Global meta-analysis for controlling factors on carbon stable isotope ratios of lotic periphyton.

Carbon stable isotope ratios (δ(13)C) are widely used to trace resource transfer pathways, yet δ(13)C variation in freshwater autotrophs is not yet fully understood. We have analyzed data from 42 published studies, supplemented with some unpublished data, to show the determinants of lotic periphyton δ(13)C. At large spatial scales, we observed broad differences in periphyton δ(13)C among biomes and consistent longitudinal variation related to watershed area. Longitudinal increases in δ(13)C indicate the importance of in-stream processes on lotic carbon cycles and autotroph δ(13)C variation. At local spatial scales, periphyton δ(13)C was negatively related to canopy cover and water current velocity and positively related to chlorophyll a density. Autotroph δ(13)C varied among taxonomic groups. Cyanobacteria and red algae had significantly higher and lower δ(13)C than other taxa, respectively. A hierarchical model across spatial scales showed that local controls for periphyton δ(13)C were nested by regional controls, which suggested that productivity and CO(2) availability determine δ(13)C. Overall, our results reveal general patterns of periphyton δ(13)C and provide improved information for study design and the use of δ(13)C in isotopic mixing models in lotic food web studies

An interferon-inducible neutrophil-driven blood transcriptional signature in human tuberculosis

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis (M. tuberculosis), is a major cause of morbidity and mortality worldwide and efforts to control TB are hampered by difficulties with diagnosis, prevention and treatment 1,2. Most people infected with M. tuberculosis remain asymptomatic, termed latent TB, with a 10% lifetime risk of developing active TB disease, but current tests cannot identify which individuals will develop disease 3. The immune response to M. tuberculosis is complex and incompletely characterized, hindering development of new diagnostics, therapies and vaccines 4,5. We identified a whole blood 393 transcript signature for active TB in intermediate and high burden settings, correlating with radiological extent of disease and reverting to that of healthy controls following treatment. A subset of latent TB patients had signatures similar to those in active TB patients. We also identified a specific 86-transcript signature that discriminated active TB from other inflammatory and infectious diseases. Modular and pathway analysis revealed that the TB signature was dominated by a neutrophil-driven interferon (IFN)-inducible gene profile, consisting of both IFN-γ and Type I IFNαβ signalling. Comparison with transcriptional signatures in purified cells and flow cytometric analysis, suggest that this TB signature reflects both changes in cellular composition and altered gene expression. Although an IFN signature was also observed in whole blood of patients with Systemic Lupus Erythematosus (SLE), their complete modular signature differed from TB with increased abundance of plasma cell transcripts. Our studies demonstrate a hitherto under-appreciated role of Type I IFNαβ signalling in TB pathogenesis, which has implications for vaccine and therapeutic development. Our study also provides a broad range of transcriptional biomarkers with potential as diagnostic and prognostic tools to combat the TB epidemic

Phosphorus Transport in Intensively Managed Watersheds

An edited version of this paper was published by AGU. Copyright 2019 American Geophysical Union.Understanding controls of P movement through watersheds are essential for improved landscape management in intensively managed regions. Here, we analyze observational data from 104 gaged river sites and 176 nongaged river sites within agriculturally dominated watersheds of Minnesota, USA, to understand the role of landscape features, land use practices, climate variability, and biogeochemical processes in total, dissolved and particulate P dynamics at daily to annual scales. Our analyses demonstrate that factors mediating P concentration‐discharge relationships varied greatly across watersheds and included near‐channel sediment sources, lake and wetland interception, assimilation by algal P, and artificial land drainage. The majority of gaged sites exhibited mobilizing behavior for all forms of P at event (i.e., daily) timescales and chemostatic behavior at annual timescales. The large majority of watershed P export (>70%, on average) occurred during high flow conditions, suggesting that more frequent large storm events arising from climate change will drive increased P losses from agricultural watersheds without substantial management changes. We found that P export could be dominated by dissolved P, particulate P, or an even mix of the two forms, depending on watershed attributes. Implementation of management practices to control P losses must be guided by understanding of how local landscapes interact with current and future climate conditions. Managing for both dissolved and particulate P is required to reduce overall P load in many agricultural watersheds

Photodegradation of methylmercury in stream ecosystems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109966/1/lno20135810013.pd

Imbalance of global nutrient cycles exacerbated by the greater retention of phosphorus over nitrogen in lakes

Imbalanced anthropogenic inputs of nitrogen (N) and phosphorus (P) have significantly increased the ratio between N and P globally, degrading ecosystem productivity and environmental quality. Lakes represent a large global nutrient sink, modifying the flow of N and P in the environment. It remains unknown, however, the relative retention of these two nutrients in global lakes and their role in the imbalance of the nutrient cycles. Here we compare the ratio between P and N in inflows and outflows of more than 5,000 lakes globally using a combination of nutrient budget model and generalized linear model. We show that over 80% of global lakes positively retain both N and P, and almost 90% of the lakes show preferential retention of P. The greater retention of P over N leads to a strong elevation in the ratios between N and P in the lake outflow, exacerbating the imbalance of N and P cycles unexpectedly and potentially leading to biodiversity losses within lakes and algal blooms in downstream N-limited coastal zones. The management of N or P in controlling lake eutrophication has long been debated. Our results suggest that eutrophication management that prioritizes the reduction of P in lakes-which causes a further decrease in P in outflows-may unintentionally aggravate N/P imbalances in global ecosystems. Our results also highlight the importance of nutrient retention stoichiometry in global lake management to benefit watershed and regional biogeochemical cycles

Stormwater Pond Maintenance, and Wetland Management for Phosphorus Retention

(c) 1036202Reduction in phosphorus is critical because phosphate, a dissolved form of phosphorus, sustains algal and cyanobacteria growth and causes a wide range of water-quality impairments in the ponds and downstream waters including algal blooms, excess floating plants, taste, and odor problems. Many stormwater ponds and wetlands that treat stormwater appear to be less effective than expected or originally intended in phosphorus retention, a key function of these ponds in urban environments. There is evidence that many old ponds are releasing phosphorus from bottom sediments at high rates and likely exporting phosphorus to downstream surface water bodies. A major outcome of this project is a pond Assessment Tool to assess the risk of high phosphorus concentrations in ponds and sediment release of phosphorus. The tool is based on 20 ponds with detailed water quality and phosphorus release measurements and a meta-analysis of 230 ponds in the Twin Cities metro area. Other outcomes included a working definition of a constructed stormwater pond and a wetland treating stormwater in the framework of water-body regulations, the development of recommendations for stormwater pond maintenance and wetland management, and an update to the sections on the constructed stormwater ponds section of the 2009 Stormwater Maintenance BMP Guide

Climate change exacerbates the environmental impacts of agriculture

We thank the reviewers for their constructive comments and suggestions.Peer reviewe

Climate change exacerbates the environmental impacts of agriculture

This is the author accepted manuscript. The final version is available from the American Association for the Advancement of Science via the DOI in this recordData availability: Data presented in figures are based on previously published studies that are cited in the Review.Agriculture's global environmental impacts are widely expected to continue expanding, driven by population and economic growth and dietary changes. This Review highlights climate change as an additional amplifier of agriculture's environmental impacts, by reducing agricultural productivity, reducing the efficacy of agrochemicals, increasing soil erosion, accelerating the growth and expanding the range of crop diseases and pests, and increasing land clearing. We identify multiple pathways through which climate change intensifies agricultural greenhouse gas emissions, creating a potentially powerful climate change-reinforcing feedback loop. The challenges raised by climate change underscore the urgent need to transition to sustainable, climate-resilient agricultural systems. This requires investments that both accelerate adoption of proven solutions that provide multiple benefits, and that discover and scale new beneficial processes and food products.National Natural Science Foundation of ChinaUS National Science Foundatio

Impacts of Poultry House Environment on Poultry Litter Bacterial Community Composition

Viral and bacterial pathogens are a significant economic concern to the US broiler industry and the ecological epicenter for poultry pathogens is the mixture of bedding material, chicken excrement and feathers that comprises the litter of a poultry house. This study used high-throughput sequencing to assess the richness and diversity of poultry litter bacterial communities, and to look for connections between these communities and the environmental characteristics of a poultry house including its history of gangrenous dermatitis (GD). Cluster analysis of 16S rRNA gene sequences revealed differences in the distribution of bacterial phylotypes between Wet and Dry litter samples and between houses. Wet litter contained greater diversity with 90% of total bacterial abundance occurring within the top 214 OTU clusters. In contrast, only 50 clusters accounted for 90% of Dry litter bacterial abundance. The sixth largest OTU cluster across all samples classified as an Arcobacter sp., an emerging human pathogen, occurring in only the Wet litter samples of a house with a modern evaporative cooling system. Ironically, the primary pathogenic clostridial and staphylococcal species associated with GD were not found in any house; however, there were thirteen 16S rRNA gene phylotypes of mostly Gram-positive phyla that were unique to GD-affected houses and primarily occurred in Wet litter samples. Overall, the poultry house environment appeared to substantially impact the composition of litter bacterial communities and may play a key role in the emergence of food-borne pathogens