Coastal Science for Sea Turtle Conservation

Abstract

Sandy beaches provide a wide range of ecosystem services, including flood protection, sediment and water storage, recreational values, and habitat for diverse flora and fauna. Over the past centuries, humans have increasingly developed settlements and infrastructure on the landward side, while waves, storm surges, and sea level rise encroach from the ocean side. These stressors may lead to ecological impacts across varying temporal and spatial scales, threatening the ecosystem services for humans and animals alike.
Among the species particularly vulnerable to the degradation of sandy beaches are sea turtles, who rely on these habitats for nesting. These endangered reptiles play key ecological roles in coastal and marine ecosystems worldwide, for instance by maintaining healthy coral reefs and sea grass meadows. Unfortunately, climate change and human activity severely threaten their populations. Among the challenges they face are the flooding and erosion of their nesting beaches. Incubating nests require a narrow temperature and moisture window to develop, making them susceptible to inundation. Episodic erosion can destroy nests and change beach morphology over several seasons. Long-term, chronic erosion and coastal squeeze may gradually diminish suitable nesting beaches worldwide. Although both flooding and erosion are recognized as significant threats, they remain under-represented in conservation management and research. Nature-based solutions—such as turtle-friendly sand nourishments or restoration of coastal vegetation and reefs—may offer promising opportunities to preserve existing nesting habitats, and potentially enable sea turtles to expand to currently unused beaches. However, we first need to understand the coastal processes that enable and threaten sea turtle nesting to effectively design such solutions.
This thesis identifies coastal processes that govern the vulnerability of sea turtle nesting beaches, and assesses their implications for global habitat suitability and conservation. Specifically, it investigates processes related to nest flooding and long-term erosion, while also examining how regional coastal characteristics influence global nesting habitat suitability. Employing detailed local case studies and global analyses, this thesis integrates diverse methods—including field experiments, numerical modeling, remote sensing, statistical analyses, global datasets, and machine learning—to illustrate the broad potential of coastal science tools for sea turtle conservation, which are essential for developing an integrative approach to assess nesting beach vulnerability and inform targeted interventions...