Beach rock as a keystone habitat for amphibious sea snakes

Abstract

SUMMARY The shorelines of coral islets are subject to strong anthropogenic pressure, being highly coveted for tourism. These landforms contain unique biotic assemblages but unfortunately are limited in size making them extremely vulnerable to perturbation. Robust information linking habitat structure and species requirements is urgently needed to promote and guide the conservation of these fragile areas. New Caledonia contains critical shore habitats for two species of amphibious sea snakes. One species (Laticauda laticaudata) shelters almost exclusively under mobile beach rocks, which are both easily accessible from the sea and regularly submerged at high tide. The scarcity of such specific and spatially limited habitat restricts the distribution of this species to highly localized areas. The other species (L. saintgironsi)usesagreatervarietyofterrestrialrefuges, but has a preference for shores with abundant beach rocks. These findings offer a robust basis to promote the conservation of these crucial habitats and to justify their inclusion in marine protected areas(MPA), which in turn should benefit a wide array of other organisms also dependent on beach rocks.