Janina Kwandrans

Diatom communities of acidic mountain streams in Poland

A comparison has been made of the species composition of diatom communities developing in acidic Polish mountain streams which flow over calcium-poor substrates: sandstones in the Silesian Beskid (section of the Western Carpathians), the Świetokrzyskie Mts, and over granite in the Karkonosze range (in the Sudetic Mts). The number of taxa and diversity of the diatom assemblages decreased along a decreasing pH gradient. The correlation between pH and the number of taxa was positive and significant (r2 = 0.69, p < 0.005). A small number of species (< 20) and low diversity were found in the communities developing in strongly acidic streams such as in the Świetokrzyskie Mts with pH 4.1–5.2, and in the Silesian Beskid with pH 3.5–4.0. In the stream of the Karkonosze Mts, with pH 5.2–6.0, the communities were characterized by their greater number of species and higher diversity.

Molecular and morphological evidence for Sheathia gen. nov. (Batrachospermales, Rhodophyta) and three new species

The freshwater red algal genus Batrachospermum has been shown to be paraphyletic since the first molecular studies of the Batrachospermales. Previous research, along with this study, provides strong support for the clade Batrachospermum section Helminthoidea. This study has found that heterocortication, the presence of both cylindrical and bulbous cells on the main axis, is an underlying synapomorphy of this clade. Based on support from DNA sequences of the rbcL gene, the COI barcode region and the rDNA ITS 1 and 2, along with morphological studies, the new genus Sheathia is proposed. Seven heterocorticate species were recognized from the molecular clades. Sheathia boryana and S. exigua sp. nov. appear to be restricted to Europe, whereas S. confusa occurs in Europe and New Zealand. Sheathia involuta is widespread in the USA and reported for the first time from Europe. Sheathia americana sp. nov., has been collected in the USA and Canada, and S. heterocortica and S. grandis sp. nov. have been collected only in the USA. Sheathia confusa and S. grandis can be distinguished based on morphological characters, whereas DNA sequence data are required to conclusively distinguish the other species. Sheathia fluitans and S. carpoinvolucra also are placed within this genus based on the presence of heterocortication. These data also hint at greater diversity among non‐heterocorticate Sheathia than is recognized by the single species name S. arcuata.

Diversity of freshwater red algae in Europe

Diversity of freshwater red algae in Europe Of the total number of freshwater red algae (ca. 180 taxa), one third are found in Europe (ca. 60 taxa). Over one third (24 taxa) of European taxa have been found at only one single location or at very few locations. The majority of taxa live in running waters, but some occur in lakes, on wet ground, in hot springs or in garden ponds. Diversity in the Nordic countries of Sweden and Finland seems to be somewhat higher (27 and 28 taxa, respectively) than in the central and southern parts of Europe (e.g. Austria 23, Belgium 22, Hungary 9, Poland 22, Slovakia 15, Switzerland 12 and Spain 20 taxa).

Circumscription of species in the genus Sirodotia (Batrachospermales, Rhodophyta) based on molecular and morphological data

Species level taxonomy and phylogeographical distribution patterns in the freshwater rhodophyte Sirodotia are resolved through phylogenetic inferences based on rbcL and cox2–3 sequence data. Previous studies focused on the taxonomy of specific Sirodotia species or the distributions across a limited geographical region. Our molecular phylogenies included samples attributable to five recognized Sirodotia species and include collections from Australia, Brazil, Costa Rica, Canada, Finland, Mexico, New Zealand, South Africa and the United States. Both rbcL and cox2–3 phylogenies inferred S. suecica, S. tenuissima and S. goebelii as a monophyletic group with little sequence divergence. This result supports the synonymy of S. tenuissima and S. goebelii with S. suecica (the species name with priority). Within this clade, samples collected from Australia and New Zealand formed a monophyletic group with no other discernible phylogeographical patterns within S. suecica. This result seems to be somewhat unusual in the Batrachospermales, as other species have shown greater genetic variation among geographically distant locations. As in previous studies, S. huillensis and S. delicatula were inferred as a separate species based on the rbcL phylogeny, supporting the current taxonomy. A specimen of S. aff. huillensis from South Africa, may represent a new species but further research is necessary before it can be designated as such.

Diatoms: unicellular surrogates for macroalgal community structure in streams?

As wholesale biodiversity assessment is often impractical, the use of surrogates that reflect the assemblage structure and diversity of other taxa has attracted increased attention. We sampled 47 boreal streams for diatoms and macroalgae and examined their assemblage patterns along major environmental gradients. Our main intention was to examine whether diatoms might be useful surrogates for macroalgae in boreal streams. We also assessed whether taxon richness and community composition provided similar insights into the patterns of cross-taxon concordance. According to canonical correspondence analysis, diatom distribution was most strongly related to water pH, conductivity, latitude and longitude, and macroalgal distribution to water pH and iron content, latitude and bed instability. In Mantel’s test, diatoms and macroalgae showed significant cross-taxon concordance. However, there was no significant correlation between taxon richness of the two algal groups, likely reflecting their differing responses to environmental variables. We found evidence that although diatoms and macroalgae are partly controlled by different environmental factors, they are segregated rather similarly along latitude and a few environmental gradients such as water pH and iron content. We conclude that, at least at broad geographical extents and in small streams, diatoms reflect the structure of the macroalgal community and are therefore useful surrogates for cost-effective biomonitoring of algal communities in streams.

Water quality of the River Vantaanjoki (South Finland) described using diatom indices

River water quality is monitored in Finland almost always by monitoring physical an d chemical parameters such as water transparency, colour and turbidity, concentrations of oxygen, nutrients and toxic compounds, and water pH. The hygienic state of the water is also measured as well as the chlorophyll a content of the seston. The system is developed primarily to describe lake water quality but is used with some modifications also for rivers (HEINONEN &. HERVE 1987). River monitoring and evaluation is, however, rather difficult when monitoring physical and chemical variables due to the rapid changes that can occur e.g. after short rainfall, when the concentrations may change in a small river system by one or two orders of magnitude in few hours. This wellknown fact is the main reason for using biological methods for river monitoring such as indices based on benthic fauna (e.g. WooDIWISS 1964, CHANDLER 1970) or on benthic algae (see e.g. WHIITON et al. 1991, WHIITON & Rorr 1996) which reflect water quality over longer periods.