Award: OCE-1045252

The pelagic brown algae Sargassum supports an oasis of biodiversity and productivity within the otherwise featureless ocean surface. The vast pool of floating oil fed by the release of over 760 million liters of oil as a result of the Deepwater Horizon explosion persistedfor 3-4 months in summer 2010 and may have severely degraded this critical ursery habitat. The neustonic nature of both Sargassum and floating oil enhance contact between the two at small and meso-scale convergence zones in the Gulf. Aerial surveys performed during and after the spill show strong evidence of loss and subsequent recovery of Sargassum. Experimental studies indicate three possible pathways for injury of Sargassum and its associated animals: (1) Sargassum accumulates floating oil on the surface exposing animals to high concentrations of contaminants along the algaeÆs horizontal oceanic journey; (2) application of dispersant rapidly sinks Sargassum thus removing the habitat and potentially transporting oil and dispersant vertically to mesopelagic and benthic systems; and (3) low oxygen forms around the habitat as a result of microbial degradation of oil and dispersant further stressing animal remaining on the surface and reducing their fitness. Our pathways represent sublethal and indirect effects that are rarely considered in evaluating the effect of oil spills and response procedures. Last Modified: 10/20/2012 Submitted by: Sean Powers