Diversity, distribution and community composition of fish in perialpine lakes – “ Projet Lac ” synthesis report Author Alexander, Timothy Author Seehausen, Ole Eawag: Das Wasserforschungsinstitut des ETH-Bereichs Überlandstrasse 133, CH- 8600 Dübendorf text 2021 2021-11-12 Eawag: Swiss Federal Institute of Aquatic Science and Technology https://www.dora.lib4ri.ch/eawag/islandora/object/eawag:24051 book http://doi.org/10.5281/zenodo.5779569 723c8018-f87a-440a-bed1-3d2fe2a46e42 978-3-906484-76-1 5779569 Alburnus arborella has unfortunately become very rare in Lake Lugano. Only two individuals were caught in Projet Lac ( Figure 38 ). One was a large ( 115 mm TL ) individual of typical appearance with the high count of lateral line scales that Buj et al. [146] describe for A. maxima . The second was of very different appearance, and could not be assigned to A. arborella , A. maxima or A. alburnus . The COI gene (barcode) was sequenced for both fish. They were separated by several mutations, falling into two distinct subclades within samples currently considered A. arborella . The identity and diversity of Alburnus from Lake Lugano should urgently be investigated. Our unquantified impression is that the phenotype that corresponds to A. maxima is shared with Lake Maggiore whereas the other kind seems to resemble Alburnus from Lake Garda. A second unusual observation in Alburnus requires reporting here: we noticed a previously undocumented phenotypic and ecological polymorphism of Alburnus alburnus in Lake Brienz. In this lake, we observed considerable variation in shape: on one hand fish with very long snouts, and on the other hand, blunt-snouted fish that resemble Alburnus alburnus from other lakes ( Figure 39 ). The long-snouted type was commonly caught near the surface whereas the blunt-snouted type could be caught near the surface or in considerable depths down to 20 m .