Floating Sargassum communities of the Gulf of Mexico: data collection for the continued assessment of associated faunal assemblages, trophic interactions and habitat function in the wake of the Deepwater Horizon oil spill (2011)

The pelagic brown algae complex of Sargassum natans and S. fluitans supports large and diverse assemblages of marine fish early life history stages. Fish larvae and juveniles presumably utilize these pelagic habitats as protection from predators, but Sargassum may also provide enhanced feeding opportunities and serve to concentrate larvae and juveniles with flotsam-seeking behaviors. Sargassum, therefore, serves as pelagic "nursery habitats" for many important fisheries species, including mahi mahi, grey triggerfish, tripletail, billfish and amberjack, as well as ecologically important forage fish species, such as butterfishes and flyingfishes. For these reasons, Sargassum has been designated as Essential Fish Habitat. The Deepwater Horizon spill placed a large pool of oil in the northern Gulf of Mexico surface waters. Because Sargassum clumps, mats and weedlines are found in the neuston, these habitats and associated fauna were at severe risk of exposure to surface oil, sheens,

and chemical dispersants introduced as a result of the Deepwater Horizon incident. More than one year removed from the oil spill, the effects of this prolonged exposure to oil/dispersant products on the algal complex and its function as nursery habitat for associated fauna are unknown.