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Title: Vertical Distribution Of Zooplankton And Physico-Chemical Conditions During A 24-Hour Period In An Amazon Floodplain Lake - Lago Calado, Brazil
Authors: Fisher, Thomas R.
Melack, John M.
Robertson, Barbara A.
Hardy, Elsa Rodrigues
Alves, Luiz Fernando
Issue Date: 1983
metadata.dc.publisher.journal: Acta Amazonica
metadata.dc.relation.ispartof: Volume 13, Número 3-4, Pags. 475-487
Abstract: In May 1980 Lago Calado was 9 meters deep, the water level was rising slowly, and below 4 meters the water was anoxic. Virtually all of the zooplankton was in the oxygenated layer. Adult and juvenile Daphnia gessneri, the most abundant crustacean species, occurred between 0.5 and 4.5 meters. Copepod nauplii tended to occur nearer to the surface, in the 0-2 meter stratum. No clear vertical migration was observed. The epilimnion was undersaturated ( < 40% oxygen) and contained < 0.1 μ M phosphate, ammonium and nitrate. The hypolimnion contained substantial phosphate ( > 2 μ M) and ammonium ( > 5 μ M), but little nitrate ( < 0.1 μ. M). A peak in particulate carbon and nitrogen occurred between 4-5 meters, just below the thermocline, and was associated with a pigment maximum.
metadata.dc.description.resumo: Em maio de 1980 o lago Calado apresentava uma profundidade de 9 metros e, abaixo dos 4 metros, condições anóxicas. Todo o zooplâncton se encontrava na camada oxigenada. Adultos e jovens de Daphnia gessneri, a espécie mais abundante, ocorreram entre 0.5 - 4.5 metros. Nauplius de copepoda ocorreram mais perto da superfície entre 0-2 metros. Não houve uma migração vertical evidente. No epilimnion, o oxigênio apresentava baixos valores de saturação ( < 40%), e fosfato, amônia e nitrato concentrações de < 0.1 μ M. No hipolimnion observou-se maiores concentrações de fosfato ( > 2 μ M) e amônia ( > 5 μ M), mas pouco nitrato ( < 0.1 μ M). Um pico de carbono e nitrogênio particulado ocorreu entre 4-5 metros, abaixo da termoclina, associado à um máximo de pigmento.
metadata.dc.identifier.doi: 10.1590/1809-439219831334475
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