Assessing the performance of morphologically based river typing in Scotland using a geomorphological and ecological approach

Traditionally, the interactions between geomorphic character and aquatic biodiversity have been widely acknowledged, but poorly quantified. However, the coupling of these disciplines is currently rising up legislative and political agendas, such as the European Union Water Framework Directive (EU WFD). The Directive requires Member States to classify rivers into types based on their natural morphology and geomorphic processes, and to link the biota to river types existing under natural conditions. Typing now forms the basis for evaluating environmental sensitivity to river engineering and determining reference conditions for river restoration. The Scottish Environment Protection Agency (SEPA) has adapted the Montgomery and Buffington (1997) channel typology developed in the Pacific Northwest of the USA for use in Scotland. The modified typology identifies eleven distinct channel types (e.g. bedrock, plane-bed, wandering and meandering). In this study, 43 reference condition sites in the upper River Dee catchment in the Cairngorms, Scotland were chosen to determine the geomorphic validity of the proposed typology, and assess whether channel types support a distinct macroinvertebrate community. Agglomerative Hierarchical Cluster Analysis failed to clearly identify eleven channel types based on catchment controls or on physical habitat characteristics. Four clusters were observed based on catchment drivers and six on physical habitat. Boundaries appear to be fuzzy, relating to a collective number of interacting environmental variables, geological discontinuities, and the geographic complexity of a river system. Multivariate ordinations and Analysis of Similarity indicated that macroinvertebrate communities only differed significantly between bedrock and step-pool reaches. A redundancy analysis showed differences in macroinvertebrate abundances among channel types were related to hydraulic, catchment drivers, physical habitat and physico-chemical variables. The results of the study have important implications for the use of geomorphic typologies in predicting aquatic biota

Assessing the performance of morphologically based river typing in Scotland using a geomorphological and ecological approach

Traditionally, the interactions between geomorphic character and aquatic biodiversity have been widely acknowledged, but poorly quantified. However, the coupling of these disciplines is currently rising up legislative and political agendas, such as the European Union Water Framework Directive (EU WFD). The Directive requires Member States to classify rivers into types based on their natural morphology and geomorphic processes, and to link the biota to river types existing under natural conditions. Typing now forms the basis for evaluating environmental sensitivity to river engineering and determining reference conditions for river restoration. The Scottish Environment Protection Agency (SEPA) has adapted the Montgomery and Buffington (1997) channel typology developed in the Pacific Northwest of the USA for use in Scotland. The modified typology identifies eleven distinct channel types (e.g. bedrock, plane-bed, wandering and meandering). In this study, 43 reference condition sites in the upper River Dee catchment in the Cairngorms, Scotland were chosen to determine the geomorphic validity of the proposed typology, and assess whether channel types support a distinct macroinvertebrate community. Agglomerative Hierarchical Cluster Analysis failed to clearly identify eleven channel types based on catchment controls or on physical habitat characteristics. Four clusters were observed based on catchment drivers and six on physical habitat. Boundaries appear to be fuzzy, relating to a collective number of interacting environmental variables, geological discontinuities, and the geographic complexity of a river system. Multivariate ordinations and Analysis of Similarity indicated that macroinvertebrate communities only differed significantly between bedrock and step-pool reaches. A redundancy analysis showed differences in macroinvertebrate abundances among channel types were related to hydraulic, catchment drivers, physical habitat and physico-chemical variables. The results of the study have important implications for the use of geomorphic typologies in predicting aquatic biota.EThOS - Electronic Theses Online ServiceNatural Environment Research Council (NERC) : Scottish Environment Protection Agency (SEPA)GBUnited Kingdo

Deliverable D4.4-5: Precision and behaviour of fish-based ecological quality metrics in relation to natural and anthropogenic pressure gradients in European estuaries and lagoons

This report summarises the work conducted in Work Package 4.4 – BQE fish in transitional (i.e. estuarine and lagoon) waters (TW) within the project WISER under the sponsorship of the European Commission. It omits most technical details of the analyses given in the four previous Work Package reports, but still provides the necessary information to understand the rationale, approach and underlying assumptions necessary to discuss the results. The focus is therefore to discuss and integrate the results obtained within Work Package 4.4 and with this, make recommendations to improve fish-based ecological assessments in TW, principally estuaries and lagoons. In addition, and to assist with the WFD implementation which is the overarching theme of WISER, the deliverable includes, where appropriate, case studies where we have used multi-metric fish indices currently under development, or already in use for WFD compliance monitoring across Europe. Furthermore, results of the work package have been shared with relevant Geographical Intercalibration Groups (GIGs) supporting the harmonization and equalization process across transitional fish indices in Europe. Development strategies for fish indices in TW vary but generally include: (1) the calibration of metrics to anthropogenic pressures, (2) the development of reference conditions, (3) the calculation of ecological quality ratios, and (4) the designation of thresholds for Ecological Status (ES) class. New fish indices are developed for a defined geographical area, using specific sampling method and under locally relevant pressure fields. The former two factors, area and sampling methods, define the relevant reference condition in the calculation of Ecological Quality Ratios (EQR) and the latter factor, human pressures, define the índex structure and especially the fish metric selection. To assess index relevance across areas, we calculated a suite of transitional fish indices on a standardized WISER dataset and then compared the agreement of the outcomes (using correlation analysis). The application of current indices to areas (or countries) different from the area in which it was originally developed leads to inconclusive or spurious results. The failure to accommodate the diferente indices to a standardized dataset in this work clearly demonstrates the fundamental reliance of current fish indices on the sampling methods and design of monitoring programmes used in the development of the index. Despite this, for some indices, correlations although weaker are statistically significant, also indicating the possible agreement in successful intercalibration between these indices. Harmonization of BQE fish methodologies across Europe (common metrics) is unlikely by adapting or creating new fish indices but inter-comparison assessments are possible and valid using a common pressure index to harmonise diferente indices on a common scale. We found a negative response of fish quality features to pressure gradients which make BQE fish in TW suitable for greater ecological integration than other BQEs. However, successful assessment of Ecological Status (ES) require a matching combination of fish index, reference values and local dataset gathered with compatible sampling methods. Whole indices provide more consistent overall ES assessments but fish metrics considered individually may be more useful as a means to focus restoration measures. Future work is needed to identify those specific pressures affecting fish assemblages providing targets for minimising the effects of stress in mitigation and restoration plans. In order to achieve this, and although the interpretation of outcomes is still difficult, more recent transitional fish indices are leading in the use of comprehensive appraisal and validation exercises to test the responsiveness of BQEs for the assessment of ES. Here we proposed for the first time a simple sensitivity exercise under realistic scenarios of metric change to explore the expected inertia (i.e. the tendency to buffer ES change after quality alterations), dynamic range (i.e. the ratio between the largest and smallest possible ES values) and most relevant metric components (i.e. the those driving the most likely scenarios leading to ES change) from a multi-metric fish índex under relevant human pressure gradients. Overall, the behaviour of multi-metric índices under manipulations of metric scores clearly indicated that metric type, number of metrics used and correlations between metrics are important in determining the index performance, with indices including more and/or uncorrelated metrics or metrics with skewed distribution being less affected by extreme metric manipulations. Results of this analysis may be used to set realistic management targets and also to identify the aspects of the indices that are more likely to affect the outcomes leading to more robust and responsive indices. Further improvements of fish indices may be attained by reducing the variability confounding biological quality metrics. This variability is undesirable noise in assessments and can be technical (i.e. linked to the method of assessment including sampling effort) or natural (physicochemical and biological). The implication for assessments is that different facts might then confound the metric-pressure correlation (the ‘signal’ in the signal-to-noise ratio in the assessments) increasing uncertainty in ES assignment. Models showed that salinity class, depth, season, time of fishing (day vs. night) and year of fishing may influence the values of the fish metrics. The modelling exercise also demonstrated that unexplained variance remains generally much higher within-systems than between-systems suggesting a higher importance of sources of variability acting at the WB level. Modelling and improved standardization in monitoring campaigns should reduce uncertainty in ES assignment. One important factor that was assessed further was the effect of sampling effort. The results suggest that richness-based metrics require larger sampling efforts although a similar effortrelated bias may be an issue for density-based metrics if fish distribution is very patchy (i.e. schooling fish or those aggregated in specific habitats) and insufficient replicates are taken to fully characterise the patchiness in their distribution. It is apparent that to overcome a potential large source of error, the Reference Conditions must be defined according to the level of effort used in the monitoring programme or, conversely, the monitoring must be carried out at the same level of effort used to derive the Reference Condition. The WP finally explored the use of a predictive linear modelling approach to define reference conditions for fish metrics in transitional waters. The fish response data was modelled together with Corine Land Cover (CLC)-derived pressure proxies (% agricultural, urban and natural land coverage). Based on the obtained models, the expected metric score was predicted by setting pressure levels either to the lowest observed pressure in the dataset or to zero in order to define the sample and theoretical reference condition, respectively. Even when significant, the effect of pressures on fish metrics was generally very weak, probably reflecting the use of too-generic pressure indicators (such as land cover data instead of more relevant estuarine proxies such as dredging, port development, waterborne pollutants, etc). The best explanatory models included sampling factors and natural characteristics considered important discriminant features in the definition of water body types. In particular, the present work argues for considering not only estuaries and lagoons as different typologies but also other natural and design characteristic such as the gear type, the sampling season and the salinity class. Furthermore, a relevant reference needs to account for survey design bias, including rare species contribution to assessment datasets, patchiness, choice of pressure proxies or sampling gear. The modelling approach of fish metrics against the physicochemical variables has proved useful to derive Reference Conditions. This is important for the computation of relevant EQRs in Europe where there is a general lack of pristine areas or historical data on fish BQE and it provides an alternative to best professional judgment. Taking all WP analysis and case studies together, the work conducted has highlighted the following key messages and linked research needs necessary to optimize BQE fish for the quality assessment of transitional waters: Key Message 01: Harmonization of BQE fish methodologies across Europe (common metrics) is unlikely by adapting or creating new fish indices but inter-comparison assessments are possible and valid using a common pressure index to harmonise diferente indices on a common scale. Research needs to be focused on more widely-applicable fish indices will require the formulation of completely new indices based on a more flexible use of fish metrics according to system typologies, relevance and, probably, an increased use of functional traits. For current indices, further research on a method of intercalibration is needed. Key Message 02: BQE Fish in TW respond consistently to human pressure gradients across transitional waters providing the means to assess Ecological Status (ES). Further work will be needed to identify those specific pressures affecting fish assemblages providing targets for minimising the effects of stress in mitigation and restoration plans. Key Message 03 Although the interpretation of outcomes is still difficult, more recente transitional fish indices are leading in the use of comprehensive appraisal and validation exercises to test the performance of BQEs in the assessment of Ecological Status (ES). Further appraisal of fish indices behaviour is needed to understand the meaning of the quality outcomes, to set realistic management targets and also to identify the aspects of the índices that are more likely to affect the outcomes leading to more robust and responsive indices Key Message 04 Uncertainty levels associated with metric variability in multi-metric fish indices can be managed to increase the confidence in Ecological Status (ES) class assignment. Further research is needed to include knowledge of habitat partition within systems, to understand metrics behaviour and precision, to test new combination rules allowing metric weighting by robustness and importantly to evaluate more robust sampling tools and methods. Key Message 05 Reference conditions for BQE fish-based quality assessments can be objectively estimated using predictive modelling. Further refinements will require the use of better pressure proxies, robust metrics amenable to modelling and to account for survey design bias (effort & choice of sampling gear) at the relevant scales used in monitoring programmes.info:eu-repo/semantics/publishedVersio

Hydroecological investigations on the hyporheic zone to support river management from reaches to catchments

The hyporheic zone (HZ) is an area of interaction between surface and ground waters in riverbeds. It is characterized by a diverse fauna and by a bidirectional flow (hyporheic exchange flow - HEF). HZ plays a signifi cant role in river ecosystems as location of major physical, biogeochemical and ecological processes. Yet, predicting HEF in rivers and assessing its ecological effects is challenging due to physical and biological process- interactions in time and space. This thesis investigates HEF from a hierarchical scaling perspective and it has two components: (i) physical, and (ii) biological. The fi rst component includes discriminating and integrating the drivers of HEF across spatial scales and developing a multiscale statistical method for river restoration planning. The second component consists of testing the interaction between physical and biological processes on in-channel large wood (LW), by quantifying, in the field, the effects on hyporheic and benthic invertebrates assemblages taxonomic structure and functional traits. The multiscale approach shows that suitable areas for HEF-focused restoration embed a summary of environmental information across the domains of hydrology, geomorphology, and ecology. Field results about invertebrates' taxonomic and functional metrics, demonstrate that the increased spatial and temporal variability of abiotic conditions at LW sites drives changes in abundance, biomass, diversity and functional traits of hyporheic meiofaunal assemblages. In contrast, benthic macrofaunal assemblages were less wood-impacted. To support restoration targeting the HZ, this research emphasizes the need to (i) recognize different spatial scales of HEF to identify the underlying processes; (ii) coordinate approaches to pool hyporheic data and create long-term datasets to quantitatively assess model predictions; and (iii) establish further knowledge on how LW effects HZ in different valleys and river types

Hydrology, carbon dynamics and hydrochemical properties of ponds in an extensive low gradient High Arctic wetland, Polar Bear Pass, Bathurst Island, Nunavut, Canada

Ponds form the dominant feature of Polar Bear Pass (PBP), one of the largest wetlands in the Canadian High Arctic, and in order to understand the ramifications of climatic changes on PBP we must first understand the ponds' responses to seasonal changes in climatic, physical, chemical, and carbon components. Fieldwork (2007-2010) at PBP aimed (i) to determine water budgets of ponds with various hydrologic settings, (ii) to identify the processes controlling the changes in pond carbon and geochemistry on seasonal and inter-annual bases with a special focus on the snowmelt period, and (iii) to establish the baseline hydrochemistry and hydrology of ponds within the PBP wetland complex. Pond systems at PBP have two hydrologic settings: (i) ones which are hydrologically connected to additional sources of water from their catchments beyond seasonal inputs of snowmelt and rainfall, or (ii) ponds which fail to form a link or only have a limited connection with their surrounding catchments. Intensive seasonal monitoring of water and carbon mass balance showed that elevated loads of dissolved organic carbon (DOC) in ponds were mostly of terrestrial origin and occurred in ponds receiving meltwater from snowbeds and/or discharge from hillslope creeks. The seasonal strength in the connectivity of a pond to its catchment from snowmelt to the postsnowmelt period was critical in controlling DOC loads and concentrations. This study provided the first estimates of DOC yields at Polar Bear Pass, and reported elevated DOC loadings from wet meadow catchments into ponds. This highlights their importance as a source of carbon to pond ecosystems during snowmelt and heavy rainfall events. The water chemistry and environmental data showed that waters at PBP were dominated by calcium and bicarbonate ions that fell on a common dilution line, however, they had distinct proportional major ionic variability due to the location, lithology, and level of water-bedrock interaction, and these dynamics were controlled by differences in climatic conditions and hydrologic connectivity. Results relating to pond-landscape linkages and their role in solute transport to ponds showed (i) elevated surface and subsurface water contribution to ponds in hydrologically connected catchments. The primary mechanism for solute and carbon transport was overland flow during snowmelt and surface/subsurface inflow during the post-snowmelt season. There was (ii) a potential for higher solute inflow during seasons with frequent or large precipitation events. Lastly, (iii) isolated ponds were subject to evapo-concentration resulting in solute enrichment in pond waters during warm, dry periods. An analysis of carbon dioxide (C02) concentrations in surface waters during snowmelt was conducted to provide the first estimates of this greenhouse gas in ponds at PBP and to further support the interpretation of hydro logic and carbon dynamics in ponds during the snowmelt and early post-snowmelt season. Surface waters at PBP were strong sources of C02 to the atmosphere, with C02 emissions dramatically increasing at the beginning of snowmelt and then declining during peak snowmelt. The required inputs of carbon to support the estimated C02 emissions could be explained by surface or subsurface inflows of dissolved organic carbon and dissolved inorganic carbon, and possibly from mineralization of terrestrial organic carbon in the water column and sediments of ponds. The findings of this study will aid in the future management of the PBP wetland, and may be applied to other arctic ponds situated in High Arctic wetland environments or in any area in the circumpolar Arctic that has similar geomorphologic features and climatic setting

An Integrated Approach to Assessing Spread of Commercial Horticulture and Related Environmental Impacts on Watersheds : Cases in Central Highlands of Kenya

Intensive horticulture production has broad environmental implications due to the high dependency on natural resources. Numerous reports indicate positive socio-economic gains associated with the Kenyan horticulture sub-sector. Even so, few highlight the extent of the negative environmental impacts. We adopt a holistic approach that integrates deskwork, Geographical Information Systems (GIS), field study and remote sensing tools to evaluate the spread and growth of commercial horticulture, and the effects on: i) surface water quality, and ii) vegetation condition, in watersheds experiencing increased production within the central highlands. The desk research utilized Google Earth archives and GIS data, to map greenhouse distribution, determining area under production and factors predicting choice of location. This was followed by a field study to sample and characterize surface water quality in select sub-watersheds with intensive horticulture, thereby highlighting potential pollutant source-processes. Twenty five years of remote sensing data were also analyzed to establish vegetation condition and responses to increased farming and human disturbances. This was followed by a detailed study to quantify land use and land cover changes, and finally a chapter illustrating trends in horticulture exports volumes. Results from the desk research showed heterogeneous spread of farming, where area under production increased rapidly between 2000 and 2011. Population density, average slope, average rainfall and dams were significant predictors to farming location. Results from the field study show predominance of anthropogenic trace elements of cadmium, phosphate, and zinc in waters draining from regions with intensive large scale horticulture. The long-term vegetation study indicates spatially varying inter-annual NDVI, which continuously declined post 1990s in sub watersheds with increased farming. The study to quantify land transformation dynamics, indicate varying magnitudes of change with rates of change differing between land-uses, and between case studies, attributable to socio-economic drivers. We also find that horticultural exports had positive trends until 2008/2009, and 2010, where the effects of post-election violence and volcanic eruption are evident. Overall, the research has demonstrated the efficacy of integrated approaches in understanding implications intensified production on watershed resources. This knowledge is important in developing policies and regulatory frameworks that supports sustainable resource utilization and best management practices

Spatiotemporal dynamics of the bacterial community in the German Bight

Microbes comprise the most abundant and diverse group of organisms on earth, contribute substantially to every conceivable biogeochemical cycle and thus, are fundamental to ecosystem functioning. Research on marine microbial communities has proven the existence of biogeographic patterns, but the mechanisms that shape the microbial assemblages are still not understood properly, as most of the studies revealed different driving forces for different temporal and spatial scales and individual habitats. However, to predict and estimate potential ecological impacts that arise from microbial community variation, it is of utmost importance to unveil the mechanisms that are generating and maintaining community assembly. This thesis aimed at providing detailed insight into the spatiotemporal variation of bacterioplankton communities in the German Bight, to deconvolute spatial and temporal signals and to identify the main regulating forces driving these dynamics

Biological assessment of tropical riverine systems using aquatic macroinvertebrates in Tanzania, East Africa

Includes bibliographical references.In Tanzania, and in East Africa in general, bioassessment methods for monitoring and assessing riverine ecosystems are not yet in place. This thesis describes the development of a macroinvertebrate-based bioassessment method for assessing the degree of anthropogenic disturbance in Tanzanian rivers. The hypotheses that, 'macroinvertebrate assemblages reflect disturbance in river systems'; 'rivers with similar abiotic features have similar macroinvertebrate assemblages'; and 'spatio-temporal variation in macroinvertebrate assemblages influence bioassessment', are tested. Macroinvertebrate and environmental data were collected from the Pangani, Rufiji and Wami-Ruvu basins. Univariate analyses; constrained and un-constrained ordinations and a linear response model were used to test the hypotheses. Five important bioassessment aspects were investigated. A set of 20 criteria for screening reference sites was established and used to identify and distinguish between reference and test sites in the study area. A two-level hierarchical framework for classifying homogenous river types was developed and validated. Three river types were classified: Pangani highland uplands, central eastern Africa uplands and central eastern Africa lowlands, each with two sub-Groups. A macroinvertebrate-based biotic index, the Tanzanian River Scoring System (TARISS), was established for monitoring and assessing anthropogenically induced disturbance in Tanzanian rivers. TARISS has three metrics; number of taxa, TARISS score and average score per taxon (ASPT) for measuring disturbance. Spatio-temporal variations in macroinvertebrate taxa, assemblages and TARISS metrics were examined. Spatial variation within river types was driven by catchment characteristics such as geographical location, geology, altitude and local characteristics such as active channel width, proportions of boulder, cobble and sand on the bottom, influenced reference conditions in all three river types. Temporal variations were significant in the central eastern Africa lowlands, with higher TARISS metrics in wet than in dry periods. Biological and physico-chemical reference conditions were identified for each river type and sub-Group. Guidelines for interpreting TARISS data were established for the validated sub-Groups. In conclusion, TARISS proven to be reliable in detecting anthropogenic disturbance in Tanzanian rivers and is recommended as a national bioassessment method