Year

2016

Degree Name

Doctor of Philosophy

Department

School of Biological Sciences

Abstract

Areas of the subantarctic are isolated, cold, harsh and generally pristine. However, the presence of humans invariably leads to contamination, particularly around research stations and legacy refuse sites. Increases in ship visits to the region will heighten the chance of fuel spills and increase concentrations of contaminants including copper, due to its use as a biocide on ship hulls. Despite this increased risk of contamination, there is currently very limited data available on the sensitivity of subantarctic marine biota to contaminants, and no environmental quality guidelines exist for this region. This study is therefore the first marine-based comprehensive ecotoxicology study within the subantarctic. The aim of my thesis was to determine sensitivities of ten subantarctic marine invertebrates to a range of common metal contaminants (copper, lead, zinc). These data are intended ultimately to contribute to the development of water quality guidelines and risk assessments for the protection of the subantarctic. These guidelines would be applicable to many areas of the subantarctic, extending potentially to the southern areas of South America and the Antarctic Peninsula. In addition, I determined the interactive effects of climate change stressors on the toxicity of copper to four taxa. This was particularly important as many areas of the subantarctic are already experiencing relatively rapid changes in climate. I conducted toxicity tests on ten marine invertebrate species at different life stages, collected from a variety of habitats within the intertidal and subtidal zones of subantarctic Macquarie Island. This required the development of specific test procedures in order to account for the unique characteristics of each species and of subantarctic biota in general. Copper was found to be the most toxic of the three metals tested. Sensitivity differed substantially between the ten species, and patterns appeared to correlate with the species distribution and habitat on the shoreline. Additionally, early life stages were generally more sensitive than adults, and additional climate change stressors altered copper toxicity. For example, an increase in as little as 2 °C significantly increased the toxicity of copper to a subantarctic copepod. Sensitivity to copper was particularly high for some species compared to analogous species from temperate and tropical regions. My work therefore highlights the need for the development of specific water quality guidelines for the subantarctic region based on the sensitivity of local taxa, as guidelines developed in other regions may not adequately protect subantarctic species from contaminants. This study emphasises that while the subantarctic is a relatively pristine environment, in the event of a large-scale contamination event, some species within the marine community would be highly susceptible and therefore long term impacts on this community are likely. Exacerbating this scenario, stressors associated with climate change are likely to further intensify impacts. I recommend that any future environmental guideline development for the subantarctic region consider early life stage sensitivity, include species from a wide range of habitats, and incorporate interactions with climate change variables.

Share

COinS