17fresh - BIO 20 FRESH 1 FRESHWATER ECOSYSTEMS 1A. LAKES...

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BIO 20 FRESH 1 FRESHWATER ECOSYSTEMS 1A. LAKES lakes - also ponds if smaller - inland depression of freshwater - outlet into stream, wave action if large - originate from glacial melt, volcanic crater, oxbow river, beaver dam temperature - vary by season & depth - winter surface colder, may freeze - summer surface warms up, limited O2 thermocline between temp. zones - spring/fall uniform, no thermocline, overturning mixes nutrients + O2 1B. ZONATION stratification - diff depths - epilimnion - upper, variable temp. - metalimnion - middle, cool - hypolimnion - lower, cold, overturn littoral - shallow water near shore - max light-O2, most productive-diverse - plants rooted, emergent or submerged limnetic - surface layer of open water - also max light-O2 profundal - lower layer of open water - less productive-diverse - too dark for photosynthesis benthic - bottom mud, mainly decompose - low O2, productive if close to shore 1C. ECOLOGY diversity - highest at surface (plankton)
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This note was uploaded on 08/12/2010 for the course BIO 20 taught by Professor Hom during the Spring '08 term at City College of San Francisco.

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17fresh - BIO 20 FRESH 1 FRESHWATER ECOSYSTEMS 1A. LAKES...

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