Understanding the coastal erosion vulnerability influence over sea turtle (Eretmochelys imbricata) nesting in NE of Brazil

Abstract

Most of the studies on sea turtle nesting activity nowadays are focused on the impacts of climate change. However, there is a lack of studies gathering knowledge about the influence of coastal vulnerability to erosion and settlement to assess sea turtle nesting. This study aims to verify the influence of coastal erosion vulnerability over sea turtle nesting in five Brazilian Northeast beaches, in Pernambuco state, at Ipojuca coast. The main analyzed parameters were the urban settlement, coastal erosion indicators and the conservation status of the dunes by assessing shoreline change rates, backshore extension, vegetation cover and beaches morphodynamics associated aspects. Spearman’s rank correlation coefficient and tests of Kruskal–Wallis, Mann–Whitney, Shapiro–Wilk and Levene were employed as a set of statistical analyses. The results state that Eretmochelys imbricata is the predominant species that nests at the Ipojuca coast (93.2% of nesting females). There is a significant difference in the number of nests among the studied beaches (Kruskal–Wallis; p = 0.004). A strong and positive correlation between the backshore width and the number of nests was verified (Spearman’s rank correlation, rs = 0.881; p = 0.0002). The results indicate the preference for nesting on wave-dominated beaches, where the coastal reefs are absent and there is a well-developed backshore, mainly due to the lower urban settlement in these areas. Thus, efforts focused on preserving nesting beaches, especially those under high urbanization, are a key factor for sea turtle preservation.