OBSERVATIONS ON THE PRESENCE OF Anguilla anguilla (Linnaeus, 1758) IN LIGURIAN KARST ENVIRONMENTS AND THE DISCOVERY OF LIVE INDIVIDUALS IN THE BORGIO VEREZZI CAVES

Two observations (11/02/2022, 05/12/2023 from Davide Barberis) of Anguilla anguilla (Linnaeus, 1758) individuals in a not-touristic part of the Borgio Verezzi show cave (Liguria, NW Italy) raises intriguing questions regarding the phenology of the species and its potential troglophilic behavior in karst environments adjacent to the coastline. Thanks to the first observation, this preliminary work aimed to confirm the presence of the eel in the hydrographic basins of the karst system to which the Borgio Verezzi cave belong, an area mainly composed of limestone and dolomitic rocks. While awaiting monitoring of the waters within the caves, an initial quantitative sampling was conducted on the Bottassano Brook, one of the few surface watercourses in the area. Its terminal sector is characterized by temporary surface flows as well as potential subsurface flows, whereas, at the confluence with the Rio Carlando, the water contribution and the impermeability of the riverbed allow a residual surface flow useful for the passage and development of the eel. The sampling resulted in the capture of five specimens at different life stages. Future steps should include further sampling in adjacent basins and investigations to understand whether the cave might serve as a passage site (ascending from the sea or descending from adjacent streams via karst connections), or might even represent a trophic and growth area of interest.