The Influence of Temperature on Toxicity towards Mytilus Edulis (L.) exposed to the Heavy Metal Copper and Polycyclic Aromatic Hydrocarbon, Phenanthrene

Environmental monitoring agencies are increasingly utilising biological markers during assessment of ecosystem anthropogenic contamination in marine, terrestrial and atmospheric environments. The majority of biological markers used in such investigations have been established under temperate conditions, and little is known about the biomarker responses of organisms acclimated to different temperatures. In light of this, the current investigation examined the response of a suite of biomarkers (heart rate, neutral red retention, spontaneous cytotoxicity and the single cell gel assay) of the common mussel, Mytilus edulis L. exposed to the heavy metal, copper, and the polycyclic aromatic hydrocarbon, phenanthrene, at temperatures of 5°C, 10°C and 20°C. The influence of temperature was clearly shown with each biomarker and also through 100% mortality of individuals exposed to copper at the highest temperature (20°C). The heart rate of phenanthrene exposed individuals showed little variability throughout the 14 day exposure period, however did show a temperature related increase; median rates for each temperature (+/- S.D) found 5°C = 17bpm (+A 3.3bpm), 10°C = 19bpm (+/- 2.6bpm) and at 20T = 20bpm (+/- 5.7bpm). The median heart rates of copper exposed individuals declined throughout the exposure time, but the median heart rate also displayed the influence of temperature; 5°C = 17bpm (+/- 1.8bpm), and 10°C = 20bpm (+/-4.3bpm). Increasing temperature resulted in significant differences in the retention of the neutral red dye at higher temperatures for phenanthrene (P<0.001), but not copper. The immune response of M. edulis was compromised to a significant degree at 5°C and 10°C (P<0.0001) for copper exposed mussels, but only at 20° for phenanthrene exposed mussels (P< 0.001). Genotoxicity attributable to copper was noted at a significant level (P