Can air temperature be used to project influences of climate change on stream temperature?

Worldwide, lack of data on stream temperature has motivated the use of regression-based statistical models to predict stream temperatures based on more widely available data on air temperatures. Such models have been widely applied to project responses of stream temperatures under climate change, but the performance of these models has not been fully evaluated. To address this knowledge gap, we examined the performance of two widely used linear and nonlinear regression models that predict stream temperatures based on air temperatures. We evaluated model performance and temporal stability of model parameters in a suite of regulated and unregulated streams with 11–44 years of stream temperature data. Although such models may have validity when predicting stream temperatures within the span of time that corresponds to the data used to develop them, model predictions did not transfer well to other time periods. Validation of model predictions of most recent stream temperatures, based on air temperature–stream temperature relationships from previous time periods often showed poor performance when compared with observed stream temperatures. Overall, model predictions were less robust in regulated streams and they frequently failed in detecting the coldest and warmest temperatures within all sites. In many cases, the magnitude of errors in these predictions falls within a range that equals or exceeds the magnitude of future projections of climate-related changes in stream temperatures reported for the region we studied (between 0.5 and 3.0°C by 2080). The limited ability of regression-based statistical models to accurately project stream temperatures over time likely stems from the fact that underlying processes at play, namely the heat budgets of air and water, are distinctive in each medium and vary among localities and through time.Keywords: Temperature biases, Mohseni model, Salmon, Stream temperature, Air temperature, Climate change, Climate projectio

A Stable Isotope Tracer Study of the Influences of Adjacent Land Use and Riparian Condition on Fates of Nitrate in Streams

The influence of land use on potential fates of nitrate (NO3-) in stream ecosystems, ranging from denitrification to storage in organic matter, has not been documented extensively. Here, we describe the Pacific Northwest component of Lotic Intersite Nitrogen eXperiment, phase II (LINX II) to examine how land-use setting influences fates of NO3- in streams. We used 24 h releases of a stable isotope tracer ((NO3)-N-15-N) in nine streams flowing through forest, agricultural, and urban land uses to quantify NO3- uptake processes. NO3- uptake lengths varied two orders of magnitude (24-4247 m), with uptake rates (6.5-158.1 mg NO3-N m(-2) day(-1)) and uptake velocities (0.1-2.3 mm min(-1)) falling within the ranges measured in other LINX II regions. Denitrification removed 0-7% of added tracer from our streams. In forest streams, 60.4 to 77.0% of the isotope tracer was exported downstream as NO3-, with 8.0 to 14.8% stored in wood biofilms, epilithon, fine benthic organic matter, and bryophytes. Agricultural and urban streams with streamside forest buffers displayed hydrologic export and organic matter storage of tracer similar to those measured in forest streams. In agricultural and urban streams with a partial or no riparian buffer, less than 1 to 75% of the tracer was exported downstream; much of the remainder was taken up and stored in autotrophic organic matter components with short N turnover times. Our findings suggest restoration and maintenance of riparian forests can help re-establish the natural range of NO3- uptake processes in human-altered streams.Keywords: Oregon, Organic matter storage, Streams, Spiraling, Land use, N-15, Isotope tracer, Denitrification, Nitroge

Factors affecting ammonium uptake in streams - an inter-biome perspective

The Lotic Intersite Nitrogen experiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of \u275~-ammonium and downstream measurements of 15N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake. 4. Nitrogen uptake varied little among sites, reflecting metabolic compensation in streams in a variety of distinctly different biomes (autotrophic production is high where allochthonous inputs are relatively low and vice versa). 5. Both autotrophic and heterotrophic metabolism require nitrogen and these biotic processes dominate inorganic nitrogen retention in streams. Factors that affect the relative balance of autotrophic and heterotrophic metabolism indirectly control inorganic nitrogen uptake

The paradox of cooling streams in a warming world:Regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States

Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream temperature. Here, we examined the evidence for this using long-term stream temperature data from minimally and highly human-impacted sites located across the Pacific continental United States. Based on hypothesized climate impacts, we predicted that we should find warming trends in the maximum, mean and minimum temperatures, as well as increasing variability over time. These predictions were not fully realized. Warming trends were most prevalent in a small subset of locations with longer time series beginning in the 1950s. More recent series of observations (1987-2009) exhibited fewer warming trends and more cooling trends in both minimally and highly human-influenced systems. Trends in variability were much less evident, regardless of the length of time series. Based on these findings, we conclude that our perspective of climate impacts on stream temperatures is clouded considerably by a lack of long-term data on minimally impacted streams, and biased spatio-temporal representation of existing time series. Overall our results highlight the need to develop more mechanistic, process-based understanding of linkages between climate change, other human impacts and stream temperature, and to deploy sensor networks that will provide better information on trends in stream temperatures in the future. Citation: Arismendi, I., S. L. Johnson, J. B. Dunham, R. Haggerty, and D. Hockman-Wert (2012), The paradox of cooling streams in a warming world: Regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States, Geophys. Res. Lett., 39, L10401, doi:10.1029/2012GL051448.Keywords: River temperature, Wildfire tests, Western, Snowpac

Does the Social Capital in Networks of ‘‘Fish and Fire’’ Scientists and Managers Suggest Learning?

Patterns of social interaction influence how knowledge is generated, communicated, and applied. Theories of social capital and organizational learning suggest that interactions within disciplinary or functional groups foster communication of knowledge, whereas interactions across groups foster generation of new knowledge. We used social network analysis to examine patterns of social interaction reported in survey data from scientists and managers who work on fish and fire issues. We found that few fish and fire scientists and managers interact with one another, suggesting low bridging social capital and thus, limited opportunity for generation of new knowledge. We also found that although interaction occurs among scientists—suggesting modest bonding social capital—few managers interact with other managers, indicating limited opportunity for communication of scientific knowledge for the purposes of application. We discuss constraints and opportunities for organizational learning evident in these patterns of social interaction among fish and fire scientists and managers.Keywords: riparian and aquatic issues, natural resource agencies, organizational learning, social network analysis, wildland fire, social capita

Spatial and Temporal Patterns in Atmospheric Deposition of Dissolved Organic Carbon

Atmospheric deposition of dissolved organic carbon (DOC) to terrestrial ecosystems is a small, but rarely studied component of the global carbon (C) cycle. Emissions of volatile organic compounds (VOC) and organic particulates are the sources of atmospheric C and deposition represents a major pathway for the removal of organic C from the atmosphere. Here, we evaluate the spatial and temporal patterns of DOC deposition using 70 data sets at least one year in length ranging from 40° south to 66° north latitude. Globally, the median DOC concentration in bulk deposition was 1.7 mg L−1. The DOC concentrations were significantly higher in tropical (25°) latitudes. DOC deposition was significantly higher in the tropics because of both higher DOC concentrations and precipitation. Using the global median or latitudinal specific DOC concentrations leads to a calculated global deposition of 202 or 295 Tg C yr−1 respectively. Many sites exhibited seasonal variability in DOC concentration. At temperate sites, DOC concentrations were higher during the growing season; at tropical sites, DOC concentrations were higher during the dry season. Thirteen of the thirty-four long-term (>10 years) data sets showed significant declines in DOC concentration over time with the others showing no significant change. Based on the magnitude and timing of the various sources of organic C to the atmosphere, biogenic VOCs likely explain the latitudinal pattern and the seasonal pattern at temperate latitudes while decreases in anthropogenic emissions are the most likely explanation for the declines in DOC concentration.publishedVersio

Spatial and Temporal Patterns in Atmospheric Deposition of Dissolved Organic Carbon

Atmospheric deposition of dissolved organic carbon (DOC) to terrestrial ecosystems is a small, but rarely studied component of the global carbon (C) cycle. Emissions of volatile organic compounds (VOC) and organic particulates are the sources of atmospheric C and deposition represents a major pathway for the removal of organic C from the atmosphere. Here, we evaluate the spatial and temporal patterns of DOC deposition using 70 data sets at least one year in length ranging from 40° south to 66° north latitude. Globally, the median DOC concentration in bulk deposition was 1.7 mg L$^{−1}$. The DOC concentrations were significantly higher in tropical (25°) latitudes. DOC deposition was significantly higher in the tropics because of both higher DOC concentrations and precipitation. Using the global median or latitudinal specific DOC concentrations leads to a calculated global deposition of 202 or 295 Tg C yr$^{−1}$ respectively. Many sites exhibited seasonal variability in DOC concentration. At temperate sites, DOC concentrations were higher during the growing season; at tropical sites, DOC concentrations were higher during the dry season. Thirteen of the thirty-four long-term (>10 years) data sets showed significant declines in DOC concentration over time with the others showing no significant change. Based on the magnitude and timing of the various sources of organic C to the atmosphere, biogenic VOCs likely explain the latitudinal pattern and the seasonal pattern at temperate latitudes while decreases in anthropogenic emissions are the most likely explanation for the declines in DOC concentration

The impact of behavioral and mental health risk assessments on goal setting in primary care

Patient-centered health risk assessments (HRAs) that screen for unhealthy behaviors, prioritize concerns, and provide feedback may improve counseling, goal setting, and health. To evaluate the effectiveness of routinely administering a patient-centered HRA, My Own Health Report, for diet, exercise, smoking, alcohol, drug use, stress, depression, anxiety, and sleep, 18 primary care practices were randomized to ask patients to complete My Own Health Report (MOHR) before an office visit (intervention) or continue usual care (control). Intervention practice patients were more likely than control practice patients to be asked about each of eight risks (range of differences 5.3-15.8 %, p < 0.001), set goals for six risks (range of differences 3.8-16.6 %, p < 0.01), and improve five risks (range of differences 5.4-13.6 %, p < 0.01). Compared to controls, intervention patients felt clinicians cared more for them and showed more interest in their concerns. Patient-centered health risk assessments improve screening and goal setting.Trial RegistrationClinicaltrials.gov identifier: NCT01825746

Clinical Laboratories Collaborate to Resolve Differences in Variant Interpretations Submitted to ClinVar

Purpose Data sharing through ClinVar offers a unique opportunity to identify interpretation differences between laboratories. As part of a ClinGen initiative, four clinical laboratories (Ambry, GeneDx, Partners Healthcare Laboratory for Molecular Medicine, and University of Chicago Genetic Services Laboratory) collaborated to identify the basis of interpretation differences and to investigate if data sharing and reassessment resolves interpretation differences by analyzing a subset of variants. Methods: ClinVar variants with submissions from at least two of the four participating laboratories were compared. For a subset of identified differences, laboratories documented the basis for discordance, shared internal data, independently reassessed with the ACMG-AMP guidelines, and then compared interpretations. Results: 6,169 variants in ClinVar were interpreted by at least two of the participating laboratories, of which 88.3% were initially concordant. Laboratories reassessed 242/724 initially discordant variants, of which 87.2% (211) were resolved by reassessment with current criteria and/or internal data sharing. 12.8% (31) of reassessed variants remain discordant due to differences in application of the ACMG-AMP guidelines. Conclusion: Participating laboratories increased their overall concordance from 88.3% to 91.7%, indicating that sharing variant interpretations in ClinVar, allowing identification of differences and motivation to resolve those differences, is critical to move toward more consistent variant interpretations