Title page for ETD etd-11182005-112454


Type of Document Master's Thesis
Author Gossman, Bryan Paul
Author's Email Address bgossm1@lsu.edu
URN etd-11182005-112454
Title Use of Terraced Marsh Habitats by Estuarine Nekton in Southwestern Louisiana
Degree Master of Science (M.S.)
Department Renewable Natural Resources
Advisory Committee
Advisor Name Title
Megan K. La Peyre Committee Chair
D. Allen Rutherford Committee Member
J. Andrew Nyman Committee Member
Keywords
  • habitat restoration
  • nekton
  • marsh terracing
Date of Defense 2005-11-11
Availability unrestricted
Abstract
A variety of techniques have been employed in attempts to mitigate the extensive wetland loss occurring in coastal Louisiana. Marsh terracing is a wetland restoration technique that has rapidly gained in popularity in recent years. Terraces are assumed to benefit coastal restoration by providing areas for emergent plant growth, reducing wave energies, and increasing edge habitat to support nekton communities. The objectives of this study were to: 1) determine the effect of marsh terraces on adjacent water quality and sediment characteristics, 2) compare nekton abundance, species richness, and diversity in edge and open water habitats within terraced and unterraced ponds, and 3) compare the condition of numerically dominant fishes between terraced and unterraced ponds as an indicator of habitat quality. Three study sites located in southwest Louisiana at Sabine National Wildlife Refuge and Rockefeller State Wildlife Refuge were selected for the study. Each study site consisted of a terraced pond and a nearby unterraced reference pond. Nekton was quantitatively sampled in four different habitat types at each study site with a 1-m2 throw trap. The habitat types sampled were: 1) terraced marsh edge, 2) unterraced marsh edge, 3) open water within terraced ponds, and 4) open water within unterraced ponds. Nekton density (P = 0.0004), biomass (P = 0.002), species richness (P = 0.0007), and diversity (H', P = 0.01) (1-D, P = 0.007) were all significantly greater at terraced edge habitats (treatment) as compared to unterraced open water habitats (control). There was no significant difference in these variables between terraced and unterraced edge habitats. While terraced pond habitats were superior to pre-restoration conditions in terms of nekton habitat value, they lacked functional equivalency with comparable unterraced ponds in several areas: 1) nekton community composition differed between terraced and unterraced edge habitats, and 2) several fish species were found to be in poorer condition in terraced ponds as compared to unterraced ponds. A lack of functional equivalency between terraced and unterraced habitats may be partially attributable to the relatively young age of the terraces studied, as many functions of created marshes may take years to develop.
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