Ceriodaphnia ephippia and Bosmina remains as paleolimnological indicators of fish community alterations

摘要

Although paleolimnology has become an established technique in defining lake restoration goals, few studies (e.g. Kitchell & Kitchell 1980, Leawitt et al. 1989) compare fossil records with corresponding zooplankton data in lakes with varying history of planktivorous predation (Jeppesen 2002). By examining sediment of manipulated and control lakes, this study evaluates the possibility of distinguishing differences in the zooplankton fossil record before and after manipulation, as well as to assess the magnitude of natural variation. We established a quotient between ephippia of intermediate-sized, semi-littoral, Ceriodaphnia quad-rangula and remains of small-sized, pelagic, Bosmina longispina, in each sediment layer to evaluate use of this quotient to reflect past changes in fish assemblage and to determine the influence of natural variation. The quotient was particularly interesting since both species included are relatively small-sized (in contrast to Daphnia spp. often used in similar studies). Therefore, the potential responses of alterations in planktivorous predation and natural variability were expected to be expressed on a smaller scale.