Danijela P. Vidaković

New taxa of the genus Navicula (Bacillariophyceae) in the diatom flora of Serbia

The main objective of this paper is to report two benthic, epilithic diatom species from the Raška River. Samples were collected in April, June, August and November 2011 and March and May 2012 from 5 localities along the Raška River by scraping off the stone surface using a brush. Diatom frustules were first cleaned using the cold acid method, and then mounted on permanent slides. Descriptions (main valve measurements of the populations in the Raška River), ecology, distribution in Serbia and Europe, and appropriate photomicrographs of two species are presented. Navicula jakovljevicii Hustedt and Navicula catalanogermanica Lange-Bertalot & Hofmann are rarely found in Europe and these are new distributional records. These new taxa significantly contribute to diatom floristic diversity of the Raška River.

The application of benthic diatoms in water quality assessment (Mlava River, Serbia)

Abstract The main objective of this study was to assess the ecological status of the Mlava River based on epilithic diatoms and to test the use of diatom indices as a tool for estimating the quality of flowing waters in Serbia. Quantitative analysis showed that in April Achnanthidium minutissimum was dominant at each site, except at the fifth site, where Amphora pediculus was dominant. In July and September, Achnanthidium minutissimum, Achnanthidium pyrenaicum, Amphora pediculus, Denticula tenuis, Diatoma vulgaris, Gomphonema elegantissimum, Cocconeis pseudolineata and Cocconeis placentula var. lineata dominated. Detrended correspondence analysis (DCA) was used to detect the major patterns of variation in species composition. The first DCA axis summarizes the distribution of the diatom community, mainly through temperature, conductivity, oxygen and water hardness gradient. The second DCA axis was weakly correlated with few variables. Based on the average values of the pollution sensitivity index (IPS), commission for economical community metric (CEE) and biological diatom index (IBD), the water of the Mlava River belonged to water class I during all three seasons. Values of the diatom-based eutrophication/pollution index (EPI-D) indicated class II water quality. According to calculated trophic diatom index (TDI) values, water of the Mlava River was characterized by intermediate nutrient concentrations during three seasons. Principal components analysis was used to represent the correlation between diatom indices, and the highest correlation among the selected diatom indices is seen between EPI-D, IPS and IBD.

Additional information on the distribution and ecology of the recently described diatom species Geissleria gereckei

Abstract The main objective of this paper is to report new information about the distribution and ecology of a recently described diatom species, Geissleria gereckei. The opportunity for updating the information on the distribution and ecology of the species was provided by the finding of well-developed G. gereckei populations on the lithic material and bryophytes in the Raška and Mlava rivers (Serbia). For several years after the first description, G. gereckei has been known only from the type locality and from another spring in the Dolomiti Bellunesi National Park (the south-eastern Alps). After accurate LM and SEM observations, we provide evidence for the occurrence of the species also in the two above-mentioned rivers in Serbia, as well as in the south-western and south-eastern Alps. After an extensive literature search, it appears that the species is known with certainty only from these sites. Our observations and details from the literature suggest that the species is able to occupy a much broader ecological niche than the very-specific one observed at the time of discovery. The two main determinants for the species’ occurrence appear to be the carbonate nature of the catchments or aquifers, and the ability of the species to be competitive in habitats or microhabitats exposed to seasonal desiccation.

Uncertainty of using habitat fidelity in biomonitoring based on benthic diatoms - the Raška River case study

Epilithic diatoms are frequently recommended for river biomonitoring, while much less emphasis is placed on epiphytic communities. This study considers use of epiphytic and epilithic diatom communities from the Raška River in biomonitoring. A total of 212 diatom taxa were recorded in both communities. Dominant diatoms were Achnanthidium minutissimum (Kützing) Czarnecki, A. affine (Grunow) Czarnecki, A. subatomus (Hustedt) Lange-Bertalot, Amphora pediculus (Kützing) Grunow, Diatoma vulgaris Bory, Gomphonema tergestinum (Grunow) Fricke, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Melosira varians Agardh and Navicula tripunctata (Müller) Bory. Redundancy analysis (RDA) was used to detect the relationships between diatoms, some environmental factors and sampling sites. Diatoms of the epiphytic community showed a clearly grouping in relation to the sampling sites as compared with diatoms of the epilithic community. Species common to both communities showed a similar correlation with some environmental variables (BOD, pH, NH4+, TP, NO3− and conductivity), with three exceptions (Diatoma vulgaris, Cymbella compacta, and Encyonema silesiacum). Pearson’s correlation coefficient showed correlation between selected environmental variables and diatom indices calculated using OMNIDIA 6.2 software (TDI, IPS, CEE, GENRE, TID, SID, SHE and IDSE/5). Diatoms of the epiphytic community are more clearly clustered in relation to the sampling sites as compared with diatoms of the epilithic community. According to our results there is still “place” in biomonitoring for epiphytic community. The present study highlights the necessity of sampling both epiphytic and epilithic communities because substrate specificity could play important role in biomonitoring.

Diatoms of the Dojkinci River (Stara Planina Nature Park, Serbia)

Abstract Diatom samples were collected during July 2010 at 15 localities from different types of substrate (stone surfaces, sand, mud, filamentous algae and submerged mosses) from the Dojkinci River. During the research period, 124 taxa were determined within 43 genera. Among numerous common diatoms we recorded three taxa for the first time in Serbia: Brachysira intermedia (Øst.) Lange-Bertalot, Chamaepinnularia mediocris (Krass.) Lange-Bertalot and Navicula tridentula Krass. Also, we observed 21 taxa which are rarely recorded taxa for Serbia. The most interesting was Diatomella balfouriana Grevill. that was previously known only from the River Tisa near Titel. In the studied material, it was identified only in samples collected from the surface of boulders with mosses at the third locality. Their morphology, distribution and ecology are presented in this paper.