1,009 research outputs found

    Monitoring Near-Shore Bathymetry Using a Multi-Image Satellite-Derived Bathymetry Approach

    Get PDF
    ABSTRACT Two advanced survey systems for hydrographic surveying are multi-beam echsounder (MBES) and airborne lidar bathymetry (ALB). Compared to more traditional hydrographic surveying methods, these systems provide both highly accurate and a dense coverage of depth measurements. However, high cost and logistic challenges that are required for either type of hydrographic survey operation limit the number of surveys and coverage area that can be conducted. As a result, most survey efforts primarily focus on updating existing chart information, and do not provide more enhanced charting capabilities, such as identifying dynamic seafloor areas or monitoring changes due to natural disasters (e.g., hurricanes, floods, or tsunamis) along the charted coastlines. An alternative reconnaissance approach is the use of Satellite Derived Bathymetry (SDB). Although SDB provide bathymetry products at a coarser spatial resolution compared to MBES or ALB, satellite imagery can be repeatedly collected over the same area. In addition, some of the multi-spectral satellite imagery is publically-available, and at low at no cost. In this paper, we describe a practical approach that is based on a multitemporal analysis of the SDB using Landsat 8 imagery. The study results presented here are based on a time series of two sites (Barnegat Bay Inlet, NJ and Nantucket Sound, MA). Preliminary results indicate that it is possible to identify both stable and dynamic seafloor areas that have implications for charting and coastal zone management application

    Geodatabase Development to Support Hyperspectral Imagery Exploitation

    Get PDF
    Geodatabase development for coastal studies conducted by the Naval Research Laboratory (NRL) is essential to support the exploitation of hyperspectral imagery (HSI). NRL has found that the remote sensing and mapping science community benefits from coastal classifications that group coastal types based on similar features. Selected features in project geodatabases relate to significant biological and physical forces that shape the coast. The project geodatabases help researchers understand factors that are necessary for imagery post processing, especially those features having a high degree of temporal and spatial variability. NRL project geodatabases include a hierarchy of environmental factors that extend from shallow water bottom types and beach composition to inland soil and vegetation characteristics. These geodatabases developed by NRL allow researchers to compare features among coast types. The project geodatabases may also be used to enhance littoral data archives that are sparse. This paper highlights geodatabase development for recent remote sensing experiments in barrier island, coral, and mangrove coast types

    Color, Marbling, and Firmness Characteristics of Fresh Hams from Barrows Supplemented with Conjugated Linoleic Acid

    Get PDF
    This study is a part of a continuing research project investigating the feeding of conjugated linoleic acid (CLA) to market pigs to achieve improvements in carcass growth and pork-quality characteristics. The CLA was fed at a constant level (0.75%) from 40 kg to 115 kg of body weight. This resulted in an increase in subjective uniformity, color, marbling, and tended to increase objective L* values of hams from pigs supplemented with CLA compared with hams that were from pigs fed a control diet. No treatment differences were observed for pH, ham weight, firmness, and Hunter a* and b* values. This report will focus on the subjective and objective quality and compositional characteristics of fresh pork hams form CLAsupplemented pigs. Pigs supplemented CLA in finishing diets had as high ham quality as controls. Therefore, CLA would be beneficial in swine diets

    Functional diversity and nutritional content in a deep-sea faunal assemblage through total lipid, lipid class, and fatty acid analyses

    Get PDF
    Lipids are key compounds in marine ecosystems being involved in organism growth, reproduction, and survival. Despite their biological significance and ease of measurement, the use of lipids in deep-sea studies is limited, as is our understanding of energy and nutrient flows in the deep ocean. Here, a comprehensive analysis of total lipid content, and lipid class and fatty acid composition, was used to explore functional diversity and nutritional content within a deep-sea faunal assemblage comprising 139 species from 8 phyla, including the Chordata, Arthropoda, and Cnidaria. A wide range of total lipid content and lipid class composition suggested a diversified set of energy allocation strategies across taxa. Overall, phospholipid was the dominant lipid class. While triacylglycerol was present in most taxa as the main form of energy storage, a few crustaceans, fish, jellyfishes, and corals had higher levels of wax esters/steryl esters instead. Type and amount of energy reserves may reflect dietary sources and environmental conditions for certain deep-sea taxa. Conversely, the composition of fatty acids was less diverse than that of lipid class composition, and large proportions of unsaturated fatty acids were detected, consistent with the growing literature on cold-water species. In addition, levels of unsaturation increased with depth, likely suggesting an adaptive strategy to maintain normal membrane structure and function in species found in deeper waters. Although proportions of n-3 fatty acids were high across all phyla, representatives of the Chordata and Arthropoda were the main reservoirs of these essential nutrients, thus suggesting health benefits to their consumers

    Very Shallow Water Bathymetry Retrieval from Hyperspectral Imagery at the Virginia Coast Reserve (VCR\u2707) Multi-Sensor Campaign

    Get PDF
    A number of institutions, including the Naval Research Laboratory (NRL), have developed look up tables for remote retrieval of bathymetry and in-water optical properties from hyperspectral imagery (HSI) [6]. For bathymetry retrieval, the lower limit is the very shallow water case (here defined as \u3c 2m), a depth zone which is not well resolved by many existing bathymetric LIDAR sensors, such as SHOALS [4]. The ability to rapidly model these shallow water depths from HSI directly has potential benefits for combined HSI/LIDAR systems such as the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) [10]. In this study, we focused on the validation of a near infra-red feature, corresponding to a local minimum in absorption (and therefore a local peak in reflectance), which can be correlated directly to bathymetry with a high degree of confidence. Compared to other VNIR wavelengths, this particular near-IR feature corresponds to a peak in the correlation with depth in this very shallow water regime, and this is a spectral range where reflectance depends primarily on water depth (water absorption) and bottom type, with suspended constituents playing a secondary role

    External and internal grouping characteristics of juvenile walleye pollock in the Eastern Bering Sea

    Get PDF
    Size and shape patterns of fish groups are collective outcomes of interactions among members. Consequently, group-level patterns are often affected when any member responds to changes in their internal state, external state, and environment. To determine how groups of fish respond to components of their physical and ecological environment, and whether the response is influenced by a component of their external state (i.e., fish age), we used a multibeam system to collect three-dimensional grouping characteristics of 5 age categories of juvenile walleye pollock (age 1, age 2, age 3, mixed ages 1 and 2, and mixed ages 2 and 3) across the eastern Bering Sea shelf over two consecutive years (2009–2010). Grouping data were expressed as metrics that described group size (length, height), shape (roundness, spread), internal structure (density, internal heterogeneity), and position (depth, distance above bottom). Physical data (water temperature measurements) were collected with temperature-depth probes, and ecological data (densities of predators and prey − adult walleye pollock and euphausiids, respectively) were collected with an EK60 vertical echosounder. Juvenile pollock maintained a relatively constant shape, size-dependent density (number fish/mean body length3), and internal horizontal heterogeneity among age categories and in the presence of predators and prey. There were changes to group structure in the face of local physical forcing. Groups tended to move towards the seafloor when bottom waters became warmer, and groups became vertically shorter, denser, and had more variation in horizontal internal density as group depth increased. These results are explored in relation to the value and limitations of using multibeam data to describe how external and internal group structure map onto environmental influences
    • …
    corecore