THE SYNERGISTIC EFFECTS OF TEMPERATURE, SALINITY, AND MERCURY ON SURVIVAL AND METABOLISM OF THE ADULT FIDDLER CRAB, UCA PUGILATOR'

Abstract

Gill tissues of fiddler crab, Ucapugilator, were the major site of mercury concentration; lesser amounts accumulated in the hepatopancreas and green gland. Very small amounts were found in the carapace and muscle tissue. No significant differences in the amount of mercury in tissues of males and females were found. A concentration of mercury sublethal to fiddler crabs under optimum conditions of temperature and salinity greatly reduced survival times when crabs were placed under conditions of temperature and salinity stress. Males were more susceptible to the synergistic effects of mercury in combination with environmental stress than were females. Metabolic rates of male and female fiddler crabs were affected by prolonged exposure to mercury both under optimum environmental conditions and under temperature and salinity stress. Metabolic rates of males were more adversely affected than those of females. Estuaries are an extremely important part of ~he marine environment. Yet often an estuary ~comes so grossly polluted that much of the bIota is destroyed before it is recognized that the quatlity of water affects the biology of such an area. Part of the problem is the subtleness of ~he effects of sublethal concentrations of man­ Introduced pollutants. In low concentration the P?llutant may have no observable effect on a gWen population of animals if environmental Conditions remain at an optimum. However, when another environmental parameter becomes stressful, it may synergistically interact with the sUblethal concentration of pollutant and the or­ g.anism dies. Many estuaries are polluted, and ~Ince one of the chief characteristics of estuaries Is the rather extreme environmental fluctuations that occur throughout the year, knowledge of ~Ynergistic interaction on estuarine animals is ImPortant in the preservation of estuarine eco­ sYstems.