Scientific publications

In this study, 8 of the 11 lakes on Valaam Island were surveyed: Leshchevoe, Nikonovskoe, Krestovoe, Sisjarvi, Igumenskoe, Chernoe, Ossievo, and Germanovskoe. Ichthyological fieldwork on lakes Nikonovskoe and Leschevoe in June 2025 was the first effort of this kind for these lakes; additionally, interview data and photographic materials from 2004–2026 were used. The fish species composition in Lake Nikonovskoe was described for the first time: the common crucian carp (Carassius carassius (L., 1758)), the silver crucian carp (C. auratus (L., 1758)), and the sunbleak (Leucaspius delineatus (Heckel, 1843)) were identified. The presence of 6 fish species was confirmed for Lake Leschevoe, and 3 species for Lake Sisjarvi. The ichthyological types of the lakes were compared with classifications based on macrophytes, plankton, and abiotic factors. The results show that data on the fish community add qualitatively meaningful information to the limnological description of water bodies, allowing for a finer rating of trophicity and saprobity (e.g., dystrophic and hypereutrophic conditions) and reflecting the long term status of the ecosystem. These results can be used to develop a bioindication system for small lakes of Karelia and to model aquatic ecosystems of the Valaam Archipelago.