206 research outputs found
Mutualism between ribbed mussels and cordgrass enhances salt marsh nitrogen removal
Salt marsh ecosystems have declined globally and are increasingly threatened by erosion, sea level rise, and urban development. These highly productive, physically demanding ecosystems are populated by core species groups that often have strong trophic interactions with implications for ecosystem function and service provision. Positive interactions occur between ribbed mussels (Geukensia demissa) and cordgrass (Spartina alterniflora). Mussels transfer particulate nitrogen from the water column to the marsh sediments, which stimulates cordgrass growth, and cordgrass provides predator and/or heat stress refuge for mussels. Here, we test mussel facilitation of two functions in salt marshes that relate to N removal: microbial denitrification and water filtration. Microcosm experiments revealed that the highest rates of N-2 production and nitrification occurred when mussels were present with marsh vegetation, suggesting that mussels enhanced coupling of the nitrification-denitrification. Surveys spanning the York River Estuary, Chesapeake Bay, showed that the highest densities of mussels occurred in the first meter for all marsh types with mainstem fringing (1207 +/- 265 mussels/m(2)) being the most densely populated. The mussel population was estimated to be similar to 197 million animals with a water filtration potential of 90-135 million L/hr. Erosion simulation models demonstrated that suitable marsh habitat for ribbed mussels along the York River Estuary would be reduced by 11.8% after 50 years. This reduction in mussel habitat resulted in a projected 15% reduction in ribbed mussel abundance and filtration capacity. Denitrification potential was reduced in conjunction with projected marsh loss (35,536 m(2)) by 205 g N/hr, a 16% reduction. Because of the predominant occurrence of ribbed mussels at the marsh seaward edge and because the highest proportional loss will occur for fringing marshes (20%), shoreline management practices that restore or create fringing marsh may help offset these projected losses
NLOAD : an interactive, web-based modeling tool for nitrogen management in estuaries
Author Posting. © Ecological Society of America, 2007. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 17, Supple. (2007): S17âS30, doi:10.1890/05-1460.1.Eutrophication of estuaries is an increasing global concern that requires development of new tools to identify causes, quantify conditions, and propose management options that address this environmental problem. Since eutrophication is often associated with increased inputs of land-derived nitrogen to estuaries, we developed NLOAD, a user-friendly, web-based tool that brings together six different published models that predict nitrogen loading to estuaries and two models that estimate nitrogen concentrations in coastal waters. Here we describe each of the models, demonstrate how NLOAD is designed to function, and then use the models in NLOAD to predict nitrogen loads to Barnegat Bay, New Jersey (USA). The four models that we used to estimate nitrogen loads to Barnegat Bay, when adjusted, all had similar results that matched well with measured values and indicated that Barnegat Bay receives roughly 26 kg N·haâ1·yrâ1. Atmospheric deposition was the dominant source of nitrogen to Barnegat Bay, followed by fertilizer nitrogen. Wastewater in Barnegat Bay is diverted to an offshore outfall and contributes no nitrogen to the system. The NLOAD tool has an additional feature that allows managers to assess the effectiveness of a variety of management options to reduce nitrogen loads. We demonstrate this feature of NLOAD through simulations in which fertilizer inputs to the Barnegat Bay watershed are reduced. Even modest cutbacks in the use of fertilizers on agricultural fields and lawns can be shown to reduce the amount of N entering Barnegat Bay.Support for the NLOAD tool came from the Cooperative
Institute for Coastal and Estuarine Environmental Technologies
(CICEET, CICEET-UNH grants #02-610 and #04-833).
Additional funding was received from Environmental Defense
Safety and immunogenicity of novel 5T4 viral vectored vaccination regimens in early stage prostate cancer: a phase I clinical trial.
Prostate cancer (PCa) has been under investigation as a target for antigen-specific immunotherapies in metastatic disease settings for the last two decades leading to a licensure of the first therapeutic cancer vaccine, Sipuleucel-T, in 2010. However, neither Sipuleucel-T nor other experimental PCa vaccines that emerged later induce strong T-cell immunity.
In this first-in-man study, VANCE, we evaluated a novel vaccination platform based on two replication-deficient viruses, chimpanzee adenovirus (ChAd) and MVA (Modified Vaccinia Ankara), targeting the oncofetal self-antigen 5T4 in early stage PCa. Forty patients, either newly diagnosed with early-stage PCa and scheduled for radical prostatectomy or patients with stable disease on an active surveillance protocol, were recruited to the study to assess the vaccine safety and T-cell immunogenicity. Secondary and exploratory endpoints included immune infiltration into the prostate, prostate-specific antigen (PSA) change, and assessment of phenotype and functionality of antigen-specific T cells.
The vaccine had an excellent safety profile. Vaccination-induced 5T4-specific T-cell responses were measured in blood by ex vivo IFN-Îł ELISpot and were detected in the majority of patients with a mean level in responders of 198 spot-forming cells per million peripheral blood mononuclear cells. Flow cytometry analysis demonstrated the presence of both CD8+ and CD4+ polyfunctional 5T4-specific T cells in the circulation. 5T4-reactive tumor-infiltrating lymphocytes were isolated from post-treatment prostate tissue. Some of the patients had a transient PSA rise 2-8 weeks following vaccination, possibly indicating an inflammatory response in the target organ.
An excellent safety profile and T-cell responses elicited in the circulation and also detected in the prostate gland support the evaluation of the ChAdOx1-MVA 5T4 vaccine in efficacy trials. It remains to be seen if this vaccination strategy generates immune responses of sufficient magnitude to mediate clinical efficacy and whether it can be effective in late-stage PCa settings, as a monotherapy in advanced disease or as part of multi-modality PCa therapy. To address these questions, the phase I/II trial, ADVANCE, is currently recruiting patients with intermediate-risk PCa, and patients with advanced metastatic castration-resistant PCa, to receive this vaccine in combination with nivolumab.
The trial was registered with the U.S. National Institutes of Health (NIH) Clinical Trials Registry (ClinicalTrials.gov identifier NCT02390063)
Passive and active ventricular elastances of the left ventricle
BACKGROUND: Description of the heart as a pump has been dominated by models based on elastance and compliance. Here, we are presenting a somewhat new concept of time-varying passive and active elastance. The mathematical basis of time-varying elastance of the ventricle is presented. We have defined elastance in terms of the relationship between ventricular pressure and volume, as: dP = EdV + VdE, where E includes passive (E(p)) and active (E(a)) elastance. By incorporating this concept in left ventricular (LV) models to simulate filling and systolic phases, we have obtained the time-varying expression for E(a )and the LV-volume dependent expression for E(p). METHODS AND RESULTS: Using the patient's catheterization-ventriculogram data, the values of passive and active elastance are computed. E(a )is expressed as: [Image: see text]; E(p)is represented as: [Image: see text]. E(a )is deemed to represent a measure of LV contractility. Hence, Peak dP/dt and ejection fraction (EF) are computed from the monitored data and used as the traditional measures of LV contractility. When our computed peak active elastance (E(a,max)) is compared against these traditional indices by linear regression, a high degree of correlation is obtained. As regards E(p), it constitutes a volume-dependent stiffness property of the LV, and is deemed to represent resistance-to-filling. CONCLUSIONS: Passive and active ventricular elastance formulae can be evaluated from a single-beat P-V data by means of a simple-to-apply LV model. The active elastance (E(a)) can be used to characterize the ventricle's contractile state, while passive elastance (E(p)) can represent a measure of resistance-to-filling
The influence of salinity on the effects of Multi-walled carbon nanotubes on polychaetes
Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multiwalled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.publishe
High Levels of Sediment Contamination Have Little Influence on Estuarine Beach Fish Communities
While contaminants are predicted to have measurable impacts on fish assemblages, studies have rarely assessed this potential in the context of natural variability in physico-chemical conditions within and between estuaries. We investigated links between the distribution of sediment contamination (metals and PAHs), physico-chemical variables (pH, salinity, temperature, turbidity) and beach fish assemblages in estuarine environments. Fish communities were sampled using a beach seine within the inner and outer zones of six estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. All sampling was replicated over two years with two periods sampled each year. Shannon diversity, biomass and abundance were all significantly higher in the inner zone of estuaries while fish were larger on average in the outer zone. Strong differences in community composition were also detected between the inner and outer zones. Few differences were detected between fish assemblages in heavily modified versus relatively unmodified estuaries despite high concentrations of sediment contaminants in the inner zones of modified estuaries that exceeded recognized sediment quality guidelines. Trends in species distributions, community composition, abundance, Shannon diversity, and average fish weight were strongly correlated to physico-chemical variables and showed a weaker relationship to sediment metal contamination. Sediment PAH concentrations were not significantly related to the fish assemblage. These findings suggest that variation in some physico-chemical factors (salinity, temperature, pH) or variables that co-vary with these factors (e.g., wave activity or grain size) have a much greater influence on this fish assemblage than anthropogenic stressors such as contamination
Nycthemeral and Monthly Occupation of the Fish Assemblage on a Sheltered Beach of BaĂa Norte, FlorianĂłpolis, Santa Catarina State, Brazil
Interpreting fish community records is challenging for several reasons, including the lack of past ichthyofauna data, the cyclical temporal variations in the community, and the methodology employed, which usually underestimates fish assemblages. The objective of this study was to describe short-scale and meso-scale (nycthemeral period and months, respectively) temporal variations in the ichthyofauna composition and structure of a sheltered beach of BaĂa Norte (FlorianĂłpolis, Santa Catarina state, Brazil), using a capĂ©chade net. Samples were collected monthly for a period of 48 hours. During the period from December 2010 to November 2011, a total of 19,302 individuals belonging to 89 species and 39 families were captured. The number of individuals that were sampled during the day and/or night was dependent on the sampling month. On average, the daytime assemblage was more abundant and different in structure and composition than the nighttime assemblage. Of the eight species that had the highest Index of Relative Importance (%IRI), five had higher variations (ANOVA F) between the day and night than between the months. This finding reinforced the need for sampling during both the day and night. The capĂ©chade net effectively captured demersal and pelagic individuals in a broad range of sizes
Hydrokinetic Turbine Effects on Fish Swimming Behaviour
Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines
already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect
fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis
hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring
fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed
that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their
movements through the area when the rotor was present. This deterrent effect on fish increased with current speed.
Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish
were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms-1. The
effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape
influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the
investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish
movements, particularly for large species, with possible effects on habitat connectivity if migration routes are
exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of
several metres width to allow large fish to pass through. In combination with further research the insights from this
study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological
impacts
Oyster Reefs as Natural Breakwaters Mitigate Shoreline Loss and Facilitate Fisheries
Shorelines at the interface of marine, estuarine and terrestrial biomes are among the most degraded and threatened habitats in the coastal zone because of their sensitivity to sea level rise, storms and increased human utilization. Previous efforts to protect shorelines have largely involved constructing bulkheads and seawalls which can detrimentally affect nearshore habitats. Recently, efforts have shifted towards âliving shorelineâ approaches that include biogenic breakwater reefs. Our study experimentally tested the efficacy of breakwater reefs constructed of oyster shell for protecting eroding coastal shorelines and their effect on nearshore fish and shellfish communities. Along two different stretches of eroding shoreline, we created replicated pairs of subtidal breakwater reefs and established unaltered reference areas as controls. At both sites we measured shoreline and bathymetric change and quantified oyster recruitment, fish and mobile macro-invertebrate abundances. Breakwater reef treatments mitigated shoreline retreat by more than 40% at one site, but overall vegetation retreat and erosion rates were high across all treatments and at both sites. Oyster settlement and subsequent survival were observed at both sites, with mean adult densities reaching more than eighty oysters mâ2 at one site. We found the corridor between intertidal marsh and oyster reef breakwaters supported higher abundances and different communities of fishes than control plots without oyster reef habitat. Among the fishes and mobile invertebrates that appeared to be strongly enhanced were several economically-important species. Blue crabs (Callinectes sapidus) were the most clearly enhanced (+297%) by the presence of breakwater reefs, while red drum (Sciaenops ocellatus) (+108%), spotted seatrout (Cynoscion nebulosus) (+88%) and flounder (Paralichthys sp.) (+79%) also benefited. Although the vertical relief of the breakwater reefs was reduced over the course of our study and this compromised the shoreline protection capacity, the observed habitat value demonstrates ecological justification for future, more robust shoreline protection projects
- âŠ