Aspects of the thermal tolerance of the tropical mussel Trichomya hirsuta L.– a multivariable approach

Abstract

The mussel T. hirsuta was held in the laboratory at 31 salinity-temperature combinations (ranges: 5-35‰; 5-30ºC). The survival response after 19 days is described by response surface analysis. Salinities less than 15‰ are beyond the tolerance of the species. At higher salinities a thermal range of 10-32º C can be tolerated. The effect of a sudden temperature increase of 10º C to simulate power station output over the 19-day survival regime is described for exposure periods up to 114 h over 26 salinity-temperature combinations. The area of minimum mortality shifts toward higher salinities along the 17º C temperature axis with increase in exposure time, indicating that high salinities aid thermal resistance. The effect of acclimation on the response surface in the upper temperature region is negligible. The biological reasons for this are discussed with implications for the use of this method as a tool in thermal studies. In relation to thermal addition in Lake Macquarie at least 50% mortality is expected with pronounced sublethal effects under summer conditions. No influence of size on thermal resistance was detected.