This study examined the effects of intrahabitat variability on marsh edge use by fishes and decapod crustaceans. The objectives were to (1) identify quantitative measures of habitat complexity that describe the structural design of marsh edge habitats, and (2) examine differences in nekton use between cut-bank and gently sloping marsh edge habitats. The study was conducted in Barataria Bay, Louisiana at 75, 10-m marsh edge study sites. Monthly seining was conducted in fall 2003 and spring 2004 and measures of habitat complexity were recorded at each sample location. Indices of tidal inundation and site exposure to wind and wave action were calculated. Results showed significantly greater complexity (i.e., irregularity, elevation, bank height, bank undercut, vegetation densities and percent vegetated cover) at cut-bank edges over gently sloping edges (P < 0.0001). Nekton diversity (fall: P = 0.0236, spring: P = 0.0297) and mean abundance of bay anchovy Anchoa mitchilli (fall: P = 0.0010) were also significantly greater at cut-bank edges over gently sloping edges. Lower mean elevation at gently sloping edges resulted in significantly greater levels of inundation over cut-bank edges (P < 0.0001), providing earlier and prolonged use of inner marsh habitats. Mean abundances of marsh residents that frequent the vegetated marsh surface (naked goby Gobiosoma bosc (fall: P = 0.0055), gulf killifish Fundulus grandis (fall: P = 0.0280), and grass shrimp Palaemonetes pugio (fall: P = 0.0017) were significantly greater at gently sloping edges over cut-bank edges. Several associations were observed between nekton community parameters and measures of habitat complexity, including strong positive correlations between species diversity (fall: P < 0.0001, spring: P < 0.0001), species richness (fall P = 0.0001, spring P = 0.0029), and exposure to wind and wave action. Differences in use between cut-bank and gently sloping edges and associations between nekton variables and measures of habitat complexity suggest that differences in habitat structure exist among marsh edge habitats and that these differences do influence habitat selection by nekton. This study highlights the need for methods that provide more explicit identification of EFH by determining relationships between productivity and the different habitats used by aquatic organisms.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11112004-171053 |
| Date | 12 November 2004 |
| Creators | Birdsong, Timothy W. |
| Contributors | D. Allen Rutherford, William E. Kelso, Charles A. Wilson, Megan K. La Peyre |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11112004-171053/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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