Diatom communities and vegetation of springs in the south-western Alps

Abstract

-Springs are unique but understudied habitats. Diatom communities have received some attention but have remained largely unknown in the south-western Alps. We therefore studied the springs of the south-western extreme of the Alpine mountain range. We analysed epilithic and epiphytic assemblages in 48 springs of different ecomorphological types, located on contrasting lithological substrata (carbonate/siliceous). Moreover, phytosociological relevés were carried out for carbonate springs. The diatom fl ora consisted of 223 taxa. Most (198) of the taxa were included in the Red List, and 12.5% belonged to threatened categories. Characteristic spring taxa (crenophiles) were present. The ecological preferences of crenophilous diatom species described in the eastern Alps were confi rmed. Diatom species characteristic of the lake-littoral zone were found in pool springs. We observed no signifi cant differences in species richness and diversity between epilithic and epiphytic assemblages, but some species showed a preference for bryophytes, and fi ve occurred in the epibryon only. As regards moisture conditions, 15% of the taxa occurred on wet or temporarily dry sites, and 4% lived mostly outside water bodies. The main environmental factors infl uencing diatom assemblages were pH, conductivity, altitude, and shading. The carbonate-substratum crenic vegetation was composed of a mixture of vascular plants and bryophytes, which fi nd their ecological optimum in springs. Bryophyte cover was dominant, with the most abundant taxa belonging to the genus Palustriella. The vegetation corresponded to the Cratoneuretum commutati association.

Microbial mats as shelter microhabitat for amphipods in an intermittent karstic spring

“…circulare is a pennate araphid diatom with thickened silica ribs (costae) oriented transversely across the valve (Kociolek et al, 2011). It is a widely distributed member of benthic and periphytic (epilithic and epiphytic) communities of various freshwater ecosystems including brooks (Krejci and Lowe, 1987), streams (B-Béres et al, 2016), karstic springs and spring-fed streams (Cantonati and Ortler, 1998;Delgado et al, 2013) and alpine springs (Cantonati and Lange-Bertalot, 2010;Mogna et al, 2015). It forms fan-shaped colonies with cells enclosed within a mucilaginous polysaccharide matrix (Lock et al, 1984).…”

Valuable habitats of protected areas in southern Poland – a source of rare and poorly known diatom species

“…The species occurred under oligotrophic conditions, where the pH was alkaline (8.0) and conductivity was low [57]. The species was later reported several times from sources in the Alps [58][59][60], and recently in Serbia in two small mountain rivers, in the epilithon and epibryon [61]. The species developed in oligotrophic conditions in the upper, shaded parts of small streams with a rapid current, and among mosses.…”

Diatoms in Paleoenvironmental Studies of Peatlands

“…Diatoms are one of the most ubiquitous and diverse photosynthetic microorganisms in aquatic ecosystems [27] and one of the most widely represented algal groups in peat bogs (e.g., [28][29][30][31][32]). The diversity of diatoms in the peatlands of Europe is very high, with around 403 recorded taxa, and a majority representation of the genera Pinnularia (14%), Eunotia (10%), and Navicula (10%), with respect to the total number of taxa [28,29,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], and with similar species numbers and compositions to those found in peatlands in other regions of the world due to the cosmopolitan nature of diatom species (e.g., [30,31,51,52]). However, knowledge about the ecology of diatom communities in peatlands is still insufficient compared with other types of wetlands [25].…”