National Ocean Service

About: National Ocean Service is a government organization based out in Silver Spring, Maryland, United States. It is known for research contribution in the topics: Algal bloom & Population. The organization has 500 authors who have published 643 publications receiving 46096 citations.

Impact of Hurricane Irene on Vibrio vulnificus and Vibrio parahaemolyticus concentrations in surface water, sediment, and cultured oysters in the Chesapeake Bay, MD, USA

Abstract: To determine if a storm event (ie, high winds, large volumes of precipitation) could alter concentrations of Vibrio vulnificus and Vibrio parahaemolyticus in aquacultured oysters (Crassostrea virginica) and associated surface water and sediment, this study followed a sampling timeline before and after Hurricane Irene impacted the Chesapeake Bay estuary in late August 2011 Aquacultured oysters were sampled from two levels in the water column: surface 03 m and near-bottom just above the sediment Concentrations of each Vibrio spp and associated virulence genes were measured in oysters with a combination of real-time PCR and most probable number enrichment methods, and in sediment and surface water with real-time PCR While concentration shifts of each Vibrio species were apparent post-storm, statistical tests indicated no significant change in concentration change for either Vibrio species by location (surface or near bottom oysters) or date sampled (oyster tissue, surface water and sediment concentrations) V vulnificus in oyster tissue was correlated with total suspended solids (r=041, p=004), and V vulnificus in sediment was correlated with secchi depth (r=-093, p< 001), salinity (r=-046, p=002), tidal height (r=-045, p=003), and surface water V vulnificus (r=098, p< 001) V parahaemolyticus in oyster tissue did not correlate with environmental measurements, but V parahaemolyticus in sediment and surface water correlated with several measurements including secchi depth (r=-048, p=002[sediment]; r=-097 p< 001[surface water]) and tidal height (r=-096 p< 001[sediment], r=-059,p< 001 [surface water]) The concentrations of Vibrio spp were higher in oysters relative to other studies (average V vulnificus 4x105 MPN g-1, V parahaemolyticus 1x105 MPN g-1), and virulence-associated genes were detected in most oyster samples This study provides a first estimate of storm-related Vibrio density changes in oyster tissues, sediment and surface w

Health and climate – opportunities

Abstract: While Hippocrates recognized that health is influenced by the external environment, it is only recently that the relationship between health and climate has become a focus of community and public health services. Advances in understanding of weather and climate sciences on the one hand and human health on the other are providing new opportunities for early detection, prediction and prevention of the adverse health effects of hazards as diverse as tropical cyclones, floods, heatwaves and cold spells, air quality, wildfires, droughts and disease epidemics. Early warning of disease outbreaks and a timely response makes prevention possible. For some climate-sensitive diseases, our understanding is sufficient to make health forecasting possible; for others, the relationship between the disease and any causal environmental effect remains unclear, and the focus of active research programs. Institutional changes are also taking place to improve operational and research cooperation between the health sector and the weather and climate communities, ranging from joint service delivery platforms to combined research and development programs.

Wind And Nadir Angle Effects On Airborne Lidar Water Surface Returns

Abstract: The reflection of optical energy from the air/sea interface and by the volume backscattering immediately below involves a number of complex phenomena which have critical effects on the design and performance of airborne laser hydrography systems. Both of these reflections can be considered as "surface" return, because when the interface return is weaker than the volume return, the latter will be detected, although at a somewhat biased location, as found during lidar/sonar depth measurement intercomparisons. The character of the surface return depends on the ratio of the peak volume backscatter power and the peak interface reflection power. Analytic expressions are derived for mean values of these quantities. The functionalities of the volume-to-interface peak power ratio on wind speed and direction, off-nadir beam incidence angle, and water clarity parameters are examined to determine the parameter ranges for which the a priori origin of surface returns is uncertain. Depth measurement error magnitudes are calculated for the case of a volume return being mistaken for an interface return. The error model sucessfully predicts the shoal bias observed in field data. Potential methods for reducing this error are discussed. An expression for the temporal profile of a volume backscatter return is presented, and a potential method of estimating a key water clarity parameter from the airborne data is reported.