Global phosphorus retention by river damming Maavara, Taylor; Parsons, Christopher T.; Ridenour, Christine ...
Proceedings of the National Academy of Sciences - PNAS,
12/2015, Letnik:
112, Številka:
51
Journal Article
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More than 70,000 large dams have been built worldwide. With growing water stress and demand for energy, this number will continue to increase in the foreseeable future. Damming greatly modifies the ...ecological functioning of river systems. In particular, dam reservoirs sequester nutrient elements and, hence, reduce downstream transfer of nutrients to floodplains, lakes, wetlands, and coastal marine environments. Here, we quantify the global impact of dams on the riverine fluxes and speciation of the limiting nutrient phosphorus (P), using a mechanistic modeling approach that accounts for the in-reservoir biogeochemical transformations of P. According to the model calculations, the mass of total P (TP) trapped in reservoirs nearly doubled between 1970 and 2000, reaching 42 Gmol y−1, or 12% of the global river TP load in 2000. Because of the current surge in dam building, we project that by 2030, about 17% of the global river TP load will be sequestered in reservoir sediments. The largest projected increases in TP and reactive P (RP) retention by damming will take place in Asia and South America, especially in the Yangtze, Mekong, and Amazon drainage basins. Despite the large P retention capacity of reservoirs, the export of RP from watersheds will continue to grow unless additional measures are taken to curb anthropogenic P emissions.
While in recent years environmental DNA (eDNA) metabarcoding surveys have shown great promise as an alternative monitoring method, the integration into existing marine monitoring programs may be ...confounded by the dispersal of the eDNA signal. Currents and tidal influences could transport eDNA over great distances, inducing false‐positive species detection, leading to inaccurate biodiversity assessments and, ultimately, mismanagement of marine environments. In this study, we determined the ability of eDNA metabarcoding surveys to distinguish localized signals obtained from four marine habitats within a small spatial scale (<5 km) subject to significant tidal and along‐shore water flow. Our eDNA metabarcoding survey detected 86 genera, within 77 families and across 11 phyla using three established metabarcoding assays targeting fish (16S rRNA gene), crustacean (16S rRNA gene) and eukaryotic (cytochrome oxidase subunit 1) diversity. Ordination and cluster analyses for both taxonomic and OTU data sets show distinct eDNA signals between the sampled habitats, suggesting dispersal of eDNA among habitats was limited. Individual taxa with strong habitat preferences displayed localized eDNA signals in accordance with their respective habitat, whereas taxa known to be less habitat‐specific generated more ubiquitous signals. Our data add to evidence that eDNA metabarcoding surveys in marine environments detect a broad range of taxa that are spatially discrete. Our work also highlights that refinement of assay choice is essential to realize the full potential of eDNA metabarcoding surveys in marine biodiversity monitoring programs.
Despite its recognised importance for species’ persistence, integrating genetics into conservation management has proved problematic, creating a “conservation genetics gap”, which could widen with ...the advent of advanced genomic techniques. Bridging this gap requires a clear understanding of the barriers to use of genetics by conservation practitioners, but few (if any) papers on this topic involve direct consultation with practitioners themselves. We surveyed 148 conservation practitioners in New Zealand’s Department of Conservation regarding their attitude to, knowledge of, and experiences with genetics for conservation. Although practitioners were largely receptive to using genetics for conservation management, access to expertise and funding remains a barrier to use. Practitioners would like to collaborate with geneticists at universities or other institutes, but do not necessarily know who to talk to or fully understand how genetics might benefit them. We contend these barriers or similar likely exist at an international level, suggest ways they might be overcome, and emphasise the need for clearer communication between geneticists and practitioners.
Inbreeding depression (reduced fitness of individuals with related parents) has long been a major focus of ecology, evolution, and conservation biology. Despite decades of research, we still have a ...limited understanding of the strength, underlying genetic mechanisms, and demographic consequences of inbreeding depression in the wild. Studying inbreeding depression in natural populations has been hampered by the inability to precisely measure individual inbreeding. Fortunately, the rapidly increasing availability of high‐throughput sequencing data means it is now feasible to measure the inbreeding of any individual with high precision. Here, we review how genomic data are advancing our understanding of inbreeding depression in the wild. Recent results show that individual inbreeding and inbreeding depression can be measured more precisely with genomic data than via traditional pedigree analysis. Additionally, the availability of genomic data has made it possible to pinpoint loci with large effects contributing to inbreeding depression in wild populations, although this will continue to be a challenging task in many study systems due to low statistical power. Now that reliably measuring individual inbreeding is no longer a limitation, a major focus of future studies should be to more accurately quantify effects of inbreeding depression on population growth and viability.
Genetic marker‐based estimators remain a popular tool for measuring relatedness (rxy) and inbreeding (F) coefficients at both the population and individual level. The performance of these estimators ...fluctuates with the number and variability of markers available, and the relatedness composition and demographic history of a population. Several methods are available to evaluate the reliability of the estimates of rxy and F, some of which are implemented in the program COANCESTRY. I used the simulation module in COANCESTRY since assess the performance of marker‐based estimators of rxy and F in a species with very low genetic diversity, New Zealand's little spotted kiwi (Apteryx owenii). I also conducted a review of published papers that have used COANCESTRY as its release to assess whether and how the reliability of the estimates of rxy and F produced by genetic markers are being measured and reported in published studies. My simulation results show that even when the correlation between true (simulated) and estimated rxy or F is relatively high (Pearson's r = 0.66–0.72 and 0.81–0.85, respectively) the imprecision of the estimates renders them highly unreliable on an individual basis. The literature review demonstrates that the majority of studies do not report the reliability of marker‐based estimates of rxy and F. There is currently no standard practice for selecting the best estimator for a given data set or reporting an estimator's performance. This could lead to experimental results being interpreted out of context and render the robustness of conclusions based on measures of rxy and F debatable.
The performance of genetic marker‐based estimators of relatedness and inbreeding is known to be highly variable and repeated calls have been made for researchers using these tools to assess their likely performance for the marker set in question before implementing them; software such as COANCESTRY facilitates this a priori assessment. Using empirical allele frequencies from a species of conservation concern with low genetic variation, I demonstrate the pitfalls of relying on marker‐based relatedness and inbreeding estimates. I also review the scientific literature and demonstrate that, though marker‐based estimators of relatedness and inbreeding are widely used, the majority of studies fail to assess or report the likely reliability of their estimates, leaving their conclusions open to question. I suggest that a standardised format for evaluating the reliability of marker‐based relatedness and inbreeding estimates is required and discuss the form this could take.
The aim of this review is to describe the challenges and barriers to conducting research in long-term care facilities.
A literature search was conducted in Ovid MEDLINE, Embase, Cochrane Central, ...PsycINFO and CINAHL. Keywords used included "long term care", "nursing home", "research", "trial", "challenge" and "barrier", etc. Resulting references were screened in order to identify relevant studies that reported on challenges derived from first-hand experience of empirical research studies. Challenges were summarized and synthesized.
Of 1723 references, 39 articles were selected for inclusion. To facilitate understanding we proposed a classification framework of 8 main themes to categorize the research challenges presented in the 39 studies, relating to the characteristics of facility/owner/administrator, resident, staff caregiver, family caregiver, investigator, ethical or legal concerns, methodology, and budgetary considerations.
Conducting research in long-term care facilities is full of challenges which can be categorized into 8 main themes. Investigators should be aware of all these challenges and specifically address them when planning their studies. Stakeholders should be involved from an early stage and flexibility should be built into both the methodology and research budget.
Pregnant women with type 1 diabetes are a high-risk population who are recommended to strive for optimal glucose control, but neonatal outcomes attributed to maternal hyperglycaemia remain ...suboptimal. Our aim was to examine the effectiveness of continuous glucose monitoring (CGM) on maternal glucose control and obstetric and neonatal health outcomes.
In this multicentre, open-label, randomised controlled trial, we recruited women aged 18–40 years with type 1 diabetes for a minimum of 12 months who were receiving intensive insulin therapy. Participants were pregnant (≤13 weeks and 6 days' gestation) or planning pregnancy from 31 hospitals in Canada, England, Scotland, Spain, Italy, Ireland, and the USA. We ran two trials in parallel for pregnant participants and for participants planning pregnancy. In both trials, participants were randomly assigned to either CGM in addition to capillary glucose monitoring or capillary glucose monitoring alone. Randomisation was stratified by insulin delivery (pump or injections) and baseline glycated haemoglobin (HbA1c). The primary outcome was change in HbA1c from randomisation to 34 weeks' gestation in pregnant women and to 24 weeks or conception in women planning pregnancy, and was assessed in all randomised participants with baseline assessments. Secondary outcomes included obstetric and neonatal health outcomes, assessed with all available data without imputation. This trial is registered with ClinicalTrials.gov, number NCT01788527.
Between March 25, 2013, and March 22, 2016, we randomly assigned 325 women (215 pregnant, 110 planning pregnancy) to capillary glucose monitoring with CGM (108 pregnant and 53 planning pregnancy) or without (107 pregnant and 57 planning pregnancy). We found a small difference in HbA1c in pregnant women using CGM (mean difference −0·19%; 95% CI −0·34 to −0·03; p=0·0207). Pregnant CGM users spent more time in target (68% vs 61%; p=0·0034) and less time hyperglycaemic (27% vs 32%; p=0·0279) than did pregnant control participants, with comparable severe hypoglycaemia episodes (18 CGM and 21 control) and time spent hypoglycaemic (3% vs 4%; p=0·10). Neonatal health outcomes were significantly improved, with lower incidence of large for gestational age (odds ratio 0·51, 95% CI 0·28 to 0·90; p=0·0210), fewer neonatal intensive care admissions lasting more than 24 h (0·48; 0·26 to 0·86; p=0·0157), fewer incidences of neonatal hypoglycaemia (0·45; 0·22 to 0·89; p=0·0250), and 1-day shorter length of hospital stay (p=0·0091). We found no apparent benefit of CGM in women planning pregnancy. Adverse events occurred in 51 (48%) of CGM participants and 43 (40%) of control participants in the pregnancy trial, and in 12 (27%) of CGM participants and 21 (37%) of control participants in the planning pregnancy trial. Serious adverse events occurred in 13 (6%) participants in the pregnancy trial (eight 7% CGM, five 5% control) and in three (3%) participants in the planning pregnancy trial (two 4% CGM and one 2% control). The most common adverse events were skin reactions occurring in 49 (48%) of 103 CGM participants and eight (8%) of 104 control participants during pregnancy and in 23 (44%) of 52 CGM participants and five (9%) of 57 control participants in the planning pregnancy trial. The most common serious adverse events were gastrointestinal (nausea and vomiting in four participants during pregnancy and three participants planning pregnancy).
Use of CGM during pregnancy in patients with type 1 diabetes is associated with improved neonatal outcomes, which are likely to be attributed to reduced exposure to maternal hyperglycaemia. CGM should be offered to all pregnant women with type 1 diabetes using intensive insulin therapy. This study is the first to indicate potential for improvements in non-glycaemic health outcomes from CGM use.
Juvenile Diabetes Research Foundation, Canadian Clinical Trials Network, and National Institute for Health Research.
Population genetic data underpin many studies of behavioral, ecological, and evolutionary processes in wild populations and contribute to effective conservation management. However, collecting ...genetic samples can be challenging when working with endangered, invasive, or cryptic species. Environmental DNA (eDNA) offers a way to sample genetic material non-invasively without requiring visual observation. While eDNA has been trialed extensively as a biodiversity and biosecurity monitoring tool with a strong taxonomic focus, it has yet to be fully explored as a means for obtaining population genetic information. Here, we review current research that employs eDNA approaches for the study of populations. We outline challenges facing eDNA-based population genetic methodologies, and suggest avenues of research for future developments. We advocate that with further optimizations, this emergent field holds great potential as part of the population genetics toolkit.
Bladder cancer incurs a higher lifetime treatment cost than other cancers due to frequent recurrence of non-invasive disease. Improved prognostic biomarkers and localized therapy are needed for this ...large patient group. We defined two major genomic subtypes of primary stage Ta tumors. One of these was characterized by loss of 9q including TSC1, increased KI67 labeling index, upregulated glycolysis, DNA repair, mTORC1 signaling, features of the unfolded protein response, and altered cholesterol homeostasis. Comparison with muscle-invasive bladder cancer mutation profiles revealed lower overall mutation rates and more frequent mutations in RHOB and chromatin modifier genes. More mutations in the histone lysine demethylase KDM6A were present in non-invasive tumors from females than males.
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•Two genomic subtypes (GS1 and GS2) of non-invasive bladder cancer (NIBC) defined•GS2 subtype shows upregulated mTORC1 signaling associated with distinct metabolic profile•Mutations in chromatin modifier genes are more frequent in NIBC than in MIBC•KDM6A showed more mutations in non-invasive tumors from females than males
By analyzing 140 primary patient samples, Hurst et al. identify two genomic subtypes of stage Ta non-invasive bladder cancer. The more genomically unstable subtype is distinguished by loss of chromosome 9q sequences, upregulated mTORC1 signaling, and altered metabolic profile. They also find that females have a higher frequency of KDM6A mutations than males.
Describes characteristics of mature semen collected from male tuatara, both during mating and from urine after courting, for analysis of motility and viability. Details the collection methods ...developed. Assesses the success of various storage buffers, both diluents and cryoprotectants, for tuatara semen. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
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