Species richness and composition patterns of clitellate (Annelida) assemblages in the treeless spring fens: the effect of water chemistry and substrate

Abstract

Spring fens are isolated treeless wetlands of a high conservation value. Their environmental conditions are strongly related to their groundwater chemistry, which controls species distribution within various groups of organisms. Clitellates, a dominant group of non-insect aquatic fauna, however, have never been studied in these habitats. It is unclear from previous studies to what extent the distribution of aquatic non-insect taxa reflects water chemistry rather than the substrate structure. We studied 34 spring fens sampled in 17 isolated sites in the Western Carpathian Mountains to determine mainly the effects of water chemistry and substrate structure on variation in species richness and composition of clitellate assemblages as examples of the non-insect fauna. A total of 34 taxa were found, with 3-15 taxa collected per sample. Species richness was negatively correlated with water mineral concentration measured as water electric conductivity (r = -0.57, P \ 0.001) and positively with TOC (r = 0.60, P \ 0.001). Surprisingly, the lowest number of taxa was found in calcareous fens and richness increased towards Sphagnum-fens. There was a species turnover related to changes in mineral richness and substrate characters. The main change of species composition was promoted by changes in substrate structure. The second gradient of species composition was linked with the amount of nutrients, moisture, and dominance of sphagna, and was associated with an increase of eurytopic species in fens with high nutrient availability. It was difficult to separate the effects of water chemistry and substrate on clitellate species distributions owing to the fact that variation in tufa precipitation and vegetation was driven by water chemistry changes. This study presented the first quantitative data on fen clitellate assemblages, which appear to have an unusual pattern of species richness. In contrast to plants and molluscs, calcareous fens appeared to be a harsh environment for clitellate species. Only few specialized species, mainly Trichodrilus strandi, were able to establish viable populations. The significant effect of water chemistry on clitellate distribution patterns raises questions about the direct influence of water chemistry on non-insect aquatic taxa, which have previously been considered to be mostly determined by substrate characteristics.

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

“…In the West Carpathians spring fens, the gradient of nutrients is indicated by an increasing number of nutrient-demanding grassland species in low-productive fen vegetation Rozbrojová and Hájek, 2008). This change is accompanied by a decrease of fen specialists and their replacement by ubiquitous species, as has been confirmed for the assemblages of molluscs and clitellates (Bojková et al, 2011). Despite a possible influence of pasture on some of the sites, the degradation of spring fens to more fertile fen meadows is predominantly generated by a natural process of mineralisation, which follows desiccation of the upper soil layer due to seasonal decreases of water table, and it is not connected with pollution .…”

“…site) as unweighted averages of values for all vascular plants present in the phytosociological relevé, using the JUICE 7.0 software (Tichý, 2002). Although the EIVs are based on the empirical knowledge of vegetation scientists, they have proved to be also very useful in studies on animal and aquatic ecology, yielding good estimates of environmental variables which are difficult to measure directly in the field (Horsák et al, 2007;Bojková et al, 2011).…”

“…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).…”

Springs☆

“…Geology Location of discharge Subaerial (emerges onto land surface) Subglacial (emerges beneath a glacier) Subaqueous or submerged (emerges underneath a large body of water) Sublacustrine (emerges beneath a lake) Subriverine (emerges beneath a river) Submarine (emerges beneath an ocean) Karstic openings on ocean floor (called vruljas) Geothermal vents on ocean floor 1, 21, 36, 39, 43 Onshore springs (discharge above mean low-tide line; includes subaerial, sublacustrine, and subriverine springs) Offshore springs (discharge below mean low-tide line; synonymous with submarine springs) 36 Other (nonexclusive) types include base-level springs that emerge at sea or lake level or at valley floor, hanging springs that emerge above bodies of surface water or above valley floor, buried springs that emerge below a valley floor, intertidal springs that emerge between high tide and low tide, and riverbed springs that emerge in riverbeds 1st magnitude (>2830 l s À1 ) 2nd magnitude (283-2830 l s À1 ) 3rd magnitude (28.3-283 l s À1 ) 4th magnitude (6.3-28.3 l s À1 ) 5th magnitude (0.63-6.3 l s À1 ) 6th magnitude (63-630 ml s À1 ) 7th magnitude (8-63 ml s À1 ) 8th magnitude (<8 ml s À1 ) 2 5 Low volume (<0.01 m 3 s À1 ) Medium volume (0.01-0.5 m 3 s À1 ) High volume (>0.5 m 3 s À1 ) 9 Source(s) of discharge Diffuse versus conduit (tubular) 37 Single opening versus multiple openings 15, 21 Seepage or filtration spring (discharge oozing from numerous small openings in porous rock material) Vent spring (discharge flowing from an opening or openings larger than the mean pore space of surrounding rock material) 36 Full-flow (fed by entire aquifer) Underflow (fed constantly and continuously by baseflow of aquifer because of relatively low elevation of discharge point) Overflow (fed variably and/or discontinuously by overflow of aquifer during flood conditions because of relatively high elevation of discharge point) Underflow-overflow (fed by baseflow and overflow because of intermediate elevation of discharge point) 13,38,49 Conduit type at spring Open, horizontal conduit with airspace (gravity spring) Water-filled, vertical conduit (pressure, artesian or vauclusian spring) 38 Size of aquifer and length of flow path Local springs fed by small, shallow aquifers (short flow paths with fluctuating discharges) Regional springs fed by large, extensive aquifers (long flow paths, with relatively constant discharges) 34 Location of aquifer Above impermeable rock material (perched springs) Below impermeable rock material (confined springs) 38 Source of recharge water…”

Environmental impact of heated mining waters on clitellate (Annelida: Clitellata) assemblages

“…However, in stagnant waters, the diversity of clitellates was reduced to only a few of the most resistant species in very low densities (Krodkiewska 2005). Conductivity has been found to be one of the basic variables that induce changes in clitellate assemblages, with a decrease in diversity being caused by increasing conductivity (Bojková et al 2011). While results have been recorded for conductivity resulting from Ca 2+ and Mg 2+ ion concentration, there have been no previous reports about the effect of SO 2− 4 ion concentration on clitellate assemblage changes.…”