Diamondback Terrapins (Malaclemys terrapin) of Charleston, South Carolina: Population Estimate, Sex Ratios and Distribution
Date
2014-08-26
Authors
Broyles, Elizabeth
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Very little is known about the current population number, sex ratio, and distribution of Diamondback terrapin populations in Charleston, South Carolina estuaries. Terrapins were caught in the Ashley River, and population estimates were calculated using mark and recapture techniques and analyzed using the MARK program. Population size was estimated to be 3060 with a 95% confidence interval of 1964-4156. This gives around 179-378 terrapins per km² of marsh habitat. The sex ratio was 1.7:1 male biased (p<0.001). Investigations into changes in land usage were used to reveal reasons for change in terrapin abundance in the watersheds of the Ashley River, the Wando River and the Charleston Harbor from 1995-2009. The number of terrapins caught at all Wando River sites combined significantly decreased during the study period (r=0.83, p<0.001). There has been approximately 12.9 km² (10% of 127.72 km²) of land use change in the Wando River watershed from 1996-2006. Diamondback terrapin abundance, estimated via catch per unit effort, has remained constant for most of the Ashley River and Charleston Harbor areas. Land use change has been minimal (≤2%) in both of these watersheds during the same time frame. The Wando River, on the other hand, had a significant decline in terrapin CPUE and also had a much greater amount (10%) of land use change. Land use can encroach on terrapin habitats, nesting sites and impact food and foraging areas. If the declining trend of the terrapin population in the Wando River continues, regulatory intervention may need to be considered. This information on population size, sex ratios, and distribution can be used as a baseline to track long term changes in terrapin populations.
Description
Keywords
Diamondback terrapin -- South Carolina -- Ashley River -- Geographical distribution; Diamondback terrapin -- South Carolina -- Ashley River -- Sex ratio; Diamondback terrapin -- South Carolina -- Charleston Harbor -- Geographical distribution; Diamondback terrapin -- South Carolina -- Charleston Harbor -- Sex ratio; Diamondback terrapin -- South Carolina -- Wando River -- Geographical distribution; Diamondback terrapin -- South Carolina -- Wando Harbor -- Sex ratio.