abyssal plain.