RS03 – Presentation

High trait variability in a globally invasive cyanobacterium

Sarah Bolius (bolius@uni-potsdam.de), University of Potsdam, Dept. Ecology and Ecosystem Modelling
Claudia Wiedner, Brandenburg University of Technology Cottbus-Senftenberg

Guntram Weithoff, University of Potsdam
Biological invasions are severe threats to freshwater biodiversity. One globally important species is the tropic diazotrophic cyanobacterium Cylindrospermopsis raciborskii, which expanded its distribution worldwide in the last decades. The reasons of its invasion success are still not fully understood. In two experiments, under nutrient replete (eutrophic lake) and P-limited conditions (bloom) we investigated relevant ecophysiological traits in 12 genetically different isolates of C. raciborskii, from Northeast German lakes and determined how variable they are. C. raciborskii was highly variable and exhibited a wide range of nutrient ratios (C:N:P), growth rates, nitrogen fixation and grazing losses. However, we found no trade-offs between the two experimental conditions. The grazing loss of C. raciborskii depended on its filament length.
Our results imply that Cylindrospermopsis is adapted to both, P-replete and bloom conditions, reflecting a generalists behaviour. The invasiveness may be mostly related to the C to nutrient ratio under P-limitation and the subsequent P-uptake after P-pulses. This high flexibility appears to be more important than the ability to fix nitrogen or low grazing losses. Nevertheless, in a community context, a combination of various traits in relation to the ambient community will finally determine the invasion success.
SS09 – Presentation

Spatial arrangement of EU habitats in lowland wetlands: contribution of Natura 2000 to biodiversity in a hyper-exploited agricultural landscape

Rossano Bolpagni (rossano.bolpagni@unipr.it), University of Parma
Simone Guareschi, Alex Laini
Wetlands are among the most impacted ecosystems worldwide and the species they support among the most threatened taxa. This is especially true in agricultural landscape, where wetlands play multiple key processes for local biodiversity and ecosystem functioning. A case example is the Po plain (Northern Italy), one of the most productive plains in the northern Hemisphere. Here, inland wetlands cover less than 5% of the pristine surfaces. Focusing on a complex of 22 Natura 2000 sites of the Emilia-Romagna region, we explored the spatial patterns of European Union (EU) habitats of conservation concern to assess the effectiveness of local programs for nature conservation on aquatic taxa and wetland habitats. A total of 271 wetlands were characterized with the aim to identify the role played by geography, hydrology, connectivity, land use and climate in determining the spatial patterns of habitat richness. Additionally, we tested the relationships between habitats, community composition and species richness of waterbirds and other taxa of community interest. Site and water surface area, as well as connectivity were the major drivers of habitat diversity, whereas land use in the surroundings had scarce effect. Our results showed a good concordance between assemblage patterns of both habitats and taxonomic groups that may be related to the complexity of local niche availability. The present results also suggest the need to improve the hydrological connectivity of wetlands, favouring multiple submerging/emerging phases.
RS15 – Presentation

The effect of thermopeaking on the development and composition of periphyton

Elisabeth Bondar-Kunze (elisabeth.bondar@boku.ac.at), Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, University of Natural Resources and Life Sciences, Vienna, Max Emanuelstr. 17, A-1180 Vienna, Austria
Veronica Kasper, Thomas Hein
Periphyton plays a major role in lotic ecosystems and is often affected by multiple stressors. Thermopeaking (TP) combines stress of sudden flow velocity increase and abrupt water temperature alteration. The aim of this study was to provide knowledge about the impact of TP on periphyton, considering as well successional and habitat aspects. An experiment was conducted for 52 days in Lunz am See (Austria) in an experimental flume setting. The major investigated algal parameters were biomass, algal pigment distribution and phosphatase activity. Periphyton was exposed to two treatments (cold TP and warm TP, ± appr. 10°C) and no treatment (control), whereas TP was performed daily for one hour. Additionally, flumes were subdivided into pool and riffle sections and habitat specific effects were investigated. The findings showed that TP had an effect on periphyton, foremost only when treatment time and habitat effects were included: After 52 days of treatment periphyton exposed to warm TP showed lower biomass, while cold TP enhanced phosphatase activity. Furthermore, in pools algal community composition after 52 days was altered (cold TP increase of diatoms, control increase of chlorophytes). Also, in pools and riffles algal biomass was triggered by TP. The main conclusion was that TP altered community composition which in turn impacted other investigated parameters. Restoration projects should address effects of hydropower plant operation by considering the seasonal development of algae, local habitat conditions and environmental flow approaches.
SS16 – Presentation

The effect of desiccation events on the phosphorus adsorption of floodplain sediments and the contribution of the microbial community to the phosphorus up-take

Elisabeth Bondar-Kunze (elisabeth.bondar@boku.ac.at), Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, University of Natural Resources and Life Sciences, Vienna, Max Emanuelstr. 17, A-1180 Vienna, Austria
Thomas Hein
Large river floodplain systems play a key role in the transport, transformation and storage of nutrients, especially phosphorus. The introduced phosphorus is either subject to short-term storage mediated by plants and algae or to long-term storage mediated by sediment deposition or adsorption. Sorption–desorption processes within the sediment are influenced by the mineral composition of the sediment, microbial activity and dry-wet cycles. Due to major changes such as climate change, human alteration of flow regime and land use, the hydrology of riverine floodplains can be altered. This can lead to longer dry periods in the floodplain which may also alter the sorption and desorption processes. The present study was conducted to evaluate the impact of drying on the adsorption capacity of two different floodplain sediment types (different grain size and organic content) and the contribution of the microbial community to the phosphorus up-take. Core samples were collected at two different connected sites in the Danube floodplain area “Untere Lobau”, east of Vienna. Sediment characteristics (nutrient content, organic content, grain size) were analysed and after two desiccation periods (10 and 20 days) phosphorus adsorption capacity was measured with gamma sterilized sediment to exclude microbial activity and with untreated sediment (with microbial activity). The presentation wants to give an overview on the first results of this laboratory experiment and the conclusions which can be drawn for restoration measures.
SS17 – Presentation

Thermal variability drives CO2 evasion from Alpine coldwater streams

Kyle Boodoo (kyle.boodoo@univie.ac.at), University of Vienna
Jakob Schelker
Tom Battin *
Gravel bars (GB) are capable of absorbing and transferring heat to the underlying hyporheic zone (HZ). We studied seasonal and diurnal thermal and CO2 flux variability within an Alpine cold water stream (Oberer Seebach, Austria - OSB) over the course of a year and conducted spot sampling at this and 12 other gravel bars within the surrounding catchments. We found the vertical temperature profiles within the OSB to vary seasonally and with discharge. Temperatures within the active (wetted) hyporheic zone of the OSB were warmer than both end members, surface water and groundwater >18% of the year. CO2 fluxes from the GB varied spatially and temporally, and average daily and seasonal fluxes exceeded that of its stream. Higher temperature gradients were associated with increased CO2 evasion fluxes within the OSB, particularly during summer. This is likely the result of downward heat transfer in the GB in summer, potentially enhancing GB metabolism and therefore CO2 evasion. Per unit area CO2 fluxes from all 13 GBs studied exceeded that of their streams. Vertical temperature gradient as a measure of heat flux to the hyporheic zone explained 55% and 69% of the variability in observed CO2 efflux from the OSB (seasonal samplings during summer 2015 – winter 2016) and during spot sampling. These results highlight the effect of increasing temperature on physical and biochemical stream processes, and are increasingly important due to the occurrence of more frequent and intense warm temperature events, as well as altered flow regimes, likely consequences of climatic change.
RS17 – Presentation

Conserving freshwater ecosystems: past, present and future

Philip Boon (philipjboon@btinternet.com), The Freshwater Biological Association
This paper looks back over the last 30 years and reflects on the way that freshwater nature conservation has changed, particularly in the UK and Europe, and identifies some areas where further progress is needed. This period has seen significant evolution in the philosophy, perspectives and practice of conservation, with one of the major drivers the passage of national and international legislation. International agreements such as the Convention on Biological Diversity, and European Union statutes such as the Habitats Directive and the Water Framework Directive have led to a reassessment of priorities in catchment management. The conservation of freshwater habitats and species, while not yet as distinct a field of endeavour as its marine counterpart, has spread into new areas. Many of these trends are reflected in the publication history of Aquatic Conservation: Marine and Freshwater Ecosystems, a journal that began life 25 years ago. Environmental pressures that were scarcely discussed then, such as climate change and the spread of invasive species, have grown in significance. New tools and techniques – in fields such as remote sensing, genetics, and data analysis – have been developed and applied in conservation studies, and new approaches focused on managing freshwater ecosystems at the catchment scale are increasingly being adopted. Yet despite many advances, weaknesses still remain, especially in the relationship between freshwater science and conservation. Those involved in conservation must articulate better the science needed for effective conservation; conversely, scientists must cultivate a greater awareness of the relevance of their research to conservation.
RS17 – Poster

Integrating hydrobiology and landscape architecture in the touristic development and management of a thermal lake

Zsombor Boromisza (zsombor.boromisza@gmail.com), Szent István University, Department of Landscape Protection and Reclamation
Dr. Ferenc Szilágyi, Budapest University of Technology and Economics, Department of Sanitary and Environmental Engineering
The importance of this study is nested in the unique water quality and in the complexity of the challenges. The increasing demand for thermal water generates a number of environmental issues, starting form the effects of abstraction, to emitting them into surface waters as waste water. In 2014, a comprehensive touristic project was started in Zalakaros (Hungary), with a construction of an 1,2 ha artificial lake – as a new attraction and a secondary use of water – filled up with a spa’s used thermal water. The physical and chemical conditions make this standing water a unique lake, and special habitat (e.g. high conductivity, low productivity). To fit this new development into the landscape, protected plant relocation, aquatic and riparian machropyte planting, lake management – maintenance, nature interpretation had to be planned as well. To ensure a reasoned decision-making process, we analysed the terrestrial vegetation, sediment and water quality sampling processes had been performed, and the succession of machrophytes are systematically monitored.
In the third year, the results cover natural succession processes (“rise and fall” of specific macrophyte species in various years: Echinochloa crus-galli, Cladophora sp., Myriophyllum sp.), planted macrophyte survival rates, change tendencies of water chemistry, phytoplankton species composition (dominant species: Cladophora sp., Navicula sp., Nitzschia sp., picoalgae species), management strategies, as well. To maximize the ecosystem services in a dynamic, rapidly changing lake ecosystem, to balance between social demands and long-term sustainability, a cooperation of various experts and decision-makers is required, coupled with crucial timing of interventions and maintenance processes.
RS09 – Presentation

The impact of melting processes on macrobenthic communities within an alpine headwater stream

Roberta Bottarin (Roberta.Bottarin@eurac.edu), Eurac Research - Institute for Alpine Environment
Ulrike Tappeiner - University of Innsbruck, Institute of Ecology (A)
Alberto Scotti - Eurac Research, Institute of Alpine Environment (I)
High alpine catchments are characterized by significant variations of meteorological conditions in space and time, complex hydrogeological situations and heterogeneous snow cover dynamics. Typically, alpine streams lead to large increases of runoff rates during the melting period, in spring and early summer. Even minor changes of the environmental conditions can have significant consequences on biological communities. Although numerous small alpine valleys are still often not investigated at all from the zoological point of view.
The main objective of this research is to assess the effects of climate change and in particularly of the melting period on the macrobenthic community of the Saldura Stream (BZ). This perennial glacier alpine stream is located within the Central Alps (South Tyrol, Italy). The whole catchment (ca. 100 km2) belongs to an LTER-site. Three sampling stations are monitored since 7 years monthly during the snow free period (April - September). The biological analysis allows to determine taxa distribution patterns along an altitudinal transect of a glacier stream and their changes in space and time. The results show that the presence of a glacier within the drainage basin influences the abiotic parameters of the water course (in particular the discharge) over a wide range of time-scales. Longitudinal as well as seasonal distribution patterns of macroinvertebrate communities are evident. In particular, the increasing discharge due to the snow- and ice melting corresponds to a decreasing trend of total faunal density and number of taxa.
SS08 – Presentation

On the way to implementation of ecogenomic indices for river biomonitoring: a French progress report for diatoms

Agnès BOUCHEZ (agnes.bouchez@inra.fr), UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
Kermarrec L., Asconit Consultants, Parc Scientifique Tony Garnier, 6-8 Espace Henry Vallée, 69366 Lyon Cedex 07, France
Reyjol Y., French National Agency for Water and Aquatic Environments, DAST, 5 sq. Félix Nadar, 94300 Vincennes, France
Tapolczai K.,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
Vasselon V.,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
Rimet F.,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
The best picture of an ecosystem health is provided by the biological characteristics of the communities that live in it, in comparison to a reference state, free from anthropogenic pressures. These are the founding ideas of the WFD. In France, the long-standing efforts to monitor water quality have led to the development of bioassessment methods based on diatoms since the 1980s. These methods have then been brought into compatibility with the WFD for freshwater.
The simultaneous development of DNA barcoding and of high-throughput DNA sequencing (HTS) has led to the emergence of the idea of using such approaches to characterize environmental communities. Since the 2010s, “proof of concept” as well as environmental scaling-up have shown their potential to evaluate health status of rivers. Tools and tests have been progressively released for applying diatom DNA metabarcoding in the context of bioassessement. Although many technical issues have been enlightened for diatoms (DNA barcode, DNA extraction, Reference library…), many are still pending (DNA preservation, HTS technology, sequencing depth, quantification…).
Different indicators can then be produced: WFD-friendly ones (community structure at species level, comparison to reference state), or indicators better exploiting the big data from HTS. However, taxonomical and ecological expertise of current stakeholders and comparability to historical data should not be left out when implementing these indicators. Going towards WFD implementation of DNA-based diatom indicators will also require standardized procedures (CEN standards) and collective implementation with the numerous stakeholders (SMEs, academics, environmental managers…) at national and European levels.
SS08 – Poster

SYNAQUA: A French-Swiss program to modernize the environmental biomonitoring of Lake Geneva and transboundary rivers

Agnès BOUCHEZ (agnes.bouchez@inra.fr), UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
A. Cordonier,Direction Générale de l'Eau, Canton de Genève, avenue Sainte-Clotilde 25, CP 78, 1211 Genève 8, Switzerland
I. Domaizon,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
B.J.D. Ferrari,Centre Ecotox, Eawag/EPFL, EPFL-ENAC-IIE-GE, station 2, 1015 Lausanne, Switzerland
S. Jacquet,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
E. Lefrançois,Asconit Consultants, Parc Scientifique Tony Garnier, 6-8 Espace Henry Vallée, 69366 Lyon Cedex 07, France
A.L. Mazenq, Asters, Conservatoire d’Espaces Naturels de Haute-Savoie, 84 route du Viéran, PAE de Pré Mairy, 74370 Pringy, France
A. Pawlowska,ID-Gene Ecodiagnostics, c/o fondation Eclosion, 14 chemin des Aulx, 1228 Plan-les-Ouates, Switzerland
L. Perret-Gentil, UNIGE, 30 quai Ernest Ansermet, 1211 Genève 4, Switzerland
F. Rimet,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
J.F. Rubin, Fondation Maison de la Rivière, Chemin du Boiron 2, 1131 Tolochenaz, Switzerland
E. Servoli,ID-Gene Ecodiagnostics, c/o fondation Eclosion, 14 chemin des Aulx, 1228 Plan-les-Ouates, Switzerland
D. Trevisan,UMR CARRTEL, INRA, Université Savoie Mont Blanc, 74200 Thonon-les-bains, France
R. Vivien,Centre Ecotox, Eawag/EPFL, EPFL-ENAC-IIE-GE, station 2, 1015 Lausanne, Switzerland
J. Pawlowski, UNIGE, 30 quai Ernest Ansermet, 1211 Genève 4, Switzerland
Rivers and lakes play a major role in the environment by providing not only habitat for fauna and flora, but also improving the landscape and therefore the quality of life. The effectiveness of environmental protection measures rests on the early and precise identification of pressure points, which should be facilitated by environmental genomics. To implement measures to preserve or restore aquatic areas, the SYNAQUA project proposes to use the genetic tools based on the recognition of bio-indicator organisms present in the aquatic environment directly from their DNA. The method of environmental DNA analysis, will be tested by Swiss and French scientists in collaboration with public and private stakeholders on two groups of bioindicators commonly used for water quality assessment: diatoms and oligochaetes.
The aim is to bring together scientists, environment managers as well as public and private partners in Switzerland and France to develop and apply this DNA-based broadband approach to biomonitoring of regional aquatic ecosystems. Collaboration between public and private stakeholders will help to develop a robust and reliable tool that is tailored to their needs and will strengthen the current practice of environmental diagnosis. The innovative tools that will be developed in synergy in France and Switzerland should make it possible to respond to the need for better monitoring and protection of the regional heritage of aquatic environments in a rapidly changing area subject to multiple pressures.