Some factors affecting the abundance and distribution of macroscopic benthos of Moose Lake, Manitoba

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Howard, William Norton
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Between 1963 and 1965 a series of benthological surveys was carried out in the Moose Lake area of the Saskatchewan River delta, Manitoba. The object of this study was to relate various morphometric, physiocochemical and biological factors to benthic distribution and abundance previous to impoundment. Qualitative and quantitative benthic composition, including standing crops, was estimated periodically along predetermined transects in each basin. Statistical tests were used to determine whether the biomass and numbers of benthic animals varied significantly along the various transects among sampling periods, among basins and between years. Moose Lake is a shallow temperate eutrophic lake of the third order. The study area was composed of three basins which varied considerably from one another with respect to morphometry, water chemistry and benthic populations. Analysis of variance procedures showed that the biomass and numbers of benthic animals along a transect did not vary significantly on a seasonal basis... Significant differences did occur in the benthic production of each basin. Benthic production and distribution were influenced by exposure, substrate, shoreline relief, depth, benthic composition and seasonal changes in the size and number of benthic animals... High concentrations of total dissolved solids and alkalinity were probably conducive to the high production of mollusks on this lake. Where off-shore substrates were subject to decomposition, chemical conditions at the mud-water interface may have limited the abundance and distribution of the Ephemeroptera and Crustacea...