11 resultados para Lewis Spring

em Aquatic Commons


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Five short bottom sediment cores taken in Wakulla Spring Wakulla County, Florida, were described lithologically and sampled for palynological study. Four of the cores were recoveredfrom sediments at the spring cave entrance (130 feet water depth). One core was taken in a fossil vertebrate bone bed, 280 feet distance into the main spring cave at a water depth of 240 feet. Sediments in the cores are composed of alternating intervals of quartz sand and calcilitite, containing freshwater diatoms, freshwater mollusk shells and plant remains. The predominant pollen present in all cores consists of a periporate variety typical of the herb families Chenopodiaceae and Amaranthaceae. Arboreal flora, typical of the area surrounding the spring today, represent a very low percentage of thle pollen assemblage in the cores. Clustered Chenopod-Amaranth type pollen observed in one core suggest minimal transport prior to deposition, and indicate that the bottom sediments in the cave may be essentially In situ. An absence of exotic flora suggests a Quaternary age for the sediments. (PDF contains 11 pages.)

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There is strong evidence to suggest that ground-water nitrate concentrations have increased in recent years and further increases are expected along portions of the central Gulf coast of Florida. Much of the nitrate enriched groundwater is discharged into surface waters through numerous freshwater springs that are characteristic of the area and the potential for eutrophication of their receiving waters is a legitimate concern. To test the potential effects of elevated nutrient concentrations on the periphyton community an in situ nutrient addition experiment was conducted in the spring-fed Chassahowitzka River, FL, USA, during the summer of 1999. Plastic tubes housing arrays of glass microscope slides were suspended in the stream. Periphyton colonizing the microscope slides was subjected to artificial increases in nitrogen, phosphorus or a combination of both. Slides from each tube were collected at 3- to 4- day intervals and the periphyton communities were measured for chlorophyll concentration. The addition of approximately 10 g/L of phosphate above ambient concentrations significantly increased the amount of periphyton on artificial substrates relative to controls; the addition of approximately 100 g/L of nitrate above ambient concentrations did not. The findings from this experiment implicated phosphorus, rather than nitrogen, as the nutrient that potentially limits periphyton growth in this system.(PDF contains 4 pages.)

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(1 poster)

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This cruise report is a summary of a field survey conducted in coastal-ocean waters off Florida from Anclote Key to West Palm Beach and from approximately 1 nautical mile (nm) offshore seaward to the shelf break (100 m). The survey was conducted May 15 - May 28, 2007 on NOAA Ship NANCY FOSTER Cruise NF-07-08-NCCOS. Multiple indicators of ecological condition were sampled synoptically at each of 50 stations throughout the region including 10 stations within the Florida Keys National Marine Sanctuary (FKNMS) using a random probabilistic sampling design. Samples were collected for the analysis of benthic community structure and composition; concentrations of chemical contaminants (metals, pesticides, PAHs, PCBs, PBDEs) in sediments and target demersal biota; nutrient and chlorophyll levels in the water column; and other basic habitat characteristics such as depth, salinity, temperature, dissolved oxygen, pH, sediment grain size, and organic carbon content. The overall purpose of the survey was to collect data to assess the status of ecological condition in coastal-ocean waters of the region, based on these various indicators, and to provide this information as a baseline for determining how environmental conditions may be changing with time. The results will be of value in helping to broaden our understanding of the status of ecological resources and their controlling factors, including impacts of potential ecosystem stressors, in such strategic coastal areas. (PDF contains 34 pages

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This cruise report is a summary of a field survey conducted in coastal-ocean waters of the Mid-Atlantic Bight from Nags Head, North Carolina to Cape Cod, Massachusetts and from approximately 1 nautical mile (nm) of shore seaward to the shelf break (100 m). The survey was conducted May 12 - May 21, 2006 on NOAA Ship NANCY FOSTER Cruise NF-06-06-NCCOS. Multiple indicators of ecological condition were sampled synoptically at each of 49 stations throughout the region using a random probabilistic sampling design. Samples were collected for the analysis of benthic community structure and composition; concentrations of chemical contaminants (metals, pesticides, PAHs, PCBs, PBDEs) in sediments and target demersal biota; nutrient and chlorophyll levels in the water column; and other basic habitat characteristics such as depth, salinity, temperature, dissolved oxygen, pH, sediment grain size, and organic carbon content. The overall purpose of the survey was to collect data to assess the status of ecological condition in coastal-ocean waters of the region, based on these various indicators, and to provide this information as a baseline for determining how environmental conditions may be changing with time. The results will be of value in helping to broaden our understanding of the status of ecological resources and their controlling factors, including impacts of potential ecosystem stressors, in such strategic coastal areas. (18pp.) (PDF contains 24 pages)

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As part of an ongoing program of benthic sampling and related assessments of sediment quality at Grays Reef National Marine Sanctuary (GRNMS) off the coast of Georgia, a survey of soft-bottom benthic habitats was conducted in spring 2005 to characterize condition of macroinfaunal assemblages and levels of chemical contaminants in sediments and biota relative to a baseline survey carried out in spring 2000. Distribution and abundance of macrobenthos were related foremost to sediment type (median particle size, % gravel), which in turn varied according to bottom-habitat mesoscale features (e.g., association with live bottom versus flat or rippled sand areas). Overall abundance and diversity of soft-bottom benthic communities were similar between the two years, though dominance patterns and relative abundances of component species were less repeatable. Seasonal summer pulses of a few taxa (e.g., the bivalve Ervilia sp. A) observed in 2000 were not observed in 2005. Concentrations of chemical contaminants in sediments and biota, though detectable in both years, were consistently at low, background levels and no exceedances of sediment probable bioeffect levels or FDA action levels for edible fish or shellfish were observed. Near-bottom dissolved oxygen levels and organic-matter content of sediments also have remained within normal ranges. Highly diverse benthic assemblages were found in both years, supporting the premise that GRNMS serves as an important reservoir of marine biodiversity. A total of 353 taxa (219 identified to species) were collected during the spring 2005 survey. Cumulatively, 588 taxa (371 identified to species) have been recorded in the sanctuary from surveys in 2000, 2001, 2002, and 2005. Species Accumulation Curves indicate that the theoretical maximum should be in excess of 600 species. Results of this study will be of value in advancing strategic science and management goals for GRNMS, including characterization and long-term monitoring of sanctuary resources and processes, as well as supporting evolving interests in ecosystem-based management of the surrounding South Atlantic Bight (SAB) ecosystem. (PDF contains 46 pages)

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Comparative night and day catches of herring larvae were taken during the Rgen-Herring-Larval-Survey (RHLS) in 2007 and 2008 in the Greifswalder Bodden which is the main spawning area of the Western Baltic Spring Spawning Herring. The quantities and the size composition of larvae caught during night and day were examined. During night more larvae were caught compared to the samples taken at daytime, especially with larvae larger than 25 mm. This indicates avoidance reactions, which increase with the developmental stage of the larvae. The differences of the night and day catches are relatively constant until a length of about 25 mm, thus the night/day effect does not influence estimations concerning larvae smaller than 25 mm (e.g. N20 index). There might be an impact on estimations for larger larvae due to the night/day effect. For further research other aspects like cloud coverage at night, phase of the moon, underwater visibility and turbidity should be taken into account. These aspects might influence the avoidance reactions.

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The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the northern stock since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stren

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Professionals who are responsible for coastal environmental and natural resource planning and management have a need to become conversant with new concepts designed to provide quantitative measures of the environmental benefits of natural resources. These amenities range from beaches to wetlands to clean water and other assets that normally are not bought and sold in everyday markets. At all levels of government from federal agencies to townships and counties decisionmakers are being asked to account for the costs and benefits of proposed actions. To non-specialists, the tools of professional economists are often poorly understood and sometimes inappropriate for the problem at hand. This handbook is intended to bridge this gap. The most widely used organizing tool for dealing with natural and environmental resource choices is benefit-cost analysis it offers a convenient way to carefully identify and array, quantitatively if possible, the major costs, benefits, and consequences of a proposed policy or regulation. The major strength of benefit-cost analysis is not necessarily the predicted outcome, which depends upon assumptions and techniques, but the process itself, which forces an approach to decision-making that is based largely on rigorous and quantitative reasoning. However, a major shortfall of benefit-cost analysis has been the difficulty of quantifying both benefits and costs of actions that impact environmental assets not normally, nor even regularly, bought and sold in markets. Failure to account for these assets, to omit them from the benefit-cost equation, could seriously bias decisionmaking, often to the detriment of the environment. Economists and other social scientists have put a great deal of effort into addressing this shortcoming by developing techniques to quantify these non-market benefits. The major focus of this handbook is on introducing and illustrating concepts of environmental valuation, among them Travel Cost models and Contingent Valuation. These concepts, combined with advances in natural sciences that allow us to better understand how changes in the natural environment influence human behavior, aim to address some of the more serious shortcomings in the application of economic analysis to natural resource and environmental management and policy analysis. Because the handbook is intended for non-economists, it addresses basic concepts of economic value such as willingness-to-pay and other tools often used in decision making such as costeffectiveness analysis, economic impact analysis, and sustainable development. A number of regionally oriented case studies are included to illustrate the practical application of these concepts and techniques.

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The stomach contents of the minimal armhook squid (Berryteuthis anonychus) were examined for 338 specimens captured in the northeast Pacific during May 1999. The specimens were collected at seven stations between 145165W and 3949N and ranged in mantle length from 10.3 to 102.2 mm. Their diet comprised seven major prey groups (copepods, chaetognaths, amphipods, euphausiids, ostracods, unidentified fish, and unidentified gelatinous prey) and was dominated by copepods and chaetognaths. Copepod prey comprised four genera, and 86% by number of the copepods were from the genus Neocalanus. Neocalanus cristatus was the most abundant prey taxa, composing 50% by mass and 35% by number of the total diet. Parasagitta elegans (Chaetognatha) occurred in more stomachs (47%) than any other prey taxon. Amphipods occurred in 19% of the stomachs but composed only 5% by number and 3% by mass of the total prey consumed. The four remaining prey groups (euphausiids, ostracods, unidentified fish, and unidentified gelatinous prey) together composed <2% by mass and <1% by number of the diet. There was no major change in the diet through the size range of squid examined and no evidence of cannibalism or predation on other cephalopod species.