PHYSIOLOGICAL MONITORING OF CONTAMINANT EFFECTS IN INDIVIDUAL ROCK CRABS, HEMIGRAPSUS-EDWARDSI - THE ECOTOXICOLOGICAL SIGNIFICANCE OF VARIABILITY IN RESPONSE

1) Heart rates and midgut gland wet weight/dry weight (WW/DW) ratios o f rock crabs (Hemigrapsus edwardsi) were measured in individuals colle cted along a contaminant gradient in Otago Harbour, New Zealand. 2) Me dian heart rates decreased by 15-20% while midgut gland WW/DW ratios i ncreased by 25-30% with increasing contamination of field sites. 3) In tra and inter-individual variability in heart rate increased markedly at the most severely contaminated sites, as did inter-individual varia bility in midgut gland WW/DW ratio. 4) The findings are discussed in t he context of the use of the biomarker approach to address ecotoxicolo gical problems.