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Keywords:

  • agriculture;
  • flint river basin;
  • Graptemys barbouri;
  • land use;
  • reptile;
  • river turtle assemblage;
  • Trachemys scripta

Abstract

Agriculture is the dominant land use in the Lower Flint River Basin (LFRB) of south-western Georgia, USA, and is often a significant disturbance factor affecting streams and riparian habitats. Streams in the LFRB harbor a great diversity of freshwater turtles, which are among the many groups of aquatic fauna impacted by agricultural disturbance to riparian habitats. The objective of this study was to assess turtle diversity and abundance in both agriculturally impacted and unimpacted or restored reaches of streams in the LFRB. In 2007 and 2008, we used hoop traps and effort-managed snorkel surveys to sample turtles on 14 reaches of two streams (Ichawaynochaway and Spring Creeks). We recorded 823 captures of 674 individuals representing nine turtle species. There was a measurable association between the percentage of riparian undisturbed land cover and the number of turtles captured for the four most frequently captured species (Trachemys scripta, Graptemys barbouri, Pseudemys concinna and Sternotherus minor). We found a negative relationship between the total number of turtles captured and percentage of undisturbed land cover within a 287 m buffer width due to a significant increase in the number of T. scripta in less-forested sections of the creeks; however, the number of G. barbouri captures declined with reduced undisturbed land cover. Species evenness was positively correlated with percentage of undisturbed land. These results suggest that loss of riparian forest is associated with a decline in freshwater diversity (evenness) and a decline in the abundance of the endemic, state protected G. barbouri; however, overall turtle abundance may remain stable or increase with loss of riparian forest cover due to an increase in common, cosmopolitan species. Our results suggest that maintenance or restoration of riparian forests is critical to freshwater turtle conservation.