Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures


A Trophic Analysis of Deep-Pelagic Assemblages in the Northern Gulf of Mexico

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Joint Meeting of Ichthyologists and Herpetologists, New Orleans, LA, July 6-10, 2016

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The Deepwater Horizon oil spill, which released hydrocarbons into the deep-pelagic environment of the Gulf of Mexico (GoM), revealed significant data gaps with respect to the Gulf’s largest habitat and resulted in a concerted effort to understand the structure and function of deep-pelagic assemblages. As part of a larger collaborative effort tasked with characterizing assemblage structure of the GoM deep-pelagic fauna and determining the biotic and abiotic drivers underlying that structure, we examined the isotopic ratios of model taxa in order to (1) establish an isotopic baseline for bathypelagic, mesopelagic, and epipelagic assemblages of the northern GoM, (2) trace the vertical flow of organic matter among these three depth domains via active (vertical migration) and passive transport (sinking marine snow), and (3) investigate potential spatial and temporal variation in trophic structure of deep-pelagic assemblages. In 2015, samples were collected during two cruises in the northern GoM using a 10-m2 MOCNESS midwater trawl sampling specific stratified depths from the surface to 1500 m. Here we present preliminary isotopic data from the deep-pelagic food web which represent several distinct trophic levels including carbon sources, zooplankton, gelatinous zooplankton, cephalopods, and fishes encompassing an array of feeding strategies (planktivores, gelativores, piscivores), and vertical distributions (migratory vs. non-migratory). By describing the trophic structure of deep-pelagic assemblages and evaluating the nature of vertical trophic connectivity in the GoM, this project will provide baseline trophic data to inform ecosystem models and identify taxa that may serve as important “vectors” between depth domains in the oceanic GoM.

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