Turbidity and wave energy affect community composition and trophic interactions
| dc.contributor.advisor | Smee, Delbert Lee | |
| dc.contributor.author | Lunt, Jessica | |
| dc.date.accessioned | 2014-07-25T18:55:35Z | |
| dc.date.accessioned | 2014-07-25T18:55:35Z | |
| dc.date.available | 2014-07-25T18:55:35Z | |
| dc.date.available | 2014-07-25T18:55:35Z | |
| dc.date.issued | 7/25/2014 | |
| dc.description | Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. | en_US |
| dc.description.abstract | Abiotic variables are well known community regulators and can strongly influence species distributions when they are outside of a species physiological tolerance limits. However, environmental variables within tolerance limits may also alter species distributions, morphology, predator-prey interactions, and influence the structure and function of communities. The purpose of this study was to determine how abiotic variables (notably turbidity) alter diversity, species distributions and abundances, predation rates on and species morphology. Texas Parks and Wildlife Department Fisheries Independent Survey Data from 1991-2008 were used in addition to field surveys of St. Charles Bay to determine the effects of turbidity on fish and crab diversity and abundance. Feeding assays were conducted in the field using groups of 5 mud crabs and 10 juvenile oysters to assess feeding rates in high and low turbidity. Juvenile oysters were also allowed to grow in the field to test the effects of turbidity on oyster growth. In addition, the effects of wave energy on oyster reef species composition and size were assessed using field surveys. I found that turbidity affects top-down control and biodiversity in estuaries and has similar effects to salinity and temperature. Elevated turbidity reduced fish diversity and abundance (p < 0.01), while increasing the diversity and abundance of crabs (p < 0.01). Predation by visual fish predators was also reduced in elevated turbidity (p = 0.02), which leads to an increase in the abundance of crabs and increased predation on mud crabs in high turbidities (p = 0.03). Juvenile oysters respond to increased crab abundance by growing heavier shells, which may lower fecundity. In laboratory assays, increased turbidity decreased the predation efficiency of visual predators (fish) but not of chemosensory predators (crabs). Differences were found between wave exposed and wave protected areas. Areas with higher wave energy had fewer species (p < 0.001) and the average size of species was smaller. This research identifies turbidity as an important variable within estuarine systems and extends the effects of wave energy from rocky intertidal systems to oyster reef communities. Both of these variables should be considered for effective management and restoration of estuarine communities. | en_US |
| dc.description.college | College of Science and Engineering | en_US |
| dc.description.department | Life Sciences | en_US |
| dc.identifier.uri | http://hdl.handle.net/1969.6/564 | |
| dc.language.iso | en_US | en_US |
| dc.rights | This material is made available for use in research, teaching, and private study, pursuant to U.S. Copyright law. The user assumes full responsibility for any use of the materials, including but not limited to, infringement of copyright and publication rights of reproduced materials. Any materials used should be fully credited with its source. All rights are reserved and retained regardless of current or future development or laws that may apply to fair use standards. Permission for publication of this material, in part or in full, must be secured with the author and/or publisher. | en_US |
| dc.subject | oyster reefs | en_US |
| dc.subject | predator-prey interactions | en_US |
| dc.title | Turbidity and wave energy affect community composition and trophic interactions | en_US |
| dc.type | Text | en_US |
| dc.type.genre | Dissertation | en_US |
| thesis.degree.discipline | Marine Biology | en_US |
| thesis.degree.grantor | Texas A & M University--Corpus Christi | en_US |
| thesis.degree.level | Doctoral | en_US |
| thesis.degree.name | Doctor of Philosophy | en_US |