Aquatic BiodiversityChapters 8 and 11

plankton◦ Phytoplankton

(photosynthetic)◦ Zooplankton

(consumers)◦ Ultraplankton

(bacteria) nekton

◦ strong swimming consumers (fish, turtles, whales)

benthos◦ bottom-dwelling

organisms (starfish, anemones, oysters)

decomposers

Aquatic Food Webs

Saltwater/Marine ◦ oceans, bays, estuaries, coastal wetlands,

shorelines, coral reefs, mangrove forests Freshwater

◦ lakes, rivers, streams, inland wetlands

◦ In these ecosystems populations are limited by temperature, dissolved oxygen (DO), turbidity, food, light, and nutrients required for photosynthesis.

Aquatic Life Zones (biomes)

Ocean◦ poorly understood

ecosystem

◦ reservoir of biodiversity

◦ divided into coastal zones, open ocean, and ocean bottom

Marine Ecosystems

warm, nutrient-rich, shallow water

extends from the high tide mark to the edge of the continental shelf

less than 10% of the ocean but contains 90% of all ocean species

site of most commercial fishing

high net primary productivity

Coastal Zone

Estuaries◦ where rivers meet the sea◦ fresh and salt water mixes

(along with sediment and pollutants)

Coastal Wetlands◦ coastal land areas covered with

water all or part of the year◦ high nutrient inputs◦ harsh environments--significant

daily and seasonal changes in temperature, salinity, soil runoff and pollutants

◦ low diversity

Coastal Zone

intertidal Zone◦area of the shoreline between low and

high tide◦organisms must adapt to pounding

waves, under water (high tide), no water (low tide), salinity changes

◦rocky shores (tide pools)◦sandy shores (sand dunes)

Coastal Zone

Coral Reefs◦ most diverse and

productive ecosystems

◦ complex interactions among species

◦ 1/4 of marine species live here

Coastal Zone

vast volume of ocean beyond the edge of the continental shelf

divided into three vertical zones (temp. changes with depth)◦ euphotic zone: brightly lit upper zone, contains

phytoplankton, low nutrients, high DO, large fast swimming predatory fish live here upwelling zones-areas of high nutrients where

currents bring nutrients up from ocean bottom◦ bathyal zone: dimly lit middle zone, zooplankton and

smaller fishes live here◦ abyssal zone: dark, very cold zone at bottom of ocean,

little DO, but supports high numbers of living organisms

Open Ocean

supports high diversity of organisms◦ food from “marine snow”

◦ deposit or filter feeders

poorly understood ecosystem

Ocean Bottom

Standing water (lentic bodies)◦ lakes, ponds, inland wetlands

Flowing water (lotic bodies)◦ streams and rivers

◦ these systems cover less than 2.5% of the earths surface

Freshwater Systems

large bodies of water created when precipitation and runoff fill depressions in the earth’s surface

Four general layers◦ littoral zone: near shore, shallow sunlit waters, high diversity◦ limnetic zone: open sunlit surface layer, extends to the depth

penetrated by sunlight, photosynthetic zone of the lake◦profundal zone: deep open water, too dark for

photosynthesis, low oxygen levels, ◦benthic zone: bottom layer, decomposers and bottom

feeders, includes dead matter and sediment

Lakes

lakes classified by nutrient content◦ Oligotrophic: poorly

nourished, clear water, small populations of fish and plankton

◦ Eutrophic: large supply of nutrients, sediments, shallower, murky water with high turbidity

cultural eutrophication: human increase rate of eutrophication

◦ mesotrophic: middle of two extremes

streams begin in mountainous or hilly areas, then flow downstream

three general zones◦ source zone: headwaters, shallow, cold, clear and

swiftly flowing, high DO content, low productivity◦ transition zone: form wider deeper and warmer

streams, more turbid, slower flowing, less DO, support more producers

◦ floodplain zone: sediment deposited here over time, wide deep rivers that flow through valleys, higher temps, low DO , slow moving, muddy, high silt concentration

Streams and Rivers

lands located away from coastal areas that are covered with freshwater all or part of the time◦excludes lakes, reservoirs and streams

highly productive, lots of nutrients important habitat for many species filter pollutants, recharge ground water,

recreation

Inland Wetlands