In April 2010, the explosion of the Deepwater Horizon oil platform caused a massive oil spill. For months, oil spread through the sea, affecting the coastlines as well as the deep waters. The visible consequences made headlines around the world.
After the disaster, American researchers studied ocean species for more than a decade. They focused in particular on lanternfish, shrimp, krill, squid and other animals that swim in the depths. These species provide food for many predators, including tuna and cetaceans.
The Deepwater Horizon oil platform on fire in 2010
Public domain · Wikimedia
By comparing observations made just after the disaster with those from subsequent years, the team discovered a considerable decline. Depending on the groups studied, populations fell by 60 to 85% over a period of about three and a half years. For fish as a whole, the measured decline reached approximately 63%.
The researchers used nets to collect animals and acoustic instruments to detect their presence in the water. Both methods tell a similar story: a rapid collapse, followed by very little recovery through the latest observations, in 2023.
Why such a decline? The scientists examined several natural explanations, such as water temperature, lack of oxygen and food availability. None matched the observed trend well. The 2010 oil spill therefore appears to be the most likely explanation.
But the study alone does not prove that the oil caused all of these losses. Above all, it establishes a strong temporal coincidence, supported by the absence of another convincing natural factor. The possible effects of the oil and the products used to disperse the pollution remain difficult to disentangle.
The phenomenon does not affect only the smallest animals. Fish and crustaceans feed other species, sometimes much larger ones. A sustained decline in their abundance could therefore weaken a substantial part of the food chain.
This study shows that a disaster occurring at the surface can leave a mark for years on an almost invisible world. It also reminds us that an immense environment such as the deep ocean does not necessarily regain its balance quickly after major pollution.