Aquatic_Ecosystems.docx

First 2 Labs are in cambell hall 119 Ecosystem: a biotic community or assemblage and its associated physical environment in a specific place Integrates biotic and abiotic factors and considers net effect on process like primary production respiration, C & N exchanges Environmental setting alters ecosystem function at many levels (hierarchy) Natural system Climate Nutrients Altered systems Nutrient and sediment input Climate change Estuaries: where the ocean meets fresh water Streams: small free flowing forms of water Lakes: static reservoir Ocean: almost all water is in the oceans Major Gradients to distinguish aquatic ecosystems: Physics Chemical Geological Biological Climate-scale Why are the oceans far saltier than inland waters? When the water evaporates the salt is not evaporated with it Streams are always flushing so salts do not accumulate Lentic: standing water, slow moving, water motion not continuous and directional Wetlands, ponds, lakes, bogs Wetlands differ in permanence, depth, and vegetation Lakes differ in climatic zone, mixing regime, trophic status(fertility), and electrolytes(alkalinity, hardness) Polar lakes Amicitc Monomictic Polymictic Temperate lakes Tropical lakes Lotic: water continuous and directional motion Streams, rivers Steam order: any permanently flowing body of water 1st order: smallest flowing body of water (little run in woods) N+1 Oceans in middle of these Saline vs. Fresh water Freshwater <3ppt (3g/L = 0.3%) dissolved salts Saline waters >3ppt dissolved salts Hyposaline: 3-20ppt Mesosaline: 20-50 Hypersaline: >50ppt Saturation: 350ppt (Death Valley) Sea Water: ~35ppt Inland saline waters are called athalassohaline: waters are Ca & Mg carbonates and sulfates a = not thalasso = sea haline = salt What makes lakes saline? Evaporation & precipitation Temperature driven Hypersaline lakes tend to have very simple food webs of few trophic levels (usually only lower levels e.g. halophilic bacteria, brine-shrimp, etc) Salt add a very demanding physical toll