Predicting the impacts of sea level rise in sea turtle nesting habitat on Bioko Island, Equatorial Guinea

Abstract

Sea level is expected to rise 44 to 74 cm by the year 2100, which may have critical, previously un-investigated implications for sea turtle nesting habitat on Bioko Island, Equatorial Guinea. This study investigates how nesting habitat will likely be lost and altered with various increases in sea level, using global sea level rise (SLR) predictions from the Intergovernmental Panel on Climate Change. Beach profiling datasets from Biokos five southern nesting beaches were used in GIS to create models to estimate habitat loss with predicted increases in sea level by years 2046-2065 and 2081-2100. The models indicate that an average of 62% of Biokos current nesting habitat could be lost by 2046-2065 and 87% by the years 2081-2100. Beach D is predicted to be the least vulnerable to increases in sea level. Erosion and tall vegetation berms have been documented on Beaches A and B, causing green turtles to nest uncharacteristically in front of the vegetation line. Development plans are currently underway for Beach D. With Beach D being the least susceptible to future increases in sea level, development and anthropogenic encroachment here would be especially detrimental to nesting turtle populations. Identified habitat sensitivities to SLR will be used to inform the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations and projected climate change implications when planning for future development. To our knowledge this is the first study to predict the impacts of SLR on sea turtle nesting habitat in Africa.