Aquatic Biodiversity Chapters 8 and 11 Aquatic Food

Aquatic Biodiversity Chapters 8 and 11

Aquatic Food Webs � plankton ◦ Phytoplankton (photosynthetic) ◦ Zooplankton (consumers) ◦ Ultraplankton (bacteria) � nekton ◦ strong swimming consumers (fish, turtles, whales) � benthos ◦ bottom-dwelling organisms (starfish, anemones, oysters) � decomposers

Aquatic Life Zones (biomes) � 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.

Marine Ecosystems � Ocean ◦ poorly understood ecosystem ◦ reservoir of biodiversity ◦ divided into coastal zones, open ocean, and ocean bottom

� warm, water nutrient-rich, shallow � 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

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

Open Ocean � � 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

Ocean Bottom � supports high diversity of organisms ◦ food from “marine snow” ◦ deposit or filter feeders � poorly understood ecosystem

Freshwater Systems � 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

Lakes � 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 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 and Rivers � � 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

Inland Wetlands � 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 � filter habitat for many species pollutants, recharge ground water, recreation