Mapping spatial and temporal variation of seafloor organic matter Δ14C and δ13C in the Northern Gulf of Mexico following the Deepwater Horizon Oil Spill.

Following the Deepwater Horizon oil spill of 2010, large amounts of biodegraded oil (petrocarbon) sank to the seafloor. Our objectives were to 1) determine post-spill isotopic values as the sediments approached a new baseline and 2) track the recovery of affected sediments. Sediment organic carbon δ13C and Δ14C reached a post-spill baseline averaging -21.2 ± 0.9‰ (n = 129) and -220 ± 66‰ (n = 95). Spatial variations in seafloor organic carbon baseline isotopic values, 13C and 14C, were influenced by river discharge and hydrocarbon seepage, respectively. Inverse Distance Weighting of surface sediment Δ14C values away from seep sites showed a 50% decrease in the total mass of petrocarbon, from 2010 to 2014. We estimated a rate of loss of -2 × 109 g of petrocarbon-C/year, 2-11% of the degradation rates in surface slicks. Despite the observed recovery in sediments, lingering residual material in the surface sediments was evident seven years following the blowout.

The southern Gulf of Mexico: A baseline radiocarbon isoscape of surface sediments and isotopic excursions at depth.

The southern Gulf of Mexico (sGoM) is home to an extensive oil recovery and development infrastructure. In addition, the basin harbors sites of submarine hydrocarbon seepage and receives terrestrial inputs from bordering rivers. We used stable carbon, nitrogen, and radiocarbon analyses of bulk sediment organic matter to define the current baseline isoscapes of surface sediments in the sGoM and determined which factors might influence them. These baseline surface isoscapes will be useful for accessing future environmental impacts. We also examined the region for influence of hydrocarbon deposition in the sedimentary record that might be associated with hydrocarbon recovery, spillage and seepage, as was found in the northern Gulf of Mexico (nGoM) following the Deepwater Horizon (DWH) oil spill in 2010. In 1979, the sGoM experienced a major oil spill, Ixtoc 1. Surface sediment δ13C values ranged from -22.4‰ to -19.9‰, while Δ14C values ranged from -337.1‰ to -69.2‰. Sediment δ15N values ranged from 2.8‰ to 7.2‰, while the %C on a carbonate-free basis ranged in value of 0.65% to 3.89% and %N ranged in value of 0.09% to 0.49%. Spatial trends for δ13C and Δ14C were driven by water depth and distance from the coastline, while spatial trends for δ15N were driven by location (latitude and longitude). Location and distance from the coastline were significantly correlated with %C and %N. At depth in two of twenty (10%) core profiles, we found negative δ13C and Δ14C excursions from baseline values in bulk sedimentary organic material, consistent with either oil-residue deposition or terrestrial inputs, but likely the latter. We then used 210Pb dating on those two profiles to determine the time in which the excursion-containing horizons were deposited. Despite the large spill in 1979, no evidence of hydrocarbon residue remained in the sediments from this specific time period.

Predicting the exposure of coastal species to plastic pollution in a complex island archipelago.

Plastic pollution in the marine environment is a pervasive and increasing threat to global biodiversity. Prioritising management actions that target marine plastic pollution require spatial information on the dispersal and settlement of plastics from both local and external sources. However, there is a mismatch between the scale of most plastic dispersal studies (regional, national and global) and the scale relevant to management action (local). We use a fine-resolution hydrodynamic model to predict the potential exposure of coastal habitats and species (mangroves, coral reefs and marine turtles) to plastic pollution at the local scale of a management region (the 1,700 km2 Whitsunday Islands, Queensland, Australia). We assessed the potential exposure of mangroves, coral reefs and marine turtles to plastics during the two dominant wind conditions of the region; the trade wind and monsoon wind seasons. We found that in the trade wind season (April to September) all habitats and species had lower exposure than during the monsoon wind season (October to March). In both wind seasons we found a small proportion of coral reef habitat and large area of turtle habitat were in high potential exposure categories. Unlike coral reefs or marine turtles, mangroves had consistent hotspots of high exposure across wind seasons. Local scale management requires data at fine resolution to capture the variability that occurs at this scale. The outputs of our study can inform the development of conservation resources and local scale management action.

Translating Marine Animal Tracking Data into Conservation Policy and Management.

There have been efforts around the globe to track individuals of many marine species and assess their movements and distribution, with the putative goal of supporting their conservation and management. Determining whether, and how, tracking data have been successfully applied to address real-world conservation issues is, however, difficult. Here, we compile a broad range of case studies from diverse marine taxa to show how tracking data have helped inform conservation policy and management, including reductions in fisheries bycatch and vessel strikes, and the design and administration of marine protected areas and important habitats. Using these examples, we highlight pathways through which the past and future investment in collecting animal tracking data might be better used to achieve tangible conservation benefits.

Does behaviour affect the dispersal of flatback post-hatchlings in the Great Barrier Reef?

The ability of individuals to actively control their movements, especially during the early life stages, can significantly influence the distribution of their population. Most marine turtle species develop oceanic foraging habitats during different life stages. However, flatback turtles (Natator depressus) are endemic to Australia and are the only marine turtle species with an exclusive neritic development. To explain the lack of oceanic dispersal of this species, we predicted the dispersal of post-hatchlings in the Great Barrier Reef (GBR), Australia, using oceanographic advection-dispersal models. We included directional swimming in our models and calibrated them against the observed distribution of post-hatchling and adult turtles. We simulated the dispersal of green and loggerhead turtles since they also breed in the same region. Our study suggests that the neritic distribution of flatback post-hatchlings is favoured by the inshore distribution of nesting beaches, the local water circulation and directional swimming during their early dispersal. This combination of factors is important because, under the conditions tested, if flatback post-hatchlings were entirely passively transported, they would be advected into oceanic habitats after 40 days. Our results reinforce the importance of oceanography and directional swimming in the early life stages and their influence on the distribution of a marine turtle species.

Detección molecular mediante RT-PCR de calicivirus y enterovirus en niños menores de 6 años con síndrome diarreico / Calicivirus and enterovirus molecular detection through RT-PCR in children under 5 years old with diarrheal syndrome

Mundialmente, la diarrea es una de las causas más importantes de morbi-mortalidad en la población. En Venezuela, se reportan anualmente cerca de 480.000 consultas y 706 fallecimientos a causa de diarreas, de las cuales el 32% se registran en el Zulia. Entre los virus con capacidad patogénica involucrados en cuadros diarreicos se encuentran los calicivirus y enterovirus. Con el objetivo de evaluar la prevalencia de estos agentes virales en el municipio Maracaibo, se colectaron 150 muestras de heces diarreicas de niños menores de 6 años, en las que se analizó la presencia de calicivirus y enterovirus mediante RT-PCR. Se observó una mayor prevalencia de infección por enterovirus (31,3%), lo que indica la existencia de posibles problemas de higiene y/o contaminación del agua. Además, se evidenció disminución de la infección por enterovirus con el aumento de la edad, posiblemente por la adquisición de anticuerpos por exposiciones previas al virus. La prevalencia de calicivirus en la población fue baja (3,0%), considerándolos así casos aislados. La ausencia de este virus durante el primer año de vida se ve favorecida por la protección inmunitaria que confiere la alimentación con leche materna. El presente estudio indica que los enterovirus son agentes etiológicos importantes de diarreas en la población infantil estudiada.

Worldwide, diarrhea is one of the most important morbility-mortality causes in the general population. In Venezuela, there are annual reports of around 480,000 consultations and 706 deaths due to diarrhea, 32% of which are registered in Zulia State. Calicivirus and enterovirus are among the viruses with pathogenic capacity involved in diarrheal episodes. With the purpose of evaluating the prevalence of these viruses at the Maracaibo Municipality, we collected 150 diarrheal feces samples from children under 5 years old, and calicivirus and enterovirus presence was determined through RT-PCR. There was a greater prevalence of enterovirus infections (31.3%), which indicates the probable existence of hygiene problems and/or water contamination. There was also evidence of a decrease of enterovirus contamination with age, possible due to the development of antibodies during previous exposure to the virus. Calicivirus prevalence in this population was low (2.9%), and they were considered as isolated cases. Absence of this virus during the first year of life is favored by the immunological protection conferred by maternal breast-feeding. The present study indicates that enteroviruses are important diarrheal etiologic agents in the child population studied.