Crustacean Plankton in Lake Winnipeg: Variation in Space and Time as a Function of Lake Morphology, Geology, and Climate

Abstract

Rivers draining different geological basins have the most important impact on the formation of the planktonic community in Lake Winnipeg. Very diverse patterns of distribution of individual species reflected the complexity of the water masses structured by lake morphology and the configuration of river inflows. Of the 34 species identified (15 copepods and 19 cladocerans), 12 were found exclusively in the South Basin, 7 exclusively in the North Basin, and 15 were common to both basins. A "core" group of 12 species was distributed over the whole lake, but the remaining 22 species ("unsuccessful invaders") were present only in restricted areas, mostly adjacent to river inflows. Plankton species composition has not exhibited major changes after 40 yr, but abundance has at least doubled, probably due to eutrophication. Several times more planktonic crustaceans were found in the western part of the lake, affected by sedimentary drainage, than in the eastern part, influenced by the Precambrian Shield. The plankton community in a lake as large as Lake Winnipeg can be affected by differences in climate within its shores. Midsummer epilimnion temperature was the single best parameter predicting crustacean abundance in Lake Winnipeg and other North American great lakes and, combined with phosphorus loading, explained 97% of variance.

Differences in rotifer communities in two freshwater bodies of different trophic degree (Lake Ohrid and Lake Dojran, Macedonia)

“…The Jaccard similarity coefficient (Patalas & Salki 1992) was used to compare community structures between the two lakes. Differences in species richness in both lakes were visualised through the inspection of rarefaction curves calculated using EcoSim7 (Gotelli & Entsminger 2001).…”

Spatial heterogeneity as a multiscale characteristic of zooplankton community

“…native concept of `functional heterogeneity' has been less explored, even though it offered more biological relevance by relating the observed patterns of distribution to environmental processes operating over different scales . Such zooplankton `functional heterogeneity' has been investigated in recent studies (Simard & Mackas, 1989 ;Price, 1989 ;Pinel-Alloul et al, 1990 ;Johannsson et al ., 1991 ;Sameoto & Herman, 1992 ;Mackas, 1992 ;Patalas & Salki, 1992 ;Pace et al, 1992), using mapping, spatial analysis, and canonical correspondence analysis .…”

Lake‐wide distributions of temperature, phytoplankton, zooplankton, and fish in the pelagic zone of a large lake

“…Dominant factors explaining spatial variations are windinduced circulations (Lacroix and Lescher-Moutoué 1995;Thackeray et al 2004), water temperature (Patalas and Salki 1992;Pinel-Alloul et al 1999), basin morphology (Pothoven et al 2004) or local eutrophication, e.g., by river inflows (Patalas and Salki 1992;Fietz et al 2005). Such factors inducing patchy plankton distributions in lakes may be separated in two different modes of patch generation (George and Heaney 1978); factors inducing spatial variation in the rate of population increase or decrease, e.g., local differences in resource availability, predation pressure or temperature, and factors bringing about a spatial redistribution of the population.…”