983 resultados para Brian Willmett


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Toxic chemicals can enter the marine environment through numerous routes: stormwater runoff, industrial point source discharges, municipal wastewater discharges, atmospheric deposition, accidental spills, illegal dumping, pesticide applications and agricultural practices. Once they enter a receiving system, toxicants often become bound to suspended particles and increase in density sufficiently to sink to the bottom. Sediments are one of the major repositories of contaminants in aquatic envronments. Furthermore, if they become sufficiently contaminated sediments can act as sources of toxicants to important biota. Sediment quality data are direct indicators of the health of coastal aquatic habitats. Sediment quality investigations conducted by the National Oceanic and Atmospheric Administration (NOAA) and others have indicated that toxic chemicals are found in the sediments and biota of some estuaries in South Carolina and Georgia (NOAA, 1992). This report documents the toxicity of sediments collected within five selected estuaries: Savannah River, Winyah Bay, Charleston Harbor, St. Simons Sound, and Leadenwah Creek (Figure 1). (PDF contains 292 pages)

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Executive Summary: Tropical marine ecosystems in the Caribbean region are inextricably linked through the movement of pollutants, nutrients, diseases, and other stressors, which threaten to further degrade coral reef communities. The magnitude of change that is occurring within the region is considerable, and solutions will require investigating pros and cons of networks of marine protected areas (MPAs), cooperation of neighboring countries, improved understanding of how external stressors degrade local marine resources, and ameliorating those stressors. Connectivity can be broadly defined as the exchange of materials (e.g., nutrients and pollutants), organisms, and genes and can be divided into: 1) genetic or evolutionary connectivity that concerns the exchange of organisms and genes, 2) demographic connectivity, which is the exchange of individuals among local groups, and 3) oceanographic connectivity, which includes flow of materials and circulation patterns and variability that underpin much of all these exchanges. Presently, we understand little about connectivity at specific locations beyond model outputs, and yet we must manage MPAs with connectivity in mind. A key to successful MPA management is how to most effectively work with scientists to acquire the information managers need. Oceanography connectivity is poorly understood, and even less is known about the shape of the dispersal curve for most species. Dispersal kernels differ for various systems, species, and life histories and are likely highly variable in space and time. Furthermore, the implications of different dispersal kernels on population dynamics and management of species is unknown. However, small dispersal kernels are the norm - not the exception. Linking patterns of dispersal to management options is difficult given the present state of knowledge. The behavioral component of larval dispersal has a major impact on where larvae settle. Individual larval behavior and life history details are required to produce meaningful simulations of population connectivity. Biological inputs are critical determinants of dispersal outcomes beyond what can be gleaned from models of passive dispersal. There is considerable temporal and spatial variation to connectivity patterns. New models are increasingly being developed, but these must be validated to understand upstream-downstream neighborhoods, dispersal corridors, stepping stones, and source/sink dynamics. At present, models are mainly useful for providing generalities and generating hypotheses. Low-technology approaches such as drifter vials and oceanographic drogues are useful, affordable options for understanding local connectivity. The “silver bullet” approach to MPA design may not be possible for several reasons. Genetic connectivity studies reveal divergent population genetic structures despite similar larval life histories. Historical stochasticity in reproduction and/or recruitment likely has important, longlasting consequences on present day genetic structure. (PDF has 200 pages.)

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Executive Summary: The Connectivity Colloquium evolved from an exhortation by Dan Basta, Director of the National Marine Sanctuary Program, to come together and assess what we know about the condition of our natural resources, identify information gaps and how to fill them, and transform science and management from an emphasis on documentation to a nexus for action. This purpose in some ways reflects the initiation of the Florida Keys National Marine Sanctuary itself, which was designated by an act of the U.S. Congress in 1990 in the aftermath of the 1989 Exxon Valdez oil spill in Alaska and three major ship groundings of the Florida Reef Tract in late 1989. Over the next seven years NOAA worked with federal, state, and local partners to develop a comprehensive management plan for the Sanctuary implemented under a co-trustee partnership between NOAA and the State of Florida. (PDF contains 270 pages; 14Mb)

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This study has investigated the medium to long term costs to Higher Education Institutions (HEIs) of the preservation of research data and developed guidance to HEFCE and institutions on these issues. It has provided an essential methodological foundation on research data costs for the forthcoming HEFCE-sponsored feasibility study for a UK Research Data Service.It will also assist HEIs and funding bodies wishing to establish strategies and TRAC costings for long-term data management and archiving. The rising tide of digital research data raises issues relating to access, curation and preservation for HEIs and within the UK a growing number of research funders are now implementing policies requiring researchers to submit data management, preservation or data sharing plans with their funding applications.

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Data has always been fundamental to many areas of research but in recent years it has become central to more disciplines and inter-disciplinary projects and grown substantially in scale and complexity. There is increasing awareness of its strategic importance as a resource in addressing modern global challenges and the possibilities being unlocked by rapid technological advances and their application in research (NAS2009). The first Keeping Research Data Safe study funded by JISC made a major contribution to understanding of long-term preservation costs for research data by developing a cost model and identifying cost variables for preserving research data in UK universities (Beagrie et al, 2008). The Keeping Research Data Safe 2 (KRDS2) project has built on this work.

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Presentation slides as part of the Janet network end-to-end performance initiative

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The Tortugas South Ecological Reserve, located along the margin of the southwest Florida carbonate platform, is part of the largest no-take marine reserve in the U.S. Established in July 2001, the reserve is approximately 206 km2 in area, and ranges in depths from 30 m at Riley’s Hump to over 600 m at the southern edge of the reserve. Geological and biological information for the Tortugas South Reserve is lacking, and critical for management of the area. Bathymetric surveys were conducted with a Simrad EM 3000 multibeam echosounder at Riley’s Hump and Miller’s Ledge, located in the northern and central part of the reserve. Resulting data were used to produce basemaps to obtain geological ground truth and visual surveys of biological communities, including reef fishes. Visual surveys were conducted using SCUBA and the Phantom S2 Remotely Operated Vehicle (ROV) at Riley’s Hump. Visual surveys were conducted using the ROV and the Deepworker 2000 research submersible along Miller’s Ledge, within and outside of the reserve. A total of 108 fishes were recorded during SCUBA, ROV, and submersible observations. Replicate survey transects resulted in over 50 fishes documented at Miller’s Ledge, and eight of the top ten most abundant species were planktivores. Many species of groupers, including scamp (Mycteroperca phenax), red grouper (Epinephelus morio), snowy grouper (E. niveatus), speckled hind (E. drummondhayi), and Warsaw grouper (E. nigritus), are present in the sanctuary. Numerous aggregations of scamp and a bicolor phase of the Warsaw grouper were observed, indicating the importance of Miller’s Ledge as a potential spawning location for both commercially important and rare deep reef species, and as a potential source of larval recruits for the Florida Keys and other deep reef ecosystems of Florida

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Functional linkage between reef habitat quality and fish growth and production has remained elusive. Most current research is focused on correlative relationships between a general habitat type and presence/absence of a species, an index of species abundance, or species diversity. Such descriptive information largely ignores how reef attributes regulate reef fish abundance (density-dependent habitat selection), trophic interactions, and physiological performance (growth and condition). To determine the functional relationship between habitat quality, fish abundance, trophic interactions, and physiological performance, we are using an experimental reef system in the northeastern Gulf of Mexico where we apply advanced sensor and biochemical technologies. Our study site controls for reef attributes (size, cavity space, and reef mosaics) and focuses on the processes that regulate gag grouper (Mycteroperca microlepis) abundance, behavior and performance (growth and condition), and the availability of their pelagic prey. We combine mobile and fixed-active (fisheries) acoustics, passive acoustics, video cameras, and advanced biochemical techniques. Fisheries acoustics quantifies the abundance of pelagic prey fishes associated with the reefs and their behavior. Passive acoustics and video allow direct observation of gag and prey fish behavior and the acoustic environment, and provide a direct visual for the interpretation of fixed fisheries acoustics measurements. New application of biochemical techniques, such as Electron Transport System (ETS) assay, allow the in situ measurement of metabolic expenditure of gag and relates this back to reef attributes, gag behavior, and prey fish availability. Here, we provide an overview of our integrated technological approach for understanding and quantifying the functional relationship between reef habitat quality and one element of production – gag grouper growth on shallow coastal reefs.

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ENGLISH: The map method, the Jones method, the variance-covariance method, and the Skellam method were used to study the migrations of tagged yellowfin tuna released off the southern coast of Mexico in 1960 and 1969. The first three methods are all useful, and each presents information which is complementary to that presented by the others. The Skellam method, as used in this report, is less useful. The movements of the tagged fish released in 1960 appeared to have been strongly directed, but this was probably caused principally by the distribution of the fishing effort. The effort was much more widely distributed in 1970, and the movements of the fish released in 1969 appeared to have been much less directed. The correlation coefficients derived from the variance-covariance method showed that it was not random, however. The small fish released in the Acapulco and 10°N-100°W areas in 1969 migrated to the Manzanillo area near the beginning of February 1970. The medium and large fish released in the same areas in the same year tended to migrate to the southeast throughout the first half of 1970, however. SPANISH: El método de mapas, el de Jones, el de la variancia-covariancia y el de Skellam fueron empleados para estudiar las migraciones del atún aleta amarilla marcado y liberado frente a la costa meridional de México en 1960 y 1969. Los tres primeros métodos son todos útiles, y cada uno presenta información que complementa la presentada por los otros. El método de Skellam, conforme se usa en este informe, es menos útil. Parece que los desplazamientos de los peces marcados y liberados en 1960 hubieran sido fuertemente orientados, pero ésto probablemente fue causado principalmente por la distribución del esfuerzo de pesca. El esfuerzo se distribuyó más extensamente en 1970, y parece que los desplazamientos de los peces liberados en 1969 fueran menos orientados. Los coeficientes de correlación derivados del método variancia-covariancia indicaron, sin embargo, que no eran aleatorios. Los peces pequeños liberados en las áreas de Acapulco y los 10°N-100°W en 1969 migraron al área de Manzanillo a principios de febrero 1970. Los peces medianos y grandes liberados en las mismas áreas en el mismo año tuvieron, sin embargo, la tendencia a desplazarse al sudeste durante el primer semestre de 1970. (PDF contains 64 pages.)

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Freshwater fish of the genus Apteronotus (family Gymnotidae) generate a weak, high frequency electric field (< 100 mV/cm, 0.5-10 kHz) which permeates their local environment. These nocturnal fish are acutely sensitive to perturbations in their electric field caused by other electric fish, and nearby objects whose impedance is different from the surrounding water. This thesis presents high temporal and spatial resolution maps of the electric potential and field on and near Apteronotus. The fish's electric field is a complicated and highly stable function of space and time. Its characteristics, such as spectral composition, timing, and rate of attenuation, are examined in terms of physical constraints, and their possible functional roles in electroreception.

Temporal jitter of the periodic field is less than 1 µsec. However, electrocyte activity is not globally synchronous along the fish 's electric organ. The propagation of electrocyte activation down the fish's body produces a rotation of the electric field vector in the caudal part of the fish. This may assist the fish in identifying nonsymmetrical objects, and could also confuse electrosensory predators that try to locate Apteronotus by following its fieldlines. The propagation also results in a complex spatiotemporal pattern of the EOD potential near the fish. Visualizing the potential on the same and different fish over timescales of several months suggests that it is stable and could serve as a unique signature for individual fish.

Measurements of the electric field were used to calculate the effects of simple objects on the fish's electric field. The shape of the perturbation or "electric image" on the fish's skin is relatively independent of a simple object's size, conductivity, and rostrocaudal location, and therefore could unambiguously determine object distance. The range of electrolocation may depend on both the size of objects and their rostrocaudal location. Only objects with very large dielectric constants cause appreciable phase shifts, and these are strongly dependent on the water conductivity.

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Demixing is the task of identifying multiple signals given only their sum and prior information about their structures. Examples of demixing problems include (i) separating a signal that is sparse with respect to one basis from a signal that is sparse with respect to a second basis; (ii) decomposing an observed matrix into low-rank and sparse components; and (iii) identifying a binary codeword with impulsive corruptions. This thesis describes and analyzes a convex optimization framework for solving an array of demixing problems.

Our framework includes a random orientation model for the constituent signals that ensures the structures are incoherent. This work introduces a summary parameter, the statistical dimension, that reflects the intrinsic complexity of a signal. The main result indicates that the difficulty of demixing under this random model depends only on the total complexity of the constituent signals involved: demixing succeeds with high probability when the sum of the complexities is less than the ambient dimension; otherwise, it fails with high probability.

The fact that a phase transition between success and failure occurs in demixing is a consequence of a new inequality in conic integral geometry. Roughly speaking, this inequality asserts that a convex cone behaves like a subspace whose dimension is equal to the statistical dimension of the cone. When combined with a geometric optimality condition for demixing, this inequality provides precise quantitative information about the phase transition, including the location and width of the transition region.

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The Tanzania Coastal Management Partnership (TCMP) works to implement the National Integrated Coastal Environmental Management Strategy (ICEMS) in Tanzania’s coastal landscapes and seascapes, funded in large measure by the U.S. Agency for International Development. The overarching goal of the Sustainable Coastal Communities and Ecosystems in Tanzania (SUCCESS Tanzania) initiative is to conserve coastal and marine biodiversity while improving the well being of coastal residents through implementation of the Tanzania ICEMS and related ICM policies and strategies. It does this by focusing on three key results: -Policies and Laws that Integrate Conservation and Development Applied -Participatory Landscape Scale Conservation Practiced -Conservation Enterprises Generate Increased and Equitable Benefits from Sustainable Use An additional result sought in the program is gender equity and HIV/AIDS preventive behaviors promoted through communicating HIV/AIDS, environment, and equity messages. (PDF contains 3 pages)

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Competing uses, sensitive and valuable marine resources, and overlapping jurisdictions complicate management decision making in the marine environment. States are developing marine spatial planning capacity to help make better decisions, particularly as demand for ocean space and resources is growing because of emerging human uses (renewable energy, aquaculture) and traditional human uses (commercial fishing, commerce). This paper offers perspectives on marine spatial planning efforts being carried out in four states across the US, and demonstrates similarities and differences between them. The approach to marine spatial planning in each state is discussed with specific attention given to issues such as what is driving the effort, data availability, maturity of the effort, and level of resources devoted to it. Highlighting the similarities and differences illustrates state and region specific challenges and the approaches being used to meet them. (PDF contains 4 pages)

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The interactions of N2, formic acid and acetone on the Ru(001) surface are studied using thermal desorption mass spectrometry (TDMS), electron energy loss spectroscopy (EELS), and computer modeling.

Low energy electron diffraction (LEED), EELS and TDMS were used to study chemisorption of N2 on Ru(001). Adsorption at 75 K produces two desorption states. Adsorption at 95 K fills only the higher energy desorption state and produces a (√3 x √3)R30° LEED pattern. EEL spectra indicate both desorption states are populated by N2 molecules bonded "on-top" of Ru atoms.

Monte Carlo simulation results are presented on Ru(001) using a kinetic lattice gas model with precursor mediated adsorption, desorption and migration. The model gives good agreement with experimental data. The island growth rate was computed using the same model and is well fit by R(t)m - R(t0)m = At, with m approximately 8. The island size was determined from the width of the superlattice diffraction feature.

The techniques, algorithms and computer programs used for simulations are documented. Coordinate schemes for indexing sites on a 2-D hexagonal lattice, programs for simulation of adsorption and desorption, techniques for analysis of ordering, and computer graphics routines are discussed.

The adsorption of formic acid on Ru(001) has been studied by EELS and TDMS. Large exposures produce a molecular multilayer species. A monodentate formate, bidentate formate, and a hydroxyl species are stable intermediates in formic acid decomposition. The monodentate formate species is converted to the bidentate species by heating. Formic acid decomposition products are CO2, CO, H2, H2O and oxygen adatoms. The ratio of desorbed CO with respect to CO2 increases both with slower heating rates and with lower coverages.

The existence of two different forms of adsorbed acetone, side-on, bonded through the oxygen and acyl carbon, and end-on, bonded through the oxygen, have been verified by EELS. On Pt(111), only the end-on species is observed. On dean Ru(001) and p(2 x 2)O precovered Ru(001), both forms coexist. The side-on species is dominant on clean Ru(001), while O stabilizes the end-on form. The end-on form desorbs molecularly. Bonding geometry stability is explained by surface Lewis acidity and by comparison to organometallic coordination complexes.