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Author(s): Deanne Erdmann MS

Aquatic Ecosystems

Aquatic ecosystems make up the largest part of the biosphere. The term "biome" is based on dominant vegetation and is not applicable to aquatic environments. Water depth, flow, chemistry, available light, and temperature are key factors in describing aquatic ecosystems.

Flowing bodies of water - Rivers, streams, and creeks are influenced by excess water draining from the surface of land. Organisms are well adapted to the flow.

Lakes - Have three major areas: Littoral (shallow, near shore), limnetic (farther from shore, near surface), and profundal zones (deep, below light penetration).

Wetlands - Swamps, marshes, and bogs may contain fresh, salty, or brackish water. Many wetlands are productive ecosystems, serving as important breeding grounds for animals.

Estuaries - Form where a freshwater river meets the ocean. Estuaries are extremely productive because of the rich organic nutrients and available light, and they are usually bordered by coastal wetlands.

Oceans - Communities living in oceans are greatly influenced by depth and light penetration.

Intertidal or littoral region - Where land meets water, between high and low tide.

Coastal or neritic zone - Extends from the low tide mark to the continental shelf drop-off.

Coral Reefs - Found in shallow warm coastal areas, diverse and productive communities. Dinoflagellates occur as symbionts in many corals, providing the nutrients to make coral reefs one of the most productive ecosystems in the world.

Open Ocean - Divided into photic (enough light for photosynthesis) and aphotic (insufficient light for photosynthesis) zones.

Benthic - Bottom layer, varies in productivity.