Greater structural complexity is often associated with more diverse and abundant species assemblages. Biogenic reefs formed by the eastern oyster (Crassostrea virginica) are structurally complex in nature and have been recognized for their potential habitat value in estuarine systems along the Atlantic and Gulf of Mexico coasts. To determine how the structural complexity of newly created oyster reefs may influence the abundance and distribution of species, three objectives were established. First, to examine spatial and temporal patterns of nekton use at newly created oyster reefs, as well as the impact of wave exposure, six paired oyster reef and mud-bottom treatments at low and medium wave energy shorelines were sampled quarterly, from June 2009 to March 2010, at Caillou (Sister) Lake, Louisiana, using gill nets, seine, and substrate trays. Transient species showed seasonal shifts with no evidence of habitat preference. Resident species were consistently more abundant at oyster reefs than mud-bottom treatments. There were no patterns in nekton use that could be directly attributed to wave exposure. Second, to determine how changes within the structural complexity of newly created oyster reefs may influence nekton use, oyster reef treatments of various complexities were created and sampled using a drop sampler. The presence of oyster reefs per se was the most important factor determining nekton assemblages; newly created oyster reefs provided habitat for nekton assemblages, but there was little difference between reef treatments. Lastly, to determine how oyster reefs mediate predator foraging success, treatments of various complexities were created and trials executed in a laboratory setting using wild red drum (Scianops occelatus) and grass shrimp (Palaemonetes pugio). Foraging success was negatively correlated to the structural complexity of oyster reefs, indicating there may be a point above which increased complexity no longer increases the refuge value of the reef. These results show that oyster reefs may support a high abundance and diversity of resident nekton, but that after structure is introduced, further increasing structural complexity does not automatically increase species abundance and diversity, or the amount of refugia provided.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-07092010-100458 |
| Date | 09 July 2010 |
| Creators | Humphries, Austin T. |
| Contributors | Baltz, Donald M., Nyman, Andrew, Rozas, Lawrence, La Peyre, Megan K. |
| 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-07092010-100458/ |
| 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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