Files
Abstract
Ecological modeling is a popular tool to assess the functionality of marine ecosystems and quantify an ecosystem’s response to anthropogenic stressors (e.g., fishing, oil spills, climate change). However, much of the global modeling effort has been focused on coastal regions that are generally more data-rich than the area seaward of the continental shelf (i.e., oceanic zone). A concerted effort has been placed on collecting holistic, ecosystem-scale data in the oceanic, northeast Gulf of Mexico since the 2010 Deepwater Horizon oil spill (DWHOS), particularly in the deep-pelagic zone (water column deeper than 200m depth), which has notably experienced declines in several mesopelagic micronekton (organisms 2–20cm) populations since 2011. Because of this effort, sufficient data now exist to develop ecological models in the oceanic Gulf of Mexico to evaluate the ecosystem-level effects of observed population trends and quantify the consumer-mediated transport of nutrients from the near-surface waters to the deep sea, and vice versa.
This dissertation consists of five chapters: two utilizing the ecosystem modeling software, Ecopath with Ecosim, to quantify potential trophic structure changes in the oceanic zone following the DWHOS (Chapter 1) and predict the mortality exerted on mesopelagic micronekton since the oil spill to forecast population trends to 2030 (Chapter 3), two bioenergetic models focused on consumer-mediated nutrient transport by mesopelagic fishes (Chapter 2) and oceanic cetaceans (Chapter 4) to quantify the active vertical transport of carbon and nitrogen, respectively, by these two assemblages. This dissertation concludes with a systematic literature review of ecosystem-based modeling in the deep sea that discusses a 47-year history of ecosystem modeling in the deep-sea, and ideas to how these efforts can become more inclusive of all geographical regions, more accurate, and more robust to uncertainty, which is necessary for ecosystem-based resource management among the several, synergistic stressors on oceanic regions. The oceanic, northeast Gulf of Mexico is a data-rich system relative to many other open-ocean regions, making this system a suitable case study for ecological modeling in the oceanic zone.