Approximately 2,300 petroleum platforms are currently operating in the Gulf of Mexico (GOM), and are estimated to provide an additional 4 to 12 km2 of artificial reef habitat. The ecological role of platforms has often been overlooked and little is known about the effect of artificial light from the active platforms on surrounding fish communities. This is the first study to address the potential impacts of artificial light on the trophic ecology of fish communities surrounding offshore platforms through gut content (GCA) and stable isotope (SIA) analyses. Red snapper (Lutjanus campechanus) were collected quarterly from February 2014 to November 2015 (n=424). Samples were taken at two active lit platforms and two unmanned unlit platforms located approximately 130 km from the coast of Louisiana. Results reveal seasonal, ontogenetic, and platform-type related differences. Although light was not a significant factor in the non-parametric GCA analysis, a higher abundance of fish prey items was observed in the diets at lit platforms. Trophic niche breadth analysis revealed significantly different niches between types of platforms. Higher δ15N at lit platforms corresponds to higher concentration of fish prey in the diets, compared to the lower δ15N associated with the abundance of tunicates in the diets at unlit platforms. A mixing model revealed that phytoplankton is the dominant carbon source in these oligotrophic, platform environments. Red snapper at lit platforms were slightly enriched in δ13C compared to those at unlit platforms. This could be attributable to the greater amount of green algae as a basal carbon source of individuals at lit platforms revealed by the mixing model, which is enriched in δ13C relative to phytoplankton. Feeding ecology of greater amberjack revealed fish to be the dominant prey items between lit and unlit platforms, and across both artificial and natural habitats. Trophic niche breadth analysis revealed significant differences between greater amberjack at lit and unlit platforms, which is likely attributable to the varying basal carbon resource. This study provides important information that may be used in the decision on installment or removal of platforms as fish habitats in the future and to assist with fisheries management.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-07012016-120651 |
| Date | 11 July 2016 |
| Creators | Foss, Kristin Leanne |
| Contributors | Cowan Jr., James, Polito, Michael, Xu, Kehui |
| 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-07012016-120651/ |
| 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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