Abstract
The southern elephant seal, Mirounga leonina, is one of the top predators inhabiting the Southern Ocean. Foraging at sea represents 80% of their annual cycle, during which they make extraordinary wide-ranging trips with long, deep, and continuous dives. Their feeding habits have been broadly studied using both traditional and advanced techniques, like stable isotope analysis. Here, we analyzed stable isotope ratios of C and N of host and sucking lice tissues to investigate the potential use of lice to infer the isotopic patterns of their host at a major scale while using a less invasive method. We collected samples of blood and lice, Lepidophthirus macrorhini, from 15 weaned pups in Península Valdés (Chubut, Argentina). C and N isotopic signals of lice and pups were correlated. The δ13C values of the lice were not different from those of their hosts, while the δ15N signals were statistically significantly enriched with respect to those of the pups. The isotopic composition of the lice would predictably mirror that of their hosts. However, the values of Δ13C and Δ15N (difference between lice and pup signals) differed from the literature-based reference values for hematophagous ectoparasites, indicating that lice could have changed the host recently or that the residence time in the pups has not been enough. Given that mothers and weaned pups differ isotopically due to lactation, the isotopic composition of lice could therefore be more representative of signals from females, implying a useful and a safe tool for identifying and measuring the magnitude of trophic interactions in this species.
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Acknowledgements
Centro Nacional Patagónico (National Scientific and Technical Research Council, CONICET) provided logistical support. Permits to conduct this research were issued by Subsecretaría de Conservación y Áreas Protegidas, Ministerio de Turismo de Chubut (71-SsCyAP/18 and 58-SsCyAP/19), Dirección de Fauna y Flora Silvestre de la Provincia de Chubut (14/2018-DFyFS-M.P and 64/2019-DFyFS-M.P), and Dirección Nacional de Biodiversidad Ministerio de Ambiente y Desarrollo Sostenible (IF-2022-42032445-APN-SPARN#MAD. CITES 46200). Special thanks to Ricardo Vera, Julio Rua, Eliana Lorenti, and Sebastián Poljak for their valuable assistance in the field work.
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EBE and MSL: contributed to the study conception and design. MSL: provided partial funding support. All authors participated in the field sampling and lab activities. Preparation of samples for stable isotope analysis and data analysis were performed by EBE. The first draft of the manuscript was written by EBE. All authors contributed significantly to the manuscript editing before submission and approved the final manuscript.
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The immobilization and sampling of southern elephant seals within the Área Natural Protegida Península Valdés were approved by the Subsecretaría de Conservación y Áreas Protegidas, Ministerio de Turismo and the Dirección de Fauna y Flora Silvestre, Chubut Province (Argentina). The research procedures were reviewed and approved by the Dirección de Fauna y Flora Silvestre, Chubut Province (Argentina). Field work and laboratory analysis received founding support from the Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación (PICT 2018-0537), and the Lerner-Grey Fund for Marine Research.
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Eder, E.B., Leonardi, M.S. & Soto, F.A. What a sucking louse can tell us: the use of the seal lice (Lepidophthirus macrorhini) from the southern elephant seal (Mirounga leonina) in isotopic analysis of hosts. Polar Biol 46, 253–257 (2023). https://doi.org/10.1007/s00300-023-03121-z
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DOI: https://doi.org/10.1007/s00300-023-03121-z