RÓŻNORODNOŚĆ ZBIOROWISK OKRZEMEK ROZWIJAJĄCYCH SIĘ W RZECE SAN W OKOLICACH JAROSŁAWIA

Studies on the diversity of diatom assemblages in the San River, near the Jarosław City were conducted in period of 2009–2010. On two sites – designated before and after the City a total of 262 diatom taxa were determined. The most numerous group accounted diatoms from the genus Nitzschia, Navicula and Fragilaria, in addition, frequently occurred: Diatoma vulgaris, Achnanthidium minutissimum, Amphora pediculus, Encyonema ventricosum and Nitzschia acicularis. Studies conducted in the San River showed that among the enormous richness of diatoms dominated common species, cosmopolitan, α- and β-mesosaprobic, as well as oligo-and meso-eutrophic. Among the all identified taxa, 10% accounted diatoms rare and endangered, eg.: Pinnularia viridiformis, P. subrupestris P. microstauron. Cymbella aspera, Fragilaria dilatata, Gomphonema sarcophagus, Sellaphora bacillum, Stauroneis phoenicenteron, Fallacia subhamulata or Geissleria deccussis.