Diet Composition of Salmonids from two Alpine Lakes: Preliminary Insights from Stomach Content Analysis
1
, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, Torino, TO - 10154, Italia
2
, Centro di Referenza Regionale per la Biodiversità degli Ambienti Acquatici (BioAqua), Via Lino Maritano 22, Avigliana, TO - 10051, Italia
3
Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri 10, Trieste, TS - 34127, Italia
4
Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, Perugia, PG - 06123, Italia
Alpine lakes are ecologically sensitive and relatively pristine ecosystems where fish introductions or changes in predator populations can have significant cascading effects on native biota. In this study, we investigate the diet composition of salmonids in three glacial lakes of the Friuli Venezia Giulia region in northeastern Italy: Fusine Inferiore (928 m a.s.l.), Fusine Superiore (929 m a.s.l.), and Raibl (959 m a.s.l., also known as Lago del Predil). These oligotrophic lakes, of glacial origin and located near the border with Slovenia, host populations of alpine char Salvelinus umbla. Its status in the region remains uncertain, whether native or introduced, making it crucial to assess its ecological role and potential impact on lake food webs. We analyzed stomach contents from multiple individuals across different size classes to explore possible ontogenetic dietary shifts and spatial variation in feeding behavior. Prey items were identified to the lowest feasible taxonomic level, including both aquatic and terrestrial invertebrates. Preliminary results and multivariate analysis reveal marked differences in diet composition among lakes, likely influenced by variation in habitat structure and local prey availability. Chironomid larvae, trichopterans, and other benthic macroinvertebrates dominated the diet, with some variation linked to fish size. These early findings highlight the trophic plasticity of S. umbla and the importance of understanding its feeding ecology for assessing the potential effects on native macrobenthic communities and terrestrial insects. Continued investigation will support conservation and management strategies in these fragile alpine systems.
Effetti del disturbo sui sistemi ecologici