O papel ecológico da tartaruga-verde: um megaherbívoro no ambiente recifal

Abstract

Herbivory is an essential process for the health and resilience of reefs, Where primary producers have their growth limited by the intense grazing of several herbivores. The knowledge of herbivory is restricted to studies with fish and hedgehogs, with a gap in the understanding of the role of megaherbivores, such as the green turtle. The green turtle is the only species of sea turtle that throughout its ontogeny adopts a mostly herbivorous diet. In this study, the ecological role of the green turtle in reef environments in the APA Costa dos Corais was investigated, evaluating the feeding ecology of juveniles and sub- adults. This evaluation comprised analysis of diet (n = 36), and niche overlap of the green turtle groups. We used análise3C and 15N stable isotope analysis to broaden the understanding of the inter and intraspecific trophic interactions of the green turtle with other reef herbivores, as well as the contribution of primary sources in the diet. The results showed that red algae had the greatest relative contribution to the diet in both groups, juveniles and sub-adults, with emphasis on the Gelidiales family, which was the most preferred. Niche overlap was high, but sub-adult turtles had a greater horizontal niche breadth, reflecting the use of more basal resources. Immature green turtles play the role of macroalgae scavenger megahebivores in reef environments, acting as an agent with redundant and possibly complementary functions at different scales.