Structure of planktonic and benthic diatom communities in the Zelenci springVideska, Anastasija (Avtor) Zelnik, Igor (Mentor) limnocrene springsdiatomstychoplanktonepipelonZelenciThis study focused on the diatom communities in the limnocrene spring Zelenci, chosen for its unique structure. Our aim was to assess how underwater springs and abiotic factors influence the structure of diatom communities in different habitats. Four sampling sites were chosen, two for tychoplankton and two for epipelon, located on the accessible side of the pool. Plankton was collected from the piers using a plankton net and epipelon was collected from the silty substrate in the littoral zone. Abiotic parameters were measured on all sites, and water samples were taken for chemical analysis. Different statistical analyses were performed to reveal the relations between abiotic factors and the structure of diatom communities. Water level and temperature reflected seasonal patterns, higher and colder in winter, lower and warmer in summer. conductivity was relatively high due to the limestone substrate. Occasional peaks in PO₄³⁻, NH₄⁺, and NO₃⁻ were likely caused by anthropogenic activity in the catchment area. Achnanthidium minutissimum was the most abundant species in both mesohabitats, while Navicula was the most numerous genus. Tychoplanktonic communities showed greater internal similarity among samples compared to epipelic communities. The trophic index indicated eutrophic conditions, while the Shannon–Wiener index remained high, particularly at the epipelic sampling sites, reflecting the structural complexity and stability of that mesohabitat. Planktonic diatoms dominated tychoplankton samples, while motile ecological type dominated the epipelon. Of all taxa, 23.5% had some endangerment status, and 31.3% had preferences for oligotrophic conditions. Key factors influencing the Shannon-Wiener diversity index were water level, temperature, and concentration of NH₄⁺. The factors, which are most important for the tychoplankton community, were temperature and NH₄⁺, while the most important factors influencing the structure of epipelon communities were water level, NH₄⁺, pH, and concentration of dissolved oxygen.[A. Videska]20252025-09-17 07:16:37Magistrsko delo/naloga173375sl