Implications for toxicity tests with amphipod Gammarus aequicauda: effects of Temperature and Salinity on life cycle.

This study explored the effect of temperature and salinity on G. aequicauda life history in order to establish temperatures and salinities ranges advantageous for chronic testing. A broad range of salinity-temperature conditions (salinities of 10-20-36‰ and temperatures of 10-18-24°C combined in nine different treatments) significantly influenced various aspects of G. aequicauda reproductive biology reared in the laboratory from newly-released juveniles through first brood production by mature adults. There was a significant linear regression between the brood size and the length of the female. The number of juveniles released per female was higher at 10°C and lower at 24°C. The temperatures and salinities variations had significant effect on the fecundity in G. aequicauda. High temperature has shown a faster individual growth, anticipated age at maturity than at lower temperature. A temperature acceptable for chronic toxicity tests can be 18°C to which an acceleration of the life history without lower the amphipod’s performance was observed. Regarding salinity, results from this study showed that salinities down to 36‰ may also be used in sediment toxicity tests with G. aequicauda providing a proper and gradual acclimation.