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vol.13 issue3-4OS ARGULÍDEOS (CRUSTACEA: BRANCHIURA) DA AMAZÔNIA BRASILEIRA 4 ASPECTOS DA ECOLOGIA DE ARGULUS MULTICOLOR STEKHOVEN, 1937 E ARGULUS PESTIFER RINGUELET, 1948. author indexsubject indexarticles search
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Acta Amazonica

Print version ISSN 0044-5967On-line version ISSN 1809-4392

Acta Amaz. vol.13 no.3-4 Manaus July/Sept. 1983

http://dx.doi.org/10.1590/1809-439219831334475 

BIOLOGIA AQUÁTICA

VERTICAL DISTRIBUTION OF ZOOPLANKTON AND PHYSICO-CHEMICAL CONDITIONS DURING A 24-HOUR PERIOD IN AN AMAZON FLOODPLAIN LAKE - LAGO CALADO, BRAZIL1

Thomas R. Fisher2 

John M. Melack3 

Barbara Robertson4 

Elsa R. Hardy4 

Luiz Fernando Alves4 

2Horn Point Environmental Laboratory, University of Maryland, Cambridge, Maryland, U.S.A.

3Department of Biological Sciences and Marine Science Institute, University of California, Santa Barbara, California, U.S.A.

4Instituto Nacional de Pesquisas da Amazonia, Manaus, Amazonas, Brazil.

Summary

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.

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.

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1 Financial support is provided by U.S. National Science Foundation grants DEB 78 -23642 and DEB 81—11398 to TRF and JMM.

Creative Commons License  This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.