Dipteran assemblages of spring fens closely follow the gradient of groundwater mineral richness

Abstract

Groundwater chemistry is a major determinant of assemblages of various taxonomic groups in spring fens, but its effect on insect assemblages has not been proved yet. We investigated dipteran assemblages at 17 isolated spring fens, which encompass the whole mineral richness gradient from rich (calcareous) to poor (highly acidic) sites, and analyzed faunal patterns at two contrasting mesohabitats: flowing water and standing water. The effect of water chemistry, substratum features, discharge, and temperature on the dipteran assemblages were assessed using PERMANOVA and GAM. Highly diverse dipteran assemblages (156 taxa) were closely related to the mineral richness gradient at both mesohabitats, showing a continual and nearly complete species exchange along the gradient, while their total abundance and taxa density did not change significantly. The assemblages included both habitat generalists and taxa specifically associated with acidic, moderate, or calcareous conditions. The mineral richness gradient was also reflected by changes in substratum properties, thus creating a complex environmental gradient that we suggest is the main environmental gradient structuring aquatic assemblages in spring fens.

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

“…This family includes a range of organic matter-dwelling taxa such as Tanypodinae and Tanytarsini, which inhabit muddy fPOM sediments, and subfamily Orthocladiinae associated with bryophytes adjoining mud and gravel (Lencioni et al, 2012). This distribution pattern is in line with other studies (Thienemann, 1924(Thienemann, , 1934Hahn, 2000;Staudacher & Füreder, 2007;Lencioni et al, 2011;Omelková et al, 2013).…”

“…The convergence of these different habitats, paired with the very special hydrochemical characteristics of travertine-depositing springs and headwaters, leads to distinct taxa sets combining both groundwater-dwelling and headwater-dwelling organisms present in other spring areas as well (Hahn, 2000;Staudacher & Füreder, 2007;Křoupalová et al, 2011;Omelková et al, 2013). A well-known example of a species confined to stable, travertine-depositing springs is the caddisfly Rhyacophila pubescens which was present in 6 out of 14 sites in the present study.…”

The harpacticoid assemblages (Copepoda: Harpacticoida) in the Western Carpathian spring fens in relation to environmental variables and habitat age

“…Negative effect of low pH in the spring fens of Western Carpathians has been confirmed especially for calcium-dependent invertebrates, e.g. molluscs (Horsák and Hájek, 2003), calcified dipteran larvae (Omelková et al, 2013), and ostracods (Zhai et al, 2015). For noncalcified crustaceans including copepods it has been reported from other springs and streams (e.g.…”

“…Palmer et al, 1995;Robertson et al, 1995). Although differences in flow conditions between or within sites can be significant for spring invertebrate fauna (Roca and Baltanás, 1993;Stoch et al, 2011;Omelková et al, 2013;Rádková et al, 2014a), permanent spring fens exhibit relatively temporally stable conditions (Cantonati et al, 2006).…”

“…It comprises joint changes in many parameters of the water chemistry, such as conductivity, pH, dissolved oxygen, redox potential, and concentrations of Ca 2+ , Mg 2+ , and HCO 3− ions . This gradient significantly influences the structure of various aquatic and terrestrial assemblages, including algae (Poulíčková et al, 2003(Poulíčková et al, , 2005Fránková et al, 2009), bryophytes and vascular plants , testate amoebae (Opravilová and Hájek, 2006), molluscs (Horsák and Hájek, 2003), clitellates (Bojková et al, 2011), dipteran larvae (Omelková et al, 2013), and ostracods (Zhai et al, 2015). Other environmental gradients which have been shown to have a significant influence in determining aquatic assemblages in the Western Carpathian spring fens are: total organic matter, sediment structure, and amount of nutrients Bojková et al, 2011;Omelková et al, 2013).…”