Effects of a Major Oil Spill on Nektonic Assemblages of Salt Marshes and Adjacent SAV Habitats in Florida and Alabama

Photo by Ryan Moody

Effects of a Major Oil Spill on Nektonic Assemblages of Salt Marshes and Adjacent SAV Habitats in Florida and Alabama

Salt marsh ecosystems along the Gulf Coast of Florida and Alabama are highly productive. They provide critical habitat for a diverse assemblage of fish and shellfish species; many of these are commercially important. Salt marsh ecosystems afford a patchwork of refuge and foraging habitat to nektonic organisms, and they serve as vital nursery habitat for many transient species (species with separate juvenile and adult habitats). Resident nekton (species that utilize the same habitats as juveniles and adults) constitute the majority of the prey base of transient species and serve as important vectors for the transfer of production from intertidal marshes to subtidal, estuarine habitats. This study measures the direct and indirect impacts on nektonic assemblages of the oiling of marsh adjacent subtidal habitats as a result of the Deepwater Horizon spill, in April 2010, and will explore the effects of the oil flow on the spawning stock of species that rely on salt marsh ecosystems for nursery habitat.

The project is testing the following hypotheses about the impacts of the spill on salt marsh ecosystems and adjacent habitats: (1) nekton (both transient and permanent residents) movement from oiled habitats will result in enhanced species abundance, diversity, and biomass in nearby, non-impacted habitats; (2) impacts to the offshore spawning stock of transients will result in declined recruitment to coastal habitats relative to populations of permanent residents; and (3) a prolonged period (defined as the time necessary to encompass one or more known species-specific spawning and recruitment events) of oiling will result in the decline of both transient- and permanent-resident populations. The results will allow us to evaluate the relative influences of the Deepwater Horizon spill and other influences such as seasonal temperature variations and natural, year-to-year fluctuations in recruitment on the food webs of salt marsh ecosystems and other SAV-dominated ecosystems.