Use of biopsy sample of humpback whale (Megaptera novaeangliae) skin for stable isotope (d13C) determination

Previous work has shown that stable isotope indicators taken from the muscle tissue of dead, stranded cetaceans can be used to assess diet. Recent advances in remote biopsy techniques have provided a means to collect skin and blubber tissues from live animals. This study examines the potential of biopsy samples taken from humpback whales (Megaptera novaeangliae) for isotopic assessments of diet by 1) determining if isotopic differences exist between the two tissue types obtained in a biopsy (skin and blubber) and the traditional source for isotopic analysis, muscle tissue, 2) examining the effects of two different lipid extraction techniques on the removal of the preservative dimethyl sulfphoxide (DMSO) from tissues, and 3) assessing procedural reproducibility for auto-mated isotopic analysis of skin derived from biopsy samples. Results demonstrate that carbon isotopic values ( δ 13C) of muscle were not significantly different from those of skin (Scheffé, p = 0.4985; δ 13C =-19.1 ‰ ± 0.7 and-19.5 ‰ ± 0.5 for muscle and skin respectively; mean ± SD). The values for blubber ( δ 13C =-23.7 ‰ ± 0.2) were significantly lower than those of muscle or skin (Scheffé, p = 0.0001). Thi