APES Ch. 8 Aquatic Biodiversity

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global ocean

single and continuous body of water, divided by geographers into the Atlantic, Pacific, Arctic, and Indian Oceans (separated by continents)

aquatic life zone

Marine & freshwater portions of the biosphere. Examples include freshwater life zones (such as lakes and streams) and ocean or marine life zones (such as estuaries, coastlines, coral reefs, and the open ocean).

salinity

This property of water primarily determines the distribution of many aquatic organisms.

brackish

This term is used to describe a mix of freshwater and saltwater. Examples include estuaries.

plankton

Small plant organisms (phytoplankton) and animal organisms (zooplankton) that float in aquatic ecosystems

phytoplankton

"drifting plants" includes many types of algae. They are primary producers that support most aquatic food webs. Can be found near shorelines.

zooplankton

"drifting animals" Primary consumers (herbivores) that feed on phytoplankton or secondary consumers that feed on others (of their own kind). They range from single-celled protozoa to large invertebrates such as jellyfish.

ultraplankton

Consists of huge populations of much smaller plankton that are photosynthetic bacteria. They may be responsible for 70% of the primary productivity near the ocean surface.

nekton

strongly swimming consumers such as fish, turtles, and whales that can swim against the current.

benthos

consists of bottom dwellers such as oysters, which anchor themselves to one spot; clams & 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 & wastes of aquatic organisms into nutrients that can be used by aquatic primary producers.

euphotic zone

In deep aquatic systems, photosynthesis is largely confined to this upper layer through which sunlight can penetrate. The depth of this zone can be reduced when the water is clouded by excessive algal growth resulting from nutrient overloads.

turbidity

cloudiness [in water]

coastal zone

The warm, nutrient-rich, shallow water that extends from the high-tide mark on land to the gently sloping, shallow edge of the continental shelf. It makes up less than 10% of the world's ocean area but contains 90% of all marine species & is the site of most large commercial marine fisheries. Include estuaries, coastal wetlands, mangrove forests, and coral reefs. Has a high NPP per unit of area due to ample supplies of sunlight & plant nutrients from wind and ocean currents' distribution from the land.

estuaries

where rivers meet the sea. They are partially enclosed bodies of water where seawater mixes with freshwater as well as nutrients & pollutants from streams, rivers, & runoff from the land.

coastal wetlands

coastal land areas covered with water all or part of the year. Include river mouths, inlets, bays, sounds, and salt marshes in temperate zones, and mangrove forests in forest zones.

seagrass beds

Consist of 60+ species of plants that grow underwater in shallow marine & estuarine areas along most continental coastlines. These highly productive & physically complex systems support a variety of marine species. They also help stabilize shorelines & reduce wave impacts.

mangrove forests

tropical equivalent of salt marshes, found along 70% of gently sloping & silty coastlines in tropical & subtropical regions, esp. SE Asia

intertidal zone

area of shoreline between low & high tides. Organisms living in this zone must be able to avoid being swept away or crushed by waves, & must deal with being immersed during high tides & left high & dry (& much hotter) at low tides, as well as changing levels of salinity when heavy rains dilute saltwater.

barrier islands

low, narrow, sandy islands that form offshore, parallel to some coastlines

open sea

vast volume of the ocean

bathyal zone

dimly lit middle zone, which, because it gets little sunlight, does not contain photosynthesizing producers.

abyssal zone

dark & very cold; deepest zone. Has little DO.

marine snow

showers of dead & decaying organisms drifting down from upper lighted levels of the ocean. Reason why abyssal zone teems with life.

deposit feeders

Organisms that take mud into their guts & extract nutrients from it, e.g. worms

filter feeders

Organisms which pass water through/over their bodies & extract nutrients from it, e.g. oysters, clams, sponges

lentic

"standing" ex: lakes, ponds, inland wetlands

lotic

"flowing" ex: streams, rivers

lakes

large natural bodies of standing freshwater formed when precipitation, runoff, or groundwater seepage fills depressions in the earth's surface. Causes of depressions include glaciations, crustal displacement, & volcanic activity. Are supplied with water from rainfall, melting snow, & streams that drain their surrounding watershed.

littoral zone

top layer near the lakeshore and consists of the shallow sunlit waters to the depth at which rooted plants stop growing. Species living here include turtles, frogs, crayfish, & many fishes such as bass, perch, & carp.

limnetic zone

the open, sunlit surface layer away from the lakeshore that extends to the depth penetrated by sunlight. Produces the food & oxygen that support most of the lake's consumers.

profundal zone

the deep, open water where it is too dark for photosynthesis to occur in a lake

benthic zone

lake bottom inhabited mostly by decomposers, detritus feeders, & some fishes. Nourished mainly by dead matter that falls from the littoral & limnetic zones & by sediment washing into the lake

oligotrophic lakes

lakes that have a small supply of plant nutrients; poorly nourished. Often deep and has steep banks

eutrophic lakes

lakes with a large supply of nutrients needed by producers; well nourished. Often shallow with murky brown/green water with high turbidity.

cultural eutrophication

The acceleration of eutrophication of lakes caused by human inputs of nutrients from the atmosphere & from nearly urban & agricultural areas

hypereutrophic

describes lakes with excessive nutrients

mesotrophic

describes lakes that fall somewhere between the two extremes of nutrient enrichment

surface water

precipitation that does not sink into the ground or evaporate

runoff

surface water that flows into streams

watershed

aka drainage basin, the land area that delivers runoff, sediment, & dissolved substances to a stream.

source zone

headwaters/mountain highland streams are usually shallow, cold, clear, and swiftly flowing in this zone.

transition zone

in this zone, headwater streams merge to form wider, deeper, & warmer streams that flow down gentler slopes with fewer obstacles. They can be more turbid, slower flowing, & have less DO.

floodplain zones

In these zones, streams join into wider & deeper rivers that flow across broad, flat valleys. Are usually higher in temperature and have less DO

marshes

inland wetlands dominated by grasses & reeds with few trees

swamps

inland wetlands dominated by trees & shrubs

prairie potholes

inland wetlands that are depressions carved out by ancient glaciers

floodplains

inland wetlands which receive excess water during heavy rains & floods

arctic tundra

In the summer, this wet ecosystem can be considered to be an example of inland wetlands.

seasonal wetlands

wetlands which remain under water or are soggy for only a short time each year, e.g. prairie potholes, floodplain wetlands, & bottomland hardwood swamps

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