Friday, July 20, 2012

Oil Effects Blue Carbon Ecosystems

Deep Sea News report on Deepwater Horizon oil spill research

Excerpted from - Deep Sea News | Wednesday, July 18th, 2012 | by DR BIK

A new Silliman et al. PNAS paper is looking at the effects of the 2010 Deepwater Horizon oil spill on heavily-impacted salt marsh ecosystems around Barataria Bay, Louisiana. In contrast to Deep Sea News' own study, looking at oil impacts on sandy Gulf Coast beaches, marshlands provide a particularly interesting contrast: 

"Past studies investigating effects of oil spills on salt marshes indicate that negative impacts on plants can be overcome by vegetation regrowth into disturbed areas once the oil has been degraded (8, 28–30). This finding suggests that marshes are intrinsically resilient to (i.e., able to recover from) oil-induced perturbation, especially in warmer climates such as the Gulf of Mexico, where oil degradation and plant growth rates may be high." (Silliman et al. 2012)

"These data provide evidence of salt-marsh community die-off in the near-shore portion of the Louisiana shoreline after the BP-DWH oil spill because of high concentrations of oil at the edge of the marsh. Specifically, these findings suggest that the veg- etation at the marsh edge, by reaching above the highest high- tide line in the microtidal environment of the Gulf of Mexico, blocked and confined incoming oil to the shoreline region of the marsh. This shoreline containment of the oil may have protected inland marsh but led to extensive mortality of marsh plants lo- cated from the marsh edge to 5–10 m inland and to sublethal plant impacts on plants 10–20 m from the shoreline, where plant oiling was less severe….These data also suggest that the mechanism of the lethal effects of oil are more likely derived from interference with respiration and photosynthesis than from direct toxicity because plant death only occurred at high levels of oil coverage." (Silliman et al. 2012)



Silliman BR, van de Koppel J, McCoy MW, Diller J, Kasozi GN, Earl K, et al. (2012): Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America 109 (28), pp 11234-11239. doi:10.1073/pnas.1204922109

- Posted by Sven Stadtmann, GRID-Arendal