The iconic Torrey Canyon oil spill of 1967 - Marking its legacy.

March 2017 marks the 50th anniversary of the SS Torrey Canyon oil spill and cleanup, off the Cornwall coast in the English Channel. It was the world's first major supertanker disaster. It was a signature event in the marine pollution field, especially related to oil spill response and the initiation of scientific studies of monitoring and researching the fate and effects of oil in the sea. This paper recalls this event, notes our growing understanding of marine pollution and global efforts for cleaner seas, and encourages further work on both oil and the many emerging environmental issues affecting the marine environment.

Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish.

The Deepwater Horizon disaster released more than 636 million L of crude oil into the northern Gulf of Mexico. The spill oiled upper surface water spawning habitats for many commercially and ecologically important pelagic fish species. Consequently, the developing spawn (embryos and larvae) of tunas, swordfish, and other large predators were potentially exposed to crude oil-derived polycyclic aromatic hydrocarbons (PAHs). Fish embryos are generally very sensitive to PAH-induced cardiotoxicity, and adverse changes in heart physiology and morphology can cause both acute and delayed mortality. Cardiac function is particularly important for fast-swimming pelagic predators with high aerobic demand. Offspring for these species develop rapidly at relatively high temperatures, and their vulnerability to crude oil toxicity is unknown. We assessed the impacts of field-collected Deepwater Horizon (MC252) oil samples on embryos of three pelagic fish: bluefin tuna, yellowfin tuna, and an amberjack. We show that environmentally realistic exposures (1-15 µg/L total PAH) cause specific dose-dependent defects in cardiac function in all three species, with circulatory disruption culminating in pericardial edema and other secondary malformations. Each species displayed an irregular atrial arrhythmia following oil exposure, indicating a highly conserved response to oil toxicity. A considerable portion of Gulf water samples collected during the spill had PAH concentrations exceeding toxicity thresholds observed here, indicating the potential for losses of pelagic fish larvae. Vulnerability assessments in other ocean habitats, including the Arctic, should focus on the developing heart of resident fish species as an exceptionally sensitive and consistent indicator of crude oil impacts.

Impact of crude oil exposure on nitrogen cycling in a previously impacted Juncus roemerianus salt marsh in the northern Gulf of Mexico.

This study investigated potential nitrogen fixation, net nitrification, and denitrification responses to short-term crude oil exposure that simulated oil exposure in Juncus roemerianus salt marsh sediments previously impacted following the Deepwater Horizon accident. Temperature as well as crude oil amount and type affected the nitrogen cycling rates. Total nitrogen fixation rates increased 44 and 194 % at 30 °C in 4,000 mg kg(-1) tar ball and 10,000 mg kg(-1) moderately weathered crude oil treatments, respectively; however, there was no difference from the controls at 10 and 20 °C. Net nitrification rates showed production at 20 °C and consumption at 10 and 30 °C in all oil treatments and controls. Potential denitrification rates were higher than controls in the 10 and 30 ºC treatments but responded differently to the oil type and amount. The highest rates of potential denitrification (12.7 ± 1.0 nmol N g(-1) wet h(-1)) were observed in the highly weathered 4,000 mg kg(-1) oil treatment at 30 °C, suggesting increased rates of denitrification during the warmer summer months. These results indicate that the impacts on nitrogen cycling from a recurring oil spill could depend on the time of the year as well as the amount and type of oil contaminating the marsh. The study provides evidence for impact on nitrogen cycling in coastal marshes that are vulnerable to repeated hydrocarbon exposure.

Rapid degradation of Deepwater Horizon spilled oil by indigenous microbial communities in Louisiana saltmarsh sediments.

The Deepwater Horizon oil spill led to the severe contamination of coastal environments in the Gulf of Mexico. A previous study detailed coastal saltmarsh erosion and recovery in a number of oil-impacted and nonimpacted reference sites in Barataria Bay, Louisiana over the first 18 months after the spill. Concentrations of alkanes and polyaromatic hydrocarbons (PAHs) at oil-impacted sites significantly decreased over this time period. Here, a combination of DNA, lipid, and isotopic approaches confirm that microbial biodegradation was contributing to the observed petroleum mass loss. Natural abundance (14)C analysis of microbial phospholipid fatty acids (PLFA) reveals that petroleum-derived carbon was a primary carbon source for microbial communities at impacted sites several months following oil intrusion when the highest concentrations of oil were present. Also at this time, microbial community analysis suggests that community structure of all three domains has shifted with the intrusion of oil. These results suggest that Gulf of Mexico marsh sediments have considerable biodegradation potential and that natural attenuation is playing a role in impacted sites.

Oil biodegradation and bioremediation: a tale of the two worst spills in U.S. history.

The devastating environmental impacts of the Exxon Valdez spill in 1989 and its media notoriety made it a frequent comparison to the BP Deepwater Horizon spill in the popular press in 2010, even though the nature of the two spills and the environments impacted were vastly different. Fortunately, unlike higher organisms that are adversely impacted by oil spills, microorganisms are able to consume petroleum hydrocarbons. These oil degrading indigenous microorganisms played a significant role in reducing the overall environmental impact of both the Exxon Valdez and BP Deepwater Horizon oil spills.