Which factors shape macrozoobenthic communities in tufa springs? Results from Austrian meteogene travertine-depositing sites

Abstract

By studying 14 travertine-depositing springs all over Austria, we hypothesized the existence of (1) key elements of the physical and chemical template ultimately defining the structure of macroinvertebrate taxa composition and (2) a specific, travertine-associated macrozoobenthic taxa community in an environment shaped by ongoing deposition of calcium carbonate and the ever-changing limestone structures thereby created. For testing these hypotheses, we measured 29 geological and limnochemical parameters and collected benthic macroinvertebrates on travertine, coarse and fine particular organic matter microhabitats in a spring and autumn sampling run. The results identified four parameters significantly shaping taxa composition: sinter coverage, total phosphorous, oxygen concentration and the Langelier saturation index. The macroinvertebrate community was predominantly composed of stygobiontic taxa from groundwater refugia and of immigrated generalists that prefer the stable conditions offered in spring habitats. We found only few species and specialists separating study sites, the majority being well-known spring- and headwater-dwelling species without adaptation to high carbonate precipitation or association with travertine. Nonetheless, carbonate precipitation leads to higher structural heterogeneity and provides a range of new niches, which contribute to broader ranges of taxonomic diversity.