The Effect of Beach Nourishment with Aragonite Versus Silicate Sand on Beach Temperature and Loggerhead Sea Turtle Nesting Success

Abstract

Heavy erosion and dwindling offshore sand sources have resulted in increased pressure to find alternate sand sources for Florida beach renourishment. One potential economically viable source is oolitic aragonite commercially mined in the Bahamas, however the environmental impacts of aragonite sand on Florida beaches has not been determined. This study was undertaken to examine the effects of oolitic aragonite on one organism, the threatened loggerhead sea turtle (Caretta caretta), which nests in great numbers on beaches of the Southeastern United States. Temperature grain size distribution, and hydric potential were measured, and the effects of these physical factors on loggerhead nest hatching and emergence success were compared for nests buried in aragonite versus native Florida silicate sand. There were no significant differences in grain size distribution or water potential between nests in each sand type: however temperature regimes in the two sands differed significantly. While both sand types had similarly high hatching and emergence success rates of 86% to 97%, the study raises important questions concerning the possible effects of observed nest temperature differences on hatchling sex ratios.