Lampenflora, the alien of show caves: monitoring and treatments

Caves are often subject to tourist adaptations, causing an irreversible impairment of the bio-geochemical equilibria, which are still not entirely understood, due to the scarcity of information. Between the most worrisome consequences, there is the development of photoautotrophic and mixotrophic communities, called “lampenflora”, growing because of artificial lighting. They are considered the main responsible of the surface alterations, with possible damaging effects, jeopardizing the speleothem conservation, included the still scarcely known vermiculations. This work aims to shed light on the efficacy of monthly chemical (15% H2O2 and commercial bleach) and physical (one night UV-C) growth-control treatments, as well as the triggered alteration processes, on small test surfaces covered by lampenflora, with and without vermiculations. The study, carried out in the tourist lit trail of the Pertosa-Auletta Cave (southern Italy), reports preliminary findings on the photosynthetic activities of such communities, before and after the treatments. The analysis of maximal photochemical yield (MINI-PAM, Walz) was performed through in situ non-destructive chlorophyll fluorescence measurements. The preliminary findings of the research show promising results, highlighting a reduced photosynthetic activity of the lampenflora already after the first two treatments. Indeed, pre-treatment measurements on the dark-adapted surfaces, with and without vermiculations, showed Fv/Fm values between 0.766-0.713 and 0.710-0.663, respectively. After the first H2O2 and bleach treatments, the maximal PSII photochemical efficiency was similar, on average 0.024, and did not change for a month nor after the second treatment, indicating an almost complete reduction of biological activity. For the surfaces interested by UV -C treatments, no detectable effect occurred in relation to the photosynthetic activity, suggesting the need to increase the number of such treatments to twice a month, or even weekly