Chapter 8: Aquatic Biodiversity

aquatic life zones

aquatic equivalents of biomes, salt and freshwater portions of the biosphere that can support life

saltwater (marine)

oceans and their bays, estuaries, coastal wetlands, shorelines, coral reefs, and mangrove forests

freshwater

lakes, rivers, streams, and inland wetlands

plankton

weakly swimming and free-floating; divided into 3 smaller groups (phytoplankton, zooplankton, and ultraplankton)

nekton

strongly swimming consumers such as fish, turtles, and whales

benthos

bottom dwellers such as oysters, which anchor themselves to one spot; clams and worms, which burrow into the sand or mud; and lobsters and crabs, which walk about on the sea floor

decomposers

mostly bacteria; break down organic compounds in the dead bodies and wastes of aquatic organisms into nutrients that can be used by aquatic primary producers

turbidity

cloudiness that can occur naturally from algal growth or result from disturbances such as clearing of land

coastal zone

warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf

estuaries

where rivers meet the sea; partially enclosed bodies of water where sea-water mixes with freshwater as well as nutrients and pollutants from streams, rivers, and runoff from the land

coastal wetlands

coastal land areas covered with water all or part of the year, they include coastal marshes and mangrove forests

sea-grass beds

grow underwater in estuaries and shallow waters along most continental coastlines, they are high in nutrients and plant life

ocean acidification

decreasing pH of ocean waters due to absorption of excess atmospheric carbon dioxide from the burning of fossil fuels

intertidal zone

the area of shoreline between low and high tides

open sea

the vast volume of the ocean; past the sharp increase in water depth at the edge of the continental shelf

euphotic zone

brightly lit upper zone, where phytoplankton carry out about 40% of the world's photosynthetic activity

bathyal zone

the dimly lit middle zone which receives little sunlight and therefore does not contain photosynthesizing producers, zooplankton and small fishes populate this zone

marine snow

dead and decaying organisms drifting down from the lighted levels of the ocean

lakes

large natural bodies of standing freshwater formed when precipitation, runoff, or groundwater seepage fills depressions in the earth's surface

oligotrophic lakes

lakes that have a small supply of plant nutrients; often deep with steep banks; poorly nourished, formed from glaciers and mountain streams

eutrophic lakes

lakes with a large supply of nutrients needed by producers; well-nourished; often shallow with murky brown or green water and high turbidity

cultural eutrophication

human inputs of nutrients from the atmosphere and from nearby urban and agricultural areas can accelerate the eutrophication of lakes

hypereutrophic

lakes with excessive nutrient levels

mesotrophic lakes

lakes that fall somewhere between the two extremes of nutrient enrichment

surface water

precipitation that does not sink into the ground or evaporate

runoff

when surface water flows into streams

watershed (drainage basin)

land area that delivers runoff, sediment, and dissolved substances to a stream

inland wetland

lands covered with freshwater all or part of the time and located away from coastal areas

coral reefs

form in clear, warm coastal waters of the tropics and subtropics

2 major aquatic zones

saltwater and freshwater

NPP in aquatic life zones is affected by 3 key factors:

1) depth of the water (affects amount of sunlight)

2) turbidity (cloudiness caused by excess algae growth or sediment runoff)

3) nutrients (nitrates, phosphates, iron needed for photosynthesis)

4 types of aquatic life

1) plankton. 2) nekton. 3) benthos. 4) decomposers

3 aquatic life zones in a downhill flow of water

source zone, transition zone, and the floodplain zone

delta

an area at the mouth of a river that was built up by deposited sediment and contains coastal wetlands and estuaries.

floodplain zones

low lying areas where sediment builds, this is where streams join into wider and deeper rivers that flow across broad, flat valleys.