21. A Predictive Strategy for Mapping Locations Where Future MOSSFA Events Are Expected

A MOSSFA (marine oil snow sedimentation and flocculent accumulation) event was the reason that substantial amounts of the spilled oil were transported to the seafloor during the Deepwater Horizon (DWH) oil well blowout. The region-wide sinking and flocculent accumulation of marine oil snow on the sediment surface changed redox conditions, slowed down the biodegradation of the oil, and increased the spatial and temporal impacts on the benthic community and habitat suitability. Recent field research has confirmed that, in addition to the DWH MOSSFA event in the northern Gulf of Mexico (nGoM), another extensive MOSSFA event occurred in a biologically sensitive area in the southern Gulf of Mexico (sGoM) during the 1979–1980 Ixtoc 1 oil well blowout. Thus, MOSSFA events are not unexpected and have the potential to not only alter sediment chemical conditions but also to extend, expand, and intensify the ecological impact of an oil spill. Consequently this risk should be taken into consideration when preparing response strategies for potential future oil spills and subsurface oil well blowouts. To illustrate this approach, MOSSFA-sensitive areas were identified in offshore areas where deepwater oil production and exploration are occurring. Based on the newly gained insights into the factors that can initiate and contribute to a MOSSFA event, global maps showing the presence of oil/gas platforms, phytoplankton biomass, and suspended mineral matter are developed in order to infer the probability that future MOSSFA events are likely to occur. These maps are of particular importance for oil spill responders who will be deciding locations and which oil spill response strategies (i.e., applying large volumes of dispersants, burning in situ burnings, increasing riverine inputs of nutrients, and fine-grained clay particles) would result in the development of a MOSSFA event.