Trophic ecology and foraging areas of cetaceans sampled in the coastal waters of south-eastern Brazil assessed through skin δ 13 C and δ 15 N

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Paschoalini, Victor Uber, Troina, Genyffer Cibele, Campos, Laura Busin, Santos, Marcos César de Oliveira
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2021
• Subjects: baleen whales; Megaptera novaeangliae; Orca; Orcinus orca
• Online Access: http://dx.doi.org/10.1017/s0025315421000217; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315421000217

Abstract We investigated the habitat use and feeding ecology of 10 cetacean species encountered along the south-eastern coast of Brazil (24–26°S) using carbon ( δ 13 C) and nitrogen ( δ 15 N) stable isotopes. Hierarchical cluster analysis distinguished two main groups based on their isotopic patterns. One group included migratory baleen whales ( Megaptera novaeangliae and Eubalaena australis ) with the lowest δ 13 C and δ 15 N values, reflecting baseline isotopic values of their Subantarctic feeding grounds and consumption of lower trophic level prey. Resident species and those occasionally occurring in Brazilian coastal waters highly differed from the migratory whales in their isotopic values. In this group, Tursiops truncatus had the highest δ 13 C and δ 15 N values, indicating coastal habits and relatively higher trophic position. Similar δ 13 C values were observed in Sotalia guianensis , Pontoporia blainvillei , Orcinus orca and Steno bredanensis . However, the former two species had lower δ 15 N values than the latter two, indicating different trophic positions. The relatively lower δ 13 C values observed in Stenella frontalis suggest greater influence of pelagic prey in their diet. Furthermore, the lower δ 13 C values observed in Delphinus delphis and Balaenoptera edeni were associated with upwelling events that occur along the region, affecting the isotopic values of their main prey. Juvenile M. novaeangliae had higher δ 13 C and δ 15 N than the adults, which may indicate feeding in areas with different isoscapes and consumption of pelagic schooling fish with relatively higher trophic levels than krill. This study provides preliminary information that are useful to understand the habitat use and coexistence of cetacean species occurring in south-eastern Brazil.