Species composition of freshwater lichens in temperate mountain streams

Abstract

Lichens associated with aquatic and semi-aquatic habitats are a specific ecological group of symbiotic organisms. Distribution patterns, especially those of freshwater lichens and factors determining their occurrence, are poorly recognized. The species richness and composition of lichens were studied in the splash and submerged zones of Carpathian mountain streams. Habitat parameters, including pH, water conductivity, dissolved oxygen content, silting and light intensity at sampling sites, were used in the analysis. The streams differed greatly in terms of the species composition; only three lichens (Thelidium minutulum, Verrucaria hydrophila and V. praetermissa) of the entire pool of 29 recorded species were found in all streams. This fact does not directly relate to the habitat parameters measured either at the level of individual streams or considering all the streams studied. Instead, the differences in the species composition of lichens increased with the geographical distance between streams, even locally. This means that the occurrence of lichens in mountain streams is strongly site-dependent and the variability in the habitat is of less importance for species presence. Presumably lack of effective natural vectors and weak dispersal ability are strong limiting factors for freshwater lichens. Nevertheless, increased ion concentration in water can considerably promote the development of the thalli of some species of lichens, as in the case of Verrucaria praetermissa, while it can be a limiting factor for others, as in the case of V. hydrophila.

Freshwater Lichens, Including New Species in the Genera Verrucaria, Placopyrenium and Circinaria, Associated with Lobothallia hydrocharis (Poelt & Nimis) Sohrabi & Nimis from Watercourses of Sardinia

“…In recent decades, the freshwater lichen biota of northern and central Europe has been being increasingly studied [ 4 , 5 , 6 , 7 , 8 ], shedding light both on phylogenetic relationships within critical groups (such as the family Verrucariaceae) [ 9 , 10 , 11 , 12 ] and on the ecological requirements of the species [ 13 , 14 , 15 ]. In contrast, for Mediterranean areas, field inventories are scarce [ 16 , 17 , 18 ] and molecular data complementing morphologically identified material of freshwater lichens are missing.…”

New data on freshwater lichens in Mediterranean streams

“…Rocks subjected to periodic immersion by intermittent watercourses are colonized by diverse lichen species (Nascimbene & Nimis, 2006;Coste, 2009;Krzewicka et al, 2020). These rocks endure variable duration of immersion, with those close to the center of the stream being exposed much longer than those at the upper limit of the streambed (Coste, 2009;Krzewicka et al, 2017).…”

“…These rocks endure variable duration of immersion, with those close to the center of the stream being exposed much longer than those at the upper limit of the streambed (Coste, 2009;Krzewicka et al, 2017). In freshwater habitats lichen diversity is very low compared to terrestrial habitats, although they represent a unique fraction of understudied flora composed of a few taxonomic groups that are "specialist taxa" (Nascimbene & Nimis, 2006;Thüs et al, 2014;Krzewicka et al, 2020).…”

Acta Biologica Cracoviensia s. Botanica

“…There are both desiccationsensitive and desiccation-tolerant lichens (Kranner et al, 2008). Similarly, species with radically different requirements for humidity and water supply conditions can be found among lichens (Munzi et al, 2019;Krzewicka et al, 2020).…”