Chapter 46, pages 1081-1092
I. Introduction to Aquatic and Marine Habitats
A. Significant limiting factors
B.
Osmoregulation
is very difficult in freshwater. Some animals like
echinoderms
never live
there.
C. Primary ecological subdivisions of aquatic/marine organisms:
1. Plankton
a. Generally microscopic feeble swimmers
b. Carried by waves and currents
c. Many species migrate vertically on a diurnal basis
d. Two categories:
(1) Phytoplankton - plankton of plant origin
(2) Zooplankton - plankton of animal origin
2. Nekton
a. Larger more strongly swimming organisms
b. Examples: fish and whales, etc.
3. Benthos
a. Bottom-dwelling organisms
c. Some burrowing - worms and echinoderms
d. Some walking about on the bottom - lobsters and crabs
4. Abyssal
a. Organisms that live in very deep water
b. Generally has no light
c. Creatures that live in the zone may or may not live on the bottom
II. Aquatic Habitats
A. Freshwater habitats
B. Location - streams, lakes, and ponds
2. Mosquito larvae, tadpoles, fairy shrimp, water striders
3. Depends upon:
a. Strength of current
b. Water temperature
c. Oxygenation
D. Aquatic zones
a. Shallow water area around the margin of a freshwater body
b.
Contains
algae,
diatoms,
frogs,
turtles,
annelid
worms,
crayfish,
insect
larvae,
and many nongame fish
c. Neuston - surface-film dwellers like water striders
a. Open water
b. Sparse life
c. Large fish live here
a. Deep regions of lakes
b. Not enough light for photosynthesis
c.
Producers
cannot live here because it is beyond their
compensation
point (point where
photosynthesis
and
metabolism
are equal)
d. Much food drifts into this zone
e. Tends to be mineral-rich and anaerobic
f. Few forms inhabit this region
a. Cooler temperature layers as one travels toward the bottom
b.
Thermoclines
- layers of water at progressively colder temperatures as one
progresses toward the bottom
c.
Fall
turnover - water at the bottom of a lake comes to the top in the
fall and
the water at the top of the lake goes to the bottom
as air
temperatures decrease and cool the surface water
d. Blooms occur in the spring because of the spring turnover in a lake
III. Marine Habitats
A. Saltwater habitats
B. Marine Life Zones
1. Estuaries and Salt Marshes
a. Coastal river system that is influenced by the tide
b.
Salinity
fluctuates with the salt and freshwater that moves in and out of the
marshy area
c.
Estuaries
and
Salt
Marshes have marked variations in temperature,
salinity,
and
other physical properties during the the daily
tidal
cycle and yearly seasonal
cycle
d.
One of the most fertile and productive areas of the earth's ecosystem
because:
(1) Action of the tides promotes circulation of nutrients
(2) Importation of nutrients from adjacent lands and rivers
draining into the
estuary
(3) Many kinds of plants present that help to trap nutrients
in and around plants
and roots
a. The area between the high and low tides along the coast line
b. High levels of:
1. Nutrients
2. Light
3. Oxygen
c. Very stressful place
a. Sandy beaches are unstable because of shifting sand
b. Rocky shores are good for anchorage of organisms
c. Organisms get exposed to air
(1) They dry out
(2) They freeze or get too hot because of sun or cold air
(3) Get burned by the sun
(4) They get eaten by predators
d. Get beaten about by the waves as they crash ashore
a. Below the lowest tidal zone
b. Still shallow enough for photosynthesis
c. Largely protected from wave action
d. Tidal currents do exist in this region
4. Neritic Zone
a. The intermediate depth waters out to the continental shelf
b. Generally to 200 feet deep
c.
Most of the production of the ocean takes place in this zone (commercial
fishing occurs here)
d.
Most of the production occurs here because of its size even thought its
production is not as efficient as the estuary
e. Very important zone for determining a nation's territorial waters
5. Deep Waters
a. 88% of the ocean is more than 1 mile deep
b. Essentially a marine desert at this depth or deeper
c. Thermal vents that exist along the Mid-Atlantic Ridge is an exception
d. Animals at this depth have strange appearances and luminating organs
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