The infamous Deepwater Horizon spill which occurred in 2010 is still a bitter memory to many. The explosion which rocked the oil rig subsequently killed numerous workers and caused the release of more than 200 million gallons of oil. But for the ecosystems it impacted, it is not a memory but an ongoing reality of consequences.
It has been known that impacts on many species could be delayed or at least unknown for certain periods of time post-spill. Species which have been found to have consequences that were often delayed rather than immediate were dolphins, sea turtles and coral. Many other species are likely to suffer delayed reactions or unknown reactions. But one such consequence of the major oil spill in 2010 impacts a foundation of the food chain: phytoplankton.
Obviously a disruption at the bottom of the food chain could have significant consequences for the majority of the food chain above it. What scientists recently unveiled through laboratory studies has shined light on a problem which could be felt for years to come. Recently published in the journal PLoS ONE online edition, scientists found that dispersants used in the spill likely significantly impacted phytoplankton and ciliate populations.
According to statistics during the BP spill, 1.8 million gallons of chemical dispersants were applied to the oil in the Gulf of Mexico, including actually being pumped into the area of the source of the spill. Many have indicated since that the amount of dispersant used on the spill was uncommon, even for the immensity of the spill.
The study, performed at the Dauphin Island Sea Lab located in Alabama, compared the effects of applying dispersant versus allowing oil to disperse on its own. The researchers determined that the use of dispersants greatly reduced the growth of both phytoplankton and ciliates. Population and growth was not shown to be impacted when the oil was left to degrade on its own. This means that already stressed species also likely had to face reduced food availability.
One of the reasons dispersants would impact phytoplankton and ciliates is due to the oil being removed from the surface only to increase below. Therefore species on the surface of the water may see reduced exposure to the oil but the species below could see more than they would if no dispersants were used. Unfortunately it appears that both using and not using dispersants would likely cause widespread impacts.