Sandy beaches are essential nesting habitats for sea turtles but their persistence and stability is threatened by rising sea levels driven by climate change. Identifying which nesting beaches are at greatest risk from climate change is an important goal of sea turtle conservation globally. To date, efforts to identify at-risk beaches have been hindered by the ability to model complex processes and incomplete information on nesting distribution and abundance. This study explores the risk of beach erosion and inundation at sites utilised for nesting by flatback turtles (Natator depressus) in the Pilbara region of Western Australia, using the InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) Coastal Vulnerability Model.
Exposure was calculated for 402 sandy beaches, spanning more than 600 km of coastline, in terms of six bio-geophysical variables: wind and wave exposure, surge potential, relief, observed sea level rise and coastal geomorphology, and was coupled with published information on the distribution and abundance of N. depressus nesting activity. We identified that a large proportion (~30%) of beaches with the highest abundance of nesting activity also had the highest exposure. This suggests that coastal exposure is a key vulnerability for N. depressus reproductive success in the region. Promisingly, a number of beaches with the lowest exposure also had the highest abundance of nesting activity and these beaches could provide some natural resilience against coastal exposure.
Threats from climate change won’t happen in isolation however and this talk will also consider site-specific modelled sand temperatures using a mechanistic microclimate model. Taken together, these estimates of coastal exposure and sand temperature will form the basis of a stock-wide assessment of climate change vulnerability at flatback nesting sites in the Pilbara region. Vulnerability varies across spatial scales and the approach presented here allows for a broadscale assessment of climate change risks at a scale most relevant to management.