Synergistic effects of environmental variables on larvae of Uca pugilator

The effects of sublethal concentrations of mercury in combination with stressful temperature-salinity regimes were considered for larval development of the fiddler crab Uca pugilator (Bosc.). Control organisms were compared to those treated with 1.8 ppb Hg for the following suboptimal regimes: 30°C, 30 ‰ S; 30°C, 20 ‰ S; 20°C, 30 ‰ S, and 20°C, 20 ‰ S. As physiological indicators of larval response, the survival rate, the O2 consumption rate, and phototactic response were measured, following either acute 24 h doses of Hg, or chronic rearing in Hg. All response parameters were modified in larvae maintained under the suboptimal conditions; mercury compounded the effects.