Center for Integrated Modeling and Analysis of Gulf Ecosystems (C-IMAGE)

Principal Investigator
Steven Murawski -- University of South Florida, College of Marine Science

Abstract

Understanding the full ecological consequences of the Deepwater Horizon (DWH) event, determining best long-term mitigation strategies, and preparing for the next spill, requires a systems-level approach to the Gulf of Mexico ecosystem. Since no one institution has all the relevant expertise, our consortium consists of thirteen institutions, spanning a broad geographic range (five US states and four nations) and academic expertise. Our goal is to develop and integrate empirically validated models of oil plume fate and ecotoxicology to more accurately predict contaminant distribution, composition and ecosystem impacts from the DWH and any future oil-well blowouts. It begins with thermodynamic aspects at the wellhead, where a rupture results in hot, high pressure petroleum fluids and gases exiting into a cold seawater environment. Numerical modeling of such a multi-phase plume requires accurate assessment of initial hydrodynamic conditions at the deepsea rupture site and a fundamental understanding of physical-chemical interactions between high pressured oil and gas with seawater and dispersants leading to the formation of intrusive and rising plumes. The proposal will integrate a suite of high-pressure, low-temperature experiments to determine the initial phase and chemical compositions of petroleum-gas-dispersant-seawater mixtures, partitioning of chemical components into dissolved and suspended bubbles, droplets or aggregates, and particle size and density. Physical, chemical and biological processes of hydrocarbon dispersion, degradation, assimilation and sedimentation then provide the trophic level connections which determine the potential for ecological effects. The evolving spill interacts with biota at varying life stages, with differential ecological consequences in pelagic, neritic and benthic ecosystems.
In particular, we are focusing on several key ecological effects:

Impacts on pelagic food webs and phyto- and zooplankton ecology,
Benthic microbial ecology and impacts of oiled sediments on benthic communities,
Fisheries and fish population dynamics including early life history impacts and potential for ecotoxicological effects in adult fishes and their communities, and,
Impacts on marine mammal distribution, vocalization and toxicological effects.
The versatility of our concept and interdisciplinary approach promotes the integration of the findings among the multiple Centers supported by the Gulf Research Initiative, and studies funded by other entities. Our research will allow for better retrospective assessments on the impacts of the DWH spills of oil, gas, and dispersants, and is directed at improving the predictive tools so that we will be much better prepared to respond to any environmental disaster in the Gulf of Mexico or elsewhere. With our integrative approach, improved understanding of the basic rheological features and distribution of the dispersing plumes will lead to more accurate prediction of the environmental consequences and ecosystem impacts of the DWH event and any future petroleum blowouts of varying composition and environmental toxicity. The DWH spill was remarkable because of the variety of domains it affected: from deep waters at the continental shelf slope, the continental shelf, to coastal marshes, beaches and estuaries. In recognition of practical project limitations, our study area will focus on the eastern Gulf of Mexico. Through integration of newly developed numerical modules for plume formation, evolution, dispersion, and biodegradation that replicate realistic in situ conditions from here-to-fore unavailable high-pressure, low temperature experimental facilities, C-IMAGE will significantly advance petroleum blow-out modeling capabilities beyond what was available at the time of the DWH event. Continued field work will emphasize sampling where further work will help to characterize not only the residual consequences of the spill but the variability in ecological processes as they relate to interpreting impacts of the spill.