Nesting Site Preference of Marine Turtles in the Central Red Sea

Abstract

Oviposition habitat is important to species with no protracted parental care. For sea turtles, nest site selection may affect offspring fitness through microenvironmental characteristics such as moisture, beach slope, temperature and grain size. Climate change and coastal development will result in changes of nest site characteristics. In particular in Saudi Arabia, with the advent of tourism, there will be development of giga-projects such as the crossborder city of NEOM and luxury tourist resort ‘The Red Sea Project’. To evaluate the different beach characteristics, we assessed the change in parameters over the nesting season, differences in microenvironmental characteristics with regard to nest distribution and compared differences between low- and high- density nesting sites in the central Red Sea, during the 2019 nesting season. We sampled on a biweekly basis, taking various insitu measurements and collecting sand samples to be analysed for grain size, moisture content and colour. HOBO temperature loggers were deployed at sites where nesting occurred. At our low- density sites nest distribution was dictated mainly by angle of beach slope, ANOVA (P<0.05) and the presence of vegetation with most nesting clustered where the slope was steepest and at the sand to vegetation interface. Differences between highand low- density sites were revealed by differences in grain size and sorting conducive of the differences in sediment composition. The change in characteristics over time showed a sequential order of environmental cues: temperature, moisture and slope that initiate nesting. Our results establish the importance of particular beach characteristics in nest site selection of marine turtles, highlighting geologically unique nesting sites and specific environmental cues related to nest timing. This information can be used to inform future coastal development and conservation strategies in Saudi Arabia and is the first study to identify low-nesting sites in the Saudi Arabian Red Sea.