Fish Assemblages in Louisiana Salt Marshes: Effects of the Macondo Oil Spill Kenneth W. Able & Paola C. López-Duarte & F. Joel Fodrie & Olaf P. Jensen & Charles W. Martin & Brian J. Roberts & Jessica Valenti & Kathleen O’Connor & Shanina C. Halbert Received: 24 March 2014 /Revised: 11 August 2014 /Accepted: 8 September 2014 # Coastal and Estuarine Research Federation 2014 Abstract Marsh-resident fishes play important roles as both predators and prey in coastal systems, influence secondary production, and are important trophic links to adjacent coastal waters. As such, they also serve as senti- nel species in efforts to understand the magnitude and implications of anthropogenic habitat disturbance or deg- radation. An evaluation of the juvenile and adult marsh fish response to the Macondo oil spill in 2010 was con- ducted in 2012 and 2013 by sampling in both oiled and unoiled marshes in coastal Louisiana. To complement this analysis, we also examined marsh-fish assemblage struc- ture across several subhabitats (marsh edge, creeks, ponds, depressions). The fauna, collected with traps, was domi- nated by cyprinodontiform fishes (Fundulus grandis, Fundulus xenicus) and complemented by others in this group ( Cyprinodon variegatus , Poecilia latipinna , Fundulus pulvereus, Fundulus jenkinsi, Fundulus similis). Among the dominant species, abundance was often the highest in ponds and marsh surface depressions, with many fish species also commonly found in creeks, but few fish were collected along the marsh edge. Comparisons across representative oiled and unoiled sites from Caminada, Terrebonne, and Barataria Bays did not reflect any consistent differences in species composition, abundance, and size as a function of oiling 2–3 years after the oil spill reached Louisiana marshes. This interpretation may be confounded by multiple stressors, including natural events (e.g., oil redistribution by storms, and seasonal flooding of the marsh surface), and other man-made per- turbations (e.g., freshwater discharge). Keywords Macondo oil spill . Gulf of Mexico . Marshes . Subhabitat . Killifishes Introduction Salt marshes in Louisiana are exposed to multiple stressors including marsh loss due to reduced sedimentation and in- creased subsidence (Reed 1989), sea level rise (Britsch and Dunbar 1993; Sasser et al. 1986; Boesch et al. 1994; Communicated by Charles Simenstad K. W. Able (*) : P. C. López-Duarte Rutgers University Marine Field Station, Institute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 800 c/o 132 Great Bay Blvd, Tuckerton, NJ 08087, USA e-mail: able@marine.rutgers.edu O. P. Jensen Institute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Rd, New Brunswick, NJ 08901, USA F. J. Fodrie Institute of Marine Sciences & Department of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557, USA C. W. Martin Department of Oceanography and Coastal Sciences, Louisiana State University, 1229 Energy, Coast, & Environment Building, Baton Rouge, LA 70803, USA B. J. Roberts Louisiana Universities Marine Consortium (LUMCON), DeFelice Marine Center, 8124 Highway 56, Chauvin, LA 70344, USA J. Valenti The Richard Stockton College of New Jersey, 101 Vera King Farris Dr, Galloway, NJ 08205, USA K. O’Connor Colby-Sawyer College, 541 Main St, New London, NH 03257, USA S. C. Halbert Haverford College, 370 W Lancaster Ave, Lower Merion, PA 19041, USA Estuaries and Coasts DOI 10.1007/s12237-014-9890-6