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Abstract

REGIONAL MARINE DECAPOD DIVERSITY: THE GULF OF MEXICO EFFORT

Darryl L. Felder¹, Rafael Lemaitre², F. Álvarez³ and J.W. Goy^4
1University of Louisiana at Lafayette
²National Museum of Natural History
³Universidad Nacional Autónoma de México
⁴Harding University
Bio

Need exists for full and accurate documentation and comparison of diversity among regional marine systems, despite obvious challenges. Such accounts have relevance to fundamental science as well as environmental management, providing building blocks for planetary assessments. Previous attempts to so address the entire Gulf of Mexico (GOM) were premature, as one might argue they remain to date, given the failure of richness curves to become asymptotic in response to sampling effort. Heterogeneity in the quality of the historical record, sampling coverage, and systematics do limit our coverage. Approximately 1020 described decapods, representing over 400 genera and over 100 families (by current assignment) are documented to occur in GOM waters. Over half of the genera are represented by a single species. Levels of endemism are extremely difficult to establish with confidence, and are facilitated only by work in adjacent waters of Atlantic Florida and the northern Caribbean Sea. Infaunal and coarse interstitial habitats shelter large numbers of undescribed taxa; deep banks, rubble margins of bioherms, and hydrocarbon vents also harbor long-underestimated diversity, including remarkably adapted forms. Molecular phylogenetic studies reveal undescribed taxa among conspicuous and commonly encountered forms, some long-overlooked under misapplied familiar names; sequence studies have rectified erroneous generic assignments, and supported recognition of ecologically informative clades. Taxonomic descriptions and revisions lag far behind molecularly based efforts for some groups; unjustifiable lumping of taxa in some recent group revisions frustrates efforts. Targeted sampling programs in and adjacent to the Gulf of Mexico, continued molecular study, rigor in consensus taxonomy, and thorough studies of existing archives are urgently needed if credible and timely understanding of this diversity is to be attained [supported under U.S. National Science Foundation grants DEB-0315995 and EF-0531603, along with small awards from the Smithsonian Marine Station and Harte Institute for Gulf of Mexico Studies].

OBVIOUS INVADERS AND OVERLOOKED INFAUNA: UNEXPECTED CONSTITUENTS OF THE DECAPOD CRUSTACEAN ASSEMBLAGE AT TWIN CAYS, BELIZE

Darryl L. Felder¹, P.C. Dworschak², Rafael Lemaitre³, R. Robles¹, Heather D. Bracken¹, A.M. Windsor¹, and J. Felder^1
1University of Louisiana at Lafayette
²Naturhistorisches Museum in Wien
³National Museum of Natural History

Decapod crustaceans in the vicinity of Carrie Bow Cay and Twin Cays, Belize, have been under study by ourselves and colleagues for over 25 years. In the course of investigations, new species have been discovered and large collections have been assembled, with many systematic problems yet to be resolved. Much of the effort has included photographic documentation of coloration in life, yielding characters of value in identification of problematic tropical taxa. Especially at Twin Cays, our measure of diversity has been markedly elevated by sampling in shallow subtidal muds with extraction corers (yabby pumps), and this has recently revealed species, genera, and families of thalassinidean decapods not previously known from the region. This also provided opportunity to explore ecological roles of callianassid burrowers, many of which are dominant bioturbators in intertidal to subtidal grassbeds of Twin Cays, producing conspicuous mounds of sediment and constituting major infaunal biomass. By contrast, a familiar group of conspicuous brachyuran crabs and palinurid lobsters typically dominate macrocrustacean fauna of shallow rocky substrates. However, within the last four years, rocky habitats at Twin Cays have been massively invaded by the nonindigenous portunid crab, Charybdis helleri. In 2007, it was found to dominate cavities beneath coral heads in survey areas along the NE shoreline and the SW shoreline, possibly displacing populations of large Mithrax, Menippe, Callinectes and Panulirus previously found there in abundance. What we know of this fauna continues to change because of how we sample, but now also because of threats to faunal composition and stability [supported under U.S. National Science Foundation grants DEB-0315995 and EF-0531603 the Smithsonian Coral Reef Ecosystem Program].