Effects of the availability of energetic and protective resources on the abundance of daphniids (Cladocera, Daphniidae) in Chilean Patagonian Lakes (39 degrees-51 degrees S)
Effects of the availability of energetic and protective resources on the abundance of daphniids (Cladocera, Daphniidae) in Chilean Patagonian Lakes (39 degrees-51 degrees S)
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De Los Ríos Escalante, Patricio
Soto, Doris
Soto, Doris
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Abstract
The lacustrine zooplankton of Chile is characterized by a low abundance of daphniid cladocerans and a predominance of calanoid copepods, thus making up a zooplankton community quite different from that described for North American lakes. To explain this pattern, this study investigates the role of the oligotrophy, and the resulting high transparency of a considerable number of locations. Due to low levels of dissolved organic carbon, viz., Daphniidae are exposed to ultraviolet radiation. Chilean lakes located between 39 degrees and 51 degrees S were studied, and maximum depth, mixing depth, trophic status, and dissolved organic carbon concentrations were measured and considered. The results obtained revealed that daphniids were abundant in oligo-mesotrophic lakes with shallow mixing depth. Thus, daphniid abundance is directly associated with chlorophyll-a concentration as an energetic resource, but also with sufficient depth, because this last condition provides protection against the penetration of ultraviolet radiation.