An Evaluation of the Impact of Hiking Tourism on the Ecological Status of Alpine Lakes—A Case Study of the Valley of Dolina Pięciu Stawów Polskich in the Tatra Mountains

Eutrophication is one of the major threats to the quality of water in high mountain lakes. The inflow of elements having biological origin may significantly aggravate the ecological status of those ecosystems. For this reason, the aim of this study was to map and assess the impact of anthropogenic pressure on alpine lakes in the valley of Dolina Pięciu Stawów Polskich (known in English as the Valley of Five Polish Lakes) in the Tatra National Park in Poland. The effects of tourism and easy access to alpine lakes on changes in their ecological status were determined. Tourist trails were evaluated based on the difficulty of access to the water surface of analyzed alpine lakes, with a method developed for assessing anthropogenic pressure on aquatic ecosystems. The method, deployed for the first time in 2019, was modified and adapted to the local environmental conditions in the research area. The results of this study indicate that tourism pressure contributes to the growth of submerged vegetation in alpine lakes. The presence of aquatic plants (including vascular plants) shows ecosystem response to water enrichment with biogenic substances. The present findings were used to formulate practical recommendations and propose modifications to the evaluated hiking trails. The research method developed in the study can support analysis and control of tourist traffic, thus reducing anthropogenic pressure on alpine lakes in national parks located in mountain areas.