Influência das fases lunares e dos parâmetros oceanográficos no comportamento de nidificação da tartaruga-verde (Chelonia mydas) no Atol das Rocas.

Abstract

Animals tend to have patterns of synchronization of their reproductive behavior influenced by biological rhythms and environmental conditions. Thus, the choice of the oviposition moment constitutes an important stage for the survival success of sea turtles, as they do not present parental care. That being said, this work aimed to analyze the relationship of nesting behavior of Chelonia mydas with lunar luminosity, lunar phases, tides and sea surface temperature (SST) in the Atol das Rocas Biological Reserve – RN. Rocas Atoll is a distinct site for the behavioral study of green turtles because it has minimal anthropogenic disturbances and is the largest breeding area of this species in Brazil. Field data were obtained during night monitoring of the reproductive seasons, from 2018 to 2020, and were related to lunar luminosity, the lunar angle and the SST. The seasons totaled 756 occurrences of C. mydas on the Farol Island in Rocas Atoll. The year 2020 presented approximately twice the total occurrences when compared to 2018 and 2019, and different individuals were probably sampled each season due to the remigration period. Although the lunar luminosity and the lunar phases showed no statistically significant effect, there was a higher frequency of turtles climbing the beach in moments of absence of lunar luminosity, suggesting that it is a strategy to decrease exposure to predators. The green turtles showed a possible oviposition preference during new and full moon, under spring tides, since this tide allows for a longer oviposition time, since the exposure of the reefs in Rocas Atoll causes the turtles to ascend to the beach in the high tides. Sea surface temperature was the only variable that presented a statistically significant relationship in the three types of occurrences (complete oviposition, incomplete oviposition and “false crawl”), evidencing a preference of ascension to the beach by the turtles in higher temperatures, around 29.5 °C. Lunar luminosity, lunar phases and tides have some degree of influence on the green turtle's oviposition pattern, but do not limit it, as turtles climb the beach in the different environmental conditions observed. Thus, comprehending the influence of the environmental variables on the oviposition behavior of the green turtle can improve the monitoring effort for its conservation, and to understand how this endangered species will respond to climate changes.