Platforms Recruited Reef Fish, Phase II: Do Platforms Provide Habitat that Increases the Survival of Reef Fishes.

摘要

Red snapper, Lutjanus campechanus, has been an economically important reef fish in the Gulf of Mexico (Gulf) for over 150 years; it is currently overfished. Catch statistics and demographic differences have led to the population being categorized into eastern and western substocks divided by the Mississippi River, but data is recombined to set a Gulf-wide annual catch limit. During an initial pilot study, it was determined that Louisiana oil and gas platforms impart detectable signatures in otoliths. Unique signatures were also detected for artificial reefs east and west of the Mississippi River. The objectives of this study were to determine if signatures based on trace metals associated with oil and gas platforms were geographically and temporally stable, and if the signatures could discriminate between region and habitat of origin to further examine population connectivity. Otoliths of red snapper (n = 1,778) collected from platforms and other habitats off Alabama, Louisiana, and Texas during the summers of 2007 and 2008 were analyzed with sector field-inductively coupled plasma-mass spectrometry (SF-ICPMS) to determine if platforms impart detectable signatures based on seventeen trace metals. Otolith chemical signatures were significantly different among regions and habitats (MANOVA, p < 0.001). Mean jackknifed classification accuracies from QDFAs indicated higher success for discriminating among regions (86%) than habitats (79%). These otolith chemical signatures were used as baseline samples in maximum likelihood mixed-stock analyses to estimate region and habitat of origin of red snapper (n = 487) collected from natural habitats off Florida, Louisiana, and Texas during the summer of 2009. Platform signatures were evident in otoliths from red snapper collected off Florida, a region devoid of platforms, possibly reflecting a western Gulf contribution to the eastern substock. The microchemical otolith signatures of western Gulf red snapper in this study demonstrated discrete regional populations with some interpopulation mixing, further supporting a metapopulation structure.