RESUMO
The Deepwater Horizon oil spill occurred in spring and summer 2010 in the northern Gulf of Mexico. Research cruises in 2010 (approximately 2-3 months after the well had been capped), 2011, and 2014 were conducted to determine the initial and subsequent effects of the oil spill on deep-sea soft-bottom infauna. A total of 34 stations were sampled from two zones: 20 stations in the "impact" zone versus 14 stations in the "non-impact" zone. Chemical contaminants were significantly different between the two zones. Polycyclic aromatic hydrocarbons averaged 218 ppb in the impact zone compared to 14 ppb in the non-impact zone. Total petroleum hydrocarbons averaged 1166 ppm in the impact zone compared to 102 ppm in the non-impact zone. While there was no difference between zones for meiofauna and macrofauna abundance, community diversity was significantly lower in the impact zone. Meiofauna taxa richness over the three sampling periods averaged 8 taxa/sample in the impact zone, compared to 10 taxa/sample in the non-impact zone; and macrofauna richness averaged 25 taxa/sample in the impact zone compared to 30 taxa/sample in the non-impact zone. Oil originating from the Deepwater Horizon oil spill reached the seafloor and had a persistent negative impact on diversity of soft-bottom, deep-sea benthic communities. While there are signs of recovery for some benthic community variables, full recovery has not yet occurred four years after the spill.
Assuntos
Ecossistema , Poluição por Petróleo/efeitos adversos , Classificação , Sedimentos Geológicos , Golfo do México , Fatores de TempoRESUMO
The effects of Hurricane Katrina on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama, USA, were assessed in October, 2005, 2 months after the hurricane made landfall between New Orleans, LA and Biloxi, MS. Benthic macrofaunal samples, sediment chemical concentrations, and water quality measurements from 60 sites in Lake Pontchartrain and Mississippi Sound were compared with pre-hurricane conditions from 2000-2004. Post-hurricane benthic communities had significant reductions in numbers of taxa, H(') diversity, and abundance as well as shifts in composition and ranking of dominant taxa. These effects were not associated with changes in chemical contamination, organic enrichment of sediments, or hypoxia and were likely due to hurricane-related scouring and changes in salinity.
Assuntos
Tempestades Ciclônicas , Desastres , Ecossistema , Invertebrados , Características de Residência , Alabama , Animais , Monitoramento Ambiental , Água Doce , Sedimentos Geológicos/química , Humanos , Louisiana , Mississippi , Nova Orleans , Salinidade , Água do Mar , Poluentes Químicos da Água/análiseRESUMO
Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73-100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).