Ecological traits of the franciscana dolphin ( Pontoporia blainvillei ) from the Late Pleistocene to the present days based on stable isotope analysis

• Published in: Marine mammal science Vol. 39; no. 4; pp. 1106 - 1120
• Main Authors: Carrasco, Thayara S., de Lima, Renan C., da Mota, Gabriel S., Botta, Silvina, Secchi, Eduardo R., Ribeiro, Ana Maria, Ferigolo, Jorge, Buchmann, Francisco S.
• Format: Journal Article
• Language: English
• Published: Beaufort Wiley Subscription Services, Inc 01.10.2023
• Subjects: Analytical methods; Aquatic mammals; Carbon 13; Diagenesis; Dolphins; Fish; Fossils; Fourier transforms; Freshwater; Freshwater fish; Habitat selection; Habitat utilization; Human influences; Infrared analysis; Infrared spectroscopy; Inland water environment; Marine mammals; Oxygen isotopes; Pleistocene; Pontoporia blainvillei; Stable isotopes; Temporal variations
• ISSN: 0824-0469; 1748-7692
• DOI: 10.1111/mms.13031

Late Pleistocene fossils from southern Brazil provide a unique opportunity to study the diet and habitat use of the extant franciscana dolphin ( Pontoporia blainvillei ) prior to human influence. Here, we subject 19 fossil and 21 contemporary specimens to stable carbon and oxygen isotope analysis (after first ruling out diagenesis via Fourier transform infrared spectroscopy). The two groups differ in their isotopic composition (PERMANOVA, p  < .01), with fossils yielding more disparate δ 13 C values and recent samples more disparate δ 18 O values. Their isotopic niches show an overlap of ~20%, with that of the fossils being slightly wider (SEAc = 2.25‰ 2 versus 1.84‰ 2 ). We attribute these differences to impoverished modern fish communities and temporal changes in freshwater influx.