Climate Change Induced Copper Toxicity in Two Key Arctic Copepod Groups

Abstract

The Arctic marine environment is experiencing unpreceded rates of changes due to global warming. Warming Arctic environments cause permafr ost thawing and remobilisation of copper into marine environments. Calanoid copepods are an important energy source for higher trophic levels and key drivers for Arctic ecosystem functioning and food web dynamics. Acute multistressor experiments with coppe r under varying thermal regimes were conducted with Calanus spp. and Acartia longiremis collected from the Norwegian Arctic. Genetic integrity was measured by the fast micromethod assay and DNA damage was significantly elevated in Calanus spp. after 24 hou rs exposure for all treatments (0.07 ± 0.01 SSF (+3°C), 0.06 ± 0.01 SFF (Cu), 0.05 ± 0.01 SFF (Cu + 3°C), mean ± s.e.). A combination of Cu and + 3°C resulted in higher DNA damage after 4 and 8 hours compared with the Cu treatment alone. DNA damage was no longer detected after 24 hours of recovery in clean water. No Cu induced DNA damage was detected in the Arctic specialist A. longiremis , indicating higher resilience to this genotoxic stressor. Temperature induced DNA damage was detected in A. longiremis a fter 8 and 24 hours (0.05 ± 0.02 SFF, 0.02 ± 0.03 SFF, respectively). The toxicity mechanism driving the genotoxic response is still unknown, and gene expression analyses will target biomarkers for oxidative stress (e.g., cat, ferritin ) and induction of D NA repair (e.g., ercc1, parp1 ). Metal contamination and ocean warming can trigger genetic damage and wider implications on future copepod populations and food web dynamics should be investigated further.