Trophic Ecology of Sheepshead and Stone Crabs at Oil and Gas Platforms in the Northern Gulf of Mexico's Hypoxic Zone

Abstract

Oil and gas platforms (platforms) may provide important habitat for reef‐associated organisms in the Gulf of Mexico's hypoxic zone. While summer hypoxia typically affects the bottom 3.0 m of the water column, platforms span from the bottom to above the surface and provide hard substrate in oxygenated waters overlaying hypoxia. However, little is known about the effects of hypoxia on organisms living at these platforms. We compared diets of Sheepshead Archosargus probatocephalus and Gulf stone crabs Menippe adina during early and late summer at platforms with mild (shoal platforms) and intense hypoxia (seaward platforms) using a combination of stable isotopes (δ13C and δ15N) and gut contents analyses. We hypothesized that diets at seaward platforms would shift from bottom to platform‐dwelling prey during late summer when hypoxia had fully developed and decimated benthic communities, but no such effect was found. Barnacles (Balanidae) were the most common prey found in Sheepshead guts for all samples collected (64.1% of gut contents). Sheepshead gut contents showed high predation of mantis shrimp (Squillidae; 35.2% of gut contents) soon after the formation of hypoxia at seaward platforms, likely reflecting Sheepshead exploiting benthic prey that were vulnerable because of hypoxia. These findings indicate that hypoxia affected the behavior of mantis shrimp in a way that altered their availability for Sheepshead associated with platforms. Comparisons of Sheepshead and stone crab isotope values (δ13C and δ15N) to those of their potential prey and basal sources suggested a high dependence on barnacles (proxy for water column particulate organic matter) and filamentous algae throughout the summer. However, comparisons of isotope values in early and late summer indicated no apparent effect of hypoxia. High contributions of barnacles to Sheepshead diet showed that platform‐dwelling prey were an important resource for Sheepshead.

Influence of environmental factors on macrofoulant assemblages on moored buoys in the eastern Arabian Sea

“…Previous studies in shallow coastal environments revealed that assemblages on artificial substrates were not identical to that of adjacent natural substrates as they offer atypical surfaces in terms of orientation, depth range and surface [72,73]. Foraging also plays an important role in shaping the assemblages on artificial structures [74]. The influence of these factors in determining the mesoscale patterns of macrofoulant assemblages on artificial structures have to be further investigated.…”

Absolute Abundance Estimates for Red Snapper, Greater Amberjack, and Other Federally Managed Fish on Offshore Petroleum Platforms in the Gulf of Mexico

“…It was not listed by Gallaway and Lewbel (1982) as even being present on Gulf platforms, nor was it listed as being seen at coastal platforms in the northern Gulf by Wilson (1997, 2003) or by Stunz et al (2016) for platforms offshore south Texas. In contrast, Reeves (2015), Munnelly (2016) and Reeves et al (2019) observed Atlantic Bumper were abundant at coastal platforms offshore Louisiana by the mid 2000's.…”

Young-Of-The-Year Stone Crab (Genus Menippe) Recruitment in the Gulf of Mexico Off Florida: Key Shallow-Water Hotspots

“…The postlarvae of many decapod species select complex habitats for metamorphosis (Wolcott & DeVries 1994, Stevens & Kittaka 1998, Pardo et al 2007, Webley et al 2009; and high turbidity can deter aquatic predators that rely on visual prey recognition (Reustle & Smee 2020), as well as those that do not (Ortega et al 2020). The cannibalistic nature of stone crabs of all sizes (Yang & Krantz 1976, Krimsky 2008) and susceptibility of YOY stone crabs to predation by other animals (Frick & Mason 1998, Schmid 1998, Scharf & Schlicht 2000, Shervette et al 2004, Reeves et al 2019 suggests that, as in other species (Kurihara & Okamoto 1987, Fernandez 1999, Luppi et al 2001, Pirtle & Stoner 2010, refuge from predation is important in habitat selection by stone crab megalopae and PS-juveniles. Complex shelters with small openings have been shown to reduce interspecific and intraspecific competition and predation on YOY Menippe adina and enhance the density and survival of all sizes of juveniles (Gibbs 1994).…”