Chironomidae (Diptera): quantitative palaeosalinity indicators for lakes of western Canada

Publisher Website
Google Scholar
Abstract
A survey of chironomid remains preserved in the surficial sediments of 86 British Columbia lakes was conducted to assess the feasibility of reconstructing palaeosalinities from assemblages of fossil chironomid head capsules. Many taxa common in freshwater lakes were either rare or absent at higher salinities. Lakes having salinities greater than about 10.0 g∙L−1 were distinguished by the overwhelming relative abundance of Cricotopus/Orthocladius. In less saline waters, common taxa included Chironomus, Procladius, Psectrocladius, and the subtribe Tanytarsina. Heterotrissocladius, Lauterborniella/Zavreliella, Pagastiella, and Sergentia were only collected in freshwater habitats. Canonical correspondence analysis revealed that three environmental variables (late summer lakewater salinity and concentrations of Sr and total P) explained significant variation in the weighted averages of taxa. Tanytarsina and Dicrotendipes were common at low Sr concentrations in carbonate lakes. A weighted-averaging calibration function was developed to infer salinity on the basis of fossil fauna. This model will allow palaeolimnologists to detect transitions between freshwater and moderately saline states and can be used to assist palaeoclimatic reconstructions for athalassic lake sites.