engleski

Reactivated Channels Along Tufa Barrier as Favorable Habitat for Colonization of Microfauna

Uncontrolled growth of invasive tree species Ailanthus altissima (Mill.) Swinge, commonly known as tree of heaven, caused drying of water channels along the longest tufa barrier (Skradinski buk) located within the National Park Krka, Croatia. Removal of A. altissima resulted in reactivation of five channels, which have been dry for decades. Our goal was to investigate the impact of the invasive species removal on the periphytic microfauna colonization. To reach the goal, the invasive species was removed in several repetitive campaigns during 2017 and 2018. Periphyton samples were collected monthly from October 2017 to December 2018 at seven sites including five newly formed channels and two previously present channels. Periphyton was sampled on both natural (tufa) and artificial (glass slide) substrates. Additionally, water physico- chemical characteristics, organic matter content and tufa deposition rate at each site were measured. Water physico-chemical characteristics showed no significant difference among the newly formed and previously present channels, but they reflected a pronounced seasonal variability. Reactivated channels showed higher nitrite concentrations, but lower pH and dissolved oxygen concentrations, which was likely associated to higher organic matter content originating from forest soil developed on tufa barrier during dry phase. Previously present channels demonstrated denser moss cover and higher tufa deposition rate in comparison to the reactivated channels. Periphyton community in tufa substrate showed higher diversity in reactivated channels, presumably due to lower competition and predatory rates and/or intensive organic matter decomposition processes. Artificial substrate supported diverse community dominated by peritrichs, while vagile periphytic taxa dominated on tufa substrate. The latter could be partly explained by differences in sampling technique: artificial substrate allowed direct examination and is considered as a less destructive sampling method. Environmental data and protozoan assemblage patterns demonstrate that reactivated channels along the tufa barrier represent favorable habitats for microfauna colonization. Our results emphasize the need for multidisciplinary approach in monitoring tufa environments and a continuous and regular sampling in order to make a proper assessment of the complex substrate colonization processes.

multidisciplinary approach ; invasive species ; periphyton community ; Skradinski buk

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