Salt marsh denitrification is impacted by oiling intensity six years after the Deepwater Horizon oil spill. (December 2018)

• Record Type: Journal Article
• Authors: Tatariw, Corianne; Flournoy, Nikaela; Kleinhuizen, Alice A.; Tollette, Derek; Overton, Edward B.; Sobecky, Patricia A.; Mortazavi, Behzad
• Is Part Of: Environmental pollution. Volume 243(2018)Part B
• Page Start: 1606
• Page End: 1614
• Publication Date: 2018-12
• Subjects: Denitrification -- Deepwater Horizon -- Salt marsh -- 16S rRNA -- Recovery; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.09.034
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Coastal salt marshes provide the valuable ecosystem service of removing anthropogenic nitrogen (N) via microbially-mediated denitrification. During the 2010 Deepwater Horizon (DWH) spill, oil exposure killed marsh plants in some regions and contributed to rapid compositional shifts in sediment microbial communities, which can impact ecosystem denitrification capacity. Within 3–5 years of the spill, plant biomass and microbial communities in some impacted marshes can recover to a new stable state. The objective of this study was to determine whether marsh recovery 6 years after the DWH oil spill results in subsequent recovery of denitrification capacity. We measured denitrification capacity (isotope pairing technique), microbial 16S rRNA gene composition, and denitrifier abundance (quantitative PCR) at sites subjected to light, moderate, and heavy oiling during the spill that were not targeted by any clean-up efforts. There were no differences in plant belowground biomass, sediment extractable NH4 +, inorganic nitrogen flux, 16S rRNA composition, 16S rRNA diversity, or denitrifier functional gene ( nirS, norB, and nosZ ) abundances associated with oiling status, indicating that certain drivers of ecosystem denitrification capacity have recovered or achieved a new stable state six years after the spill. However, on average, denitrification capacities at the moderately and heavily oiled sites were less than 49% of that of the lightly oiled site (27.7 ± 14.7 and 37.2 ± 24.5 vs 71.8 ± 33.8 μmol N m −2 h −1, respectively). The presence of heavily weathered oiled residue (matched and non-matched for MC252) had no effect on process rates or microbial composition. The loss of function at the moderately and heavily oiled sites compared to the lightly oiled site despite the comparable microbial and environmental factors suggests that oiling intensity plays a role in the long-term recovery of marsh ecosystem services. Graphical abstract: Image 1 Highlights: Oiling intensity impacted salt marsh denitrification capacity 6 years post-spill. Neither 16S diversity nor denitrifier functional markers were affected by oiling intensity. Oiling intensity plays a role in the long-term recovery of marsh biogeochemical function. Abstract : Six years after the Deepwater Horizon oil spill, denitrification capacities were nearly 2X lower at moderately and heavily oiled salt marsh sites compared to a lightly oiled site, indicating that ecosystem service recovery is occurring at a slower temporal scale than for plant or microbial communities.