Date of Award

12-13-2012

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

First Advisor

Kevin S. Godwin

Second Advisor

Deborah A. Hutchinson

Third Advisor

Scott L. Parker

Abstract

Using a comparative ecological approach, over the course of 18 days at the transition from a particularly wet to dry season in 2010, I assessed herpetofaunal assemblages and related abiotic parameters (i.e., photosynthetically active radiation, specific conductance, temperature and coarse woody debris) between contiguous forest and human impacted areas along three paired transects across the steep elevation gradient at Laguna de Cube, Ramsar site # 1143. Visual encounter surveys were used to capture herpetofauna with species being processed (e.g., weight, digit length, photographed) and identified to the lowest taxonomic level possible. After evaluating transect data for pooling (i.e., no significant difference in abiotic parameters relative to elevation or land cover, hypotheses were evaluated statistically using Chi Square and Kruskal Wallis, and adjusted for multiple comparisons, with an a priori alpha; 0.10. I depart from convention due to the rarity of the region and accelerating human impacts. A total of 37 species (22 amphibians and 15 reptiles) were captured over 144 hours of direct sampling representative of day and night (n=4), 28 of which are newly described for Laguna de Cube, with three that have IUCN status of near threatened or endangered . As hypothesized, species richness and diversity were significantly greater in the forest than in impacted habitats [i.e., 30 forested versus 21 impacted species; Chi2;2 (2, N = 68) = 46.267, p = 8.9809E-11]. Similarly, abiotic conditions differed significantly by land cover with human impact exceeding forest analogs in 8 of 13 parameters (e.g., PAR; TopF v. TopI= , H = 27.6 df = 5, p = 0.005075) , while forests had significantly greater coarse woody debris [i.e., CWDF = 150,731.97 kg/ha v. CWDI = 47,819.97 kg/ha; Chi2;2 (1, N = 198,550.97) = 135.26, p = 2.897E-31]. Of the species collected several may serve as indicators of biotic integrity with H. pellucens serving as an indicator of degraded human modified land cover occurring in all of the 3 human impact transects and occurring at all elevations. Additionally, I observed morphological anomalies possibly indicative of anthropogenic habitat pollutants, with a majority of these species occurring in impacted environments routinely sprayed with pesticides. Conversely, several species may serve as indicators of native habitat affinity including E. boulengeri and H. fallaciosus both of which are described as forest obligates with risk of extirpation due to forest conversion. It should be noted that four species are not yet identified. When compared to similar herpetofaunal studies (n=6), my richness and diversity estimates meet or exceed those in the primary literature in five of the six comparisons.

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