Human-driven coastal erosion in marshes is not uncommon. But the Deepwater Horizon oil spill brought with it the possibility of larger scale killing of coastal plants, which could further accelerate this coastal erosion.

The authors of this article – including Abt Senior Associate Cameron Wobus – tested for spatial generality of and thresholds in this effect across 103 salt marsh sites spanning approximately 430 kilometers of shoreline in coastal Louisiana, Alabama, and Mississippi, using data collected as part of the Deepwater Horizon natural resource damage assessment. Our analyses revealed a threshold for oil impacts on marsh edge erosion, with higher erosion rates occurring for approximately one to two years after the spill at sites with the highest amounts of plant stem oiling (90 to 100 percent).

These results provide compelling evidence showing large-scale ecosystem loss following the Deepwater Horizon oil spill. More broadly, these findings provide rare empirical evidence identifying a geomorphologic threshold in the resistance of an ecosystem to increasing intensity of human-induced disturbance.