Combined effects of ocean acidification, climate change and oil related discharges

More knowledge is needed about the combined effects of climate change and pollution in the marine environment. Two relevant climate stressors, ocean acidification (OA) and increased temperature have been combined with discharges from offshore oil and gas production (drilling mud and oil). Shrimps (Pandalus borealis) have been exposed to OA (pH 7.6), increased temperature and oil. We observed earlier hatching and significantly faster larval development when the temperature was three degrees over ambient, but the larvae were smaller than in the control. In the future climate scenario the larvae had increased feeding and respiration rate. OA had considerably less effect on shrimp larvae than temperature increase. There was an additive effect of climate change and short term oil exposure on shrimp larvae, especially for larval growth. Hence shrimp larvae may be more vulnerable for pollution (e.g. an oil spill) in the future ocean due to changing climatic conditions. Similarly, we observed an additive effect of OA and oil exposure on growth of sea urchin larvae (Strongylocentrotus droebachiensis). The sea urchin larvae stopped feeding during the oil exposure, growth was reduced and fewer larvae settled. OA alone caused more negative effects on the cold water coral Lophelia pertusa than on larvae of shrimps and sea urchins, and corals were more affected by OA than suspended drilling mud particles (3mg/L). The coral skeleton slowly dissolved when kept at pH 7.6, and the coral polyps were more retracted when exposed to OA. Further, we observed additive effects of exposure to drilling mud and OA on polyp gene expression and on the number of mucus cells in coral tissue. Krill (Meganyctiphanes norvegica) eggs exposed to increased temperature and OA had lower hatching success and there was increased mortality of krill larvae. There was no difference in size of larvae in the two climate scenarios, but larval development was faster as for shrimps. Overall, the results from the project show that climate stressors and pollution stressors often cause additive effects on marine organisms.

We aim to perform experiments that can provide vital new knowledge about the combined effects of OA and global warming/oil industry discharges on fitness and physiological parameters in relevant cold water species. The existing literature on effects of OA on different marine organisms clearly shows that the responses are stage- and species specific. To improve the predictions about the fate of marine ecosystems in a high CO2 world, more information about how different species in the ecosystem respond to O A and other anthropogenic and natural stresses is needed. The proposed project will provide important data on the effects of OA alone and combined with other relevant anthropogenic stressors in adults and early life stages of key species. The experiments will include single stress and combined stress treatments. The test conditions in our experiments will be based on the emission scenarios for this century presented by IPCC. The project will be divided in four work packages (WP). In WP1 we will study the combined effects of OA and increased ocean temperature (global warming) on krill and shrimps. The experiments will start with gravid krill and female shrimps carrying their embryos and continue with studying the effects on the early life stages. In WP2 th e combined effects of OA and oil will be investigated on adults and early life stages of starfish, sea urchins and brittlestars. The aim is find out if there are synergistic effects of combined exposure to OA and oil in echinoderms. The combined effects o f OA and drilling mud on cold water coral will be studied in WP3. The aim is to study possible synergistic effects of combined exposure to OA and drilling mud discharges. In WP4, data from WP1 and WP2 will be used to model the consequences of multiple str essors at the population level.