Changes in Red Snapper Diet and Trophic Ecology Following the Deepwater Horizon Oil Spill

Abstract

Red Snapper Lutjanus campechanus were sampled at 33 natural and 27 artificial reef sites in the northern Gulf of Mexico prior to (2009–2010) and after (2010–2011) to examine potential diet and trophic shifts following the Deepwater Horizon (DWH) oil spill. We dissected 708 stomachs for gut content analysis and processed 65 muscle tissue samples for stable isotope ratio‐mass spectrometry analysis of δ13C, δ15N, and δ34S. Forty‐eight percent of stomachs contained identifiable prey, which we grouped into seven categories: fish, decapods, cephalopods, stomatopods, gastropods, zooplankton, and other invertebrates. Based on these categories, Red Snapper diet was significantly different following the DWH oil spill, and was differentially affected by fish size. The interaction between habitat (natural versus artificial reefs) and DWH oil spill effects was also significant. Significant differences in diet among Red Snapper size‐classes were due to low trophic position prey, such as pelagic zooplankton, being more abundant in the diet of larger (>500 mm) Red Snapper, while decapods and fish constituted a higher proportion of the diet of smaller individuals. Red Snapper consumed higher amounts of decapods at artificial (21.9% by mass) versus natural (14.8%) reef sites, but the habitat effect on diet was not significant. The habitat × DWH timing interaction was driven by a decrease in zooplankton consumed at both habitat types, increased benthic prey at natural reefs, and increased fish consumption at artificial reefs in post‐DWH oil spill samples. Stable isotope data indicated a postspill increase in Red Snapper trophic position (15N enrichment) and an increase in benthic versus pelagic prey (34S depletion), both consistent with observed dietary shifts. Overall, results indicate shifts in Red Snapper diet and trophic position occurred following the DWH oil spill, thus the relative abundance of prey resources likely changed. Received May 30, 2014; accepted February 3, 2015

Experimental assessment of lionfish removals to mitigate reef fish community shifts on northern Gulf of Mexico artificial reefs

“…Estimates of the spatial extent of DWH surface oil extended over our study area periodically from April to August 2010 (Goni et al 2015). There is clear evidence that some nGOM reef fishes were exposed to toxic petroleum compounds released during the spill (Murawski et al 2014), with documented impacts on fishes including genetic effects, shifts in trophic position, declines in size at age, and changes in community structure (Whitehead et al 2012, Norberg 2015, NOAA-NRDA 2015, Tarnecki & Patterson 2015. Therefore, it is possible that reef fish declines observed at study reefs in 2011−2012 were initially driven by the DWH.…”

“…Effects of the DWH on various biological communities have been documented, yet it is unclear how resilient the nGOM ecosystem will be to this largescale disturbance (Graham et al 2010, DeLaune & Wright 2011, Williams et al 2011, Whitehead et al 2012. Among reef fishes, reported DWH impacts include changes in diet and trophic position (Tarnecki & Patterson 2015, Norberg 2015, and shifts in community structure (NOAA-NRDA 2015) following exposure to toxic petroleum compounds (Murawski et al 2014). Recent ecosystem modeling simulations have indicated that depleted reef fish stocks in the region could have contributed to the rapid increase in lionfish density and biomass (Chagaris et al 2015).…”

How Did the Deepwater Horizon Oil Spill Affect Coastal and Continental Shelf Ecosystems of the Gulf of Mexico?

“…Significant changes in the abundance of some species and in trophic structure occurred on natural and artificial reefs on the continental shelf, including shifts in red snapper and tomtate diet and trophic position following the spill (Norberg, 2015;Tarnecki and Patterson, 2015). Both red snapper and tomtate displayed diet shifts to higher trophic position prey that was corroborated by higher δ 15 N values in the first two years following the DWH spill.…”

“…comm., 2016). Analysis of stable carbon and radiocarbon isotopes in reef fish muscle tissue indicates that these trophic shifts occurred at the same time that petrocarbon (depleted 13 C and 14 C signatures), likely from the DWH spill, reached the level of fishes in the food web (Norberg, 2015;Tarnecki and Patterson, 2015).…”

Assessing the Impact of Oil Spills on Marine Organisms

“…These organisms are exposed to various degree of impact during an oil spill accident. Various research have detailed the toxicological effects of oil (such as increased mortality or as sub-lethal injury, impaired feeding and reproduction and avoiding predators) on fish communities [9,10], estuarine communities, mammals, birds and turtles [11,12], deep-water corals [13], plankton [14], foraminifera [15], and microbial communities [16]. This paper seeks to review the various toxicological effects of oil spills on the marine vertebrates and invertebrates.…”