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UBC Theses and Dissertations

A study of the effects of Toxaphene on the bottom fauna of Paul Lake, British Columbia Ellickson, Peter Joseph


The density of the animals forming the bottom fauna of Paul Lake, British Columbia has been estimated for two successive seasons, based on 250 Ekman dredge samples from all zones for each year. After the sampling of the first year, the lake was treated with .004 p.p.m. Toxaphene. Density changes in the invertebrate population were considered on the basis of increase, decrease and changes in zonal distribution. Following poisoning and elimination of predatory fish, density increases occurred in the Physidae, Lymnae-idae, Oligochaeta, Planoribae, and Hirudinea. Density decreases occurred in the Watermites, Amphipods, Chiron-omidae, Planaria, Sphaeriidae and Odonata. Tricoptera, Ephemeroptera and Ceratopogonidae were not taken in any of the samples after poisoning.

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