Sulphidic spring exposed during dry period drives ecotone formation in the karst Reka River ecosystem at Skocjanske jame, Slovenia

During extremely dry period in the river bed of the Reka River before it sinks in karst caves of Skocjanske jame (Slovenia), a sulphidic spring emerged, which was first observed in 2017. Such an abrupt change in the river ecosystem had an evident impact in formation of an ecotone with geochemical gradients. The submitted 16S rRNA data contains information on microbial communities of spring water, and the white and brown biofilms that have formed in the spring.