Platform Recruited Reef Fish, Phase I: Do Platforms Provide Habitat That Increase the Survival of Juvenile Reef Fishes?

• Main Author: Nowling, Lauren Kay
• Other Authors: James H. Cowan, Jr.
• Format: Others
• Language: en
• Published: LSU 2005
• Subjects: Oceanography & Coastal Sciences
• Online Access: http://etd.lsu.edu/docs/available/etd-11142005-110327/

There are currently over 4000 functioning oil and gas platforms in the northern Gulf of Mexico (Gulf). Platform operations, and their prior drilling operations, produce trace amounts of lead, barium, vanadium, and lanthanum residues that are leached into the surrounding waters and are deposited on the sea floor. These residues have isotopic ratios different from those typical of the Gulf seafloor and can be used as harmless fingerprints if they become incorporated into hard-parts or tissues in fishes associated with oil and gas platforms. From 2002 to 2004, 115 red snapper were collected from oil and gas platforms and artificial reefs off Louisiana and Alabama. Otoliths were removed and analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The objective of this study was to determine if a trace element isotope ratio fingerprint could be detected and described as unique to red snapper inhabiting the platforms. Stepwise and canonical discriminant function analyses were used to compare red snapper otolith fingerprints from on and off platforms, and from east and west of the Mississippi River. Classification accuracies based on the probability of an individual fish being correctly classified into the habitat from which it was sampled were over 90% for each of the two main comparisons. When comparing the elemental composition of red snapper otoliths from Louisiana oil and gas platforms and Louisiana artificial reefs, the classification accuracy was 93.75%. When comparing the elemental composition of red snapper otoliths from Louisiana artificial reefs and Alabama artificial reefs, the classification accuracy was 91.06%. Vanadium 51, Lead 206, Lead 207, and Lead 208 all appear to be linked with oil and gas platforms or their prior drilling operations, as the concentrations of these four elements or isotopes were significantly higher in otoliths sampled on platforms in Louisiana than in otoliths sampled from artificial reefs in either Louisiana or Alabama. Results from this study indicate that it may be possible in future studies to determine if oil and gas platforms contribute disproportionately to the survival of juvenile and adult red snapper, and as such can be considered viable management tools for stock rebuilding.