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.

Utilizing Gliders and Acoustics to Identify Fish Habitat Hotspots. A Case Study

Abstract: Underwater gliders have become a critical component of coastal observing systems for measuring water column properties. They efficiently sample from the surface to the seafloor or their depth limit collecting essential density variables for weeks to months at a time, providing invaluable information to validate ocean circulation models. However, they can collect much more data, and how those data sets evolve into potential uses is not always fully appreciated. Obviously, if a truck can hold more gear without significantly hurting gas mileage, why not throw more in the back end? As such, over the past decade other sensing equipment has been incorporated into glider payloads such as fluorometers, dissolved oxygen sensors, ADCPs, nutrient sensors, and more. This has allowed expanded use of the same platform without sacrificing their primary design mission of CTD profiles. These additional sensors have enabled new research in fields such as hypoxia dead zones, red tide evolution, and water column heat content. The combination of the various sensors on the same platform will continue to enhance our understanding of the connections between processes that drive our coastal oceans. An additional research area with potential use for gliders is fisheries management. Fish stock assessment depend upon data sets from fishery dependent or independent surveys that are used to set harvest limits. In the eastern Gulf of Mexico, many economically important species are benthic and generally tied to preferred habitat types. State, federal, and academic groups are coordinating efforts to generate habitat-specific population estimates, the first step of which is creating habitat maps to guide visual or trap surveys for the fish. This is typically done by initially creating detailed bathymetric maps of regions and assessing the bottom types through video and other methods to characterize the seafloor structure, habitat and the distribution of biota. However, visually mapping the entire West Florida Shelf is not feasible. Autonomous systems like gliders should be employed as a first-level reconnaissance tool to opportunistically discover reef features or fish hotspots. For the past several years, we’ve attempted to assess fish populations, site fidelity, migration, and other relevant characteristics by integrating passive acoustic recorders, tag telemetry receivers, and fisheries echosounders to a glider tasked with repeated transects within a test region. Our test region has been a large, well-known artificial reef, the Gulfstream Natural Gas Pipeline, a largely linear feature between Tampa Bay and Mobile Bay. Our sampling has been seasonal and focused on the eastern portion of this feature between the 30 and 50m isobaths on the West Florida Shelf (WFS) with a total of five deployments of a single glider completed. Yet, while the linear reef is a wonderful target for the glider, gliders cannot easily traverse a straight line when coastal tidal currents are involved. So, in typical meandering fashion, the glider would spend a lot of time in the region of the pipeline, but not directly over the pipe. We accepted these data as opportunistic and another form of reconnaissance that can inform the design of follow-on surveys. During our efforts, we have used glider-collected acoustic data to identify several “hotspot” locations with high fish densities for which we do not yet have habitat maps nor measures of fish abundance. We subsequently mapped one of these regions with high resolution multibeam echosounder to create detailed bathymetric imagery of the seafloor. This has resulted in discovering previously unknown regions of habitat including seafloor ridges and demersal fish excavated zones known as “grouper holes”. This technological approach, if applied in an observing system capacity of sustained and continuous operations over a region like the West Florida Shelf, will augment existing efforts to identify and describe fish habitat and help provide data sets complimentary to fish stock assessment.

Applications of SABRE to research and management

Abstract: In this paper, we highlight the major results from the SABRE programme and applications to research and management. In particular, SABRE provided new scientific insights into the fisheries oceanography of the estuarine-dependent fishes of the South Atlantic Bight. Although we concentrated our efforts on Atlantic menhaden, we also gained insights on the coupling of physics to biology in the early life history of a number of marine fishes. Larval transport from spawning sites to and through barrier island inlets is now better understood. Analysis of menhaden population dynamics suggests survival in the late larval/early juvenile stage is particularly important to population growth. This phase of the life history appears likely to present a bottleneck to recruitment for Atlantic menhaden. We also made a number of technological breakthroughs which are already being applied elsewhere in research and assessments including the Continuous, Underway Egg Sampler (CUFES), enzyme-based approaches to evaluating condition of individual larvae and various physical and biological modelling innovations. Our experiences establishing and managing the SABRE research team also provide insights into one model for promoting multidisciplinary research in fisheries oceanography. Throughout SABRE, we have sought an open exchange of information and insights from a wide variety of researchers and environmental managers. We hope the synthesis provided here continues that dialogue.

Real-time current measurements on U.S. Coast Guard navigation buoys

Abstract: The National Oceanic and Atmospheric Administration, National Ocean Service's Center for Operational Oceanographic Products and Services (CO-OPS) operates Physical Oceanographic Real Time Systems (PORTS/spl reg/) at many of our Nation's major sea ports to provide real-time information in support of safe and efficient maritime commerce. As part of on-going efforts to improve PORTS/spl reg/, COOPS has partnered with the U.S. Coast Guard (USCG) to install current measurement systems on existing navigation buoys. These systems consist of a "clamparatus" that secures a current profiler and electronics box to the buoy. The entire package weighs less than 200 pounds and is easily deployed using a small boat and a block and tackle. Data are sent to shore via spread-spectrum radios. Deployments up to seven months have been achieved because of the low power consumption of both the profiler and radios. The biggest challenge to date has been correcting the compass error induced by the steel buoy; initial compass calibrations have removed much of the magnetic deviation. The results of comparisons with current directions from bottom-mounted acoustic Doppler current profilers (ADCPs) are encouraging, showing agreement to within +/-13/spl deg/ when all data are included. The difference improves to 11/spl deg/ when speeds less than 12.9 cm/s (.25 knots) are omitted. Recent experiments include the collection of global positioning system (GPS) compass measurements during calibration.

Preliminary analysis to estimate the spatial distribution of benefits of P load reduction: Identifying the spatial influence of phosphorus loading from the Maumee River (USA) in western Lake Erie

Abstract: Since the early 2000s, Lake Erie has been experiencing annual cyanobacterial blooms that often cover large portions of the western basin and even reach into the central basin. These blooms have affected several ecosystem services provided by Lake Erie to surrounding communities (notably drinking water quality). Several modeling efforts have identified the springtime total bioavailable phosphorus (TBP) load as a major driver of maximum cyanobacterial biomass in western Lake Erie, and on this basis, international water management bodies have set a phosphorus (P) reduction goal. This P reduction goal is intended to reduce maximum cyanobacterial biomass, but there has been very limited effort to identify the specific locations within the western basin of Lake Erie that will likely experience the most benefits. Here, we used pixel-specific linear regression to identify where annual variation in spring TBP loads is most strongly associated with cyanobacterial abundance, as inferred from satellite imagery. Using this approach, we find that annual TBP loads are most strongly associated with cyanobacterial abundance in the central and southern areas of the western basin. At the location of the Toledo water intake, the association between TBP load and cyanobacterial abundance is moderate, and in Maumee Bay (near Toledo, Ohio), the association between TBP and cyanobacterial abundance is no better than a null model. Both of these locations are important for the delivery of specific ecosystem services, but this analysis indicates that P load reductions would not be expected to substantially improve maximum annual cyanobacterial abundance in these locations. These results are preliminary in the sense that only a limited set of models were tested in this analysis, but these results illustrate the importance of identifying whether the spatial distribution of management benefits (in this case P load reduction) matches the spatial distribution of management goals (reducing the effects of cyanobacteria on important ecosystem services).