Intra-specific trophic variation in false killer whales (Pseudorca crassidens) from the southwestern South Atlantic Ocean through stable isotopes analysis

Abstract

The false killer whale (Pseudorca crassidens) is a highly social top predator difficult to study in the wild because of its wide-ranging oceanic habits. Mass strandings offer good opportunities to gather ecological information about cetacean species. In this study we analyze a possible isotopic (␦ 13 C and ␦ 15 N) variation in bone collagen among individual false killer whales that mass stranded on the south shore of the Strait of Magellan, Chile, in 1989, in relation to their ontogenetic classes, sex and total body length. We found an isotopic enrichment in ␦ 13 C and ␦ 15 N values from young and smaller to older and larger individuals, respectively. These isotopic shifts may reflect differences in foraging and diving capabilities, enabling older and larger individuals to feed more deeply in the water column and/or on larger prey. The lack of isotopic differences between females and males may suggests little evidence for sex-related resource partitioning in this group, as result of a possible coordination during feeding activities, e.g. food sharing as previous studies have found. We also found an important isotopic effect of lactation in both the carbon and nitrogen isotope composition of nursing calves, probably due to a prolonged nursing period (from 19 month to two years). This study integrate ecological information from several years to lifetime in relation to sex and total body length, obtaining information on possible changes linked to the development of foraging capabilities in false killer whale.

The abundance of false killer whale, Pseudorca crassidens (Artiodactyla: Delphinidae) in coastal waters of Golfo Dulce and Osa Peninsula, Costa Rica

“…The abundance of false killer whale, Pseudorca crassidens (Artiodactyla: Delphinidae) in coastal waters of Golfo Dulce and Osa Peninsula, Costa Rica. Revista de Biología Tropical,68(2), 580-589. and males, supporting cooperative foraging theory (Ortega-Ortiz, Elorriaga-Verplacken, Olivos-Ortiz, Liñan-Cabello, & Vargas-Bravo, 2014;Riccialdelli & Goodall, 2015). False killer whales have also been reported in mixed species aggregation, notably with bottlenose dolphins (Zaeschmar, Dwyer, & Stocking 2013).…”

Estimating the isotopic niche of males and females of false killer whales (Pseudorca crassidens) from Magellan Strait, Chile

“…, Miller et al . , Riccialdelli and Goodall ). These results agree with the higher Nr and Cr values in male bone collagen, indicating that these individuals consumed prey from different trophic levels and could have fed in different foraging areas ( e.g.…”

“…Previous studies indicate no significant intraspecific differences in the diets of odontocete species, including the false killer whales, because they are gregarious animals that show social coordination in behavior during hunting events (Stacey et al . , Baird , Riccialdelli and Goodall ). However, differences in foraging areas and/or differences in the type of prey consumed in relation to sex have been suggested in false killer whales (Andrade et al .…”

“…). Bone samples were obtained from the cranial pterygoid region of 34 adults from the first stranding (males n = 15, females n = 19), of which 24 correspond to specimens from the Museo Acatushún de Aves y Mamíferos Marinos, Estancia Harberton, Tierra del Fuego, Argentina (isotope data published in Riccialdelli and Goodall ) and 10 correspond to specimens from the Museo de Historia Natural de Río Seco, Punta Arenas, Chile. Skin samples were obtained from 15 adult specimens from the second stranding (males n = 8, females n = 7).…”

Relações tróficas e uso de área da toninha, >i<Pontoporia blainvillei>/i< (Gervais e d\'Orbigny, 1844) e do boto-cinza, >i<Sotalia guianensis>/i< (Van Bénéden, 1864) da costa sudeste do Brasil determinados pela composição de isótopos estáveis de carbono e nitrogênio

“…Os dois últimos estudos também mostraram relações positivas entre a idade estimada e os valores de δ 13 C. Aqueles autores inferiram que ambas as relações têm ligação direta com a amamentação, justificando que as mães catabolizam seus próprios tecidos para produzir leite. Esse processo levaria seus filhotes a terem assinaturas maiores de δ 15 N(NEWSOME et al, 2009;RICCIALDELLI et al, 2013) enquanto os indivíduos mais jovens de toninha apresentaram valores mais empobrecidos em δ 13 C devido ao alto teor lipídico do leite, que por sua vez é depletado em 13 C(HOBSON et al, 2004;GOODALL, 2015).O presente estudo trouxe novas informações ao cenário do conhecimento sobre o uso de área e a ecologia trófica de botos-cinza e de toninhas. Esses novos resultados foram baseados na aplicação de uma ferramenta complementar às tradicionais previamente utilizadas na área de estudo para avaliação dos referidos temas (e.g.…”