25 research outputs found

    Stress gradients structure spatial variability in coastal tidal marsh plant composition and diversity in a major Pacific coast estuary

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    Understanding the drivers of variability in plant diversity from local to landscape spatial scales is a challenge in ecological systems. Environmental gradients exist at several spatial scales and can be nested hierarchically, influencing patterns of plant diversity in complex ways. As plant community dynamics influence ecosystem function, understanding the drivers of plant community variability across space is paramount for predicting potential shifts in ecosystem function from global change. Determining the scales at which stress gradients influence vegetation composition is crucial to inform management and restoration of tidal marshes for specific functions. Here, we analyzed vegetation community composition in 51 tidal marshes from the San Francisco Bay Estuary, California, USA. We used model-based compositional analysis and rank abundance curves to quantify environmental (elevation/tidal frame position, distance to channel, and channel salinity) and species trait (species form, wetland indicator status, and native status) influences on plant community variability at the marsh site and estuary scales. While environmental impacts on plant diversity varied by species and their relationships to each other, overall impacts increased in strength from marsh to estuary scales. Relative species abundance was important in structuring these tidal marsh communities even with the limited species pools dominated by a few species. Rank abundance curves revealed different community structures by region with higher species evenness at plots higher in the tidal frame and adjacent to freshwater channels. By identifying interactions (species–species, species–environment, and environment–trait) at multiple scales (local, landscape), we begin to understand how variability measurements could be interpreted for conservation and land management decisions

    Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management

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    Atrioventricular block is classified as congeni- tal if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental pas- sage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive car- diac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe perma- nent cardiac pacing in almost all patients, including those with structural heart abnormalities

    The Coastal Carbon Library and Atlas: open source soil data and tools supporting blue carbon research and policy

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    Quantifying carbon fluxes into and out of coastal soils is critical to meeting greenhouse gas reduction and coastal resiliency goals. Numerous ‘blue carbon’ studies have generated, or benefitted from, synthetic datasets. However, the community those efforts inspired does not have a centralized, standardized database of disaggregated data used to estimate carbon stocks and fluxes. In this paper, we describe a data structure designed to standardize data reporting, maximize reuse, and maintain a chain of credit from synthesis to original source. We introduce version 1.0.0. of the Coastal Carbon Library, a global database of 6723 soil profiles representing blue carbon‐storing systems including marshes, mangroves, tidal freshwater forests, and seagrasses. We also present the Coastal Carbon Atlas, an R‐shiny application that can be used to visualize, query, and download portions of the Coastal Carbon Library. The majority (4815) of entries in the database can be used for carbon stock assessments without the need for interpolating missing soil variables, 533 are available for estimating carbon burial rate, and 326 are useful for fitting dynamic soil formation models. Organic matter density significantly varied by habitat with tidal freshwater forests having the highest density, and seagrasses having the lowest. Future work could involve expansion of the synthesis to include more deep stock assessments, increasing the representation of data outside of the U.S., and increasing the amount of data available for mangroves and seagrasses, especially carbon burial rate data. We present proposed best practices for blue carbon data including an emphasis on disaggregation, data publication, dataset documentation, and use of standardized vocabulary and templates whenever appropriate. To conclude, the Coastal Carbon Library and Atlas serve as a general example of a grassroots F.A.I.R. (Findable, Accessible, Interoperable, and Reusable) data effort demonstrating how data producers can coordinate to develop tools relevant to policy and decision‐making.Department of Energy, Grant/AwardNumber: COMPASS-FME; Division of Environmental Biology, Grant/AwardNumber: DEB-1655622; National Oceanicand Atmospheric Administration, Grant/Award Number: NA22OAR4310148; National Science Foundation, Grant/Award Number: DGE-1842473; Pew Charitable TrustsGlobal Change Biolog

    Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

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    M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe

    Common benthic algae and cyanobacteria in southern California tidal wetlands

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    Benthic algae and photosynthetic bacteria are important components of coastal wetlands, contributing to primary productivity, nutrient cycling, and other ecosystem functions. Despite their key roles in mudflat and salt marsh food webs, the extent and patterns of diversity of these organisms is poorly known. Sediments from intertidal marshes in San Diego County, California host a variety of cyanobacteria, diatoms, and multi-cellular algae. This flora describes approximately 40 taxa of common and notable cyanobacteria, microalgae and macroalgae observed in wetland sediments, principally from a small tidal marsh in Mission Bay. Cyanobacteria included coccoid and heterocyte and non-heterocyte bearing filamentous genera. A phylogenetically-diverse assemblage of pennate and centric diatoms, euglenoids, green algae, red algae, tribophytes and brown seaweeds was also observed. Most taxa are illustrated with photographs

    Functional Diversity and Composition of Microalgae and Photosynthetic Bacteria in Marine Wetlands: Spatial Variation, Succession, and Influence on Productivity

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    Phylogenetically diverse benthic producers (e.g., diatoms, green algae, cyanobacteria, and anoxygenic photobacteria) inhabit the sediments of coastal wetlands and mediate numerous ecosystem functions, including a substantial fraction of total ecosystem productivity. Despite their ubiquity and functional importance, spatia-temporal patterns in the distribution of major taxonomic groups and diversity­ related effects on function are poorly understood. Using a photopigment-based approach I investigated the composition of microproducer communities at two coastal sites in southern California and addressed (1) the temporal development of assemblages in a restored wetland, (2) the spatial distribution of major functional groups across various habitats, and (3) the influence of functional group diversity and dominance on primary productivity.Within a large restoration site at Tijuana Estuary, pigment concentrations suggested rapid recovery of assemblage biomass (< 1yr) and at least partial recovery of taxonomic composition by 0.2 yr in restored mudflats. In Spartina-dominated salt marsh, however, composition and diversity took longer to mirror natural marsh communities (-1.5-2.2 yr). In Mission Bay, study of an older restoration site (6.3 yr) also suggested differences in rates of habitat development, with Spartina marsh and creek-banks probably preceding mixed species marsh. In a spatial analysis of communities, I found that natural sediments from vegetated marshes in Mission Bay were enriched in cyanobacteria and anoxygenic photobacteria, and had higher diversity, relative to unvegetated sediments, but no mudflat versus marsh difference was evident at Tijuana Estuary. In several independent studies of diversity and productivity, including a manipulation of functional richness in lab cultures, I found no effect of variation in functional diversity on rates of oxygenic photosynthesis and only minor increases in microproducer standing stocks in more diverse assemblages. However, results also tentatively suggest unique community roles for green algae (high oxygenic production rates) and anoxygenic photobacteria (enhancement of community biomass), supporting the notion that composition may be more important than absolute diversity to function.These data re-enforce the idea that study of composition in microproducer assemblages is necessary in addition to simple measures of chlorophyll a. The functional consequences of altered diversity and composition should be further investigated in this cryptic but important flora
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