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Project aim and Work packages Project partners and Cooperation partners | |||||||||
Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems (RADICAL)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.
The project aim is to estimate the direct and indirect consequences of climate effects on autochthonous whitefish populations by analysing:
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. Objectives: 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. Objectives: 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:
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. Objectives: 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. Objectives: 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). Deliverables: Risk analysis of future whitefish population trends influenced by:
Cooperation partners:
PhD positions: Mag. Harald Ficker (WP1, WP4) Mag. Philipp Trummer (WP2) Mag. Claudia Gusek (WP3) Funding:
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