Dial behavioral responses of Metamysidopsis elongata atlantica (Crustacea, Mysida) to gradients of salinity and temperature

Metamysidopsis atlantica elongata (Bascescu, 1968) is a common mysid in the surf zone of sandy beaches from the state of Rio Grande do Sul, Brazil, where it is frequently recorded forming dense aggregations. Trough laboratory trials, behavioral responses to salinity (10, 20, 25, 28, 30, 40 e 45), temperature (10, 15, 20, 30±1ºC) and light (yes/no) were tested using adult males, adult females and juveniles. Although there was no response to temperature, the species showed clear response to salinity and light. In the presence of light, organisms remained in the bottom of the aquaria, but moved to surface when bottom salinities were increased. In the absence of light, adults moved to the surface. However, juveniles moved down to or remained on the bottom, maybe as a response to avoid adult predation.