Effects of oil exposure and oil-related compounds on the immune system of the arctic and temperate scallops, chlamysislandica and pecten maximus

Abstract

With the current expansion of offshore oil activities in Arctic regions, there is an urgent need to establish the potential effects of oil-related compounds on Arctic organisms. The scallop Chlamys islandica is distributed throughout the sub-Arctic and has been proposed as a sentinel species for this region. In addition, the temperate scallop Pecten maximus occurs in regions of oil activity and, with increasing sea temperatures, the limit of its distribution may extend further into sub-Arctic regions. P. maximus also accumulates contaminants to a greater extent than the current temperate sentinel Mytilus edulis. A hierarchical approach, similar to that adopted to assess vertebrate immune function, was used to determine immunocompetence in the Arctic scallop C. islandica and the temperate scallop P. maximus following exposure to oil and oil-related compounds. The Arctic scallop C. islandica demonstrated a reduced immunocompetence following both dispersed and acute oil exposure. Immunomodulation in the scallops exposed to low levels of dispersed oil appeared to be reversible following removal of the contaminant stress (Chapter 3). However, a simulated oil spill resulted in mortalities and it remains unclear if the organisms are able to recover from the substantial immune suppression observed (Chapter 4). A component of crude oil and the most abundant PAH in aquatic ecosystems, phenanthrene suppressed immune function in P. maximus. These results indicated a link between PAH-induced oxidative stress and the subsequent inhibition in haemocyte immune function (Chapter 5). However, the ability of scallop haemocytes to recognise and respond to a pathogen-associated molecular pattern was not affected by phenanthrene exposure (Chapter 6). The immune parameters used in this research were shown to be sensitive, reliable markers of immunocompetence that can be directly linked to host resistance (Chapter 7). These immune parameters were also used to assess the sublethal effects of drilling wastes associated with offshore oil production (Chapter 8), indicating their potential as ecotoxicological monitoring tools.