MEPS 255:183-191 (2003)  -  doi:10.3354/meps255183

ABSTRACT: A previous laboratory investigation showed that the Antarctic gammarid amphipod Paramorea walkeri is more sensitive to heavy metals when exposed to UV-B radiation. The question addressed in this study is whether this effect is also observed when the species is exposed to combined solar UV radiation and heavy-metal contamination under field conditions. In situ bioassays using P. walkeri showed that exposure to field contamination resulted in a significant decrease of survival. The effects observed were stronger than expected according to the characteristics of the contamination. The hypothesis that solar UV radiation can increase the sensitivity of organisms to metal contaminants was thus tested in an outdoor test system. This revealed that the mortality recorded under exposure to both parameters was increased compared to mortalities resulting from exposure to each single parameter. This increased sensitivity of amphipods to heavy metals in the presence of UV-radiation is discussed as an explanation for the absence of this species in contaminated shallow waters. The effects observed at the individual level would thus be reflected at a population level. This work highlights the necessity to consider environmental parameters such as UV radiation in Antarctica to improve the predictive power in ecological risk assessment.

KEY WORDS: UV-B · Heavy-metal contamination · Environmental parameters · Higher-tier risk assessment · Amphipod