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Unformatted text preview: Aquatic Ecosystems 09/11/2009 11:34:00 ← 71% of the Earth’s surface is water, 69% saltwater • the oceans distribute heat, feed the hydrologic cycle, and are critical to the world’s biogeochemical cycles • about 250,000 species of plants and animals • other resources: sand, gravel, phosphorous ← ← Marine Ecosystem • Coastal zone – high tide mark to the edge of the continental shelf • Less than 10% of the area of the ocean is contained in the coastal zone, but > 90% of all plant and animal species are in the coastal zone. Fisheries • Coastal wetlands occur in many shallow areas – more later; lot of carbon fixation, tidal cycles • Estuaries have reduced salinity and high nutrient levels with productive nurseries, access route for anadromous species (species that migrate from ocean into freshwater to spawn, i.e. salmon) • Barrier beaches and barrier islands important reduce the effect of storms on coastal communities • Some coastal zones support coral reefs ; coral bleaching is when several of the species are dying due to temperatures rising ← ← Open Ocean • Oceanic habitats differ primarily in salinity, light levels, nutrient concentrations, and depth • neritic zone shallow water habitat, phytoplankton and nutrients; felt the most impacts from human population and development • oceanic zone broken up into layers, it’s the deep ocean • euphotic zone primary production occurring, large number of animals (albatross, whales, jellyfish, tuna), less nutrients • bathyl zone bathyl and euphotic are separated y the compensation depth which is where plant respiration = plant photosynthesis (aka no oxygen being produced); not a lot of primary production, animals sparse (arrow worms, hatchet fish, flashlight fish), relatively cold (6-8C) • abyssal zone deepest part of the ocean, extremely cold (3-4C), high pressure (100-400 atmosphere of pressure), animals (gulper eels, jellyfish, angler fish) ← ← Upwelling • Upwelling areas occur off the west coast of most continents, some in east coast • warm water on coast that is pushed by wind (offshore winds) and turns right and cold water fills its place that is filled with nutrients • normally stretches for a hundred miles, sometimes doesn’t due to el nino which causes upwelling to stop/decrease ← ← Freshwater Ecosystems • Lentic systems – no flow o Distinct regions based on biotic and abiotic characteristics: o Littoral zone shallow part of the lake, emergent plants, fish, edge of littoral zone is where plants can’t grow anymore due to lack of light...
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- Spring '08
- Fisheries management