4-4 Aquatic Ecosystems

Plankton

• Tiny, free-floating organisms that occur in aquatic environments

phytoplankton

• Population of algae and other small, photosynthetic organisms found near the surface of the ocean and forming part of plankton.

zooplankton

• Tiny animals that form part of the plankton.

wetland

• 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.

estuary

• Wetlands formed where rivers meet the ocean.

detritus

• Particles of organic material that provide food for organisms at the base of an estuary’s food web

Salt Marsh

• Temperature-zone estuary dominated by salt-tolerant grasses above the low-tide line and by seagrasses under water.

Mangrove swamp

• Coastal wetland dominated by mangroves, salt-tolerated woody plants.

Photic zone

• Well-lit upper layer of the oceans

Aphotic zone

• Permanently dark layer of the oceans below the photic zone

zonation

• Prominent horizontal banding of organisms that live in a particular habitat

Coastal ocean

• Marine zone that extends from the low-tide mark to the end of the continental shelf.

Kelp forest

• Coastal ocean community named for its dominant organism-kelp, a giant brown alga

Coral reef

• Diverse and productive environment named for the coral animals that make up its primary structure.

benthos

• Organisms that live attached to or near the ocean floor

Key concept

• Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water.

Key concept

• Freshwater ecosystems can be divided into two main types: flowing-water ecosystems and standing-water ecosystems.

Key Concept

• In addition to the division between the photic and aphotic zones, marine biologists divide the ocean into zones based on the depth and distance from the shore: the intertidal zone, the coastal ocean, and the open ocean.