engleski

What lies beneath: protozoan assemblages on tufa barrier microhabitats

Tufa depositing environments create myriad of microhabitats for periphyton. Precipitation of calcite may increase heterogeneity, but it can also present a certain stress for periphyton. Different crevices in tufa and undersides of rocks might present less changing environment. The aim of this study was to determine dynamics of tufa deposition and periphyton development on artificial substrates (glass slides) facing upwards (U) and downwards (D) within tufa- depositing sites. The experiment was conducted in situ on tufa barrier Skradinski buk (Croatia) from June to September 2014 with sampling after one month of exposition. Tufa deposits were about four-foldhigher on substrates facing upwards than downwards (averagely 3.9 vs. 0.5 mg CaCO3/cm2), and there was about three-fold more organic matter on U compared to D substrates. However, diversity of protozoa and micro-metazoa was higher on D (85 taxa) compared to U substrates (65 taxa) likely due to more favorable microhabitat. Ciliates had the highest taxa numbers (51 on D and 41 on U substrates) as well as highest share in abundance (92% and 88%, respectively). Sessile forms prevailed among ciliates, having a share of 96% (D substrates) and 97% (U substrates) in abundance. Suctorians dominated on U substrates, while peritrichs had highest share in abundance on D substrates. Both groups probably utilize plenty of food flowing over the barrier from upstream Visovačko Lake, as tufa barriers in this system also function as lake outlets. Endemic folliculinid ciliate Lagotia dinaridica colonized only substrates facing downwards.

artificial substrate ; ciliates ; tufa deposition

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