Effects of hurricanes Ivan, Katrina, and Rita on a Southeastern Louisiana herpetofauna

Abstract

Tropical weather disturbances are a major influence on coastal wetlands in North America. However, studies of their impact on biotic communities are rare. The abundance and species composition of amphibians and reptiles were investigated within levee, herbaceous marsh, and forested swamp habitats in southeastern Louisiana from 2002 to 2004 and again in 2005 to 2006. During the course of this study, three major hurricanes (Ivan, Katrina, and Rita) affected our study sites. This allowed us to opportunistically document the effect of major storm disturbances by comparing species richness, diversity, community assemblage, and abundance of amphibians and reptiles before and after hurricane events. We also used a previous study conducted in the same area during the late 1980's to assess long-term community composition changes. We documented the highest species richness in the forested swamp habitat (23 species), but the most diverse assemblage was found in marsh habitat (H′ 2.082). Overall, herpetofaunal diversity decreased and evenness increased in each habitat following hurricanes Ivan and Katrina/Rita. Drastic decreases in overall abundance of amphibians occurred, while the effect on reptile abundance varied with habitat. Reduced abundance of reptiles in marsh was recorded over the course of the study, while abundances in adjacent levee habitat increased, suggesting displacement of certain reptiles from the marsh to the levee. Significant saltwater intrusion was recorded in marsh and levee habitats, but not in the forested swamp. The hurricanes altered community composition and increased species evenness within each habitat, potentially affecting long-term community dynamics and species interactions. © 2009 The Society of Wetland Scientists.