Abstract The Deepwater Horizon (DWH) oil spill in the NE Gulf of Mexico in 2010 was the largest accidental spill globally. During and after the spill, oil was incorporated into marine snow (marine‐oil‐snow or MOS) and sedimented to the seafloor, accounting for ∼21% of the oil released. We assessed the abundance, distribution, size, composition, shape, and fractal dimension of marine snow in relation to the oil spill and natural environmental conditions between May 2010 and August 2014 using SIPPER camera images. The Mississippi River outflow, which governs productivity in this region, was elevated during the oil spill resulting in a large phytoplankton bloom. Integrated marine snow abundance was significantly higher during the spill and particle size spectra showed a higher abundance of intermediate‐ and large‐sized particles during the oil spill compared to non‐spill years. Particle collision and sinking rates may be sensitive to particle composition, shape, and fractal dimension (surface area complexity). Identifiable aggregate components included chain diatoms and acantharian radiolarians and their spines. Almost all aggregates were elongated in all years. The geometric mean fractal dimension for particles in non‐oil spill years was 1.45 (range: 1.00–1.94), whereas particle fractal dimensions were significantly higher (mean: 1.49, 1.01–1.87, p = 0.03) during the oil spill, indicating that oil droplets in MOS may have decreased particle porosity compared to other years. Fractal dimensions also increased with particle size during all years. These data provide a baseline for model development, responding to future oil spills, and for investigations of biogeochemical cycles in this region.
Daly et al. (Sun,) studied this question.