1. Science and management of intermittent rivers and ephemeral streams: a European perspective

Convenors:
Thibault Datry, IRSTEA, Centre de Lyon-Villeurbanne, France
Gabriel Singer, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
Rachel Stubbington, Nottingham Trent University, UK
Daniel von Schiller, University of the Basque Country, Spain
Petr Pařil, University of Brno, Czechia

Much the European river network is composed of intermittent rivers and ephemeral streams (IRES). Intensified research in recent years has shed new light on IRES ecology, which have been overlooked by freshwater scientists for too long. IRES contribute substantially to catchment-scale biodiversity and biogeochemsitry and provide important ecosystem services. In response to growing academic interest, IRES are now also receiving increased attention from water resource managers, notably within the context of the Water Framework Directive. Building on the development of the COST Action SMIRES (www.smires.eu), this special session will present the latest European research on IRES ecology in the context of global change, to inform advances that address the challenges of managing these ecosystems.

2. Aquatic metacommunities: research and applications

Convenors:

Núria Bonada, FEHM group (Freshwater Ecology, Hydrology and Management), University of Barcelona, Spain
Miguel Cañedo-Argüelles, FEHM group (Freshwater Ecology, Hydrology and Management), University of Barcelona, Spain
Thibault Datry, IRSTEA, Centre de Lyon-Villeurbanne, France
Tibor Erős, MTA Centre for Ecological Research, Tihany, Hungary

The metacommunity framework is helpful to understand how regional freshwater biodiversity is shaped by a combination of biological traits and environmental and landscape filters. However, this rapidly evolving field faces many methodological challenges. For example: 1) quantifying the species’ dispersal abilities by considering life history and morphological traits; 2) measuring the resistance to dispersal imposed by all the landscape barriers (e.g. hydrological connectivity, topography); 3) taking into account spatial and temporal variability. The potential applications of this framework are still being explored. For example, biomonitoring tools could benefit from incorporating species’ dispersal abilities and landscape configuration to provide more realistic indicator values. Also, understanding the main routes for the exchange of species among local communities can be useful for planning biodiversity conservation. Here we will explore new methods and recent findings in metacommunity research, and discuss its potential applications within the frame of global change and the freshwater biodiversity crisis.

3. Hydrology, biogeochemistry and ecology of mountain freshwaters

Convenors:
Sophie Cauvy-Fraunié, IRSTEA, Centre de Lyon-Villeurbanne, France
Georg H. Niedrist, University of Innsbruck, SIL-Austria

Though high mountain freshwaters are generally referred as pristine and remote hydrosystems, they have been and will be affected by multifaceted direct anthropogenic pressures combined with the effects of the ongoing climate change. Water is stored in mountain watersheds during cold seasons, ensuring the availability of high quality water during summer when supply is dropping and demand is highest in lowland areas. However, mountain regions are facing unique challenges through the interaction of both indirect and direct anthropogenic stressors resulting from climate- and land-use change, such as glacier retreat or water abstraction for hydroelectric power productions, which will affect waters quantity and quality, with drastic consequences on freshwater ecosystems. This session will examine hydrology, biogeochemistry, and ecology of mountain freshwaters in relation to ongoing and predicted environmental changes in different regions worldwide and will provide monitoring-, mitigation- and adaptation plans for water management in the future.

4. 10 th UAMRICH (Use of algae for monitoring rivers and comparable habitats)

Convenors:
Marco Cantonati, Museo delle Scienze – MUSE, Trento, Italy
Aleksandra Zgrundo, University of Gdańsk, Poland

The International Symposia on the “Use of Algae for Monitoring Rivers” date back to 1991, and since then offer an opportunity to review and discuss algae-based monitoring approaches in different countries, as well as improvements to approaches, methodologies, and techniques. The main aim of these Symposia has been the standardization of methods, the improvement of legislation and directives, and the discussion of novel approaches. We think that the topic of these symposia is particularly timely nowadays when discussion and revision of algae-based environmental assessments is a “hot topic” both in the EU and in the USA, and metagenomic methods and approaches are emerging. Selected papers presented at the UAMRICH2019 SEFS Special Session Symposium and other excellent solicited or unsolicited contributions on the topic may be included on a Special Issue on the topic proposed to Ecological Indicators.

5. Understanding cross-habitat linkages between stream and riparian zones to optimize management of biodiversity and ecosystem services

Convenor:
Brendan G. McKie, Swedish University of Agricultural Sciences, Uppsala, Sweden

Stream-riparian networks are key components of green and blue infrastructure that underpin landscape integrity, support biodiversity, and sustain human societies. However, these networks are subject to multiple human pressures which affect longitudinal and lateral connectivity, drive habitat and diversity losses, and threaten ecosystem services. This special session will combine presentations from the BiodivERsA project “Understanding cross-habitat linkages between blue and green infrastructure to optimize management of biodiversity, ecosystem services and multiple human uses (CROSSLINK, www.slu.se/Biodiversa_Crosslink), with additional presentations from selected speakers working on related research outside CROSSLINK. The session will focus on how riparian buffers in urban and agricultural settings affect biodiversity, ecosystem processes, and transfers of polyunsaturated fatty acids from stream to riparian food webs. The session will include presentation of results from CROSSLINK field studies conducted in Norway, Sweden, Belgium, and Romania, and will address challenges in balancing multiple values, uses and needs in riparian-stream networks.

6. Linking natural and social science in freshwater ecosystems

Convenors:
Sonia Herrero, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
Susanne Stephan, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
Cleo Stratmann, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
Mandy Velthuis, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany

Aquatic ecosystems are prone to be altered by human-driven actions. As a basis for the sustainable preservation of ecosystems and the services they provide, cooperation between social and natural sciences is of special importance. Studies focusing on the linkage between ecology and societal perception are increasing, as well is the relevance of multidisciplinary collaborations. This session aims to bring together projects that use both natural and social science to study freshwater ecosystems and underline the importance of collaborations of e.g. scientists, managers and citizens. Therefore, we encourage oral presentations and posters on projects on (freshwater) ecosystems with multidisciplinary, collaborative and innovative character with societal relevance. Besides discussing interesting hypotheses, methodological approaches and outcomes, we also want to address the pros and cons that the intersection of natural and social sciences brings along.

7. Linking habitat heterogeneity, biofilm diversity and biogeochemistry across spatiotemporal scales

Convenors:
Ute Risse-Buhl, Department River Ecology, Helmholtz Centre for Environmental Research UFZ, Magdeburg, Germany
Clara Mendoza-Lera, Department of Freshwater Conservation, BTU Cottbus-Senftenberg, Bad Saarow, Germany
Giulia Gionchetta, Institute of Aquatic Ecology, University of Girona, Spain
Chloé Bonnineau, IRSTEA, Centre de Lyon-Villeurbanne, France

Stream biofilms are heterogeneous in space and time conforming microbial landscapes. Within these landscapes, physical habitat heterogeneity at the micro-scale shapes biofilm community development by modulating its diversity (structure and composition) and affecting meta-community dynamics. Similarly, micro-habitat heterogeneity can modulate stream biogeochemistry. Nevertheless the link between microbial diversity and biogeochemistry across spatiotemporal scales is not straightforward. Stream biogeochemistry at reach scale may not necessarily match for microbial communities and their function. In this context, the goal of our session is to explore the links between microbial landscapes and biogeochemistry across spatiotemporal scales. The session will address questions like:
Does habitat heterogeneity modulate microbial diversity and function at micro-habitat scale (e.g. EPS production; prokaryotes and micro-eukaryotes community composition)?
Does inter- or intra-biofilm heterogeneity impact biogeochemical stream processes across spatial scales?
To which extent microbial responses to stressors (e.g. physical, climate change, contaminants) observed at micro-habitat scale influence reach-scale biogeochemistry?

8. From source to sea – characterization and utilization of organic matter from different sources along the aquatic continuum

Convenors:
Katrin Attermeyer, WasserCluster Lunz, Austria
Gabriele Weigelhofer, WasserCluster Lunz, Austria

It is now widely accepted that inland waters transform huge amounts of organic matter during the passage from the source to the sea. The organic matter pools in lakes, streams and rivers originate from different terrestrial or aquatic sources, resulting in contrasting reactivity and degradability. Depending on the properties of the organic matter, its transformation within the aquatic ecosystem can differ with consequences for e.g., the transport to the sea or emissions of greenhouse gases. However, the magnitude and mechanisms of transformations of organic matter from different sources are still not adequately quantified and understood, contributing to a high uncertainty in global biogeochemical cycles. In this session, we seek to bring together research that improves our understanding of the processing of both dissolved and particulate organic matter sources along the aquatic continuum. We solicit contributions characterizing organic matter from different sources and their transformation in experimental, modelling, or field studies.

9. Research needs for European water and nature directives

Convenors:
Sandra Poikane, EC-JRC
Antonio Camacho, University of Valencia, Spain
Co-chair: Daniel Morant, University of Valencia

Science is committed both to create knowledge and to respond to the needs of the Society and Citizens to solve practical problems. We, as European freshwater scientists, are supported by the European citizens and it is our responsibility working jointly to allow a better knowledge and sustainable management of water resources and aquatic ecosystems. During the last decades, the EU developed policies aiming to achieve the improvement of management of water resources and to improve the ecological status of European ecosystems. Water and nature directives are inspired by the ecological knowledge generated by scientists, and its future improvement relies on the advancement that freshwater scientists can provide. In this session we aim to highlight which are the main research needs envisaged to increase the effectiveness of the European water and nature directives, as well as to show the knowledge-based solutions that European freshwater scientists can offer.

10. Balkan rivers, be dammed!

Convenors:
Gabriel Singer, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
Simon Vitecek, University of Vienna, Austria
Sonia Herrero Ortega, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
Marko Miliša, University of Zagreb, Croatia

Pristine ecosystems are the most precious natural heritage that nurses biodiversity, upholds ecosystem function and thus contributes to human well-being. The Balkans still harbour such near-natural areas that moreover are unique models to study biogeodiversity under preserved geomorphology and biogeochemistry and high levels of biodiversity. Because of their immense natural and socio-economic value, these systems are prime targets for multidisciplinary scientific explorations and societal advocacy. Also, they provide essential ecosystem services, such as food, water, transportation and energy. Naturally, increasing demand for these ecosystem services necessitates prudent management to sustainably develop natural resources. The aim of this session is to congregate a diverse community reflecting the complex interfaces of societal demands, scientific and economic interests, conservation planning and political decision-making. Thus, we invite contributions on freshwater biodiversity, aquatic ecology, ecosystem preservation and restoration, and sustainable management of freshwater resources with particular focus on the Balkans.

11. Nature based solutions for urban streams

Convenor:
Tadeusz Fleituch, Institute of Nature Conservation, Polish Academy of Sciences, Cracow, Poland

Nowadays, aquatic scientists and decision makers seek to explore the potential of nature-based solutions (NBS) to address contemporary water management challenges. They focus particularly on water for sustainable cities, disaster risk reduction and water quality. NBS use natural processes to enhance water availability, improve water quality and reduce risks associated with water-related disasters and climate change. The goal of the special session is to find the most appropriate NBS to maximize benefits and system efficiency while minimizing costs and trade-offs. Although NBS are not a panacea, they will play an essential role in the functioning of urban ecosystems and in creating better living conditions in heavily modified urban cities. Humans are an integral part of nature and therefore should live in harmony with it. It is expected that NBS help to improve water security for all kinds of ecological services.

12. Mesocosm approaches to ecosystem-scale questions in freshwaters

Convenors:
Meryem Beklioğlu, Middle East Technical University, Limnology Laboratory, Ankara, Turkey
Stella Berger, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
Lisette de Senerpont Domis, Netherland Institute of Ecology (NIOO), Wagenningen, The Netherlands
Jens Christian Nejstgaard, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany

To obtain mechanistic quantitative understanding of aquatic ecosystem functioning and biogeochemical processes, a range of empirical approaches have been used from laboratory to ecosystem scale. Well controlled and highly replicated small-scale laboratory microcosm experiments have been used to relate changes in food webs to altered environments (e.g. biodiversity loss, nutrient and pollutant inputs, climate change etc.). However, their realism is limited and the extrapolation to natural systems is often difficult. The need to minimize these problems has led to development of experiments on larger scales. Large-scale mesocosm (or enclosure) experiments allow a more realistic setting by including a higher complexity in terms of trophic levels, and thus potential interactions. Thus, mesocosms experiments is a powerful approach to obtain such mechanistic quantitative understanding. To this session we therefore welcome researchers to present their ecosystem-scale empirical work where scientific questions about various aspects of aquatic ecosystem functioning has been tested through using mesocosms.

13. Spring habitats: research, assessment tools and conversation efforts

Convenors:

Stefanie von Fumetti, Department of Environmental Sciences, University of Basel, Switzerland
Vladimir Pešić, Department of Biology, University of Montenegro, Podgorica, Montenegro

Natural springs are unique ecotones, which provide special environmental conditions for a highly adapted fauna and flora. In the Dinaric Alps, e.g., many endemic crenobiontic species were described in the past years. Springs worldwide are faced with severe anthropogenic impacts such as water abstraction, relocation, and cattle trampling. Climatic changes threaten springs additionally. Until now, no standard spring assessment protocol exists in Europe as springs are not included in the European Water Framework Directive. The development of global assessment tools and conservation strategies should be a focus of future efforts in order to be able to sustain or even restore valuable spring habitats globally. In this session we will discuss ongoing spring research and will focus on current assessment and conservation approaches worldwide.