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

Abstract

SUMMARY: 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. LC 50 's (96) for mercury were between 0.16-0.20 mg l ) resulted in rapid and statictically significant increases in heart rate whereas exposure to a concentration lower than LC 50 (96) (0.1 mg Hg l -1 ) resulted in progressive reduction in heart rate similar to that of control crabs.

The cardiac response of the crabChasmagnathus granulatusas an index of sensory perception

“…In decapod crustaceans many studies have used the changes in a vegetative index to monitor the effects of a wide range of environmental variables on the physiology: water currents (Larimer, 1964), P O2 (Airriess and McMahon, 1994), ammonia (NH 3 ) (Bloxham et al, 1999), heavy metals (Aagaard et al, 2000), ambient CO 2 /O 2 (Gannon and Henry, 2004), water temperature (Camacho et al, 2006). In addition, the responses to several types of stimuli (tactile and chemical cues) were examined for their effects on the heart and ventilatory rate of crayfish, finding a reflex inhibition in the majority of them (Larimer, 1964).…”