Effects of embryonic salinity exposure on larval development in two populations of the estuarine crab Chasmagnathus granulatus Dana, 1851 (Crustacea: Brachyura)

Abstract

Summary Life cycles of crabs include embryos, larvae, juveniles and adults that may inhabit different habitats and, consequently, cope with differing environmental cues. Embryos and adults of many estuarine crabs must tolerate diluted water, whereas their oceanic planktonic larvae live under constant salinity. The goal of this study was to investigate the effects of low salinity experienced during the embryonic phase on the survival and growth of larvae reared at low and high salinities. The observed effects of salinity on development (larval survival, developmental duration and first crab size) were compared between two populations (Mar Chiquita Lagoon, 37°45'S, and San Antonio Bay, 40°72'S) of Chasmagnathus granulatus, a semi-terrestrial estuarine crab of the southwestern Atlantic. We observed interpopulational differences in low salinity tolerance of embryos and larvae which may have been related to environmental differences between habitats. The strong effect of wind on the tides and the irregular influx of freshwater cause salinity at Mar Chiquita to be variable, both in time and space, in an unpredictable way. Embryos and larvae from this lagoon tolerated low salinities but their responses varied among individuals. Embryonic acclimation to low salinity here seems likely. Crabs in San Antonio Bay, on the contrary, experienced high and constant salinities and regular tides, and their embryos did not tolerate low salinities. Low salinity tolerance would not have an adaptive advantage in this area.