Dear MARMAMS,
On behalf of my co-authors I am excited to announce our new article published in Environmental Research: Genyffer C. Troina, Philip Riekenberg, Marcel T.J. van der Meer, Silvina Botta, Frank Dehairs, e Eduardo R. Secchi (2021) Combining isotopic analysis of bulk-skin and individual amino acids to investigate the trophic position and foraging areas of multiple cetacean species in the western South Atlantic. https://doi.org/10.1016/j.envres.2021.111610 Abstract: We investigated the trophic structure and habitat use of ten cetacean species occurring in the oceanic waters of the western South Atlantic using naturally-occurring stable isotopes. We analyzed δ15N in individual amino acids (AA) to estimate cetacean trophic position (TP) and to evaluate the spatial differences in baseline δ15N (source AAs). We adjusted cetacean bulk-skin δ13C and δ15N for the effect of trophic level using their estimated TPs, obtaining δ13CAdjusted and δ15NAdjusted, respectively. These values were applied to estimate the overlap in the niche areas of cetacean baseline sources. Our analyses showed spatial segregation between *Steno bredanensis *and the remaining odontocetes, and the high δ15N in this species reflects its occurrence in neritic waters of the southern region. The highest TPs were observed in *Physeter macrocephalus*, *Stenella attenuata* and *Globicephala melas*, while the lowest TPs were reported for *S. longirostris*, *S. clymene* and *Orcinus orca*. Overall, source AA-δ15N showed similar patterns as those of baseline-δ15N (zooplankton) and were higher in species sampled in the southernmost region of the study area (e.g., *Delphinus delphis)*. Isotopic niche areas estimated using δ13C Adjusted and δ15NAdjusted suggested high overlap in foraging area between *S. frontalis *and* Tursiops truncatus*, with the latter occupying a higher TP. Our analyses of δ15N in AAs provide a unique insight into the trophic ecology, forage areas and spatial segregation in resource use among these cetacean populations. Additionally, our work provides AA-δ15N baseline for future studies on the trophic ecology and habitat use of marine organisms in the western South Atlantic. Feel free to contact me if you have any questions: [email protected] Best, Genyffer -- Genyffer Troina, Ph.D. Collaborating Researcher Laboratório de Ecologia e Conservação da Megafauna Marinha (ECOMEGA) Universidade Federal do Rio Grande - FURG, BRAZIL [email protected] CV: http://lattes.cnpq.br/3997346742040354
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