A global characterisation of coastal regions to guide nature-based solutions to sea turtle nesting beaches

Sea turtles are an important part of marine and coastal ecosystems around the world. Yet, six of seven sea turtle species are endangered (IUCN, 2021). While they spend most of their lives at sea, female turtles use sandy beaches as nesting habitat, where they dig their nests in the sand to incubate for up to two months. A major challenge to sea turtles is the degradation of their nesting beaches due to anthropogenic climate-change effects, such as accelerated sea level rise (SLR) and anomalous storm activity. While it is still uncertain how sandy beaches will respond to SLR, beaches backed by hard structures cannot migrate landward, leading to ‘coastal squeeze’—the erosion and consequential narrowing of beaches. Increased storm activity may lead to persistently high water levels at nesting beaches, resulting in the flooding or even erosion of incubating nests. Moreover, beach erosion during storms can bury nests under excessive sand and limit beach access through the formation of scarps. Nature-based solutions—for example in the form of turtle-friendly design of beaches along new land reclamations or by adding coastal vegetation or reefs to limit runup and reduce erosion on existing beaches—may offer promising opportunities to preserve and even expand global habitats for turtle nesting.