Stable isotopic composition of Antarctic and Patagonian marine mammals collected before and during industrial-scale whaling:assessing the baseline for long-term changes in the marine ecosystem

Great Antarctic expeditions, seal hunting and whaling industries left a legacy in natural history collections. To provide the basis for analysing the impact of whaling on marine ecosystem structuring, we conducted bulk isotope analysis from specimens of baleen whales ( Balaenoptera musculus and Balaenoptera physalus) and seals ( Arctocephalus australis and Hydrurga leptonyx) collected between 1843 and 1951 from the South Atlantic, Patagonian waters, Southern Ocean and Antarctic coastal seas, and preserved in the collection of Natural History Museum, London. Analysis of this material indicates the pre-whaling state of these environments and changes in the trophic position (TP) of whales and seals during the period of extensive human pressure. Being controlled for the Suess effect, δ 13C values in B. musculus, B. physalus and H. leptonyx varied during the period of industrial-scale whaling. Bone collagen δ 15N values and corresponding TP indicate possible trophic changes in A. australis and variability of the foraging areas of B. musculus. This study highlights the use of museum specimens for tracing historical trends associated with changes in the population structure and distribution of species, indicating long-term variability in their foraging ecology.This article is part of the theme issue 'Shifting seas: understanding deep-time human impacts on marine ecosystems'.