The use of cardiac monitoring in the assessment of mercury toxicity in the subtropical pebble crab Gaetice depressus (Brachyura: Grapsidae: Varuninae)

Abstract

Heart rates were monitored in the pebble crab, Gaetice depressus using a non-invasive, computer aided cardiac monitoring system. A high degree of intra- and interindividual variability was observed, as was the presence of endogenous circatidal and circadian rhythms. Both acute and sublethal toxicities of mercury were determined. LC50´s (96) for mercury were between 0.16-0.20 mg l-1. Exposure to HgCl2 above LC50 (96) (0.3 mg Hg l-1) resulted in rapid and statictically significant increases in heart rate whereas exposure to a concentration lower than LC50 (96) (0.1 mg Hg l-1) resulted in progressive reduction in heart rate similar to that of control crabs

Keywords

• cardiac activity
• mercury
• pebble crab
• gaetice depressus
• endogenous rhythms