Connectivity of Coral Ecosystems in the Northwestern Gulf of Mexico

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The Science Issue and Relevance: Coral communities on the continental shelf and slope are analogous to islands in that they are discrete and spatially separated. Each local community serves as an oasis or biodiversity hotspot by locally enhancing the abundance and diversity of invertebrates and fishes. Knowledge of the factors that promote or impede the connectivity among these discrete, benthic communities is essential to ensure the resilience and sustainability of marine ecosystems in general. Connectivity among coral communities influences the probability of speciation and contributes to their ability to adapt to natural and anthropogenic stressors. Determining the distance, rate and directionality of larval and adult dispersal in key species is therefore central to understanding how populations are interconnected and the degree of resiliency in the event of a localized perturbation, such as an oil spill.

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The Gulf of Mexico (GoM) has experienced numerous environmental catastrophes (oil spills, hypoxic events) in recent history. With continued anthropogenic threats in the marine environment coupled with global ocean change, there is an urgent need to make decisions that will lead to the effective management and conservation of vulnerable marine ecosystems in the GoM. Corals play a foundational role in such ecosystems by generating three-dimensional structures that provide habitats for diverse and abundant invertebrate and fish communities, including refuge and prey for commercially valuable fisheries. As such, the Flower Garden Banks National Marine Sanctuary (FGBNMS) has proposed to expand the boundaries of current protected areas to encompass additional coral sites. The establishment of marine protected areas is not only essential to protect and conserve coral ecosystems, but it has been identified as one of the key restoration strategies for benthic communities impacted by the Deepwater Horizon oil spill. To help guide FGBNMS management decisions, this study aims to address crucial gaps in our understanding of the processes that shape connectivity patterns in shallow coral ecosystems and mesophotic coral ecosystems. We will address the fundamental question: To what degree are key coral ecosystem species vertically and horizontally connected throughout the FGBNMS and its preferred Sanctuary expansion sites?

This project is sponsored by the National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science (NOAA-NCCOS), and USGS. The USGS has a long-term commitment to providing information for preserving and protecting hard-bottom communities, including deep-sea corals, as the need for oil and gas exploration, as well as wind energy increases on the Atlantic shelf and slope.

Methodology for Addressing the Issue: This study will provide microchemistry and stable isotope analyses of coral habitats, including using submersibles and over-the-side gear, sampling multiple shallow and mesophotic coral habitats in the northwestern GoM, including the FGBNMS and its proposed expansion areas. Megafauna and primary food resources will be collected and analyzed to assess trophic connectivity using stable isotope analyses. 

Future Steps: Northwestern Gulf of Mexico shallow and mesophotic coral habitats will be sampled for fauna, sediment, and water characteristics beginning in April 2019. Additional sampling will be conducted in 2020 and 2021. Data collected on these cruises will determine the trophodynamics and connectivity of corals and fauna in these systems. Results from this study will enhance our understanding of GoM ecosystems with regional conservation initiatives to inform the restoration of degraded deepwater coral communities and preserve long-term viability of coastal ecosystems.