Alterations in zooplankton community structure after selenium-induced replacement of a fish community: a natural whole-lake experiment
✍ Scribed by David J. Marcogliese; Gerald W. Esch; Ronald V. Dimock
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 933 KB
- Volume
- 242
- Category
- Article
- ISSN
- 1573-5141
No coin nor oath required. For personal study only.
✦ Synopsis
Most of the fish species in Belews Lake, a cooling reservoir in the Piedmont area of North Carolina (USA), were eliminated in 1976-77 because of selenium poisoning . Zooplankton samples collected in 1974-75, prior to the fish kill, when the lake's fauna included a regionally-typical assemblage of piscivores and planktivores at a density of 14000 ha -', were compared to those collected in 1984-86, when the piscine community was dominated by three planktivorous fish (Notropis lutrensis, Pimephales promelas and Gambusia affinis) at a density of 28000 ha -'. Zooplankton diversity was similar in 1984-86 compared to that in 1974-75 . However, densities of the predominant cladocerans (Bosmina longirostris, Pseudosida bidentata, Ceriodaphnia pulchella, Holopedium amazonicum, Daphnia parvula, D . ambigua) and copepods (Diacyclops thomasi, Mesocyclops edax, Tropocyclops prasinus, Skistodiaptomus pallidus, S . reighardi) declined, though the magnitude of the reduction was greatest for the cladocerans and S . reighardi . Densities of copepod nauplii and rotifers also decreased markedly . No colonizations or extinctions of crustacean species occurred between 1975 and 1986 . Thus, while crustacean species richness (n = 18 species) remained the same, the relative proportions of individual species changed dramatically, most notably among the Cladocera . The observed changes in crustacean species densities and dominance are attributed to the replacement of the regionally-typical fish fauna by one consisting primarily of planktivores .