The northern Gulf of Mexico (GOM) contains approximately 2,500 oil and gas platforms, resulting in one of the largest de facto artificial reef systems in the world. As of 2013, 1,227 additional structures had ceased to produce oil and gas and have been decommissioned and removed. While active platforms are lit by high-pressure mercury vapor lights, inactive platforms are only minimally lit for navigation. The positively phototaxic behavior of many fish species causes lit oil platforms to act as fish attraction devices, especially at night. Though a variety of fish species have been reported near these structures, changes in fish abundance, biomass, and species composition in response to artificial light regimes has not been studied thoroughly. Hydroacoustic and video surveys were conducted at two lit and three unlit oil and gas platforms located approximately 130 km off the coast of Louisiana. The goal of this study was to examine the effect of artificial lighting on fish community composition and spatial distribution during the day, night, and during crepuscular periods.
Fish abundance changed with depth, season, time of day, and type of platform (lit/unlit), with blue runner (Caranx crysos) as the dominant species at both platform types. Species richness varied with season and time of day, with highest values observed in the summer and during the day. Hydroacoustic surveys were utilized to determine the spatial distribution of fish biomass (MVBS, Sv), which was largely concentrated near the structure and decreased rapidly with distance away from the platform. Platform type did not significantly impact fish biomass. Fish MVBS was highest in depth layer 3 (>60 m) and lowest in depth layer 1 (0-30 m), particularly at night. Regression trees showed a clear area of influence within 45 70 m horizontal distance around the structure, as well as fish avoidance behavior of the surface waters (< 9 m). These results suggest that though fishes are attracted to the vertical relief of the structure, they are actively avoiding the artificial light field due to nocturnal predation pressure.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-03142016-193545 |
| Date | 06 April 2016 |
| Creators | Barker, Victoria Anne |
| Contributors | Cowan, James H., Jr., Rose, Kenneth, 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-03142016-193545/ |
| 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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