Salinity and temperature tolerance of <i>Acartia spinicauda</i>

Abstract

Salinity tolerance, temperature tolerance and combined effects of temperature and salinity on survival were investigated in the laboratory on the copepod, <i>A. spinicauda</i>, obtained from the Bombay coastal waters. Salinity tolerance experiments were carried out at salinities from 35% (taken as 100% sea water) to 0% (fresh water). The copepod could tolerate salinity (expressed as percentage composition of sea water) down to% sea water when subjected to sudden exposure. Salinity acclimation increased the capacity to tolerate dilutions to as low as 5% sea water. The upper and lower lethal temperatures were 35° and 15° C, respectively, in full strength sea water. Investigation on the combined effects of temperature and salinity demonstrated that the copepod could tolerate the widest range of dilution when the experimental temperatures were close to the field temperatures and widest range of temperature when the experimental salinities were close to the field salinities. Distribution of <i>A. spinicauda</i>, on the basis of the above findings, was discussed.