Oil Dispersant Toxic To Plankton

A chemical commonly used to disperse oil slicks apparently creates a deadly cocktail for some types of plankton.

Corexit was used in the Deep Water Horizon oil spill to help break down the slick into droplets, which were then able to sinkĀ  below the surface and supposedly degrade.

Touted as a product that protects the environment as it stops the oil from sticking to wildlife such as birds, it also appears to have a darker side.

Researchers have found Corexit and oil are similar in their toxicity – until they are mixed together. When combined in a ratio used in the Deep Water Horizon spill, toxicity to a form of plankton called Brachionus plicatilis increases up to 52-fold.

Brachionus plicatilis is an important food source for many marine creatures and is also raised in the aquaculture industry as food for fish larvae.

The oil/Corexit cocktail also has a massive impact on the plankton’s eggs. According to an abstract from the research:

“Just 2.6% of the water-accommodated fraction of oil inhibited rotifer cyst hatching by 50%, an ecologically significant result because rotifer cyst in sediments are critical resources for the recolonization of populations each Spring.”

Nalco, the makers of Corexit, have a page on their web site titled “Inaccuracy vs Fact About COREXIT Products“. It states:

“Corexit products biodegrade rapidly, do not bioaccumulate, are not human carcinogens, do not degrade into endocrine disruptors, and are not reproductive toxins. Common household soaps are more toxic to marine life than Corexit.”

Somebody should tell the plankton.

But seriously, what the company states may well be correct – I assume plankton wouldn’t be too happy being dumped in a bucket of soapy water either. However, sometimes it’s information left out of these sorts of statements that is as important as what is included.

It’s also a matter of being caught between a rock and a hard place. Failing other remediation efforts, do you just let the oil do its thing without dispersants or use Corexit and hope for the best? Both scenarios have a negative environmental impact; it’s just that impact of the latter may be more than previously understood.

The best scenario of course is for oil spills to not occur in the first place. While that is a pipe dream (at least until we run out of the stuff), this research on Corexit shows there is no get out of jail free card when it comes oil spill events. Many creatures are going to suffer the fallout.

While we can point our collective finger at the companies involved, we do need to bear in mind where much of the demand for oil comes from – us.

However, if greener transportation was much more affordable and available, that demand would drop significantly – and the reason it isn’t is thanks to the fossil fuel industry.

Learn more about the effects of oils spills on the environment.