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

Author(s)

Paschoalini, Victor Uber ^[1] ; Troina, Genyffer Cibele ^[2] ; Campos, Laura Busin ^[1] ; de Oliveira Santos, Marcos Cesar ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Oceanog, Lab Biol Conservacao Mamiferos Aquat LABCMA, BR-05508120 Sao Paulo, SP - Brazil

^[2] Univ Fed Rio Grande, Lab Ecol & Conservacao Megafauna Marinha ECOMEGA, Inst Oceanog, BR-96203900 Rio Grande, RS - Brazil

• Document type: Journal article
• Source: Journal of the Marine Biological Association of the United Kingdom; v. 101, n. 2, p. 471-480, MAR 2021.
• Web of Science Citations: 0

Abstract

We investigated the habitat use and feeding ecology of 10 cetacean species encountered along the south-eastern coast of Brazil (24-26 degrees S) using carbon (delta C-13) and nitrogen (delta N-15) 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 delta C-13 and delta N-15 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 delta C-13 and delta N-15 values, indicating coastal habits and relatively higher trophic position. Similar delta C-13 values were observed in Sotalia guianensis, Pontoporia blainvillei, Orcinus orca and Steno bredanensis. However, the former two species had lower delta N-15 values than the latter two, indicating different trophic positions. The relatively lower delta C-13 values observed in Stenella frontalis suggest greater influence of pelagic prey in their diet. Furthermore, the lower delta C-13 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 delta C-13 and delta N-15 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. (AU)

• FAPESP's process: 11/51543-9 - Cetacean occurrence, distribution and movements along the coast of São Paulo State
• Grantee: Marcos César de Oliveira Santos
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants