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Characterization of fish assemblages associated with high diversity and low diversity coral reefs in the northwestern Gulf of Mexico

The majority of benthic habitat in the northwestern Gulf of Mexico (GOM) consists of soft-bottom sand, silt, and clay substrate, and it is likely that natural banks in the region represent a critical habitat for corals, as well as reef fishes requiring hard-bottom structure. Despite this, the resident fish assemblages associated with many of these features have not been thoroughly studied, and the relative importance of different bank types (i.e. high diversity coral reefs vs. low diversity coral reefs) as essential habitat for reef fish has never been quantified. Efforts to characterize reef fish communities at high diversity coral reefs (East and West Flower Garden Banks) and artificial production platforms in the northwestern GOM began in 1997 with visual surveys on SCUBA, and these were expanded in 2005-2006 to include two low diversity coral reef sites (McGrail Bank and Sonnier Bank) as well as ROV surveys of deeper reef habitats. More recent research has focused on comparing the community and trophic structure of reef fish assemblages associated with low diversity and high diversity coral reef habitats, as well as characterizing seasonal and cross-shelf patterns of recruitment to both reef types in an effort to improve our understanding of metapopulation dynamics within the GOM continental shelf reef system. To directly assess the relative nursery value of high diversity coral reefs, low diversity coral reefs, and artificial structures (i.e. production platforms) in the region, we are also in the process of analyzing dietary composition (stomach content analysis and tissue stable isotopes), growth rates (otolith microstructure analysis), and nutritional condition (RNA:DNA) for two model species of juvenile grouper collected from each habitat type in 2009 and 2010.

 


Habitat connectivity of parrotfish at Hawaiian coral reefs
We are collaborating with researchers at the University of Hawaii-Hilo to examine habitat use and connectivity for two species of parrotfish at both healthy and degraded coral reefs off the northwest coast of Hawaii (Puako, HI) using acoustic telemetry. A VR2W positioning system (VPS) is being used in conjunction with detailed habitat maps to investigate fine-scale (spatial resolution <3 meters) movement patterns of palenose (Scarus psittacus) and red lip (Scarus rubroviolaceus) parrotfish across coral reef seascapes. The goal of this study is to characterize species-specific patterns of habitat use across temporal cycles (e.g. tidal, diel) at both degraded and healthy reefs to determine how reef health affects habitat connectivity in Hawaiian parrotfish.


 

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Dr. Jay R. Rooker Department of Marine Biology
Texas A&M University @ Galveston
1001 Texas Clipper Rd, Galveston, Texas 77554
rookerj@tamug.edu 409-740-4744
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