Recovery of Brittany Coastal Marshes in the Eight Years Following the Amoco Cadiz Incident

Abstract

The salt marshes on the Brittany coast of France have undergone a number of changes and have been influenced by man-made and natural factors since the Amoco Cadiz spill of March 1978. This work catalogs the ecological changes which have occurred over the past eight years and presents original data on the present state of these marshes. The recovery of Brittany coastal marshes began following cleanup operations which were often damaging to marsh and marsh substrate. The physical and toxicological properties of the oil also were damaging in the short term, especially to annual species. Natural recovery began primarily by invasion of exposed areas with annuals and rhizome spreading of perennials. Within four years, an almost logarithmic recruitment process was begun by annuals followed by perennials. Pioneer and opportunistic species increased, facilitated by partially vegetated substrates available for seed and seedling retention and by increased seed and rhizome production. Man-induced restoration was also important and was done largely by planting wild or cultured stock. The final stage of marsh recovery, as existing today, is the emergence of perennial species of high and low marsh at elevations and tidal exposures typical for their growth. These successional changes in a marsh following a major oil spill (and various other man-made impacts) provide an understanding of the complex processes involved in marsh recovery. This understanding allows the formulation of planning guidelines to predict the long-term impacts of future incidents and to make proper recommendations for cleanup and restoration to aid the recovery process.

Synthesis and Crosscutting Topics of the GoMRI Special Issue

“…The patchiness of the oiling and the heterogeneity of the spatial and temporal aspects of return to background concentrations, or nondetectable concentrations for petroleum hydrocarbon in the marsh sediments, is consistent with results of studies of previous spills that oiled marshes or mangroves (e.g., Teal et al, 1978;Burns and Teal, 1979;NRC, 1985NRC, , 2003Baca et al, 1987;Burns et al, 1993Burns et al, , 1994Reddy et al, 2002;Bejarano and Michel, 2010).…”

Modeling photosynthesis ofSpartina alterniflora(smooth cordgrass) impacted by the Deepwater Horizon oil spill using Bayesian inference

“…Once oil penetrates the sediment, the recovery to reference conditions may take 3-4 years (Alexander and Webb 1987, Mendelssohn et al 1993, Hester and Mendelssohn 2000 or longer (Bergen et al 2000, Michel et al 2009. Under extreme circumstances, recovery may never occur due to sediment removal (Baca et al 1987, Gilfillan et al 1995 or accelerated erosion after vegetation morality . Even after plants resume growth, oil may continue to adversely affect soil microbial functions in coastal wetlands (Burns andTeal 1979, Pezeshki et al 2001).…”

Shoreline oiling effects and recovery of salt marsh macroinvertebrates from the Deepwater Horizon Oil Spill

“…Various studies of the impact of DWH on vegetation, soil parameters, microbes, benthic microalgae, and infauna ( Fleeger et al, 2015 ; Fleeger et al, 2017 ; Husseneder, Donaldson & Foil, 2016 ; Lin & Mendelssohn, 2012 ; Lin et al, 2016 ; McCall & Pennings, 2012 ; Silliman et al, 2012 ; Zengel et al, 2015 ; Zengel et al, 2016a ; Zengel et al, 2016b ) have been conducted in northern Barataria Bay. These and other studies have shown that plant species respond differently to oiling ( Alexander & Webb, 1987 ; Baca, Lankford & Gundlach, 1987 ; Culbertson et al, 2008 ; DeLaune et al, 2003 ; Hester & Mendelssohn, 2000 ; Hoff, Shigenaka & Henry, 1993 ; Lin & Mendelssohn, 1996 ; Lin & Mendelssohn, 1998 ; Lin & Mendelssohn, 2008 ; Lin & Mendelssohn, 2009 ; Lin et al, 2002 ; Mendelssohn et al, 1990 ; Mendelssohn et al, 2012 ; Michel & Rutherford, 2014 ; Pezeshki et al, 2000 ; Zengel et al, 2015 ; Zengel et al, 2016a ; Zengel et al, 2016b ). DWH impacts on vegetation include reductions in photosynthesis, transpiration, shoot height, stem density, and above- and belowground biomass.…”