Herpetofaunal Community Change in Multiple Habitats after Fifteen Years in a Southwest Florida Preserve, USA

<div><p>Herpetofaunal declines have been documented globally, and southern Florida, USA, is an especially vulnerable region because of high impacts from hydrological perturbations and nonindigenous species. To assess the extent of recent change in herpetofauna community composition, we established a baseline inventory during 1995-97 at a managed preserve in a habitat rich area of southwest Florida, and repeated our sampling methods fifteen years later (2010-11). Nine drift fence arrays were placed in four habitat types: mesic flatwood, mesic hammock, depression marsh, and wet prairie. Trapping occurred daily for one week during 7-8 sampling runs in each period (57 and 49 total sampling days, respectively). Species richness was maintained in mesic hammock habitats but varied in the others. Catch rates of several native species (<i>Anaxyrus terrestris</i>, <i>Lithobates grylio</i>, <i>Anolis carolinensis</i>, <i>Nerodia fasciata</i>) declined significantly. Other native species (<i>Lithobates sphenocephalus</i>, <i>Siren lacertian</i>, and <i>Notophthalmus viridescens piaropicola</i>) that were abundant in 1995-97 declined by greater than 50%. Catch rate of only two species (the nonindigenous <i>Anolis sagrei</i> and the native <i>Diadophis punctatus</i>) increased significantly. Hierarchical cluster analysis indicated similarity within habitat types but significant dissimilarity between sampling periods, confirming shifts in community composition. Analysis of individual species’ contributions to overall similarity across habitats shows a shift from dominance of native species in the 1990s to increased importance of nonindigenous species in 2010-11. Although natural population fluctuations may have influenced differences between the two sampling periods, our results suggest considerable recent change in the structure and composition of this southwest Florida herpetofaunal community. The causes are unknown, but hydrological shifts and ecological impacts of nonindigenous species may have contributed.</p></div

CREW Drift fence array labels, locations (WGS 84) and habitat types.

<p>CREW Drift fence array labels, locations (WGS 84) and habitat types.</p

Cumulative yearly rainfall and best-fit regression lines from three locations proximal to the CREW preserve.

<p>All three locations represent aggregated data from multiple sampling sites.</p

SIMPER results comparing mean abundance of herpetofauna collected between 1995–97 and 2010–11 and species contributions to the dissimilarity among habitat types between the two sampling periods (total average dissimilarity = 48.44%).

<p>Species accounting for similarity between habitat types within each sampling period are indicated by superscripts.</p><p>¹. Five species accounting for 56.9% cumulative similarity between habitats during the first sampling period</p><p>². Five species accounting for 61.8% cumulative similarity between habitats during the second sampling period</p><p>SIMPER results comparing mean abundance of herpetofauna collected between 1995–97 and 2010–11 and species contributions to the dissimilarity among habitat types between the two sampling periods (total average dissimilarity = 48.44%).</p

Non-metric multi-dimensional scaling ordination based on Bray-Curtis similarity.

<p>Samples are labeled by array number, habitat, and year. Circles identify groupings that hierarchical cluster analysis indicated to be significantly different from one another at the 95% confidence level.</p