GULF OF MEXICO - The site of the Deepwater Horizon oil spill has become a popular mating ground for deep-sea crabs and shrimp.
Decomposing oil from the 2010 spill could be mimicking a sex hormone, and that's what's attracting these crustaceans to get frisky in this part of the Gulf, according to an August study published in the journal Royal Society Open Science.
Spending time at the oil rig is also making these animals sick, especially as seen in the crabs. Their shells are turning black, parasites have latched on and some have lost limbs or developed mutations, according to the Louisiana Universities Marine Consortium, which led the study.
"Crabs showed clearly visible physical abnormalities and sluggish behavior compared to the healthy crabs we had observed elsewhere," Executive Director of LUMCON and lead author Craig McClain told CNN. "Once these crustaceans reach the site, they may become too unhealthy to leave."
The effects of the Deepwater Horizon oil spill are still being felt and in new ways. The deep-sea ecosystem is "recovering slowly and lingering effects may be extreme," McClain said.
Nine years ago, the explosion at the Deepwater Horizon oil rig released 4 million barrels of oil into the Gulf of Mexico. Oil and methane gas spewed from the uncapped well for 87 days in a row.
Since the 2010 environmental disaster, there have been studies on the biological impacts of the spill. Another effect of the spill that researchers are just learning about now is how it's hurting the crustaceans near the well.
The number of crabs and shrimp near the well site were almost 8 times higher than other sites explored in 2017, when the survey was conducted.
Three types of crustaceans showed up in big numbers: the red deep-sea crab and species of red shrimp and white shrimp.
People don't fish commercially for these species of crabs and shrimp in the Gulf of Mexico, so there's little risk to humans, McClain said. The concern is for larger organisms who may eat the toxic crabs, introducing the chemicals higher up into the food chain.
While there were a lot of certain animals, there was a small variety of sea creatures observed. Certain types of deep-sea dwellers that you'd expect to see were not present, the study said.
"Near the wreckage and wellhead, many of the animals characteristic of other areas of the deep Gulf of Mexico, including sea cucumbers, giant isopods, glass sponges and whip corals, were absent," McClain said. "What we observed was a homogenous wasteland, in great contrast to the rich heterogeneity of life seen in a healthy deep sea."
The LUMCON team used remote-operated vehicles to take videos 1,600 feet around the well site. The videos were compared to videos taken months after the spill in 2010.
While the deep-sea ecosystem is still recovering, more research needs to be done, say the study's authors. It's hard to know the full impact since we don't have enough sampling prior to the oil spill.
"We know little about the deep sea, so when these kinds of human impacts, occur we don't have the knowledge we need to make informed decisions about recovery," McClain said.
The deep-sea ecosystem is fragile, and it works on a much slower scale to recover, said Clifton Nunnally, co-author of the study and LUMCON Lab Manager/Senior Research Associate.
"Human impacts on the environment never really go away. Loss of biodiversity can mean one species or thousands of individuals," Nunnally told CNN.
"We can't allow this heavily impacted disaster site to slip from our collective memory and further study is needed to shed light on the long-term impacts that oil spills have on fragile deep-sea ecosystems," he said.