Environmental influences on tooth growth in sperm whales from southern Australia

Long time series are a necessary tool for investigating relationships between environmental variability and population parameters in marine predators and establishing changes in these, particularly under longer-term climatic change. Multi-decadal ecological datasets are however, generally lacking, as their collection requires substantial commitment.We examined time series of growth layer group widths measured in sperm whale teeth, as indicators of energetic history, firstly to investigate commonalities in growth both within and between individuals and secondly to investigate potential relationships between tooth growth and the marine environment. Growth layer group estimates obtained from the teeth of 27 individual whales ranged 14–52 GLGs. Time series of tooth growth were highly variable both within and between individuals, reflecting differences in overall tooth structure within individuals and independence of energetic budgets among individuals. Relationships between tooth growth and broad-scale environmental variables were unclear. Spatial relationships between sea surface temperature and tooth growth histories were identified across the austral summer and corresponded to historical foraging regions in southern Australian waters. Our results demonstrate the potential for sperm whale teeth to provide extended time series of individual growth and nutritional histories. Further research is needed to understand the influence of intrinsic and extrinsic factors on tooth growth and in association, a better understanding of the responses ofmarine mammal species to environmental variability.