4-4 Aquatic Ecosystems Water covers ¾ of Earth, has an average depth of 3.7 (deepest part is 11 km – 6.8 mi) miles, contains about 3% salt and only 3% of surface water is fresh water, and is home to a variety of organisms

1. Aquatic ecosystems A. Determined primarily by the 1. depth 2. flow 3. temperature 4. chemistry of the overlying water B. Grouped according to the abiotic factors that affect them 1. ex. depth of water determines how much light is received 2. Freshwater ecosystems A. Divided into two main types

B. Flowing water ecosystems 1. Originate in the mountains/hills and flow downhill creating rivers, streams, creeks and brooks. 2. Organisms are adapted to slow or fast flowing water.

C. Standing water ecosystems 1. Relatively still waters provide habitats for many organisms that otherwise would be washed away. 2. Lakes and ponds have some flow of water to bring in fresh oxygen. 3. Microscopic organisms exists in this habitat. a. Plankton – free-floating organisms b. Phytoplankton – microscopic plants c. Zooplankton – microscopic animals

Plankton- free floating organisms

Phytoplankton- microscopic plants

Zooplankton- microscopic animals

3. Freshwater wetlands A. Wetland is an ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year. 1. May be standing, flowing, fresh, salty, or brackish (containing some salt, brine) B. Very productive ecosystems rich in organisms. C. Three main types are 1. Bogs – dominated by moss 2. Marshes – dominated by cattails 3. Swamps – dominated by bushes and trees

Bogs- dominated by moss

Marshes – dominated by cat tails

Swamps – trees and bushes

4. Estuaries (aquatic nursery) A. Occurs where freshwater rivers and streams meet the sea. B. Contain fresh and salt water 1. Bays, salt marshes, mangroves and mud flats

5. Marine Ecosystem A. Several classifications used to describe marine ecosystems. B. Photic zone is the this surface layer (down to 200 meters) in which sunlight penetrates. C. Aphotic zone which is permanently dark D. Other zones are divided based on depth and distance from shore. 1. Intertidal zone- 2. Coastal ocean 3. Open ocean

7. The Intertidal Zone A. Organisms must be adapted to periodic exposure to air during low tide. TIDE POOLS 1. Burrow in the sand, go into shells. B. Must be able to withstand the force of the crashing waves. 1. Tube feet or muscles stick to the rocks. 2. Zonation – competition among organisms that live on this rocky surface.

Tide Pools = Intertidal Zone

Zonation – prominent banding of organisms

8. Coastal Ocean A. Extends from the low-tide mark to the outer edge of the continental shelf. Being shallow enough to fall mostly within the photic zone. Very rich in plankton and many other organism. 1. Kelp forests 2. Giant brown alga 3. Seaweed a. These support a complex food web that includes snail, sea urchins, sea otters, fish, seals and whales.

Kelp Forest

Brown Alga

Seaweed

9. Coral reefs A. Among the most diverse and productive environments on Earth. 1. Named for the coral animals whose hard, calcium carbonate skeletons make up their primary structure. 2. Small animals that use their tentacles to capture food. 3. Must live in warm high salted areas. 4. Coral and alga live symbiotically using each other to survive. 5. Usually within 40 meters of the surface.