Influence of Age-1 Conspecifics, Sediment Type, Dissolved Oxygen, and the Deepwater Horizon Oil Spill on Recruitment of Age-0 Red Snapper in the Northeast Gulf of Mexico during 2010 and 2011

摘要

The Deepwater Horizon oil spill was one of the largest oil spills in U.S. history. The timing of this spill coincided with peaks in spawning and recruitment of Red Snapper Lutjanus campechanus and may have led to reduced recruitment or to year-class failure. Artificial recruitment reefs were deployed in 2010 (n = 30) and 2011 (n = 30) to measure Red Snapper recruitment off the coast of Alabama at four sites (three inshore sites, 13km south: west, center, and east sites, each 30km apart; and one offshore site, 25km south). Substantial age-0 Red Snapper recruitment (density range= 0-34.5 fish/m(3)) occurred in 2010, with higher densities on inshore reefs than on offshore reefs. Age-0 Red Snapper recruitment was again observed in 2011 (density range = 0-108.5 fish/m(3)) along with age-1 Red Snapper (density range = 0-78.9 fish/m(3)) from the 2010 year-class. There was a negative correlation between the densities of age-0 and age-1 Red Snapper, indicating that older Red Snapper excluded younger fish from the reefs. Higher fractions of silt in the substrate at the west site compared with the center and east sites were associated with higher densities of age-0 Red Snapper, but the effects of sediment type were less important than exposure to hypoxic conditions at the west site in late August 2011 (dissolved oxygen fell to concentrations as low as 0.4mg/L), which caused an almost complete loss of fish. The abundances of age-0 and age-1 Red Snapper in 2010 and 2011 provide evidence that the oil spill did not result in a year-class failure and that the most important variables affecting age-0 Red Snapper abundances were age-1 Red Snapper presence and dissolved oxygen concentration. Received August 23, 2013; accepted December 19, 2013