Recent history of Tanytarsus barbitarsis Freeman (Diptera: Chironomidae) in the sediments of a shallow, saline lake

The present known distribution of Tanytarsus barbitarsis in Australia suggests that it is a halobiont species confined to lakes of high salinities, but of varying ionic composition. Experiments indicate that the species is capable of surviving and developing in waters of considerably lower salinity than suggested by its known natural habitat. A study of the history of the chironomid fauna of Lake Werowrap, as revealed by head capsule remains in two short sediment cores, showed that T. barbitarsis has fluctuated in abundance but appears to have been absent when Chironomus duplex was present in the lake. The facultative predator, Procladius paludicola, occurred sympatrically with T. barbitarsis during part of the lake's history. P. paludicola is perhaps the only chironomid that naturally occurs in association with T. barbitarsis. The apparent restriction of T. barbitarsis to highly saline waters may not be a direct result of its inability to tolerate waters of reduced salinity but may be, at least in part, due to its inability to compete with other tube building, sediment feeding chironomids.