Meta‐analysis of salt marsh vegetation impacts and recovery: a synthesis following the Deepwater Horizon oil spill

Abstract Marine oil spills continue to be a global issue, heightened by spill events such as the 2010 Deepwater Horizon spill in the Gulf of Mexico, the largest marine oil spill in US waters and among the largest worldwide, affecting over 1,000 km of sensitive wetland shorelines, primarily salt marshes supporting numerous ecosystem functions. To synthesize the effects of the oil spill on foundational vegetation species in the salt marsh ecosystem, Spartina alterniflora and Juncus roemerianus, we performed a meta‐analysis using data from 10 studies and 255 sampling sites over seven years post‐spill. We examined the hypotheses that the oil spill reduced plant cover, stem density, vegetation height, aboveground biomass, and belowground biomass, and tracked the degree of effects temporally to estimate recovery time frames. All plant metrics indicated impacts from oiling, with 20–100% maximum reductions depending on oiling level and marsh zone. Peak reductions of ~70–90% in total plant cover, total aboveground biomass, and belowground biomass were observed for heavily oiled sites at the marsh edge. Both Spartina and Juncus were impacted, with Juncus affected to a greater degree. Most plant metrics had recovery time frames of three years or longer, including multiple metrics with incomplete recovery over the duration of our data, at least seven years post‐spill. Belowground biomass was particularly concerning, because it declined over time in contrast with recovery trends in most aboveground metrics, serving as a strong indicator of ongoing impact, limited recovery, and impaired resilience. We conclude that the Deepwater Horizon spill had multiyear impacts on salt marsh vegetation, with full recovery likely to exceed 10 years, particularly in heavily oiled marshes, where erosion may preclude full recovery. Vegetation impacts and delayed recovery is likely to have exerted substantial influences on ecosystem processes and associated species, especially along heavily oiled shorelines. Our synthesis affords a greater understanding of ecosystem impacts and recovery following the Deepwater Horizon oil spill, and informs environmental impact analysis, contingency planning, emergency response, damage assessment, and restoration efforts related to oil spills.

[1]  T. C. Hanley,et al.  Effect of foundation species composition and oil exposure on wetland communities across multiple trophic levels , 2021 .

[2]  Greg E. Challenger,et al.  A review of Gulf of Mexico coastal marsh erosion studies following the 2010 Deepwater Horizon oil spill and comparison to over 4 years of shoreline loss data from Fall 2010 to Summer 2015. , 2021, Marine pollution bulletin.

[3]  I. Mendelssohn,et al.  Planting Spartina alterniflora in a salt marsh denuded of vegetation by an oil spill induces a rapid response in the soil microbial community , 2020 .

[4]  M. Christman,et al.  Macroinfauna responses and recovery trajectories after an oil spill differ from those following saltmarsh restoration. , 2020, Marine environmental research.

[5]  Melissa Vernon Carle,et al.  Modeling Coastal Marsh Restoration Benefits in the Northern Gulf of Mexico , 2020, Estuaries and Coasts.

[6]  Robert Taylor,et al.  Restoration Scaling Approaches to Addressing Ecological Injury: The Habitat-Based Resource Equivalency Method , 2020, Environmental Management.

[7]  E. Smith.  Ending Reliance on Statistical Significance Will Improve Environmental Inference and Communication , 2019, Estuaries and Coasts.

[8]  Buffy M. Meyer,et al.  Oiling of the continental shelf and coastal marshes over eight years after the 2010 Deepwater Horizon oil spill. , 2019, Environmental pollution.

[9]  Donald R. Deis,et al.  Legacy effects of Hurricane Katrina influenced marsh shoreline erosion following the Deepwater Horizon oil spill. , 2019, The Science of the total environment.

[10]  M. Kirwan,et al.  Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm , 2019, Current Biology.

[11]  P. Dixon,et al.  Using Meta-Analysis to Develop Evidence-Based Recovery Trajectories of Vegetation and Soils in Restored Wetlands in the Northern Gulf of Mexico , 2019, Estuaries and Coasts.

[12]  N. Lazar,et al.  Moving to a World Beyond “p < 0.05” , 2019, The American Statistician.

[13]  I. Mendelssohn,et al.  What Promotes the Recovery of Salt Marsh Infauna After Oil Spills? , 2018, Estuaries and Coasts.

[14]  W. Scheffel,et al.  Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages , 2018 .

[15]  B. J. Roberts,et al.  Effects of seasonality and environmental gradients on Spartina alterniflora allometry and primary production , 2017, Ecology and evolution.

[16]  M. Baker,et al.  Integrated effects of the Deepwater Horizon oil spill on nearshore ecosystems , 2017 .

[17]  S. Pennings,et al.  Five years of Deepwater Horizon oil spill effects on marsh periwinkles Littoraria irrorata , 2017 .

[18]  Ian J. Zelo,et al.  Nearshore exposure to Deepwater Horizon oil , 2017 .

[19]  Sarai C. Piazza,et al.  Oiling accelerates loss of salt marshes, southeastern Louisiana , 2017, PloS one.

[20]  Carol A. Jones,et al.  The role of ecosystem services in USA natural resource liability litigation , 2017 .

[21]  I. Mendelssohn,et al.  Recovery of saltmarsh meiofauna six years after the Deepwater Horizon oil spill , 2017 .

[22]  Susan L. Ustin,et al.  Marsh Loss Due to Cumulative Impacts of Hurricane Isaac and the Deepwater Horizon Oil Spill in Louisiana , 2017, Remote. Sens..

[23]  John R. White,et al.  Impacts of the long-term presence of buried crude oil on salt marsh soil denitrification in Barataria Bay, Louisiana , 2017 .

[24]  Elijah W. Ramsey,et al.  Wetland shoreline recession in the Mississippi River Delta from petroleum oiling and cyclonic storms , 2016 .

[25]  M. Baker,et al.  Field assessment of the impacts of Deepwater Horizon oiling on coastal marsh vegetation of Mississippi and Alabama , 2016, Environmental toxicology and chemistry.

[26]  P. Dixon,et al.  Thresholds in marsh resilience to the Deepwater Horizon oil spill , 2016, Scientific Reports.

[27]  Giovanna McClenachan,et al.  Islands in the oil: Quantifying salt marsh shoreline erosion after the Deepwater Horizon oiling. , 2016, Marine Pollution Bulletin.

[28]  Russell Jones,et al.  Geospatial estimation of the impact of Deepwater Horizon oil spill on plant oiling along the Louisiana shorelines. , 2016, Journal of environmental management.

[29]  M. Baker,et al.  Impacts of the Deepwater Horizon oil spill on the salt marsh vegetation of Louisiana. , 2016, Environmental pollution.

[30]  Raymond F. Kokaly,et al.  Mapping changing distributions of dominant species in oil-contaminated salt marshes of Louisiana using imaging spectroscopy , 2016 .

[31]  Irving A Mendelssohn,et al.  Response of salt marshes to oiling from the Deepwater Horizon spill: Implications for plant growth, soil surface-erosion, and shoreline stability. , 2016, The Science of the total environment.

[32]  S. Pennings,et al.  Deepwater Horizon Oil Spill Impacts on Salt Marsh Fiddler Crabs (Uca spp.) , 2016, Estuaries and Coasts.

[33]  S. Powers,et al.  Impacts of the Deepwater Horizon Oil Spill on Salt Marsh Periwinkles (Littoraria irrorata). , 2016, Environmental science & technology.

[34]  R. Delaune,et al.  United States Gulf of Mexico Coastal Marsh Vegetation Responses and Sensitivities to Oil Spill: A Review , 2015 .

[35]  J. Michel,et al.  Heavily Oiled Salt Marsh following the Deepwater Horizon Oil Spill, Ecological Comparisons of Shoreline Cleanup Treatments and Recovery , 2015, PloS one.

[36]  M Scott Miles,et al.  Distribution and recovery trajectory of Macondo (Mississippi Canyon 252) oil in Louisiana coastal wetlands. , 2014, Marine pollution bulletin.

[37]  Andrew Whitehead,et al.  Integrating Organismal and Population Responses of Estuarine Fishes in Macondo Spill Research , 2014 .

[38]  J. Farrington.  Oil Pollution in the Marine Environment II: Fates and Effects of Oil Spills , 2014 .

[39]  J. Michel,et al.  Impacts, recovery rates, and treatment options for spilled oil in marshes. , 2014, Marine pollution bulletin.

[40]  Giovanna McClenachan,et al.  Effects of oil on the rate and trajectory of Louisiana marsh shoreline erosion , 2013 .

[41]  J. Farrington.  Oil Pollution in the Marine Environment I: Inputs, Big Spills, Small Spills, and Dribbles , 2013 .

[42]  P. Macreadie,et al.  Loss of ‘Blue Carbon’ from Coastal Salt Marshes Following Habitat Disturbance , 2013, PloS one.

[43]  Elliott Taylor,et al.  Extent and Degree of Shoreline Oiling: Deepwater Horizon Oil Spill, Gulf of Mexico, USA , 2013, PloS one.

[44]  Raymond F. Kokaly,et al.  Spectroscopic remote sensing of the distribution and persistence of oil from the Deepwater Horizon spill in Barataria Bay marshes , 2013 .

[45]  C. Anderson,et al.  The effects of oil exposure and weathering on black-needle rush (Juncus roemerianus) marshes along the Gulf of Mexico. , 2012, Marine pollution bulletin.

[46]  M. W. McCoy,et al.  Degradation and resilience in Louisiana salt marshes after the BP–Deepwater Horizon oil spill , 2012, Proceedings of the National Academy of Sciences.

[47]  Gary L. Andersen,et al.  Oil Impacts on Coastal Wetlands: Implications for the Mississippi River Delta Ecosystem after the Deepwater Horizon Oil Spill , 2012 .

[48]  I. Mendelssohn,et al.  Impacts and recovery of the Deepwater Horizon oil spill on vegetation structure and function of coastal salt marshes in the northern Gulf of Mexico. , 2012, Environmental science & technology.

[49]  S. Pennings,et al.  Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill , 2012, PloS one.

[50]  R. Delaune,et al.  Projected Impact of Deepwater Horizon Oil Spill on U.S. Gulf Coast Wetlands , 2011 .

[51]  V. Engle.  Estimating the Provision of Ecosystem Services by Gulf of Mexico Coastal Wetlands , 2011, Wetlands.

[52]  Wolfgang Viechtbauer,et al.  Conducting Meta-Analyses in R with the metafor Package , 2010 .

[53]  Jacqueline Michel,et al.  Recovery of interior brackish marshes seven years after the chalk point oil spill. , 2009, Marine pollution bulletin.

[54]  Mead A. Allison,et al.  An equilibrium profile model for retreating marsh shorelines in southeast Louisiana , 2008 .

[55]  Emily E. Peacock,et al.  Long-term consequences of residual petroleum on salt marsh grass , 2008 .

[56]  Mark D. Bertness,et al.  Plant zonation in low‐latitude salt marshes: disentangling the roles of flooding, salinity and competition , 2005 .

[57]  M. Bertness,et al.  GEOGRAPHIC VARIATION IN POSITIVE AND NEGATIVE INTERACTIONS AMONG SALT MARSH PLANTS , 2003 .

[58]  I. Mendelssohn,et al.  Long-term recovery of a Louisiana brackish marsh plant community from oil-spill impact: vegetation response and mitigating effects of marsh surface elevation. , 2000, Marine environmental research.

[59]  S. Pennings,et al.  THE ADVANTAGES OF CLONAL INTEGRATION UNDER DIFFERENT ECOLOGICAL CONDITIONS: A COMMUNITY-WIDE TEST , 2000 .

[60]  Jessica Gurevitch,et al.  THE META‐ANALYSIS OF RESPONSE RATIOS IN EXPERIMENTAL ECOLOGY , 1999 .

[61]  I. Mendelssohn,et al.  The combined effects of phytoremediation and biostimulation in enhancing habitat restoration and oil degradation of petroleum contaminated wetlands , 1998 .

[62]  R. E. Turner,et al.  The value of salt marsh edge vs interior as a habitat for fish and decapod crustaceans in a Louisiana tidal marsh , 1994 .

[63]  E. Gundlach,et al.  RECOVERY OF BRITTANY COASTAL MARSHES IN THE EIGHT YEARS FOLLOWING THE AMOCO CADIZ INCIDENT , 1987 .

[64]  J. Michel,et al.  Planting after shoreline cleanup treatment improves salt marsh vegetation recovery following the Deepwater Horizon oil spill , 2021 .

[65]  I. Mendelssohn,et al.  Saltmarsh plants, but not fertilizer, facilitate invertebrate recolonization after an oil spill , 2018 .

[66]  J. Michel,et al.  Deepwater Horizon Oil Spill : salt marsh oiling conditions, treatment testing, and treatment history in northern Barataria Bay, Louisiana (interim report October 2011) , 2013 .

[67]  M. Piehler,et al.  Practical proxies for tidal marsh ecosystem services: application to injury and restoration. , 2008, Advances in marine biology.