Geology topics

Steven A. Murawski

Publications and source records attributed to Steven A. Murawski.

5 recordsLinked to original sources

USGS2024

Complex patterns of genetic population structure in the mouthbrooding marine catfish, Bagre marinus, in the Gulf of Mexico and U.S. Atlantic

Patterns of genetic variation reflect interactions among microevolutionary forces that vary in strength with changing demography. Here, patterns of variation within and among samples of the mouthbrooding gafftopsail catfish ( Bagre marinus , Family Ariidae) captured in the U.S. Atlantic and throughout the Gulf of Mexico were analyzed using genomics to generate neutral and non-neutral SNP data sets. Because genomic resources are lacking for ariids, linkage disequilibrium network analysis was used to examine patterns of putatively adaptive variation. Finally, historical demographic parameters were estimated from site frequency spectra. The results show four differentiated groups, corresponding to the (1) U.S. Atlantic, and the (2) northeastern, (3) northwestern, and (4) southern Gulf of Mexico. The non-neutral data presented two contrasting signals of structure, one due to increases in diversity moving west to east and north to south, and another to increased heterozygosity in the Atlantic. Demographic analysis suggested that recently reduced long-term effective population size in the Atlantic is likely an important driver of patterns of genetic variation and is consistent with a known reduction in population size potentially due to an epizootic. Overall, patterns of genetic variation resemble that of other fishes that use the same estuarine habitats as nurseries, regardless of the presence/absence of a larval phase, supporting the idea that adult/juvenile behavior and habitat are important predictors of contemporary patterns of genetic structure.

Alabama, Florida, Louisiana, Mississippi, Texas↗

USGS2022

Assessing per- and polyfluoroalkyl substances (PFAS) in sediments and fishes in a large, urbanized estuary and the potential human health implications

The primary source of chronic exposures to per- and polyfluoroalkyl substances (PFASs) in humans is through the ingestion of contaminated foods and drinking water, with fish and other seafood being a major contributor. Nevertheless, there is scant literature on the dietary exposure to PFASs for the general United States (U.S.) population. The Tampa Bay (Florida, USA) region has the highest population density in the State and communities and their attendant support services are arrayed in an urban to semi-rural continuum from the head of the Bay to the ocean mouth. Tampa Bay supports productive recreational and commercial fisheries, providing a diverse community of species. A variety of potential PFAS sources surround Tampa Bay including airports, industry, wastewater treatment plants, fire-fighting training areas and military installations. The objective of this study is to quantify PFASs in sediment and fishes collected from Tampa Bay to further estimate human health risks from dietary exposures. Sediment ( n = 17) and fish (24 species, n = 140) were collected throughout Tampa Bay in 2020 and 2021 and analyzed for 25 PFAS compounds. Concentrations of PFASs in sediments and edible tissues of fish ranged from 36.8 to 2,990 ng kg -1 (dry weight) and 307 to 33,600 ng kg -1 (wet weight), respectively. Generally, levels were highest in Old Tampa Bay and decreased south towards the Gulf of Mexico. Profiles in both matrices were generally dominated by perfluorooctane sulfonic acid (PFOS) with variations by location. Estimated human health risks from the consumption of contaminated fish collected in Tampa Bay exceeded concentration thresholds for minimum risk levels (MRLs) and tolerable weekly intake (TWIs) values for adults and youths. Additionally, concentrations of PFOS in edible fish tissues of several recreationally important species collected in Tampa Bay exceeded consumption guideline levels established by several governmental agencies. In the current context, the elevated levels of PFAS in Tampa Bay and the exceedances of available thresholds for potential human health risks are a cause for concern and justify a more intensive examination especially for more heavily utilized species, particularly those used in subsistence-level fishing, which, as elsewhere may be significantly under documented.

Florida↗

USGS2019

West Florida shelf pipeline serves as sea turtle benthic habitat based on in-situ towed camera observations

The use of marine offshore benthic habitats by sea turtles is poorly characterized due to the difficulty of obtaining in situ data. Understanding benthic habitat use that is important to the species’ reproduction, foraging, and migrations is critical for guiding management decisions. A towed camera-based assessment survey system (C-BASS) equipped with environmental sensors was used to characterize and assess benthic habitats on the West Florida Shelf (WFS) from 2014 to 2018. During these cruises, sea turtles were opportunistically observed during the surveys, and critical in situ data such as spatiotemporal information, species identification, habitat use, behavior, and environmental data were collected and evaluated. In total, 79 sea turtles were observed during 97 transects of approximately 2700 km of seafloor, which was recorded on 380 h of video. Several sea turtle species were spotted within the WFS, including loggerhead Caretta caretta, Kemp’s ridley Lepidochelys kempii, and green turtles Chelonia mydas. These opportunistic sightings revealed an area of high use on the WFS, an anthropogenic structure known as the Gulfstream natural gas pipeline (GSPL). C-BASS survey results suggest that 2 sea turtle species (C. caretta and L. kempii) utilize this artificial structure primarily as a resting area. We emphasize the importance of combining habitat mapping techniques (towed underwater video and multibeam bathymetry/backscatter) with tracking technology to better understand the fine-scale habitat use of sea turtles.

Florida↗

USGS2012

Science in support of the Deepwater Horizon response

This introduction to the Special Feature presents the context for science during the Deepwater Horizon oil spill response, summarizes how scientific knowledge was integrated across disciplines and statutory responsibilities, identifies areas where scientific information was accurate and where it was not, and considers lessons learned and recommendations for future research and response. Scientific information was integrated within and across federal and state agencies, with input from nongovernmental scientists, across a diverse portfolio of needs—stopping the flow of oil, estimating the amount of oil, capturing and recovering the oil, tracking and forecasting surface oil, protecting coastal and oceanic wildlife and habitat, managing fisheries, and protecting the safety of seafood. Disciplines involved included atmospheric, oceanographic, biogeochemical, ecological, health, biological, and chemical sciences, physics, geology, and mechanical and chemical engineering. Platforms ranged from satellites and planes to ships, buoys, gliders, and remotely operated vehicles to laboratories and computer simulations. The unprecedented response effort depended directly on intense and extensive scientific and engineering data, information, and advice. Many valuable lessons were learned that should be applied to future events.

Alabama, Florida, Louisiana, Mississippi, Texas↗

USGS2012

Applications of science and engineering to quantify and control the Deepwater Horizon oil spill

The unprecedented engagement of scientists from government, academia, and industry enabled multiple unanticipated and unique problems to be addressed during the Deepwater Horizon oil spill. During the months between the initial blowout on April 20, 2010, and the final well kill on September 19, 2010, researchers prepared options, analyses of tradeoffs, assessments, and calculations of uncertainties associated with the flow rate of the well, well shut in, killing the well, and determination of the location of oil released into the environment. This information was used in near real time by the National Incident Commander and other government decision-makers. It increased transparency into BP’s proposed actions and gave the government confidence that, at each stage proposed, courses of action had been thoroughly vetted to reduce risk to human life and the environment and improve chances of success.

Alabama;Florida;Louisiana;Mississippi;Texas↗