Gulf zooplankton recovery and the Deepwater Horizon spill

The Deepwater Horizon oil spill was a catastrophic man-made disaster that directly impacted oceanic aquatic ecology on land and sea. Even though the event took place in April 2010, it has continued to create a ripple effect across the Gulf of Mexico, particularly with water bodies, oceanic wildlife and communities along the Gulf coastline. To date, it is the largest marine oil spill in history.

What made the Deepwater Horizon oil spill so disastrous was the fact that the rupture was not contained for quite some time. After the oil rig exploded approximately 41 miles off the coast of Louisiana on April 20, 2010, the vessel sank two days later. Due to the lack of opposing force, oil continued to spill into the Gulf (at a peak of 60,000 barrels per day) and was not completely sealed until after a series of pressure tests in September 2010.

"Deepwater Horizon has had a ripple effect across the Gulf."

Zooplankton show their resilience
The critical link in the oceanic marine food chain is zooplankton, both in the deep sea and near the coastline that so many Gulf species call home. That's why in 2010, Frank Hernandez and other researchers from the University of Southern Mississippi took water samples from the Gulf and compared them to ratios that were determined between 2005 and 2009.

To no surprise, there were "significant variations" in the assemblage of mesozooplankton throughout the region, particularly with ostracods, cladocerans and echinoderm larvae in May and June of 2010. However, in July 2010, something surprising occurred: Many of these levels returned to normal, showing a rapid recovery for the precious food source. Scientists stated that "it is possible that increased microbial activity related to the infusion of oil carbon may have stimulated secondary production through microbial-zooplankton trophic linkages."

Whatever the reason, these results prove how resilient zooplankton species can be, even in the most dire environmental conditions.

oil drillingOil drilling in the Gulf of Mexico is a common occurrence.

Researchers comment on their findings
Previous studies showed that zooplankton tended to die at a significant rate when exposed to oil and dispersants, so these results are especially promising. However, Hernandez said that this doesn't mean the oil spill won't cause dramatic changes to the oceanic marine life of the Gulf further down the road.

"A disruption in the pelagic [open sea] food web, even for short periods, may imperil organisms that rely on zooplankton as food. Further, we should not forget lessons learned from previous accidents, such as the [1989] Exxon Valdez spill, where there were many 'latent' effects – impacts that were not detectable until years later," Hernandez explained in Environmental Research Web.

In fact, according to a study highlighted in the University of Maryland Center for Environmental Science, remnants of oil found in Gulf zooplankton prove that these substances are likely making their way up the Gulf's food chain. Considering how much seafood is harvested in the water body each year and how many communities thrive from fishing and tourism activities, further bioassessment services are needed to monitor the Gulf region in the years to come.