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Projet Lac: Building a “time zero” data base for fish in pre-alpine lakes to assess the impacts of environmental change

Fish communities in large deep lakes around the Alps are of major ecological, commercial and recreational value. They are however exposed to many anthropogenic stressors and change rapidly. To identify driving forces, quantitative fish community data is crucially needed. Such data does not exist for large pre-alpine lakes. We therefore launched an initiative to bring together government and research institutions from 3 countries to fill this gap. We designed and tested methods and applied them to several lakes.

The importance of biodiversity for human welfare is widely recognized. It is also widely recognized that the rates of loss currently exceed those in the largest mass extinctions in the history of the earth. Biodiversity loss affects all habitats but it is particularly dramatic in aquatic ecosystems. Over the last half century, organic pollution and structural habitat modification has caused substantial alterations to freshwater ecosystems worldwide, translating into massive species abundance shifts and losses of biodiversity. The task of conservation is to ensure biodiversity can be rescued with minimal loss through the coming decades of increasing environmental perturbations. Documenting, understanding and predicting the response of ecological communities to these changes is therefore of pivotal urgency. As a consequence, the European community has developed the Water Framework Directive (WFD) requesting all member states to restore rivers and lakes to a “good ecological status” by 2015. To achieve this, member states have to assess the present ecological state and biodiversity of all water bodies.

The pre-alpine lakes of Europe are a hotspot of endemic species diversity of cold-adapted fish. Switzerland carries an international responsibility to preserve this unique fish fauna. These lakes have experienced massive anthropogenic stress recently. Yet, how fish communities in these lakes respond to the major changes in the environment is largely unknown. Our own data suggest large scale loss of whitefish diversity across many lakes. Worryingly, quantitative information on the genetic and species composition of fish communities is largely lacking. A global assessment, similar to the water framework directive, is not planned in Switzerland. Yet, as a member of UNEP and the Convention on Biological Diversity (CBD), Switzerland too will have to live up to the new agreements, adopted at the 10th meeting of the Conference of the Parties (COP 10) to the 1992 Convention on Biological Diversity. These agreements include a sustainable management and harvesting of all fish stocks; reducing pollution, preventing the extinction of known threatened species; and the restoration of degraded ecosystems 14. A standardized quantitative “time zero” database is thus urgently needed as the benchmark to efficiently preserve biodiversity in lakes.