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Assessing the vulnerability of ecosystems to biodiversity loss has become increasingly crucial in conservation and ecology research. This study proposed a methodology for measuring lake vulnerability to biodiversity loss employing an established framework that combines three components. For this, we measured the resilience (functional redundancy) and sensitivity (an index considering three characteristics of rarity) components for fish and phytoplankton communities. We also measured the exposure component of the main stressors in lakes. We then combined the three components and calculated the vulnerability index (IVCLA) using data from 255 French lakes. We found that all lakes exhibited low levels of resilience, elevated sensitivity regarding average values for fish and phytoplankton groups, and medium exposure to stressors associated with human activities. In addition, there were some discrepancies in resilience and sensitivity patterns between fish and phytoplankton groups, emphasizing the importance of considering information from multiple biological groups when assessing ecosystem vulnerability. Hydrological alterations and low water quality were key stressors related to higher lake vulnerability. Most French lakes have been classified as exhibiting moderate vulnerability. It is crucial to emphasize the potential increase in exposure risks, which could lead to even higher vulnerability levels and, subsequently, biodiversity loss in the future. The IVCLA index offers several advantages, including integrating multiple taxa groups and stressors. We recommend incorporating additional data, such as the resilience and sensitivity of the entire food web, and considering temporal responses to stressors to improve accuracy and predictive power. The IVCLA was developed with the purpose of serving as an effective tool for guiding environmental managers in designing conservation strategies and making informed decisions for lake ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The characterization of lake hydromorphology is crucial to understand the dynamics of biodiversity. In Europe, it is also a regulatory requirement of the Water Framework Directive. However, according to the literature, few methods include this characterization. The aim of this study is to review the state of the art of the methods currently used or under development in European countries to assess lake hydromorphological status for the implementation of the WFD. Our analysis is based on responses to a questionnaire distributed to national experts on hydromorphology of the 28 countries implementing the WFD. Our results highlighted significant progress in the assessment of hydromorphological features and processes. Water level regime, through the range of water flow or existing water management, and structure of the shore zone through macrophytes and substrate characteristics or measurement of lateral connectivity, are the most frequently assessed features. Stratification, surface/groundwater connection and planform pattern are the lake features most frequently omitted from the methods. However, in most of the countries, the development of methods was still in progress to meet the WFD requirement. Definition of reference condition is a central component of all WFD compliant assessment tools but this is a challenge particularly in the assessment of hydromorphological alteration of reservoirs. Similarly, demonstrating strong links between hydromorphological indicators and biological quality elements remains a challenge with many knowledge gaps still evident. These results highlight the need for rapid collection of new environmental data and the need for conceptual and applied research to make methodological progress in assessing lake hydromorphology and ensuring habitat quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Lakes in Europe are subject to multiple anthropogenic pressures, such as eutrophication, habitat degradation and introduction of alien species, which are frequently inter-related. Therefore, effective assessment methods addressing multiple pressures are needed. In addition, these systems have to be harmonised (i.e. intercalibrated) to achieve common management objectives across Europe. Assessments of fish communities inform environmental policies on ecological conditions integrating the impacts of multiple pressures. However, the challenge is to ensure consistency in ecological assessments through time, across ecosystem types and across jurisdictional boundaries. To overcome the serious comparability issues between national assessment systems in Europe, a total anthropogenic pressure intensity (TAPI) index was developed as a weighted combination of the most common pressures in European lakes that is validated against 10 national fish-based water quality assessment systems using data from 556 lakes. Multi-pressure indices showed significantly higher correlations with fish indices than single-pressure indices. The best-performing index combines eutrophication, hydromorphological alterations and human use intensity of lakes. For specific lake types also biological pressures may constitute an important additional pressure. The best-performing index showed a strong correlation with eight national fish-based assessment systems. This index can be used in lake management for assessing total anthropogenic pressure on lake ecosystems and creates a benchmark for comparison of fish assessments independent of fish community composition, size structure and fishing-gear. We argue that fish-based multiple-pressure assessment tools should be seen as complementary to single-pressure tools offering the major advantage of integrating direct and indirect effects of multiple pressures over large scales of space and time., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Water resources globally are affected by a complex mixture of stressors resulting from a range of drivers, including urban and agricultural land use, hydropower generation and climate change. Understanding how stressors interfere and impact upon ecological status and ecosystem services is essential for developing effective River Basin Management Plans and shaping future environmental policy. This paper details the nature of these problems for Europe's water resources and the need to find solutions at a range of spatial scales. In terms of the latter, we describe the aims and approaches of the EU-funded project MARS (Managing Aquatic ecosystems and water Resources under multiple Stress) and the conceptual and analytical framework that it is adopting to provide this knowledge, understanding and tools needed to address multiple stressors. MARS is operating at three scales: At the water body scale, the mechanistic understanding of stressor interactions and their impact upon water resources, ecological status and ecosystem services will be examined through multi-factorial experiments and the analysis of long time-series. At the river basin scale, modelling and empirical approaches will be adopted to characterise relationships between multiple stressors and ecological responses, functions, services and water resources. The effects of future land use and mitigation scenarios in 16 European river basins will be assessed. At the European scale, large-scale spatial analysis will be carried out to identify the relationships amongst stress intensity, ecological status and service provision, with a special focus on large transboundary rivers, lakes and fish. The project will support managers and policy makers in the practical implementation of the Water Framework Directive (WFD), of related legislation and of the Blueprint to Safeguard Europe's Water Resources by advising the 3rd River Basin Management Planning cycle, the revision of the WFD and by developing new tools for diagnosing and predicting multiple stressors., (Copyright © 2014. Published by Elsevier B.V.)

The Water Framework Directive (WFD) is now well established as the key management imperative in river basins across Europe. However, there remain significant concerns with the way WFD is implemented and there is now a need for water managers and scientists to communicate better in order to find solutions to these concerns. To address this, a Science-Policy Interface (SPI) activity was launched in 2010 led by Directorate-General for Research and Innovation and Onema (the French national agency for water and aquatic ecosystems), which provided an interactive forum to connect scientists and WFD end-users. One major aim of the SPI activity was to establish a list of the most crucial research and development needs for enhancing WFD implementation. This paper synthesises the recommendations from this event highlighting 10 priority issues relating to ecological status. For lakes, temporary streams and transitional and coastal waters, WFD implementation still suffers from a lack of WFD-compliant bioassessment methods. For rivers, special attention is required to assess the ecological impacts of hydromorphological alterations on biological communities, notably those affecting river continuity and riparian covering. Spatial extrapolation tools are needed in order to evaluate ecological status for water bodies for which no data are available. The need for more functional bioassessment tools as complements to usual WFD-compliant tools, and to connect clearly good ecological state, biodiversity and ecosystem services when implementing WFD were also identified as crucial issues., (Copyright © 2014 Elsevier B.V. All rights reserved.)