Deep-pelagic plankton communities of the northern Gulf of Mexico: trophic ecology, assemblage dynamics, & connectivity with the upper ocean

January 1, 2018 – December 31, 2019

Dr. Frank Hernandez, The University of Southern Mississippi (Lead PI)

Dr. Kelly Robinson, University of Louisiana at Lafayette

Dr. Kevin Dillon, The University of Southern Mississippi

Dr. James Ruzicka, Oregon State University

Much of what is known about the Gulf of Mexico ecosystem is limited to coastal and upper ocean regions, even though >90% of the GOM’s volume occurs at depths >200 m. The Deepwater Horizon oil spill (DWHOS) occurred in the deep GOM, and the lack of baseline data for this region was a major impediment to the damage assessment efforts. Although remote and understudied, the deep-pelagic environment plays a vital role, as many deep-pelagic organisms (including fish larvae) undergo wide-ranging and daily vertical migrations that drive a “biological pump” by actively transporting nutrients from the epipelagic zone to the deep GOM.

To date, the Deep-Pelagic Nekton Dynamics (DEEPEND) Consortium is the only science team researching the deep-pelagic ecosystem. However, the focus of DEEPEND is on micronekton and nekton, and not planktonic communities, which include the early life stages of deep-pelagic fishes and invertebrates, as well as prey resources for micronekton and nekton predators. Our goal is to address major knowledge gaps for the GOM by describing the community structure and trophic ecology of deep-pelagic plankton assemblages, and their connectivity with the upper ocean.

Our specific objectives are to:

1) describe diets and trophic linkages for dominant, deep-pelagic larval and juvenile fishes using gut content analysis and stable carbon and nitrogen isotope analysis

2) identify environmental drivers that structure deep-pelagic planktonic assemblages and vertical migration patterns

3) develop a coupled plankton/upper trophic level and coupled deep-pelagic/epipelagic ecosystem model using ECOPATH and end-to-end ECOTRAN methods

4) apply data-driven ecosystem models to quantify rates of energy and biomass transfer between the epipelagic and deep-pelagic ecosystems that occur via trophic interactions and to estimate the consequences to ecosystem dynamics from perturbations in these linkages

Press:  GoMRI grant funds examination of plankton and fish populations in Gulf