The combined effects of high salinity and temperature on the survival of young Limanda limanda

Young specimens of the most common inshore flatfish, the dab Limanda limanda (Linnaeus, 1758), in the area of a proposed concentrated brine discharge, off the Yorkshire coast (England) were subjected to high salinities over temperatures corresponding to an annual temperature range. The results of these experiments have been used in the design of a dilution and dispersion system to protect the inshore fisheries. Mortality was found to be size-dependent, smaller dabs being least resistant. Response-surface analyses were utilised, showing mortality in relation to immersion time. The effect of temperature slowly declines with increased immersion time, and salinity becomes increasingly the more dominant effect. A significant salinity-temperature interaction was observed, which reached its peak effect at 3 h immersion. A 3-dimensional response-surface model of the mortality contours, for salinity, temperature, and immersion time, was produced which may be used to set upper limits to the design of the effluent disposal system. It is concluded that, provided salinity does not rise above 55, it is unlikely that significant changes in the L. limanda populations will occur.