Show your beaks and we tell you what you eat : different ecology in sympatric Antarctic benthic octopods under a climate change context
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Sympatry can lead to higher competition under climate change and other environmental pressures, including in South Georgia, Antarctica, where the two most common octopod species, Adelieledone polymorpha and Pareledone turqueti, occur side by side. Since cephalopods are typically elusive animals, the ecology of both species is poorly known. As beaks of cephalopods are recurrently found in top predator's stomachs, we studied the feeding ecology of both octopods through the evaluation of niche overlapping and specific beak adaptations that both species present. A multidisciplinary approach combining carbon (δ13C) and nitrogen (δ15N) stable isotope signatures, mercury (Hg) analysis and biomaterials' engineering techniques was applied to investigate the beaks. An isotopic niche overlap of 95.6% was recorded for the juvenile stages of both octopod species, dropping to 19.2% for the adult stages. Both A. polymorpha and P. turqueti inhabit benthic ecosystems around South Georgia throughout their lifecycles (δ13C: −19.21 ± 1.87‰, mean ± SD for both species) but explore trophic niches partially different during adult life stages (δ15N: 7.01 ± 0.40‰, in A. polymorpha, and 7.84 ± 0.65‰, in P. turqueti). The beaks of A. polymorpha are less dense and significantly less stiff than in P. turqueti. Beaks showed lower mercury concentration relative to muscle (A. polymorpha - beaks: 0.052 ± 0.009 μg g−1, muscle: 0.322 ± 0.088 μg g−1; P. turqueti - beaks: 0.038 ± 0.009 μg g−1; muscle: 0.434 ± 0.128 μg g−1). Overall, both octopods exhibit similar habitats but different trophic niches, related to morphology/function of beaks. The high Hg concentrations in both octopods will have negative consequences on their top predators and may increase under the present climate change context.
Matias , R S , Gregory , S , Ceia , F R , Baeta , A , Seco , J , Rocha , M S , Fernandes , E M , Reis , R L , Silva , T H , Pereira , E , Piatkowski , U , Ramos , J A & Xavier , J C 2019 , ' Show your beaks and we tell you what you eat : different ecology in sympatric Antarctic benthic octopods under a climate change context ' , Marine Environmental Research , vol. 150 . https://doi.org/10.1016/j.marenvres.2019.104757
Marine Environmental Research
Copyright © 2019 Elsevier Ltd. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.marenvres.2019.104757
DescriptionJ.Xavier was supported by the Investigator program (IF/00616/2013) of the Foundation for Science and Technology (FCT-Portugal) and PROPOLAR, and FRC was supported by a postdoctoral fellowship (SFRH/BPD/95372/2013) attributed by FCT-Portugal and the European Social Fund(POPH, EU). This study benefited from the strategic program of MARE, financed by FCT (MARE- UID/MAR/04292/2019). We also acknowledge FCT-Portugal through a PhD grant to J. Seco (SRFH/PD/BD/113487).
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