On April 20, 2010, the Deepwater Horizon drilling rig explosion occurred about 40 miles southeast of the Louisiana coast. It is considered to be the largest accidental marine oil spill in the world and the largest environmental disaster in U.S. history. The explosion killed 11 workers and injured 16 others. It caused the Deepwater Horizon to burn and sink, resulting in a massive offshore oil spill in the Gulf of Mexico. Millions of barrels of oil were discharged onto the shorelines of gulf coast states for almost three months. Response efforts added almost two million gallons of dispersants to the Gulf.
Six years later the researchers from the University of South Florida (USF) College of Marine Science, the lead institute for the Center for Integrated Modeling and Analysis, an international consortium created to study the effects of the Deepwater Horizon oil spill, outlined their research and listed four important lessons learned:
1. The need for baseline data throughout the oceans to determine a disaster’s effects.
2. Oil sinks to the bottom
3. Dispersants may not be as useful as once believed, particularly in the deep-sea
4. Prolonged oil toxicity in fish continues
The researchers from USF piggybacked on this research and in July of 2018, published results of a seven year study in the journal Marine and Coastal Fisheries, producing the most comprehensive data available of what fish and other wildlife call the gulf their home. The study was very important since the Gulf of Mexico had been understudied before 2010, so there was no picture of the Gulf’s condition before the oil spill limiting researcher’s abilities to fully understand the spills impact.
The team on this project in addition to USF consisted of researchers from Texas A&M, National Autonomous University of Mexico and the University of Havana. There were 12 separate research expeditions, that included two trips to Mexico and one trip to Cuba and 15,000 fish of 166 species from 343 locations were caught. The Gulf was divided into six zones, to help differentiate population changes. The most notable decline they found since the disaster is of the red snapper and southern hake in the Northern Gulf, the location of the Deepwater Horizon oil spill.
The study found that fish were most abundant in the northern and northwestern Gulf. Much of that was attributed to increased fishery protections and the area producing more phytoplankton. The average sizes of fish were larger there compared to the West Florida Shelf, Yucatan Peninsula and Cuba where fewer large predators exist. The species compositions and size data provide a basis for evaluating resiliency to overfishing, climate change, pollution, habitat loss, invasive species and other stressors on fish populations.
The fish were tested for oil residues and other pollutants. Overall, the degree of oil contamination of fish from the northern Gulf continues to decline, although no areas assessed to date are oil free.
The top five species found in the Gulf of Mexico by the research scientists were the Atlantic sharpnose shark, Red snapper, King snake eel, Tilefish and Gulf smoothhound.
“Neither the fish nor oil spills know national boundaries, “said principal investigator Steve Murawski, PhD professor at the University Of South Florida College Of Marine Science. “Providing seamless data for the Gulf as a whole is imperative if we are to prepare adequately for future oil spills.”
Photo courtesy of NOAA