Culbertson, J.B., Valiela, I., Pickart, M., Peacock, E.E. and Reddy, C.M., Long-term consequences of residual petroleum on salt marsh grass., J. of Applied Ecology, 2008; v45, 1284-1292.
| 1. |
Remnants from oil spills can persist for decades within anoxic coastal sediments affecting local flora and fauna, but few studies have examined the long-term impacts of the residual petroleum on these valuable coastal ecosystems.
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| 2. |
The Wild Harbor salt marsh (Buzzards Bay, Massachusetts, USA) still harbours residual petroleum from a 1969 oil spill, which released 700 000 L of No. 2 fuel oil. Previous effects have been noted in fiddler crabs and ribbed mussels inhabiting the oiled marsh.
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Spartina alterniflora biomass was sampled above- and below-ground in elevational transects through areas with different total petroleum hydrocarbon (TPH) content. Further, elevational differences were mapped in oiled and non-oiled locations.
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Stem density and above- and below-ground biomass decreased in oiled areas. The decreased vegetation biomass led to unconsolidated sediments, increased topographical variation and, ultimately, loss of salt marsh habitat.
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Four decades after the Florida spill, with only 100 kg of the original 595 000 kg of spilt oil persisting in salt marsh sediment, the effects on large-scale ecosystem functions are still evident.
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Synthesis and applications. Our results demonstrate specific impacts of residual petroleum on S. alterniflora biomass and coastal erosion. Further, we have defined TPH content thresholds at which to expect long-term ecosystem impacts. The recalcitrant nature of these contaminants and their chronic large-scale ecosystem effects leads to the potential demand for alternative compensation, such as preservation of coastal systems at risk elsewhere.
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