Laboratório de Ecologia e Conservação da Megafauna Marinha (ECOMEGA), Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Avenida Itália km 8, Rio Grande, RS, Brazil.
Department of Marine Microbiology & Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, Den Hoorn, 1790AB, the Netherlands.
Environ Res. 2021 Oct;201:111610. doi: 10.1016/j.envres.2021.111610. Epub 2021 Jul 2.
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 analysed δN in individual amino acids (AA) to estimate cetacean trophic position (TP) and to evaluate the spatial differences in baseline δN (source AAs). We adjusted cetacean bulk-skin δC and δN for the effect of trophic level using their estimated TPs, obtaining δC and δN, 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 δN 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-δN showed similar patterns as those of baseline-δN (zooplankton) and were higher in species sampled in the southernmost region of the study area (e.g., Delphinus delphis). Isotopic niche areas estimated using δC and δN suggested high overlap in foraging area between S. frontalis and Tursiops truncatus, with the latter occupying a higher TP. Our analyses of δN 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-δN baseline for future studies on the trophic ecology and habitat use of marine organisms in the western South Atlantic.
我们使用天然存在的稳定同位素研究了在南大西洋西部海域出现的十种鲸目动物的营养结构和栖息地利用。我们分析了个体氨基酸（AA）中的 δN，以估计鲸目动物的营养位置（TP），并评估基线 δN（来源 AA）的空间差异。我们通过估计的 TP 调整了鲸目动物的整体皮肤 δC 和 δN，分别获得 δC 和 δN。这些值用于估计鲸目动物基线来源的生态位重叠。我们的分析表明，Steno bredanensis 与其余齿鲸之间存在空间分离，该物种的高 δN 反映了其在南部近岸水域的存在。Physeter macrocephalus、 Stenella attenuata 和 Globicephala melas 的 TP 最高，而 S. longirostris、S. clymene 和 Orcinus orca 的 TP 最低。总体而言，来源 AA-δN 的模式与基线-δN（浮游动物）相似，并且在研究区域最南端采样的物种中更高（例如，Delphinus delphis）。使用 δC 和 δN 估计的生态位面积表明，S. frontalis 和 Tursiops truncatus 的觅食区域高度重叠，后者占据更高的 TP。我们对 AA 中 δN 的分析提供了对这些鲸目动物种群的营养生态、觅食区和资源利用空间分离的独特见解。此外，我们的工作为未来研究南大西洋西部海洋生物的营养生态和栖息地利用提供了 AA-δN 基线。
