The demonstrated effects of pollution by DWH crude oil and the dispersant Corexit® 9500 on P. astreoides and M. faveolata planulae strongly suggest that the use of dispersants to mitigate oil spills in the vicinity of coral reefs should be avoided.
It's been over two years since the BP oil spill, and since then scientists such as Dr. Charles Fisher of Penn State, Dr. Samantha Joye of University of Georgia and Dr. Ron Tjeerdema of UC Davis have worked tirelessly to better understand the full impact of the environmental catastrophe.
Many others, such as the researchers from Sarasota's Mote Marine Laboratory who investigated the corals for "Toxicity of Deepwater Horizon Source Oil and the Chemical Dispersant, Corexit(R) 9500, to Coral Larvae", have shown that:
- Settlement and survival of P. astreoides and M. faveolata larvae (from corals) decreased with concentrations of Corexit® 9500 and other dispersants; however, the degree of response varied by species and solution;
- Exposure to medium and high concentrations of dispersants greatly lessened larval settlement (a behavioral act when the larvae leaves the plankton, and descends to the benthos) and survival for both species;
- Exposure to Corexit® 9500 resulted in settlement failure and complete larval mortality after exposure to 50 and 100 ppm for M. faveolata and 100 ppm for P. astreoides;
- And subsequently, that exposure of coral larvae to oil spill-related contaminants, particularly Corexit® 9500, can adversely affect coral settlement and survival, "thereby affecting the resilience and recovery of coral reefs following exposure to oil and dispersants."
Authors also examined the effects of the Macondo oil on the corals, mentioning that historically:
Studies have shown that exposure of adult coral colonies to crude oil can result in a range of effects including inhibited growth rate, reduced reproductive activity, and tissue loss...
Over the past two years, this page has been dedicated to revealing how marine life and wildlife have been adversely affected by the DWH/BP disaster, and naturally, conflicting views have arisen. Further, scientists are always quick to remind that a hunch is merely that and research takes time. Papers also take time to be written and published. Politics can also play into the equation.
All of that being said, since the very genesis of the disaster there have been voices screaming that Corexit was not the answer. One of them, National Geographic explorer-in-residence Dr. Sylvia Earle, spoke before Congress in May, 2010. She called for an immediate halt on the use of the deadly disperant Corexit, saying that:
The instructions for humans using Corexit, the dispersant approved by the EPA to make the ocean look better warn that it is an eye and skin irritant, is harmful by inhalation, in contact with skin and if swallowed, and may cause injury to red blood cells, kidney or the liver. People are warned not to take Corexit internally, but the fish, turtles, copepods and jellies have no choice. They are awash in a lethal brew of oil and butoxyethanol.
TED award recipient Earle, whose marine-protected "hope spots" are a push to not only protect but restore the oceans, said changes must be made as if "our lives depend upon it, because they do."
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