Fish, M.R.

Global sea-level rise of up to 0.6 m is predicted in the next 100 years. In areas where coastal structures prevent landward mi- gration of beaches, a major impact of sea-level rise will be a loss of beach habitat, with repercussions for beach-dependent organ- isms such as sea turtles. Setback regulations, which prohibit construction within a set distance from the sea, have the potential to mitigate loss of beach area by providing a buffer zone which allows for the natural movement of beaches in response to perturbation. The potential impact of a rise in sea level on 11 important sea turtle nesting beaches in Barbados under a range of setback regu- lations was determined. Three sea-level rise scenarios were modelled under five different setback regulations (10, 30, 50, 70 and 90 m). Beach area was lost from all beaches under all sea-level rise scenarios with a 10 and 30 m setback, from some beaches with a 50 m setback and from one beach with a 70 m setback. No beach area was lost with a 90 m setback distance. Sea turtles nest within a range of beach elevations and there was an overall loss of beach habitat within the preferred nesting elevation range with both a 10 and 30 m setback under all sea-level rise scenarios. Considerable variation in the extent of beach and nesting area loss was observed. The implementation and enforcement of adequate setback regulations have the potential to maintain the ecological and economic function of beaches in the face of extensive coastal development and sea-level rise. 

The projected rise in sea level is likely to increase the vulnerability of coastal zones in the Caribbean, which are already under pressure from a combination of anthropogenic activities and natural processes. One of the major effects will be a loss of beach habitat, which provides nesting sites for endangered sea turtles. To assess the potential impacts of sea-level rise on sea turtle nesting habitat, we used beach profile measurements of turtle nesting beaches on Bonaire, Netherlands Antilles, to develop elevation models of individual beaches in a geographic information system. These models were then used to quantify areas of beach vulnerable to three different scenarios of a rise in sea level. Physical characteristics of the beaches were also recorded and related to beach vulnerability, flooding, and nesting frequency. Beaches varied in physical characteristics and therefore in their vulnerability to flooding. Up to 32% of the total current beach area could be lost with a 0.5-m rise in sea level, with lower, narrower beaches being the most vulnerable. Vulnerability varied with land use adjacent to the beach. These predictions about loss of nesting habitat have important implications for turtle populations in the region.