Up to date the ecosystem services (ES) of alpine lakes are poorly characterized. The aim of this study is to find out how ongoing climate change affects the function of alpine lakes and in consequence the provision of ES, taking climate change into account. The study design takes advantage from long-term monitoring of alpine lakes located in the Northern and Southern Alps.

First, the variability of the response of alpine lakes to global warming within the last two decades will be explored on a quantitative scale. Lake surface temperature (LST) reconstructions covering the previous decades will be validated by in situ temperature records from two decades earlier and also recorded during this study. Plankton and fish community will be analysed using modern metabarcoding techniques based on deep-amplicon sequencing.

Second, the ES will be quantitatively assessed for the lake-types. Provisioning and regulating ES will be quantified using data from limnological measurements as well as complex modelling approaches, whereas cultural ES will be based on crowd-sourced information suitable to assess human preferences or by specific surveys based on questionnaires. Validated LST models will allow for assessment of alpine lakes’ resistance towards disturbances which will affect the ability to maintain ES under potential impacts of climate change.

Third, the ES provided by those lakes will be evaluated using multi criteria decision analysis comparing representative lakes of defined lake-types in both model regions. This will include defining the most important ES through an experts' round table and a pair-wise questionnaire for ES weighing to be compiled by local stakeholders. The ES management under a scenario of climate change will be addressed through comparative ES evaluation for the near and distant future. Finally policy recommendations to facilitate future ES management in order to guarantee sustainable ES provision will be elaborated.

Environmental partitioning of manufactured nanomaterials contamination in Lake Mondsee and Irrsee was investigated in 2015-2017. During summer 2015 silver was detected in the inflow and outflow of the wastewater treatment plant (WWTP) as well as at the discharge point (DP) of the WWTP using ICP-MS. In summer 2016, silver was solely detected at the inflow of the WWTP. For all other samples, silver concentrations were below the limit of quantification (LOQ). SP-ICP-MS unveiled silver containing nanoparticles in the in- and outflow of the WWTP suggesting high removal efficiency. Total silver concentrations in WWTP sludge was found between 2.27 and 2.68 μg Ag/g sludge with little variation. In the sediment of Lake Mondsee, total silver concentrations of up to 1.76 μg Ag/g sediment were detected at the DP, whereas total silver concentrations at the sampling sites at 2, 4, and 6 km distance were low (0.08 to 0.13 μg Ag/g sediment). No silver was detected at bathing areas and the reference lake. For fish organs, ICP-MS and dark-field microscopy did not provide evidence for silver. Finally, the results of the water, sediment, and sludge analysis suggest that the WWTP constantly introduces very low doses of silver and silver containing nanoparticles to Lake Mondsee, resulting in an enrichment of silver in the lake’s sediment at the DP. Furthermore, apart from the DP, silver is evenly distributing throughout the sediment of Lake Mondsee at very low concentrations, whereas no silver was detected in the reference lake. Despite the constant inflow of wastewater to Lake Mondsee, no silver was detected in all fish samples, thus the silver discharge at very low doses to the lake do not result in detectable bioaccumulation in fish.

A slogan which became fashionable in recent years is ecosystem services. This concept was implicitly discussed by scientists for decades and finally introduced and popularized the Millennium Ecosystem Assessment (MA 2005). A brief history of the concept and a terminology of ecosystem services were offered by Daily (1997). The concept quantifies the services presented by ecosystems and their usage by man. This instrument shall allow the estimation of ecological consequences of e.g. climatic changes and their impacts on the society. The theory defines ecosystem services as benefits for people and distinguishes four categories: 1. Supporting services necessary for all other services (e.g. photosynthesis, matter cycling); 2. Provisioning services supplying products to man such as water, energy, food etc.; 3. Regulating services proving benefits by system regulation (e.g. waste decay, purification of water); 4. Cultural services which are nonmaterial benefits people obtain from ecosystems such as religious, spiritual or recreational values.

The question remains however, if there is anything like ‘ecosystem service’. Nature does not offer a ‘service’ but provides valuable prerequisites for the use of ecosystems by man. The concept is of rather hypothetical and anthro­pocentric nature, emphasizes the fictitious character of ecosystem commodities and promotes an exploitative relation to nature. It has also been argued that the concept is normative implying that all results of ecosystem processes are desirable (Schröter et al. 2014).

A critical debate on ecosystem services seems timely and essential particularly with respect to pristine mountain lakes which are more vulnerable than other ecosystems. Exploitation of such lakes can disturb or even disrupt their resistance or resilience and may conflict with biodiversity. Finally, the concept might even counteract large scale socio-economic problems such as global climate change.

Alpine lakes are considered pristine freshwater ecosystems and most sensitive to direct and indirect changes in water temperature as induced by climate change. The bacterial plankton constitutes a key component in the water column and bacterial metabolic activity has direct consequences for water quality. In order to understand bacterial response to global temperature change the planktonic bacterial community in five alpine lakes located in the Austrian Alps (1700–2188 m a.S.L.) was analysed using deep amplicon sequencing for two consecutive vegetation periods in summer 2010 and 2011. Microbial composition differed among lakes, with a greater difference among lakes in the late growing season than in the early growing season. In general water temperature (after spring circulation) as well as nutrients (Cl^-, dissolved organic carbon) were influencing the composition during early growing season, while nutrients only (nitrate) showed significant influence during later season. Besides habitat size the average water temperature (WAS) after spring circulation was related to bacterioplankton richness and diversity which fits the metabolic theory of ecology (MTE). The relative abundance of metabolism-related genes increased along with WAS implying that metabolism is also directly controlled by water temperature. In summary our study points to global temperature rise effects on bacterial community in alpine lakes during the earlier growing season. During later growth periods the limiting role of temperature rise on bacterial composition appears to be outweighed by regional and/or stochastic factors. Thus, in this study climatic change response in alpine lakes is mostly seen through reduced ice cover duration linked to earlier ice break up and subsequently reducing the limiting role of temperature in the water column.

Innovative Ecological Assessment and Water Management Strategy for the Protection of Ecosystem Services in Alpine Lakes and Rivers (Eco-AlpsWater)

Rainer Kurmayer¹, Adriano Boscaini², Jean-Marc Baudoin³, Serena Bernabei⁴, Camilla Capelli⁵, Isabelle Domaizon⁶, Stefanie Dobrovolny⁷, Tina Elersek⁸, Claudia Greco⁴, Giorgio Franzini⁹, Peter Hufnagl⁷, Aleksandra Krivograd Klemenčič¹⁰, Fabio Lepori⁵, Ute Mischke¹¹, Špela Remec-Rekar¹⁰, Nico Salmaso², Jochen Schaumburg¹¹, Michael Schubert¹², Karmen Stanic⁸, C. Vogelmann¹², Josef Wanzenböck¹, C. Zampieri⁹

¹LFUI, University of Innsbruck, Research Dep. of Limnology, Mondsee (Presenter)

²FEM, Fondazione Edmund Mach, (IT), (Lead partner),

³AFB, The French Agency for Biodiversity (FR),

⁴ISPRA, Italian National Institute for Environmental Protection and Research (IT)

⁵SUPSI, University of Applied Sciences and Arts (CH),

⁶INRA, National Institute for Agricultural Research (FR),

⁷AGES, Austrian Agency for Health and Food Safety (AT),

⁸NIB, National Institute of Biology (SI),

⁹ARPAV, Regional Environmental Agency, Veneto (IT),

¹⁰ARSO, Slovenian Environment Agency (SI),

¹¹LfU, Bavarian Environmental Agency (DE),

¹²LfL, Bavarian State Research Center for Agriculture, (DE),

A project recently co-funded through the Alpine Space program with the aim to improve surface water quality monitoring, by (i) advanced DNA sequencing techniques enabling metabarcoding of aquatic biota relevant for the implementation of the EU Water Frame Work Directive and the Swiss Water Protection Ordinance, and (ii) novel technologies in data processing (automation in data processing, data storage, information retrieval).

Along with the identification of gaps in the monitoring approaches across the Alpine regions, the new technologies will allow to define improved experimental monitoring protocols to be applied in selected areas (including large perialpine lakes and smaller waterbodies, and key rivers). The transnational approach fills the scientific divide between academia and governance agencies, putting into practice the EUSALP agenda, i.e. capacity building of research institutions, networks and infrastructure with an alpine region dimension.

More info can be found at www.alpine-space.eu/eco-alpswater .

Lake surface temperature (LST) is a key characteristic of lakes, shaping the ecological properties of these inland water bodies and their environment.

In order to provide future LSTs for alpine lakes, we employ data gained through several measuring campaigns (carried out in 1998-1999, 2010-2012, and 2019-2020) as well as techniques established and applied in LST reconstruction back to 1880. Concerning the latter, monthly temperature records from Austrian lakes covering a period of about six decades have been digitized from hydrological yearbooks and clustering techniques were applied for the identification of lake-groups sharing high inner coherence and outer separation. These clusters do not only allow for sensible quality assessments, but also provide proper starting conditions for homogenization procedures, warranting high-quality data. Therefrom, reconstructions back to 1880 have been derived via sets of transfer-functions that have been selected in an extensive validation-framework, accomplished by conducting 160 million experiments. LST developments throughout the second half of the 20th century up to date are characterized by a temperature decline until the mid-1980s induced by high atmospheric loads of industrial aerosols (‘global dimming’), followed by a pronounced increase caused by the implementation of international agreements (‘clean air acts’) gradually unmasking mankind’s CO₂ forcing.

The derivation of local-scale LST projections until 2100 is based on large-scale climate-change projections produced in a large number of GCM runs that were forced by three pathways of mankind - ‘business as usual’ (RCP8.5), ‘first measures’ (RCP4.5), and the ‘2 degree C goal, Paris 2015’ (RCP2.6,). Since GCM projections carry no significance on regional-scales downscaling is mandatory to add physics/processes between the GCM-scale and the local-scale of lakes. In doing so we make use of an empirical-statistical technique (ESD). Resulting local-scale (e.g. air-temperature) corridors for each pathway are then to be transformed into LSTs by the techniques applied in reconstruction.

The rapid melting of glacier cover is one of the most obvious impacts of climate change on alpine ecosystems and biodiversity. Our understanding of the impact of a decrease in glacier runoff on aquatic biodiversity is currently based on the “glacier-heterogeneity-diversity” paradigm, according to which there is high α-diversity at intermediate levels of glacial influence due to the high degree of environmental heterogeneity caused by glacier water. This α-diversity pattern generates high levels of between-site aquatic community variation (high β diversity) and increases regional diversity (γ-diversity). There is a rich conceptual background in favor of this paradigm, but empirical data supporting it are scarce. We investigated this paradigm by analyzing the different diversity patterns (α, β, and γ-diversity) of four aquatic groups (zooplankton, macroinvertebrates, algae and macrophytes) living in high-elevation peatlands (> 4500 m above sea level). We sampled 200 pools from 20 peatlands along a glacier gradient in the Cordillera Real of Bolivia. We performed structural equation modeling (SEM) to analyze the potential mechanisms underlying the observed diversity patterns. Intermediate levels of glacial influence (15-20% cover) resulted in high heterogeneity, but α-diversity responded to glacial influence only for the zooplankton group (Cladocera). Our SEM analysis did not identify environmental heterogeneity as a significant variable explaining the relationship between glacier and α-diversity. Peatland area had a strong positive effect on heterogeneity and diversity. β-diversity was significantly associated with glacier gradient and 12.9% of the total regional diversity (γ-diversity) was restricted to peatlands with a high degree of glacial influence. These species might be lost in a context of glacial retreat. These findings provide new insight into the potential effects of glacial retreat on the aquatic environment and biodiversity in the peatlands of the tropical Andes.