Single Catchment Research Articles

Comparing the hydrological performance of blue green infrastructure design strategies in urban/semi-urban catchments for stormwater management

ABSTRACT Blue green infrastructure (BGI), in recent decades, have been increasingly recognized as robust stormwater control measures to reduce urban flooding, promote infiltration, and restore a catchment's flow to its pre-development stage. However, studies comparing the hydrological benefits of BGI alternatives at catchment scale are often limited to single catchment or single/few BGI options scaled over a catchment. This study designed a set of BGI alternatives as a combination of different BGI facilities in terms of the following: (a) spatial distribution scale (end-of-pipe vs. decentralized) and (b) naturalness scale (less engineered vs. more engineered), in three different urban catchments representing an inner city, a residential suburb, and a new urban housing. In addition, their hydrological performances were compared. A 10-year return period design rain and a continuous rain series of 11 years were modelled for each BGI alternative using the computer model (stormwater management model). It was observed that in most catchments, decentralized alternatives (both engineered and natural) showed better potential to reduce the magnitude and frequency of flooding than centralized measures. Similarly, the tested decentralized natural, less engineered alternatives showed higher potential to increase infiltration than the decentralized engineered alternatives in all three catchments. Meanwhile, infiltration-based BGI alternatives showed similar potential to mimic pre-development flow as other decentralized BGI alternatives.

Screening log: Challenges in community patient recruitment for gynecologic oncology clinical trials

BackgroundClinical trial participation can improve overall survival and mitigate healthcare disparities for gynecologic cancer patients in low-volume community centers. This study aimed to assess the effectiveness of a centrally regulated but administratively decentralized electronic screening log system to identify eligible patients across a large catchment area for a National Cancer Institute (NCI)-designated cancer center's open clinical trials. MethodsElectronic screening log data collected between 2014 and 2021 from ten community partner sites in a single NCI-designated cancer center's catchment area were reviewed retrospectively. Clinical factors assessed included cancer site, primary versus recurrent disease status, and histology. Identification efficiency (the ratio of patients screened identified with an available trial) was calculated. Identification inefficiencies (failures to identify patients with a potentially relevant trial) were assessed, and etiologies were characterized. ResultsAcross ten community partner sites, 492 gynecologic cancer patients were screened for seven open clinical trials during the study period. This included 170 (34.5 %) ovarian cancer patients, 156 (31.7 %) endometrial cancer patients, and 119 (24.2 %) cervical cancer patients. Over 40 % had advanced stage disease, and 10.6 % had recurrent disease. Only three patients were identified as having a relevant open trial; none ultimately enrolled due to not meeting trial eligibility criteria. An additional 2–52 patients were retrospectively found to have a relevant trial available despite not being identified as such within the electronic screening log system. Up to 14.4 % of patients had one or more missing minimum data elements that hindered full evaluation of clinical trial availability. Re-screening patients when new trials open may identify 12-15 additional patients per recurrent disease trial. ConclusionsAn electronic screening log system can increase awareness of gynecologic oncology clinical trials at a NCI-designated cancer center's community partner sites. However, it is inadequate as a single intervention to increase clinical trial enrollment. Providing adequate support staff, documenting clinical factors consistently, re-screening patients at relevant intervals, and coordinating with central study personnel may increase its utility.

Effects of mixed land use on urban stormwater quality under different rainfall event types

The joint effect of mixed land uses and rainfall event types was studied using a two-year field monitoring program in four urban catchments in Calgary, Alberta, Canada. Event mean concentration (EMC) and event pollutant load (EPL) were employed to evaluate the total suspended sediment (TSS), nitrogen and phosphorus. The correlation analysis showed that most nitrogen and phosphorus components (except for NO2−/NO3− and TDP) predominantly exist in particulate form in the study areas. The correlation for EPL was notably stronger than EMC, which can be attributed to varying rainfall characteristics. The differences in EMCs and EPLs of TSS, nitrogen and phosphorus across catchments indicated that the complexity and spatial distribution of mixed land use can influence the generation and transportation of pollutants in urban runoff. The impacts of rainfall characteristics on stormwater quality are integrated rather than driven by a single rainfall characteristic. Brief but intense events tended to elevate TSS, nitrogen and phosphorus concentrations, especially in complex land-use catchments. Events with long antecedent dry days and short duration also resulted in increased pollutant concentrations, while events with long duration and low intensity could result in higher EPLs. The effect of mixed land use on water quality can vary depending on rainfall event types. Seasonal variations were found in EMC and EPL of TSS, nitrogen and phosphorus, with higher values in the spring and summer than the fall. Seasonal variations are mainly influenced by rainfall conditions, temperature and anthropogenic activities (e.g. lawn fertilization and de-icing with sands). MLR considering rainfall characteristics is an effective method for predicting stormwater quality within a single catchment. Considering complexity and spatial distribution of mixed land use can improve the accuracy of the harmonized MLR model. This research provided insights into understanding the complexities introduced by mixed land use and rainfall event types in urban stormwater quality.

Transferability of a Bayesian Belief Network across diverse agricultural catchments using high-frequency hydrochemistry and land management data

Biogeochemical catchment models are often developed for a single catchment and, as a result, often generalize poorly beyond this. Evaluating their transferability is an important step in improving their predictive power and application range. We assess the transferability of a recently developed Bayesian Belief Network (BBN) that simulated monthly stream phosphorus (P) concentrations in a poorly-drained grassland catchment through application to three further catchments with different hydrological regimes and agricultural land uses. In all catchments, flow and turbidity were measured sub-hourly from 2009 to 2016 and supplemented with 400–500 soil P test measurements. In addition to a previously parameterized BBN, five further model structures were implemented to incorporate in a stepwise way: in-stream P removal using expert elicitation, additional groundwater P stores and delivery, and the presence or absence of septic tank treatment, and, in one case, Sewage Treatment Works. Model performance was tested through comparison of predicted and observed total reactive P (TRP) concentrations and percentage bias (PBIAS). The original BBN accurately simulated the absolute values of observed flow and TRP concentrations in the poorly and moderately drained catchments (albeit with poor apparent percentage bias scores; 76 % ≤ PBIAS≤94 %) irrespective of the dominant land use, but performed less well in the groundwater-dominated catchments. However, including groundwater total dissolved P (TDP) and Sewage Treatment Works (STWs) inputs, and in-stream P uptake improved model performance (−5 % ≤ PBIAS≤18 %). A sensitivity analysis identified redundant variables further helping to streamline the model applications. An enhanced BBN model capable for wider application and generalisation resulted.

Multi-model approach in a variable spatial framework for streamflow simulation

Abstract. Accounting for the variability of hydrological processes and climate conditions between catchments and within catchments remains a challenge in rainfall–runoff modelling. Among the many approaches developed over the past decades, multi-model approaches provide a way to consider the uncertainty linked to the choice of model structure and its parameter estimates. Semi-distributed approaches make it possible to account explicitly for spatial variability while maintaining a limited level of complexity. However, these two approaches have rarely been used together. Such a combination would allow us to take advantage of both methods. The aim of this work is to answer the following question: what is the possible contribution of a multi-model approach within a variable spatial framework compared to lumped single models for streamflow simulation? To this end, a set of 121 catchments with limited anthropogenic influence in France was assembled, with precipitation, potential evapotranspiration, and streamflow data at the hourly time step over the period 1998–2018. The semi-distribution set-up was kept simple by considering a single downstream catchment defined by an outlet and one or more upstream sub-catchments. The multi-model approach was implemented with 13 rainfall–runoff model structures, three objective functions, and two spatial frameworks, for a total of 78 distinct modelling options. A simple averaging method was used to combine the various simulated streamflow at the outlet of the catchments and sub-catchments. The lumped model with the highest efficiency score over the whole catchment set was taken as the benchmark for model evaluation. Overall, the semi-distributed multi-model approach yields better performance than the different lumped models considered individually. The gain is mainly brought about by the multi-model set-up, with the spatial framework providing a benefit on a more occasional basis. These results, based on a large catchment set, evince the benefits of using a multi-model approach in a variable spatial framework to simulate streamflow.

Alternative streamflow-based approach to estimate catchment response time in medium to large catchments: case study in Primary Drainage Region X, South Africa

Event-based estimates of the design flood in ungauged catchments are normally based on a single catchment response time parameter expressed as either the time of concentration (TC), lag time (TL) and/or time to peak (TP). In small, gauged catchments, a simplified convolution process between a single observed hyetograph and hydrograph is generally used to estimate these time parameters. In medium to large heterogeneous, gauged catchments, such a simplification is neither practical nor applicable, given that the variable antecedent soil moisture status resulting from previous rainfall events and spatially non-uniform rainfall hyetographs can result in multi-peaked hydrographs. In ungauged catchments, time parameters are estimated using either empirical or hydraulic methods. In South Africa (SA), unfortunately, the majority of the empirical methods recommended for general use were developed and verified in catchments ≤ 0.45 km² without using any local data. This paper presents the further development and verification of the streamflow-based approach developed by Gericke (2016) to estimate observed TP values and to derive a regional empirical TP equation in Primary Drainage Region X, SA. A semi-automated hydrograph analysis tool was developed to extract and analyse complete hydrographs for time parameter estimation using primary streamflow data from 51 flow-gauging sites. The observed TP values were estimated using three methods: (i) duration of total net rise of a multi-peaked hydrograph, (ii) triangular-shaped direct runoff hydrograph approximations, and (iii) linear catchment response functions. The combined use of these methods incorporated the high variability of event-based time parameters, and Method (iii), in conjunction with an ensemble-event approach sampled from the time parameter distributions, should replace the event-based approaches to enable the improved calibration of empirical time parameter equations. The conceptual approach used to derive the regional empirical TP equation should also be adopted when regional equations need to be derived at a national scale in SA.

A user perception based approach to derive policy intervention areas for enhancing walkability of cities: Experience in Kerala, India

While walkable pedestrian infrastructure is essential for the sustainable growth of cities, the prevailing facilities in emerging countries such as India are not suitable for pedestrians. A user perception-based approach is presented here to identify intervention areas for enhancing the walkability of cities and also to prioritize catchment areas for improvement. The methodology includes seven stages in which perception data collected from the pedestrians are subjected to fuzzy-based Importance Satisfaction Analysis (ISA). The factor structure and management schemes developed using ISA were instrumental in deriving interventions areas. The study was conducted with reference to a road stretch of 5 km in Kollam District, Kerala, which is classified into five catchments. Among the 17 selected attributes, 12 attributes were identified as intervention areas in a single catchment, which shows the alarming situation of pedestrian infrastructure in Indian cities. The sidewalk related deficiencies were identified as common intervention areas across various catchments. Increased vehicular volume on roads, absence of guard rail, and lack of facilities for differently-abled pedestrians were the other common deficiencies. An index is developed for prioritizing pedestrian catchments. This may be useful, especially for countries with financial constraints, to prioritize the catchments based on the need for improvement. Although the findings are city-specific, the approach and experience presented here are useful for enhancing the walkability of pedestrian infrastructure in other cities.

Characterization of urban sources of antibiotics and antibiotic-resistance genes in a Dutch sewer catchment

A one year study was conducted in the city of Nijmegen, The Netherlands, to characterize various urban sources of antibiotics and antibiotic resistant genes (ARGs) in wastewater within a single sewer catchment. Prevalence of ermB, tet(W), sul1, sul2, intl1, and 16S rRNA gene was determined at 10 locations within the city. Sampling locations included a nursing home, a student residence, a hospital and an industrial area, among others. Wastewater concentrations of 23 antibiotics were measured using passive sampling. Additionally, excreted loads of 22 antibiotics were estimated based on ambulatory prescription and clinical usage data. Genes sul1 and intl1 were most abundant across most locations. Ciprofloxacin and amoxicillin together contributed over 92 % of the total estimated antibiotic selective pressure at all sampling points. The present study highlights the prominent role that hospitals can have in the prevalence and proliferation of ARGs in urban wastewater. Furthermore, results suggest that even short-term changes in the therapeutic regimen prescribed in hospitals may translate into shifting ARG abundance patterns in hospital wastewater. The methods applied present an opportunity to identify emission hotspots and prioritize intervention options to limit ARG spread from urban wastewater to the environment.

Catchment-scale life cycle impacts of green infrastructures and sensitivity to runoff coefficient with stormwater modelling

Urban green infrastructure (GI) has been widely used in sponge city construction to manage hydrological processes. While studies on environmental benefits of GI from the perspective of whole life cycle assessment (LCA) have been reported in recent years, few have explored and compared the environmental performance of different GIs within a single catchment, which is directly linked to catchment-scale hydrological control. This study focuses on a Sponge City pilot project in Shenzhen, China, including three typical types of GI: permeable pavement, green roof, and sunken green space. By collecting hydrological data, land use, and life cycle inventory of GI and employing SWMM (Storm Water Management Model)-based stormwater modelling, we have revealed the environmental impacts at different stages of the life cycle of the GI scenario and three GIs through comparative and sensitivity analyses. Notably, we have disclosed, for the first time, the effect of the runoff coefficient in LCA. Our findings indicate that over the 30-year life cycle, the total environmental impact of the GI scenario is 24 % smaller than that of the hypothetical grey scenario. Permeable pavement exhibits the largest environmental impact per unit area, being 1.8 times and 7.6 times greater than that of the green roof and sunken green space, respectively. The operation stage of the three GIs significantly mitigates eutrophication and climate change. Furthermore, sensitivity analysis demonstrates that an increase in surface runoff undermines the environmental benefits of GIs. These results highlight the importance of embedding stormwater modelling into LCA, enabling catchment-scale integrated evaluation and equivalent assessment of different GIs within a single catchment whereby the influence of external factors such as climate change can be described, which aids in understanding the dynamic environmental performance of GIs. The proposed research framework and results are anticipated to provide valuable guidance for future GI construction and carbon-neutral policies.

Diversified caregiver input to upgrade the Young Children’s Participation and Environment Measure for equitable pediatric re/habilitation practice

BackgroundPractitioner and family experiences of pediatric re/habilitation can be inequitable. The Young Children’s Participation and Environment Measure (YC-PEM) is an evidence-based and promising electronic patient-reported outcome measure that was designed with and for caregivers for research and practice. This study examined historically minoritized caregivers’ responses to revised YC-PEM content modifications and their perspectives on core intelligent virtual agent functionality needed to improve its reach for equitable service design.MethodsCaregivers were recruited during a routine early intervention (EI) service visit and met five inclusion criteria: (1) were 18 + years old; (2) identified as the parent or legal guardian of a child 0–3 years old enrolled in EI services for 3 + months; (3) read, wrote, and spoke English; (4) had Internet and telephone access; and (5) identified as a parent or legal guardian of a Black, non-Hispanic child or as publicly insured. Three rounds of semi-structured cognitive interviews (55–90 min each) used videoconferencing to gather caregiver feedback on their responses to select content modifications while completing YC-PEM, and their ideas for core intelligent virtual agent functionality. Interviews were transcribed verbatim, cross-checked for accuracy, and deductively and inductively content analyzed by multiple staff in three rounds.ResultsEight Black, non-Hispanic caregivers from a single urban EI catchment and with diverse income levels (Mdn = $15,001–20,000) were enrolled, with children (M = 21.2 months, SD = 7.73) enrolled in EI. Caregivers proposed three ways to improve comprehension (clarify item wording, remove or simplify terms, add item examples). Environmental item edits prompted caregivers to share how they relate and respond to experiences with interpersonal and institutional discrimination impacting participation. Caregivers characterized three core functions of a virtual agent to strengthen YC-PEM navigation (read question aloud, visual and verbal prompts, more examples and/or definitions).ConclusionsResults indicate four ways that YC-PEM content will be modified to strengthen how providers screen for unmet participation needs and determinants to design pediatric re/habilitation services that are responsive to family priorities. Results also motivate the need for user-centered design of an intelligent virtual agent to strengthen user navigation, prior to undertaking a community-based pragmatic trial of its implementation for equitable practice.

Impact of suspicious streamflow data on the efficiency and parameter estimates of rainfall–runoff models

ABSTRACT Many sources of error in hydroclimatic data can affect hydrological modelling, yet the impact of streamflow data quality is poorly quantified. This work aims to investigate whether inconsistencies found in streamflow time series commonly available for hydrological studies (typically in national streamflow archives) have an impact on the efficiency and the parameter estimates of rainfall–runoff models. Hydroclimatic data were gathered at the hourly time step over the period 1998–2018 for a set of 30 catchments in France. Hydrological modelling was carried out with the lumped conceptual GR5H (standing for modèle du Génie Rural à 5 paramètres Horaire, i.e. Hourly 5-parameter rural engineering model) model. A typology of “realistic” suspicious streamflow was established to set up several error models in order to corrupt the data. Our results suggest that common suspicious streamflow data do not have a strong impact on model efficiency and parameter estimates overall, but may be an important source of instability and lack of robustness when working on a single catchment.

Population structure, genetic diversity and demographic patterns unveil massive Mediterranean brown trout manipulations in a protected area of the northern Apennines (Italy)

The Salmo trutta species complex includes threatened or intensively managed taxa. Domestic-Atlantic strains are widely farmed and massively introduced into the wild to support fisheries, although such practices seriously threaten native populations of Mediterranean brown trout through anthropogenic hybridization. Characterizing the distribution and genetic composition of wild populations across river catchments is crucial to identify conservation priorities and define appropriate management strategies. Here, we genotyped 586 brown trout at the diagnostic nuclear LDH-C1 gene and the mitochondrial D-loop fragment, to assess the conservation status of 33 sites in a protected area spanning river catchments from both the Adriatic and Tyrrhenian slopes in the northern Apennines (Italy). The results indicated a critical situation of widespread domestic-Atlantic introgression. Further analyses at 15 microsatellite loci on 159 individuals from 12 natural sites (along with 113 references from hatcheries) revealed similarity to hatchery stocks, higher genetic diversity and bottleneck signals in introgressed/exotic populations, consistently with relatively recent introductions of domestic-Atlantic individuals into wild sites. Conversely, the only native sites from a single river catchment on the Adriatic slope showed genetic distinctiveness, reduced diversity and demographic stability. We also found genetic evidence of a human-mediated introduction of allochthonous Mediterranean trout in a single wild site, as well as of a putative between-slopes translocation. We provide further insight into the occurrence and consequences of human manipulations on wild Mediterranean brown trout populations, contextually offering a reliable baseline for an ongoing conservation project aiming at preserving native populations of this endangered taxon.

Perinatal Health Outcomes Across Rural and Nonrural Counties Within a Single Health System Catchment.

Perinatal health outcomes are influenced by a variety of socioeconomic, behavioral, and economic factors that reduce access to health services. Despite these observations, rural communities continue to face barriers, including a lack of resources and the fragmentation of health services. To evaluate patterns in health outcomes, health behaviors, socioeconomic vulnerability, and sociodemographic characteristics across rural and nonrural counties within a single health system catchment area. Socioeconomic vulnerability metrics, health care access as determined by licensed provider metrics, and behavioral data were obtained from FlHealthCHARTS.gov and the County Health Rankings. County-level birth and health data were obtained from the Florida Department of Health. The University of Florida Health Perinatal Catchment Area (UFHPCA) was defined as all Florida counties where ≥5% of all infants were delivered at Shands Hospital between June 2011 and April 2017. The UFHPCA included 3 nonrural and 10 rural counties that represented more than 64,000 deliveries. Nearly 1 in 3 infants resided in a rural county, and 7 out of 13 counties did not have a licensed obstetrician gynecologist. Maternal smoking rates (range 6.8%-24.8%) were above the statewide rate (6.2%). Except for Alachua County, breastfeeding initiation rates (range 54.9%-81.4%) and access to household computing devices (range 72.8%-86.4%) were below the statewide rate (82.9% and 87.9%, respectively). Finally, we found that childhood poverty rates (range 16.3%-36.9%) were above the statewide rate (18.5%). Furthermore, risk ratios suggested negative health outcomes for residents of counties within the UFHPCA for each measure, except for infant mortality and maternal deaths, which lacked sample sizes to adequately test. The health burden of the UFHPCA is characterized by rural counties with increased maternal death, neonatal death, and preterm birth, as well as adverse health behaviors that included increased smoking during pregnancy and lower levels of breastfeeding relative to nonrural counties. Understanding perinatal health outcomes across a single health system has potential to not only estimate community needs but also facilitate planning of health care initiatives and interventions in rural and low-resource communities.

Sub-sewershed Monitoring to Elucidate Down-the-Drain Pesticide Sources.

Pesticides have been reported in treated wastewater effluent at concentrations that exceed aquatic toxicity thresholds, indicating that treatment may be insufficient to adequately address potential pesticide impacts on aquatic life. Gaining a better understanding of the relative contribution from specific use patterns, transport pathways, and flow characteristics is an essential first step to informing source control measures. The results of this study are the first of their kind, reporting pesticide concentrations at sub-sewershed sites within a single sewer catchment to provide information on the relative contribution from various urban sources. Seven monitoring events were collected from influent, effluent, and seven sub-sewershed sites to capture seasonal variability. In addition, samples were collected from sites with the potential for relatively large mass fluxes of pesticides (pet grooming operations, pest control operators, and laundromats). Fipronil and imidacloprid were detected in most samples (>70%). Pyrethroids were detected in >50% of all influent and lateral samples. There were significant removals of pyrethroids from the aqueous process stream within the facility to below reporting limits. Imidacloprid and fiproles were the only pesticides that were detected above reporting limits in effluent, highlighting the importance of source identification and control for the more hydrophilic compounds. Single source monitoring revealed large contributions of fipronil, imidacloprid, and permethrin originating from a pet groomer, with elevated levels of cypermethrin at a commercial laundry location. The results provide important information needed to prioritize future monitoring efforts, calibrate down-the-drain models, and identify potential mitigation strategies at the site of pesticide use to prevent introduction to sewersheds.

Repose time patterns of debris‐flow events in alpine catchments

AbstractThe omnipresent threat of natural hazards in mountainous regions has led to a risk culture which requires knowledge about the frequency of the considered hazardous process. Observations suggest that the frequency of debris‐flow events in a single catchment is, besides climatic thresholds, also controlled by its geological, lithological and geomorphological characteristics. Based on investigations of debris‐flow event frequencies from 47 headwater catchments, our results support the classification of recurrence intervals as irregular, clustered or regular, originally proposed by Zimmermann et al. in 1997 (Eclogae Geologicae Helvetiae, 90(3), 415–420). However, instead of using geomorphological characteristics, our classification relies on quantitative analyses considering potential dependencies between events based on their inter‐event (repose) times. By employing a modified dynamic threshold concept with respect to debris‐flow initiation, we show that for irregular frequencies neither climatic nor geomorphological thresholds are altered by the last debris‐flow event. For regular and clustered time series, however, mutual dependency between events is reasonable and therefore prompts dynamic changes of climatic as well as geomorphological thresholds.

A region of influence approach for attributing fluvial climate change allowances

ABSTRACT For practical purposes the current guidance for attributing fluvial climate change allowances (recommended peak-discharge adjustments) in England is based on percentage changes to the 50-year return level attributed homogeneously to geographical regions. This proof-of-concept study introduces an approach enabling the practitioner to derive allowances for the full distribution of extremes (as opposed to single return periods) and is based on catchment characteristics. A region of influence approach, adopted by the Flood Estimation Handbook (FEH), is applied to estimate changes to the parameters of statistical models of extreme flows, as opposed to flow peaks. The approach is distribution neutral and can be applied to any catchment for which an FEH analysis has been undertaken. Results for an example scenario (Representative Concentration Pathway (RCP)8.5 2080s) are compared to a geographically regional method and an example is provided for a single catchment estimating extremes with the FEH method and adjusting them for the RCP8.5 2080s scenario.

Decolonising Flooding and Risk Management: Indigenous Peoples, Settler Colonialism, and Memories of Environmental Injustices

This paper examines the history of settler-colonialism and how settler-colonial-led policies and projects to remake the landscapes and waterscapes of Aotearoa New Zealand resulted in the production of Indigenous environmental injustices. Underpinned by theorising on ecological justice and decolonisation, we draw on archival sources and oral histories of Māori and Pākehā (European) individuals living in a single river catchment—the Waipā River—to trace how actions to remove native vegetation, drain wetlands, introduce exotic biota, and re-engineer waterways contributed to intensifying incidence of floods. While Pākehā settlers interpreted environmental transformation as inherently positive, Indigenous Māori perceived it as profoundly negative, a form of ecological dispossession. We demonstrate that while Pākehā narrated floods as disaster events, Māori viewed colonisation as the true disaster, with floods and fires merely products of settlers’ mistreatment of the environment. Moreover, the colonial government’s efforts to control floods resulted in Māori being further alienated from and losing access to their rohe (ancestral lands and waters) and witnessing the destruction of their taonga (treasures including forests, wetlands, and sacred sites). For Māori of the Waipā catchment, flood risk management regimes were far more destructive (socially, economically and spiritually) than flood events.

Thermal traits govern the response of microbial community dynamics and ecosystem functioning to warming.

Understanding the ecological processes that underpin the dynamics of community turnover in response to environmental change is critical to predicting how warming will influence ecosystem functioning. Here, we quantify the effect of changing temperature on community composition and ecosystem functioning via the action of ecological selection on population-level thermal traits. To achieve this, we use microbes isolated from a network of geothermal streams in Iceland where in situ temperatures span 8–38°C within a single catchment. We first quantified variability in thermal tolerance between taxa, and then assembled synthetic communities along a broad thermal gradient to explore how temperature-driven selection on thermal tolerance traits shaped the emergent community structures and functions. We found marked changes in community structure and composition with temperature, such that communities exposed to extreme temperatures (10, 35°C) had highly asymmetric biomass distributions and low taxonomic richness. Thermal optima were a good predictor of the presence and relative abundance of taxa in the high-temperature treatments. We also found that the evenness of the abundance distribution was related to ecosystem production, such that communities with more equitable abundance distribution were also the most productive. Our results highlight the utility of using a multi-level approach that links population-level traits with community structure and ecosystem functioning to better understand how ecological communities will respond to global warming.

Mapping silver eel migration routes in the North Sea

Recent developments in tracking technology resulted in the mapping of various marine spawning migration routes of the European eel (Anguilla anguilla). However, migration routes in the North Sea have rarely been studied, despite many large European rivers and hence potential eel growing habitat discharge into the North Sea. In this study, we present the most comprehensive map to date with migration routes by silver European eels in the North Sea and document for the first time successful eel migration through the English Channel. Migration tracks were reconstructed for 42 eels tagged in Belgium and 12 in Germany. Additionally, some eels moved up north to exit the North Sea over the British Isles, confirming the existence of two different routes, even for eels exiting from a single river catchment. Furthermore, we observed a wide range in migration speeds (6.8–45.2 km day−1). We hypothesize that these are likely attributed to water currents, with eels migrating through the English Channel being significantly faster than eels migrating northward.

A comparison of trends in population size and life history features of Atlantic salmon (Salmo salar) and anadromous and non-anadromous Brown trout (Salmo trutta) in a single catchment over 116\xa0years

We use a long time series of catch abundance from a recreational fishery over 116 years to look for population trends in Atlantic salmon, and anadromous (sea trout) and non-anadromous (brown) trout for a single catchment, Loch Lomond, west central Scotland. Year strongly predicted variation in catches but catch effort did not meaningfully increase explained variation. Salmon showed periods of increasing and decreasing trends, for sea trout and brown trout there was an overall declining trend. Since 1952, Lomond salmon population trends differed from both wider Scotland and southern Europe, indicating that the Lomond population is partially buffered from drivers of change in salmon populations more widely. In contrast Lomond sea trout showed a similar declining trend to that of populations from the wider west of Scotland over this period. The Lomond populations showed some evidence of shorter-term cycling patterns; the drivers for which are unknown. Body size in salmon and sea trout declined but increased in brown trout; salmon returned to freshwater later, and the relative proportion of all caught trout that were anadromous increased across the time series. This study shows a long and protracted period of fundamental change to populations of these two species over 116 years.