Effects of salinity and temperature on the biology of Daphnia menucoensis Paggi, 1996 (Crustacea, Cladocera)

Abstract

ABSTRACT Daphnia menucoensis is frequent in lakes of the central pampas and northern Patagonia in Argentina. It has ecological importance since its grazing on phytoplankton makes lake water transparent. As most of the information about the species comes from field studies, the objective was to determine the influence of salinity and temperature on its biology through laboratory bioassays. Treatments were carried out with 7, 12 and 17 g/L of salts at 15 and 22°C. Neonates were used and, every two days until their death, the medium was renewed; they were fed with Chlorella vulgaris, survivors and offspring were quantified and molts were measured. The optimal conditions were recorded with 12 and 7 g/L, at 15 and 22°C, respectively. In these combinations, the highest average longevity (33–35 days), number of molts (7–12), litters (2.50–4.07), offspring (27.70–26.20), and the largest specimens (> 3 mm) were recorded.