Fish Assemblages in Louisiana Salt Marshes: Effects of the Macondo Oil Spill

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 sentinel species in efforts to understand the magnitude and implications of anthropogenic habitat disturbance or degradation. An evaluation of the juvenile and adult marsh fish response to the Macondo oil spill in 2010 was conducted 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 structure across several subhabitats (marsh edge, creeks, ponds, depressions). The fauna, collected with traps, was dominated 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 perturbations (e.g., freshwater discharge).