Amelioration of Freshwater, Peat-based Marshes after Oil Contamination:
I.  A Field Experiment; II.  An Historical Spill Site Assessment

Guerry O. Holm, Jr. and Charles E. Sasser
School of the Coast and Environment & Patrick J. Bergeron
Environmental Safety and Health Consulting Services, Inc.

Abstract

Here we report on two discrete but complementary field studies pertaining to oil spills in freshwater peat-based marshes.  Our objectives were:  (1) to compare the success of marsh recovery by either transplanting or natural plant reestablishment; and (2) to compare the ecological status (plant/soil characteristics) of an oil-impacted versus un-impacted marsh, 10 years following a spill.  In the case of the first experiment, we found that the process of plant reestablishment (natural) is very slow in peat soils with moderate to high oil concentrations; however, transplant survivorship and growth of Panicum and Sagittaria is positive, in peat soils with fresh crude oil conditions.  Whether the transplants accelerated oil breakdown is uncertain.  In the case of the second study, we found that the oil-impacted marsh fell short of the target conditions represented by the un-impacted marsh.  Nonetheless, the oil-impacted marsh has become fully re-vegetated within these 10 years and exhibits comparable species richness to that of the un-impacted marsh.  Transplantation may be useful in accelerating plant coverage of crude oil impacted marshes, thereby facilitating the natural recovery process.