Stream Health Research Articles

Realist Research Design and Evaluation for Integrated Care RIC SIG - Part 1: Establishing a Special Interest Group

Background: Realist philosophy and methodology is increasingly being explicitly used in the field of integrated care to research the extant context, structure and mechanisms at play, and to design and evaluation interventions. Philosophic realism is the view that entities exist independently of our perception or our theories about them. While the realist philosophy underpins much of modern health and social science, it is only recently that this philosophical approach has been popularised within main stream health and social science literature. Realist research methodology is increasingly being described in research areas that are relevant to the study of integrated care, namely, organisational management, information science, social epidemiology, economics, and health services evaluation. Importantly realist approaches are increasingly being used in mixed method research designs and to elucidate the processes at play in experimental and quasi-experimental studies. Realist researchers seek to explain the underlying “cause” or mechanisms that generate observed phenomenon. The realist understanding of how the world is ontology includes the notion of a hidden or “real” domain where mechanisms generate forces that result in the phenomena which we observe. Realists also view the world as consisting of strata or layers of reality which may interact with other layers to produce new mechanism. This approach is proving useful for studying and developing theory about complex health and social care systems, and then designing and evaluating possible interventions. Over the last number of years a number of realist studies have been presented at the International Foundation of Integrated Care conferences including: realist studies of context and mechanisms; realist design of integrated care interventions; realist synthesis of literature; and realist evaluations of integrated-care interventions. The methodologies, and the dialectical debates, are complex, and therefore, deserving of special consideration within the Integrated Care community. This preliminary workshop will support evaluators and researchers to use realist methods in integrated care and other complex evaluations. Because realist evaluation was initially developed using smaller-scale programs, methods need to be modified for large scale programs, while remaining consistent with underlying methodological principles. The workshop will discuss the value of and the dilemmas involved in using realist methods for large and complex programs, and demonstrate strategies to address the dilemmas. Aims and Objectives: 1- Present and discuss the basic tenants of realist research, design and evaluation as it applies to the large scale and complex programs such as integrated care 2- Discuss the scope and purpose of a Realist Research, Design and Evaluation for Integrated Care Special Interest Group RIC-SIG 3- Modify the scope and purpose of a Realist Research, Design and Evaluation for Integrated Care - SIG Format: Group Discussion Target Audience: Integrated care practitioners and researchers who are familiar with realist research including the current focus on critical realism and realist evaluation Learning and Takeaway: The workshop will define the scope and purpose of a SIG for Realist Research, Design and Evaluation for Integrated Care

Response of Riparian Vegetation, Instream Habitat, and Aquatic Biota to Riparian Grazing Exclosures

AbstractImproper riparian grazing can alter riparian vegetation and reduce streambank stability, negatively impacting aquatic habitat and biota. We evaluated differences in riparian and instream habitat, benthic macroinvertebrates, and fish inside versus outside seven riparian exclosures constructed from 1982 to 2005 in Idaho. The normalized difference vegetation index from Landsat imagery (1985 to 2015) showed significant increases in riparian vegetation productivity after some but not all exclosures were constructed. Field data collected in 2015 showed woody riparian vegetation to be more abundant, streambanks less altered, and stream channels narrower inside versus outside exclosures, as we expected. However, instream habitat, a benthic macroinvertebrate index, fish species richness, and adult salmonid density showed no response. Higher age‐0 salmonid densities were the only aquatic organism response observed. Broader watershed‐scale factors likely limited strong and consistent responses by aquatic biota to exclosures. We conclude that riparian exclosures have localized effects on stream systems, such as increased riparian vegetation, reduced streambank alteration, and improved channel stability, but may not always influence aquatic biota that commonly reflect larger watershed‐scale processes and conditions. Therefore, well‐maintained riparian exclosures should be used to eliminate livestock use in localized areas of stream corridors that are sensitive to disturbance. To improve stream health at the larger watershed scale that is relevant to most aquatic biota, exclosures should only be one of several grazing management tools implemented simultaneously to reduce the impacts of improper livestock grazing.

Extracts from benthic anatoxin-producing Phormidium are toxic to 3 macroinvertebrate taxa at environmentally relevant concentrations.

Toxin-producing cyanobacteria are increasing in rivers and streams globally, leading to growing concerns over their potential impacts on aquatic ecosystems. The present study was designed to culture field-collected Phormidium in the laboratory, identify individual species, conduct chemical analyses to identify cyanotoxins, and conduct toxicity tests to investigate the potential for this genera to impact stream health. Freshwater toxicity tests were conducted with standard US Environmental Protection Agency invertebrate test protocols with culture water used to grow 3 Phormidium strains isolated from the Russian River (CA, USA). Enzyme linked immunosorbent assays were used to measure total anatoxin concentrations. Culture waters from the 3 Phormidium strains were highly toxic to Ceriodaphnia dubia, Hyalella azteca, and Chironomus dilutus. The C. dubia 7-d survival median lethal concentrations were 0.71, 0.49, and 0.56 μg/L anatoxin for Phormidum strains 1, 2, and 3, respectively. The 7-d reproduction inhibitory concentrations, 25% were 0.55, 0.32, and 0.30 μg/L anatoxin for strains 1, 2, and 3, respectively. Chironomus dilutus survival was reduced at concentrations <2 μg/L anatoxin by all 3 strains, and the H. azteca 96-h lethal concentrations, 25% were 2.82, 1.26, and 5.30 μg/L for strains 1, 2, and 3, respectively. Additional liquid chromatography-mass spectrometry analyses demonstrated that the likely anatoxin variant in these cultures was dihydro-anatoxin-a. The results suggest that anatoxins produced by Phormidium have the potential to impact stream macroinvertebrates. Environ Toxicol Chem 2018;37:2851-2859. © 2018 SETAC.

Green Infrastructure Retrofits with Impervious Area Reduction by Property Type: Potential Improvements to Urban Stream Quality

AbstractBuilding on concepts that relate stream health to extent of watershed impervious area and the capability of green infrastructure (GI) measures that remove runoff volume to reduce effective ...

A review of macroinvertebrate‐ and fish‐based stream health modelling techniques

AbstractDuring the last three decades, explaining cause–effect relationships between natural and anthropogenic disturbances with measures of stream health have motivated the growing application of statistical, machine learning, and soft computing methods. The aim of this review is to provide insight into the most widely used methods for predicting biological variables based on macroinvertebrate and fish species in riverine ecosystems. Therefore, we describe several methods including multiple linear regression, generalized linear models, generalized additive models, boosted regression trees, random forests, artificial neural networks, fuzzy logic‐based, and Bayesian belief networks along with recent applications of these. Moreover, issues regarding variable selection, model interpretability, ensemble modelling, and model evaluation and overfitting are discussed. Recent advances have suggested the need for integrated modelling systems to enhance the predictive ability and improve interpretability. However, trade‐offs between model complexity and accuracy demand research efforts in uncertainty quantification/propagation in model ensembles. Additionally, models should be perceived as complementary tools that require further validation with field measurements. Therefore, a consensus regarding monitoring and modelling practices for stream health applications is recommended.

Evaluation of the impacts of hydrologic model calibration methods on predictability of ecologically-relevant hydrologic indices

Due to the significant costs associated with stream health monitoring, hydrological modeling is widely used to calculate ecologically-relevant hydrologic indices to better understand the overall condition of streams within large and diverse watersheds. However, hydrologic modeling’s ability to replicate these indices is limited, especially when calibrating models by optimizing a single objective function or when selecting a single optimal solution. Hence, this study evaluates the performance of multi-objective model calibration in representing 167 hydrologic indices of ecological interest using the median values of different Pareto-optimal solution sets. For this purpose, two strategies based on three Nash-Sutcliffe Efficiencies (NSE), and root-mean-squared error (RMSE) with explicit hydrograph partitioning, were implemented. Additionally, the k-means clustering technique was employed to define subsets of Pareto-optimal solutions representing high, medium, and low flow conditions. The Soil and Water Assessment Tool (SWAT) was set up for the Honeyoey Creek-Pine Creek Watershed, located in Michigan, USA, and was calibrated using a single streamflow gauging station and the recently proposed multi-objective optimization algorithm – Non-dominated Sorting Genetic Algorithm III (NSGA-III). The results show that the NSE- and RMSE-based calibration strategies can represent 128 and 123 indices within a range of ±30% relative errors, respectively. In addition, the results of this study demonstrated that using different set of solutions, instead of a single optimal solution, introduces more flexibility in the predictability of different hydrologic indices of ecological interest. Moreover, it is suggested that a multi-objective calibration approach allows the systematic identification of groups of poorly represented and closely related indices. Knowing these poorly represented indices would facilitate the formulation of additional objective functions intended to improve model performance or to detect structural inadequacies.

Impacts of tropical forest cover on water quality in agricultural watersheds in southeastern Brazil

Tropical forests are under continued threat due to deforestation and fragmentation, mainly because of clear-cutting for agriculture and cattle ranching, and it can lead to water quality degradation. However, there is a need for understanding the role of forest areas as an indicator of water quality in the current diverse landscape in tropical watersheds. Thus, this study aims at evaluating forest cover as an indicator of stream health in tropical agricultural watersheds. We selected six watersheds of low-order streams in Southeastern Brazil with different percentages of forest cover, where water samples were collected to obtain the following water quality parameters: dissolved oxygen (DO), turbidity (NTU), total suspended solids (TSS), inorganic suspended solids (ISS), organic suspended solids (OSS), total nitrogen (TN), total phosphorus (TP), total coliforms (TC), and fecal coliforms (FC). A land use/land cover (LULC) map was used to extract the LULC pattern of each watershed, and a distance metric was applied to explore the differences between them. The water quality parameters were analyzed by the yearly mean, data variation and the correlation between them. We compared forested (55% of forest cover or more) and degraded (35% or less) watersheds using MANOVA and PCA. Degraded watersheds showed high values of solids, turbidity, nutrients, and coliforms. The most forested watershed showed the best water quality, whereas the watershed mainly covered by agriculture presented the poorest water quality and the greatest temporal variation. The forested watersheds showed significant difference with degraded watersheds, which presented higher value of all the parameters, excepted of DO. NTU, solids, and TP were correlated, showing that turbidity and solids represent the particles in the water, and they carry adsorbed phosphorus. Those parameters also responded to the streamflow variation. The results indicated that the pollution came from the agricultural and residential areas, whereas the tropical forest was important to keep water clean. Thus, tropical forest cover is a good indicator of water quality, and plays an important role in minimizing the impacts of human activities on ecosystem services in agricultural watersheds. Nevertheless, better soil management practices and basic sanitation implementation are still needed to improve water quality.

Volunteer monitoring as a focus for community engagement in water management in Aotearoa-New Zealand: review and prospects

Abstract This article overviews community-based water monitoring (CBWM) in Aotearoa-New Zealand (NZ). CBWM was strongly boosted in NZ around 2000 by the development of the Stream Health Monitoring and Assessment Kit (SHMAK) and the Wai Care community initiative. Reform of freshwater management in NZ may be one driver for renewed interest recently in CBWM. Because professionals perceive volunteer-monitoring data as unreliable, they currently give little support to volunteer monitoring. To address their concern, we compared CBWM with measurements by regional authorities (RAs) – the main water management agencies in NZ. Agreement was encouragingly close for a comprehensive range of variables, including the important state-of-environment (SoE) indicators: visual clarity, Escherichia coli and macroinvertebrates. Community volunteers need and want ongoing professional support and encouragement, and, fortunately, there are important benefits for water management agencies, including engagement of citizens in water management and use of volunteer data. Professional support for CBWM in NZ could include: advice and encouragement, training, database development and quality assurance. Current research and development is focused on improving resources and systems for volunteer monitoring, notably with upgrading of the SHMAK. We are enlisting volunteers, equipped with improved tools and support systems, to assess the benefits of riparian rehabilitation and the suitability of water for swimming.

Is there a limit to bioretention effectiveness? Evaluation of stormwater bioretention treatment using a lumped urban ecohydrologic model and ecologically based design criteria

AbstractIn this study, we developed the urban ecohydrology model (UEM) to investigate the role of bioretention on watershed water balance, runoff production, and streamflow variability. UEM partitions the land surface into pervious, impervious, and bioretention cell fractions. Soil moisture and vegetation dynamics are simulated in pervious areas and bioretention cells using a lumped ecohydrological approach. Bioretention cells receive runoff from a fraction of impervious areas. The model is calibrated in an urban headwater catchment near Seattle, WA, USA, using hourly weather data and streamflow observations for 3 years. The calibrated model is first used to investigate the relationship between streamflow variability and bioretention cell size that receives runoff from different values of impervious area in the watershed. Streamflow variability is quantified by 2 indices, high pulse count (HPC), which quantifies the number of flow high pulses in a water year above a threshold, and high pulse range (HPR), which defines the time over which the pulses occurred. Low values of these indices are associated with improved stream health. The effectiveness of the modelled bioretention facilities are measured by their influence on reducing HPC and HPR and on flow duration curves in comparison with modelled fully forested conditions. We used UEM to examine the effectiveness of bioretention cells under rainfall regimes that are wetter and drier than the study area in an effort to understand linkages between the degree of urbanization, climate, and design bioretention cell size to improve inferred stream health conditions. In all model simulations, limits to the reduction of HPC and HPR indicators were reached as the size of bioretention cells grew. Bioretention was more effective as the rainfall regime gets drier. Results may guide bioretention design practices and future studies to explore climate change impacts on bioretention design and management.

Assessing the relative importance of parameter estimation in stream health based environmental justice modeling

Performance of environmental justice models depends on the level of accuracy in measuring or estimating the health of the environment. In the past decades, and especially in the area of stream health modeling, significant improvement has been observed. However, the impacts of these improvements on the robustness of environmental justice models have not been evaluated. Therefore in this study, the relative importance of parameter estimation in stream health based environmental justice modeling was evaluated. The Saginaw River Basin in Michigan was considered as the study area, and four major ecological indices evaluating the response of fish and macroinvertebrates to instream stressors were used for stream health assessment. Seventeen socioeconomic and physiographic indices were evaluated at three census levels of county, census tract, and block group. Then the ecological, socioeconomic, and physiographic indices were used in the development of stream health based environmental justice models. Results showed that incorporating ecologically relevant indices and a using two-phase modeling approach not only improved the performance of stream health predictive models but also reduced the sensitivity of environmental justice models to aggregation at different census levels. In addition, using improved stream health indices reduced the redundancy of the independent variables (socioeconomic and physiographic indices), where the total number of significant parameters was reduced from 171 to 115. Besides that, more robust and meaningful spatial dependencies were observed among stream health measures and environmental justice parameters at different spatial levels. In summary having a reliable stream health information is the key for development of robust environmental justice models as evidence by improving model predictability and eliminating contradictory results compared to previous studies.

Stream Health Evaluation Using a Combined Approach of Multi-Metric Chemical Pollution and Biological Integrity Models

Bouchung Stream is a large tributary of the Geum River watershed that is simultaneously affected by wastewater treatment plant effluents and agricultural activities in the watershed area. The focal subject was to diagnose the chemical and biological health of the temperate stream by using a combined approach of the multi-metric water pollution index (WPI) and the index of biological integrity (IBIKR), using datasets from 2008–2014. Water chemistry analyses indicated seasonal and inter-annual variations mainly linked to the intensity of monsoon rainfall in the watershed, potentially causing the availability of agricultural runoff water. The main events of phosphorus inflow and nitrogen dilutions occurred during July–August. Temporal and spatial heterogeneities were observed and were largely recognizable due to nutrient enrichment and organic matter intensification. Chlorophyll showed weak linear relation to total phosphorus (R2 = 0.17) but no relation to total nitrogen (p &gt; 0.05). Fish compositions analyzed as trophic/tolerance guilds in relation to water chemistry showed visible decline and modifications. Average WPI site scores ranged from 33–23, indicating an excellent upstream to fair downstream water quality status. Correspondingly, IBIKR scores ranged between 38–28 approximating with WPI site classification, as well as both indices showed higher regression relation (R2 = 0.90). Fish guild analyses revealed tolerant and omnivore species dominating the downstream, while sensitive and insectivores depleting in approximation with changing water chemistry and was confirmed by the principal component analysis. In addition, the fish guilds meticulously responded to phosphorus inflows. In conclusion, overall stream health and water chemistry analyses indicated continuous chemical and biological degradation influencing the trophic and tolerance fish guilds. Moreover, the combined application approach of WPI and IBIKR could help in better understanding the chemical and biological mechanisms in rivers and streams.

Quantifying the connections\u2014linkages between land-use and water in the Kathmandu Valley, Nepal

Land development without thoughtful water supply planning can lead to unsustainability. In practice, management of our lands and waters is often unintegrated. We present new land-use, ecological stream health, water quality, and streamflow data from nine perennial watersheds in the Kathmandu Valley, Nepal, in the 2016 monsoon (i.e., August and September) and 2017 pre-monsoon (i.e., April and May) periods. Our goal was to improve understanding of the longitudinal linkages between land-use and water. At a total of 38 locations, the Rapid Stream Assessment (RSA) protocol was used to characterize stream ecology, basic water quality parameters were collected with a handheld WTW multi-parameter meter, and stream flow was measured with a SonTek FlowTracker Acoustic Doppler Velocimeter. A pixel-based supervised classification method was used to create a 30-m gridded land use coverage from a Landsat 8 image scene captured in the fall of 2015. Our results indicated that land-use had a statistically significant impact on water quality, with built land-uses (high and low) having the greatest influence. Upstream locations of six of the nine watersheds investigated had near natural status (i.e., river quality class (RQC) 1) and water could be used for all purposes (after standard treatments as required). However, downstream RSA measurements for all nine watersheds had RQC 5 (i.e., most highly impaired). Generally, water quality deteriorated from monsoon 2016 to pre-monsoon 2017. Our findings reinforce the importance of integrated land and water management and highlight the urgency of addressing waste management issues in the Kathmandu Valley.

Common Hydraulic Fracturing Fluid Additives Alter the Structure and Function of Anaerobic Microbial Communities.

The development of unconventional oil and gas (UOG) resources results in the production of large volumes of wastewater containing a complex mixture of hydraulic fracturing chemical additives and components from the formation. The release of these wastewaters into the environment poses potential risks that are poorly understood. Microbial communities in stream sediments form the base of the food chain and may serve as sentinels for changes in stream health. Iron-reducing organisms have been shown to play a role in the biodegradation of a wide range of organic compounds, and so to evaluate their response to UOG wastewater, we enriched anaerobic microbial communities from sediments collected upstream (background) and downstream (impacted) of an UOG wastewater injection disposal facility in the presence of hydraulic fracturing fluid (HFF) additives: guar gum, ethylene glycol, and two biocides, 2,2-dibromo-3-nitrilopropionamide (DBNPA) and bronopol (C3H6BrNO4). Iron reduction was significantly inhibited early in the incubations with the addition of biocides, whereas amendment with guar gum and ethylene glycol stimulated iron reduction relative to levels in the unamended controls. Changes in the microbial community structure were observed across all treatments, indicating the potential for even small amounts of UOG wastewater components to influence natural microbial processes. The microbial community structure differed between enrichments with background and impacted sediments, suggesting that impacted sediments may have been preconditioned by exposure to wastewater. These experiments demonstrated the potential for biocides to significantly decrease iron reduction rates immediately following a spill and demonstrated how microbial communities previously exposed to UOG wastewater may be more resilient to additional spills.IMPORTANCE Organic components of UOG wastewater can alter microbial communities and biogeochemical processes, which could alter the rates of essential natural attenuation processes. These findings provide new insights into microbial responses following a release of UOG wastewaters and are critical for identifying strategies for the remediation and natural attenuation of impacted environments.

Habitat requirements of two common aquatic snakes, Regina septemvittata and Nerodia sipedon sipedon

Regina septemvittata (Queen Snakes)and Nerodia sipedon sipedon (Common Watersnake) are semi-aquatic colubrid snakes that utilize streams for their primary source of prey. Both species are currently listed by the International Union for Conservation of Nature as stable. The goal of this study was to determine which specific habitat aspects affect the presence or absence of R. septemvittata and N. sipedon sipedon. Snakes were collected in the summer and fall of 2017 from August to October in North Fork of Short Creek, a 3rd order stream located just south of West Liberty, WV. Using the Ohio QHEI form to quantify stream quality and program PRESENCE to generate Logistic Regression Models, stream sub-habitat types were compared with occurrence data. Resulting models revealed which specific sub-habitat types were associated with positive occurrence. Univariate models selected for riparian zone determined by the width and predominant cover present with an AIC weight of 0.499. Multivariate models selected riparian zone with an AIC of 0.372 and riparian plus total stream health with AIC of 0.185. Our preliminary data indicates that snake presence is related to both riparian zone and water quality. This suggests that sufficient cover quality and stream health are required to maintain populations of Regina septemvittata and Nerodia sipedon sipedon.

Land use impacts on surface water quality by statistical approaches

Surface waters are the most important economic resource for humans which provide water for agricultural, industrial and anthropogenic activities. Surface water quality plays vital role in protecting aquatic ecosystems. Unplanned urbanization, intense agricultural activities and deforestation are positively associated with carbon, nitrogen and phosphorous related water quality parameters. Multiple buffers give robust land use land cover and water quality model and highlight the impacts of land use land cover characteristics on water quality parameters at various scales which will guide watershed managers for particular application of best management practices to enhance stream health. Traditionally, water quality data collections are based on discrete sampling and were analyzed through statistical techniques which were designed for spatially isolated measurements. Traditional multivariate statistical approaches uncover hidden information in water quality data but they are unable to expose spatial relationship. The complexity of information in water quality data needs new statistical approaches which uncover spatiotemporal variability. This review briefly discusses influences of land use land cover characteristics on surface water quality, effects of spatial scale on land use land cover- water quality relationship, and water quality modeling using various statistical approaches. Every statistical method has unique purpose, application and solves different problems. This review article pinpoints that how statistical approaches in combination with spatial scale can be applied to develop statistically significant land use land cover- water quality relationship for better water quality evaluation.

Estimation of Stream Health Using Flow-Based Indices

Existing methods to estimate stream health are often location-specific, and do not address all of the components of stream health. In addition, there are very few guidelines to estimate the health of a stream, although the literature and useful tools such as Indicators of Hydrologic Alteration (IHA) are available. This paper describes an approach developed for estimating stream health. The method involves the: (1) collection of flow data; (2) identification of hydrologic change; (3) estimation of some hydrologic indicators for pre-alteration and post-alteration periods; and (4) the use of those hydrologic indicators with the scoring framework of the Dundee Hydrologic Regime Assessment Method (DHRAM). The approach estimates the stream health in aggregate including all of the components, such as riparian vegetation, aquatic species, and benthic organisms. Using the approach, stream health can be estimated at two different levels: (1) the existence or absence of a stream health problem based on the concept of eco-deficit and eco-surplus using flow duration curves; and (2) the estimation of overall stream health using the IHA–DHRAM method. The procedure is demonstrated with a case example of the White Rock Creek watershed in Texas in the United States (US). The approach has great potential to estimate stream health and prescribe flow-based goals for the restoration of impaired streams.

Stream health, topography, and land use influences on the distribution of the Eurasian otter Lutra lutra in the Nakdong River basin, South Korea

In South Korea, Eurasian otter (Lutra lutra) habitat has increased since the 1990 s because of legal protection, forest development, and increased public awareness. Although otters have been detected throughout the country, a precise investigation of habitat conditions has not previously been undertaken. We hypothesized that higher values of stream health assessment programme (SHAP) indices would indicate better habitat for otters. Otter distribution based on spraint density was investigated along 600 m riverside transects at 250 sites in the Nakdong River basin. We defined four otter population categories (absent, rare, normal, and abundant) and compared the results with presence and absence data. Use of the four population categories provided more details about habitat conditions than presence and absence analysis. The highest spraint densities were found at higher altitudes, and densities declined in areas with high human density and urbanization. The benthic macro-invertebrate community index was highly positively related to the otter population indices. In terms of fish as prey items, the proportion of species tolerant to environmental change were negatively related to otter indices, otherwise number of species sensitive to environmental change positively related. Overall, stream health assessment indices provided the highest correlations with otter population numbers and distribution.

Forest cover correlates with good biological water quality. Insights from a regional study (Wallonia, Belgium)

Forested catchments are generally assumed to provide higher quality water in opposition to agricultural and urban catchments. However, this should be tested in various ecological contexts and through the study of multiple variables describing water quality. Indeed, interactions between ecological variables, multiple land use and land cover (LULC) types, and water quality variables render the relationship between forest cover and water quality highly complex. Furthermore, the question of the scale at which land use within stream catchments most influences stream water quality and ecosystem health remains only partially answered. This paper quantifies, at the regional scale and across five natural ecoregions of Wallonia (Belgium), the forest cover effect on biological water quality indices (based on diatoms and macroinvertebrates) at the riparian and catchment scales. Main results show that forest cover – considered alone – explains around one third of the biological water quality at the regional scale and from 15 to 70% depending on the ecoregion studied. Forest cover is systematically positively correlated with higher biological water quality. When removing spatial, local morphological variations, or population density effect, forest cover still accounts for over 10% of the total biological water quality variation. Partitioning variance shows that physico-chemical water quality is one of the main drivers of biological water quality and that anthropogenic pressures often explain an important part of it (shared or not with forest cover). The proportion of forest cover in each catchment at the regional scale and across all ecoregions but the Loam region is more positively correlated with high water quality than when considering the proportion of forest cover in the riparian zones only. This suggests that catchment-wide impacts and a fortiori catchment-wide protection measures are the main drivers of river ecological water quality. However, distinctive results from the agricultural and highly human impacted Loam region show that riparian forests are positively linked to water quality and should therefore be preserved.

Tools for managing hydrologic alteration on a regional scale: Setting targets to protect stream health

Abstract Widespread hydrologic alteration creates a need for tools to assess ecological impacts to streams that can be applied across large geographic scales. A regional framework for biologically based flow management can help catchment managers prioritise streams for protection, evaluate impacts of disturbance or interventions and provide a starting point for causal assessment in degraded streams. However, lack of flow data limit the ability to assess hydrologic conditions across a region. Hydrologic models can address this problem. Regionally calibrated hydrologic models were used to estimate current and reference flows at 572 bioassessment sites in southern and central coastal California. Flow alteration was characterised as the difference in 39 flow metrics calculated from simulations of present‐day and reference flow time‐series, calculated under up to four precipitation conditions. Biological condition was assessed with the California Stream Condition Index (CSCI) and its components. Logistic regressions were used to predict the likelihood of high scores (i.e. ≥10th percentile of the CSCI reference calibration data). Statistically significant relationships between increasing severity of hydrologic alteration and decreasing biological condition were used to set thresholds that reflected tolerance for risk of a stakeholder advisory group. An index of hydrologic alteration was created by selecting flow metrics based on their importance for predicting biological response variables in boosted regression tree models. Metrics were selected in the order of decreasing importance, and no more than two metrics per metric class were selected (i.e. duration, frequency, magnitude, timing and variability). Seven metrics were selected: HighDur (duration of high‐flow events), HighNum (# of high‐flow events), NoDisturb (duration between high‐ or low‐flow events), MaxMonthQ (maximum monthly discharge), Q99 (99th percentile of daily streamflow), QmaxIDR (interdecile range of annual maxima) and RBI (Richards–Baker Index). Applying the index to data from a probabilistic survey, 34% of stream‐miles in southern California were estimated to be hydrologically altered. One of four management priorities were assigned to each site based on biological condition and hydrologic status: protection (healthy and unaltered, 52% of stream‐miles), monitoring (healthy but altered 4%), evaluation of flow management (unhealthy and altered, 30%) and evaluation of other management (unhealthy but unaltered, 14%). Regionally derived biologically based targets for flow alteration allow catchment managers to prioritise activities and conduct screenings for causal assessments across large spatial scales. Furthermore, regional tools pave the way for incorporation of hydrologic management in policies and catchment planning designed to support biological integrity in streams. Development of regional tools should be a priority where hydrologic alteration is pervasive or expected to increase in response to climate change or urbanisation.

Juvenile coho salmon growth and health in streams across an urbanization gradient

Expanding human population and urbanization alters freshwater systems through structural changes to habitat, temperature effects from increased runoff and reduced canopy cover, altered flows, and increased toxicants. Current stream assessments stop short of measuring health or condition of species utilizing these freshwater habitats and fail to link specific stressors mechanistically to the health of organisms in the stream. Juvenile fish growth integrates both external and internal conditions providing a useful indicator of habitat quality and ecosystem health. Thus, there is a need to account for ecological and environmental influences on fish growth accurately. Bioenergetics models can simulate changes in growth and consumption in response to environmental conditions and food availability to account for interactions between an organism's environmental experience and utilization of available resources. The bioenergetics approach accounts for how thermal regime, food supply, and food quality affect fish growth. This study used a bioenergetics modeling approach to evaluate the environmental factors influencing juvenile coho salmon growth among ten Pacific Northwest streams spanning an urban gradient. Urban streams tended to be warmer, have earlier emergence dates and stronger early season growth. However, fish in urban streams experienced increased stress through lower growth efficiencies, especially later in the summer as temperatures warmed, with as much as a 16.6% reduction when compared to fish from other streams. Bioenergetics modeling successfully characterized salmonid growth in small perennial streams as part of a more extensive monitoring program and provides a powerful assessment tool for characterizing mixed life-stage specific responses in urban streams.