Stable isotopes as measure of niche breadth of nesting green turtles (Chelonia mydas) on Rocas Atoll, Brazil

The study analysed the niche breadth of nesting green turtles, Chelonia mydas, on Rocas Atoll, Brazil, through stable isotopes (δ15N and δ13C), comparing samplings of egg yolk and carapace collected from two nesting groups (2017 and 2019). The mean δ15N values in egg yolk and carapace were 7.1‰...

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Bibliographic Details
Main Authors: Agostinho, Karoline Fernanda Ferreira, Monteiro, Leandro Rabello, Carvalho, Carlos Eduardo Veiga de, Beneditto, Ana Paula Madeira Di
Format: Article in Journal/Newspaper
Language:English
Published: Sustenere Publishing 2021
Subjects:
Online Access:http://www.sustenere.inf.br/index.php/rica/article/view/CBPC2179-6858.2021.003.0008
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Summary:The study analysed the niche breadth of nesting green turtles, Chelonia mydas, on Rocas Atoll, Brazil, through stable isotopes (δ15N and δ13C), comparing samplings of egg yolk and carapace collected from two nesting groups (2017 and 2019). The mean δ15N values in egg yolk and carapace were 7.1‰ (2017) and 6.8‰ (2019), and 7.8‰ (2017) and 7.3‰ (2019), respectively. For δ13C, the mean values were -17.4‰ (2017) and -17.5‰ (2019) in egg yolk, and -18.4‰ (2017) and -17.9‰ (2019) in carapace. The results suggest herbivory in coastal-benthic environments as the main feeding pattern in this nesting population. The niche breadth was similar between 2017 and 2019 in both tissues. In general, the trophic diversity (NR, CR, CD and SEA) was comparable between years as well as the trophic redundancy (MNND and SDNND), which was overall high. The niche metrics pointed to a homogeneous feeding pattern in the two nesting groups (2017 and 2019). This study adds a piece to solve the puzzle of adult green turtle trophic ecology. O estudo analisou a amplitude do nicho de tartarugas verdes, Chelonia mydas, no Atol das Rocas, Brasil, por meio de isótopos estáveis (δ15N e δ13C), comparando amostragens de gema de ovo e carapaça coletadas de dois grupos de nidificação (2017 e 2019). Os valores médios de δ15N na gema do ovo e na carapaça foram 7,1‰ (2017) e 6,8‰ (2019), e 7,8‰ (2017) e 7,3‰ (2019), respectivamente. Para δ13C, os valores médios foram -17,4‰ (2017) e -17,5‰ (2019) na gema de ovo, e -18,4‰ (2017) e -17,9‰ (2019) na carapaça. Os resultados sugerem que a herbivoria em ambientes costeiros-bentônicos é o principal padrão alimentar nesta população. A amplitude do nicho foi semelhante entre 2017 e 2019 em ambos os tecidos. Em geral, a diversidade trófica (NR, CR, CD e SEA) foi comparável entre os anos, assim como a redundância trófica (MNND e SDNND), que em geral foi elevada. As métricas de nicho apontaram para um padrão de alimentação homogêneo nos dois grupos de nidificação (2017 e 2019). Este estudo ...