The 2010 Deepwater Horizon oil spill may have had a lasting impact on the microbiomes living on and around World War II-era and 19th century shipwrecks located in the Gulf of Mexico, according to a study in Scientific Reports.

An estimated 11 to 30% of the oil that was discharged into the sea during the Deepwater Horizon spill remains unaccounted for. Leila Hamdan and colleagues examined the possible impact of the remaining oil on historic shipwrecks located within the Deepwater Horizon spill footprint; the area in which deep-water habitats are likely to remain impacted. Historic shipwrecks serve as artificial reefs and hotspots of biodiversity, and microbial communities on shipwrecks and in the surrounding seafloor play important roles in shipwreck preservation and degradation.

The authors selected seven historic wrecks based on depth, distance to the spill site and the extent of surface oiling during the 87-day discharge from the Deepwater Horizon oil well. They compared microbiome, physical properties and chemical data of the sediment surrounding wrecks within heavily impacted, moderately impacted and reference areas. The authors found that in areas least impacted by the Deepwater Horizon spill, shipwreck proximity was associated with higher microbial diversity in surface sediments; microbiomes closer to wrecks were significantly different from those further away. However, at wrecks located in areas most heavily impacted by the spill, microbiomes close to wrecks did not differ from those further away. The authors suggest this may be due to the presence of spill residues at these sites.