ISSN:
1573-5117
Keywords:
shallow lakes
;
Daphnia
;
Ceriodaphnia
;
DHM
;
predation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Recent studies document diel horizontal migration by large zooplankton in eutrophic shallow lakes. Risk of predation from planktivorous fishes could induce such behaviour. We studied diel horizontal distribution of cladocerans in 31 mainly shallow oligotrophic and mesotrophic New Zealand (NZ) and North American (NA) temperate lakes. In terms of weight, fish catch per net (CPUE w ) in multiple mesh-sized gill nets was similar in the two sets of lakes, while CPUE by number (CPUE n ) was overall higher in the NA lakes. Unlike previous results from eutrophic, temperate lakes, we found no significant diel variations in density in the pelagic and littoral zones, suggesting no diel horizontal migration of zooplankton. In the NZ lakes, Daphniaand Ceriodaphniawere evenly distributed between the littoral zone and the pelagial, while in the NA lakes Daphniawere more abundant in the pelagial and Ceriodaphniain the littoral zone. In the oligotrophic fishless NZ lakes, large Daphnia carinatadominated, whereas the smaller Ceriodaphnia dubiadominated in lakes with high CPUE's. In both the NZ and the NA lakes, Daphniashowed no clear correlation to fish CPUE n . However, in the NA lakes, Daphniaoccurred at fish CPUE n values at which they were eliminated in the NZ lakes, which may be related to differences in water transparency, reflecting a higher chlorophyll aand humic content in the NA lakes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1017083924691
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