22 research outputs found

    Seasonal Relationships Between Phytoplankton Composition, Abundance, and Primary Productivity in Three Tidal Rivers of the Lower Chesapeake Bay

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    The seasonal abundance and successional patterns of phytoplankton, including autotrophic picoplankton, are compared to spring, summer, and fall primary production maxima that occurred in three tidal rivers. The tidal freshwaters were dominated by diatoms, chlorophytes, and cyanobacteria during a late spring through early fall period of maximum growth. In contrast, downstream assemblages were dominated by estuarine diatoms, dinoflagellates, and cryptomonads which developed spring pulses and a protracted summer-fall maximum. Autotrophic picoplankton produced a major summer pulse at all river stations with reduced abundance during other seasons. The mean annual productivity rates for the tidal James, Rappahannock, and York rivers were 409.6, 213.8, and 199.1 gC m-2 yr-1 respectively

    Phytoplankton Productivity in the Tidal Regions of Four Chesapeake Bay (U.S.A.) Tributaries

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    Monthly and annual phytoplankton productivity rates of four Virginia tidal rivers were determined based on a 12-year monitoring study that included sampling stations from tidal freshwater, oligohaline, and mesohaline regions in these rivers. The mean monthly rates and range at these locations were 5.52 (Dec.) to 175.12 (Aug.) mg C m-3 h-1 for tidal freshwater, 12.21 (Jan.) to 149.90 (May) mg C m-3 h-1 in oligohaline regions, and 16.20 (Jan.) to 151.33 (May) mg C m-3 h-1 for the mesohaline. The estimated mean annual 12 year productivity for the different Virginia river sites in this study ranged from 49 g C m-2 yr-1 to 230 g C m-2 yr-1. The dominant phytoplankton during periods of high productivity included a changing seasonal dominance of flora among the different salinity regions. At least one. station from each river experienced a significant decrease in productivity rates during the 12 years of this analysis. In comparison to an earlier segment of this study, the results indicate the value of long term monitoring to more accurately characterize the productivity dynamics in estuarine locations

    Phytoplankton Productivity in the Tidal Regions of Four Chesapeake Bay (U.S.A.) Tributaries

    Get PDF
    Monthly and annual phytoplankton productivity rates of four Virginia tidal rivers were determined based on a 12-year monitoring study that included sampling stations from tidal freshwater, oligohaline, and mesohaline regions in these rivers. The mean monthly rates and range at these locations were 5.52 (Dec.) to 175.12 (Aug.) mg C m-3 h-1 for tidal freshwater, 12.21 (Jan.) to 149.90 (May) mg C m-3 h-1 in oligohaline regions, and 16.20 (Jan.) to 151.33 (May) mg C m-3 h-1 for the mesohaline. The estimated mean annual 12 year productivity for the different Virginia river sites in this study ranged from 49 g C m-2 yr-1 to 230 g C m-2 yr-1. The dominant phytoplankton during periods of high productivity included a changing seasonal dominance of flora among the different salinity regions. At least one. station from each river experienced a significant decrease in productivity rates during the 12 years of this analysis. In comparison to an earlier segment of this study, the results indicate the value of long term monitoring to more accurately characterize the productivity dynamics in estuarine locations

    Density-Dependence Mediates the Effects of Temperature on Growth of Juvenile Blue Catfish in Nonnative Habitats

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    The combined effects of conspecific density and climate warming on the vital rates of invasive fish species have not been well studied, but may be important in predicting how successful they will be in the future. We evaluated the effects of temperature and population density on monthly time series of sizes of age-0 Blue Catfish Ictalurus furcatus in the James, York, and Rappahannock River subestuaries (defined here as tidally influenced bodies of water that feed into the Chesapeake Bay) from 1996 to 2017, using growing degree-days (GDDs, °C day) as a measure of thermal time. Our pre- dictive linear mixed-effects model explained 86% of the variation in the length of age-0 Blue Catfish. In addition, it indi- cated a strong positive effect of temperature on the growth rate of age-0 Blue Catfish, with individual fish biomass during warm years up to 63% higher than during cool years. Growth rate was influenced negatively by the abundance of age-0 and older fish, resulting in at least fourfold differences in the predicted biomass of Blue Catfish by the end of the first year of life depending on conspecific density. We also observed regional differences in the growth rates of Blue Catfish in the three subestuaries we examined; although growth occurred in all subestuaries, growth was highest for the Rappahannock River population even though this river accumulated the fewest GDDs. Rising water temperatures due to global climate change will likely increase the growth rate of age-0 Blue Catfish in the Chesapeake Bay region, potentially intensifying the negative impacts of this invasive species on the ecology of Chesapeake Bay. However, individual populations respond differently to warming temperatures, and thus, potential increases in the growth rate of age-0 Blue Catfish may be par- tially offset by local conditions that may serve to limit growth

    EAU guidelines on assessment and nonsurgical management of urinary incontinence

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    Context: The previous European Association of Urology (EAU) guidelines on urinary incontinence comprised a summary of sections of the 2009 International Consultation on Incontinence. A decision was made in 2010 to rewrite these guidelines based on an independent systematic review carried out by the EAU guidelines panel, using a sustainable methodology. Objective: We present a short version of the full guidelines on assessment, diagnosis, and nonsurgical treatment of urinary incontinence, with the aim of increasing their dissemination. Evidence acquisition: Evidence appraisal included a pragmatic review of existing systematic reviews and independent new literature searches, based on Population, Intervention, Comparator, Outcome questions. Appraisal of papers was carried out by an international panel of experts, who also collaborated on a series of consensus discussions, to develop concise structured evidence summaries and action-based recommendations using a modified Oxford system. Evidence summary: The full version of the guidelines is available online (http://www.uroweb.org/guidelines/online-guidelines/). The guidelines include algorithms that refer the reader back to the supporting evidence, and they are more immediately useable in daily clinical practice. Conclusions: These new guidelines present an up-to-date summary of the available evidence, together with clear clinical algorithms and action-based recommendations based on the best available evidence. Where such evidence does not exist, they present a consensus of expert opinion. © 2012 European Association of Urology
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