First Report on a 5-Year Monitoring of Lampenflora in a Famous Show Cave in Serbia

Many show caves are vulnerable to various disturbances, meaning that conservation of such habitats, which would include monitoring of their ecological parameters and lampenflora (a growing problem worldwide), should be a priority. For the first time in Serbia, lampenflora was monitored continously for 5 years (2016–2020), three times per year during the tourist season, in the Lazar Cave. Artificial light created favorable conditions for the proliferation of phototrophic microorganisms that were developed not only as epiliths, but also endoliths, which poses a greater danger for cave substratum and structures. Although a higher diversity in general was found in Cyanobacteria (coccoid forms mostly), Chlorophyta were more widespread and abundant in samples, among which Chlorella, Stichococcus bacillaris, and Klebsormidium flaccidum stood out. Chlorella is one of the genera making lampenflora dangerous, as it can switch from an autotrophic to a mixotrophic, and finally to a heterotrophic lifestyle. The mosses protonema and mosses itself were also present. Even though the cave is closed for 6 months every year, lampenflora “legacy” always persisted on all sites from the previous year, spreading further over the years. Measured parameters (temperature, relative air humidity, light intensity, substrate pH, and substratum moisture), primary production, and biofilm parameters showed yearly, seasonal, or sampling site variations. Statistical analyses were used to examine the effect of the sampling year, the season, and sampling site on the selected measured parameters, while multivariate analyses were performed with taxa in relation to year, season, site, and main ecological parameters. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12371-022-00771-z.