Interpretation of Quaternary paleoecology from Cladocera and midges, and prognosis regarding usability of other organisms

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Abstract
Sedimentary remains of chydorid Cladocera are abundant and can be identified precisely to species. Their percentage composition by species in sediments is integrated over habitats and seasons. Under stable conditions the relative frequency distribution of species corresponds to the MacArthur broken-stick model, so that marked departures from the predicted distributions indicate perturbations in the system. Lakes differ greatly in their capacity to buffer the effects of external changes. Cladocera can also indicate fluctuations in lake level, the changing effectiveness over time of size-selective predation, and broad patterns of climatic change through invasion and extinction of species. The remains of dipterous larvae (chiefly Chironomidae) are not only much less abundant than Cladocera but also have a much greater taxonomic uncertainty. Nevertheless, the profundal taxa provide clear insight into changing conditions in the hypolimnion over time and of the long-term readjustments and changes in the total fauna and their environmental correlates. Rhizopods, neorhabdocoeles, and rotifers, although barely studied to date, give promise in helping interpret past conditions.