(Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems)

Deep lakes in the Alps

Deep lakes in the Alps are of outermost ecological and socio-economic importance in Austria and the other Peri-Alpine countries. In the 1960 ties and 1970 ties many of these lakes have been under threat due to eutrophication, a consequence of intensive agriculture and urbanisation of the countryside and the booming tourist industry. Only due to sewage water treatment a period of re-oligotrophication was achieved starting in the 1980 ties. However, the same lakes are again under threat, as the last two decades have witnessed major changes in global climate directly resulting in a general increase of lake temperatures, longer vegetation periods and stronger thermal stratification. Indirect effects include increased run-off and nutrient input during periods of heavy precipitation. Consequently the effects of global change are likely to run counter to the reductions in nutrient loading rather than reinforcing re-oligotrophication, i.e. increasing phytoplankton and toxic cyanobacteria.

Whitefish occurring in deep lakes in the Alps

Among fish the planktivorous whitefish (Coregonus sp.) are one of the most temperature sensitive fish species as they depend on low egg developmental temperatures and high oxygen concentrations, which is only found in the cold, deep water zone of Alpine lakes. Whitefish are of high fishing value and due to their endemic nature these populations are of concern in conserving our biodiversity. Besides direct temperature effects such as shifts in spawning times, indirect effects via changes in plankton community structure causing mal-nutrition and even poisoning due to toxin-producing cyanobacteria are expected to be of even higher significance. In this project, we follow the hypothesis that deep Alpine lakes are at risk to lose a major part of their ecological and socio-economic value in the course of climate change, because.

  • coregonid fish stocks will slump, due to direct demographic effects of increased temperature and indirect effects, since

  • filamentous, toxic cyanobacteria will (re-) increase, thus counteracting re-oligotrophication efforts and adversely affecting other biota including coregonid fish.

Project aim

The project aim is to estimate the direct and indirect consequences of climate effects on autochthonous whitefish populations by analysing:

  • the effects of regional climate changes on phytoplankton growth,

  • the exposure of early life stages of whitefish to toxic cyanobacteria at chronic/subchronic levels,

  • the demographic consequences for autochthonous whitefish populations in the next few decades under a changing plankton community composition subject to various climate scenarios.

This approach is possible by combining the expertise from various interdisciplinary teams structured into four work packages (fish ecology, plankton ecology, ecotoxicology and integrative modelling). The project will focus on two contrasting study lakes, the mesotrophic Lake Mondsee (max depth 68 m) and oligotrophic Lake Hallstätter See (max depth 125 m) in the Salzkammergut Lake district. The latter is under strong influence of the Dachstein glacier and known to be most sensitive to direct temperature changes. In contrast Lake Mondsee has higher densities of toxic cyanobacteria that are known to damage the gastrointestinal tract, liver and kidneys in whitefish.

Work packages (WP)

1-4: WP1) Fish ecology

Demographic data on whitefish populations are partly available and will be collected and used to construct size- and age structured whitefish population models.


Construct an age-structured population model for whitefish in Mondsee and Hallstättersee using RAMAS (Risk Analysis and Management Alternatives Software). Derive necessary demographic data from existing databases (previous mark-recapture experiment at Mondsee, previous PhD project on population dynamics of larval/juvenile whitefish at Hallstättersee, test fishing for assessment of ecological status of lakes required for the European Water Framework Directive Calibrate model with demographic data of whitefish populations acquired during first 2 years of project (echosounding, test fishing), and cross-validate with existing models constructed for other European populations

WP2) Phytoplankton community structure

Physical conditions in the lakes affecting phytoplankton will be monitored together with the horizontal/vertical distribution of phytoplankton/zooplankton including toxic cyanobacteria.


Provide quantitative data on phytoplankton/cyanobacteria and zooplankton for risk analysis of future population trends in WP4. Furthermore, mass cultures of toxic cyanobacteria to be used in WP3 will be provided. Provide quantitative data on:

  • lake physics (vertical stratification, vertical mixing, light availability in the water column) as basis for modelling of cyanobacterial stratification

  • the variability of occurrence of hepatotoxic cyanobacteria in relation to environmental (climatic) factors in the field both temporally and vertically through the water column (as basis for algal modelling and fish exposure assessment)

  • Model cyanobacterial population/phytoplankton abundance and vertical/horizontal distribution in dependence on climate effects, physical conditions and nutrient conditions

  • Estimate vertical/horizontal variability in concentrations of microcystin in Lake Mondsee as basis for modelling in WP4.

WP3) Ecotoxicology

The pathological and life history effects of exposure to toxic cyanobacteria will be estimated through laboratory experiments while specific symptoms will also be analysed in the field.


Assess effects of cyanobacteria on whitefish populations in Mondsee and Hallstättersee conducting a field survey on free-living fishes to check histopathological damages as observed in exposure experiments. Aim of the laboratory experiments is to characterize the developmental and behavioural toxicity of Cyanobacteria/Microcystins on early life stages of the fish by means of conventional Effective Concentrations (EC-values).

WP4) Integrative modelling

The results on phytoplankton vertical and seasonal composition/distribution will be used to parameterise the phytoplankton model ultimately predicting responses of the phytoplankton community to environmental change. Together with the results obtained in WP1-3 they will be used to assess the risk of population decline in whitefish populations under various climate scenarios. The results will be of relevance to the tourism sector, the fisheries management, as well as to authorities responsible for nature and biodiversity conservation.


Integrate the results obtained in WP1-WP3 to predict whitefish population developments under future climate scenarios (direct effects) and to assess risks of cyanobacterial blooms under future climate scenarios associated with increased production of toxins, effects on various components of the plankton community and especially on future whitefish population development considering ecotoxicological risks (indirect effects).


Risk analysis of future whitefish population trends influenced by:

  • Changed climatic conditions (direct effects)
  • Increased cyanobacterial populations and higher toxin concentration (indirect effects)

Project partners

  • Univ. Doz. Dr. Josef Wanzenböck
    Research Institute for Limnology, Mondsee of the University of Innsbruck, AUT

  • Univ. Doz. Dr. Rainer Kurmayer,
    Research Institute for Limnology, Mondsee of the University of Innsbruck, AUT

  • Prof. Dr. Britta Grillitsch
    Aquatic Ecotoxicology Section, Department for Biomedical Sciences, University of Veterinary Medicine Vienna, AUT

Cooperation partners

  • Dr. Ian Winfield (WP1)
    Centre for Ecology & Hydrology, National Environment Research Council, GB

  • Dr. Hubert Gassner (WP1, WP4)
    Federal Agency for Water Management, Institute for Freshwater Ecology, Fisheries Biology and Lake Research, AUT

  • Prof. Dr. Anthony Walsby (WP2)
    School of Biological Sciences, University of Bristol, GB

  • Dr. Alex Elliott (WP2, WP4)
    Centre for Ecology & Hydrology, National Environment Research Council, GB

  • Dr. Bernhard Ernst (WP 3)
    Human & Environmental Toxicology Research Group, University of Konstanz, GER

  • Prof. Dr. Ingrid Walter (WP3)
    Histology and Embryology, Department for Pathobiology, University of Veterinary Medicine Vienna, AUT

PhD positions

  • Mag. Harald Ficker (WP1, WP4)
  • Mag. Philipp Trummer (WP2)
  • Mag. Claudia Gusek (WP3)


Niedermeyer T.H.J., Schmieder P., Kurmayer R. (2014). Isolation of Microcystins from the Cyanobacterium
Planktothrix rubescens Strain No80. Nat. Prod. Bioprospect. 4:37–45. DOI 10.1007/s13659-013-0001-3

Ficker H., Mazzucco R., Gassner H., Wanzenböck J., Dieckmann, U. (2014). Fish length exclusively determines sexual maturation in European white-fish Coregonus lavaretus (L.) species complex. Journal of Fish Biology 84: 1164-1170, doi:10.1111/jfb.12301

Presseaussendung Wanzenböck, S. (2010): “Vergiftet der Klimawandel unsere Seen? - Klimafolgenforschung am Mondsee, Austria Presseagentur, Zukunftwissen, 16. und 17.3.2010. Link


Wanzenböck, J., Kurmayer, R., Ficker, H. (2014). RADICAL – Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems – Eine (vorläufige) Endbilanz. Presentation at the 15. Österreichischer Klimatag, University of Innsbruck; April, 2-4, 2014. Link

Kurmayer, R. (2012). Modellierung der Auswirkung veränderlicher Umweltbedingungen auf das Wachstum von Cyanobakterien in einem tiefen See der Voralpen. Präsentation der Ergebnisse von WP 2 (Algenökologie). SIL-Austria Meeting, Pörtschach, Austria, September 28-29, 2012. Link

Ficker, H. interner Bericht (2012). IASA Young Scientist Summer Program. Link

Wanzenböck, J., Kurmayer, R., Grillitsch, B. (2012). Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems (RADICAL) – Eine Zwischenbilanz. Presentation at the 13. Österreichischer Klimatag: Klima, Klimawandel, Auswirkungen und Anpassung sowie Klimaschutz in Österreich, University of Natural Ressources and Life Sciences, Vienna; June, 14-1, 2012. Link

Ficker, H., Wanzenböck, J. (2011). Population projection matrix models (PPMs) for whitefish (Coregonus maraena) derived from gillnet catch data corrected by the SELECT-method. Vortrag beim "11th International Symposium on the Biology and Management of Coregonid Fishes“ – 26. - 30. Sept. 2011 in Mondsee, Österreich. Link

Trummer, P., Kurmayer, R. (2011). Modelling the response of stratifying cyanobacteria to changing climate conditions in a deep mesotrophic lake. Presentation at the 12. Österreichischer Klimatag: Forschung zu Klima, Klimawandel, Auswirkungen und Anpassung in Österreich,  University of Natural Ressources and Life Sciences, Vienna; September, 21-22, 2011. Link

Dissertantenseminar an der Universität Salzburg, Organismische Biologie – Vortrag über das Projekt RADICAL von H. Ficker, 2010.

Präsentation des Projektes beim internationalen Symposium „Fresh Blood for Fresh Water“ in Lunz, Österreich (Posterpräsentationen von H. Ficker und P. Trummer). Link

Präsentation des Projektkonzeptes bei der internationalen Konferenz: Fish and Climate Change – Fisheries Society of the British Isles, Queen's University, Belfast, Nordirland, UK 26-30 July 2010, Posterpräsentation J. Wanzenböck. Link

Wanzenböck, J., Kurmayer, R., Grillitsch, B. (2010). RADICAL Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems - Concept for a recently started project. Presentation at the 11. Österreichischer Klimatag, University of Natural Ressources and Life Sciences, Vienna; March, 11-12, 2010. Link


Logo "Klima Energie Fonds"Austrian Climate and Energy Fund – Austrian Climate Research Programme (ACRP)

Dieses Projekt wird aus Mitteln des Klima- und Energiefonds gefördert und im Rahmen des Programms „ACRP“ durchgeführt.



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