Morphotaxonomy, distribution and abundance of Spirogyra (Zygnematophyceae, Charophyta) in Lake Baikal, East Siberia

摘要

Some shallow-water zones of Lake Baikal have recently begun to show dramatic changes in phytobenthic communities. From 2012 to 2016, we studied species composition, distribution and abundance of Spirogyra, atypical of the open nearshore waters of Lake Baikal. In September 2014, Spirogyra dominated a considerable length of the coastal zone, extending the upper boundary of its previously known vertical distribution to above 0.5-m depth. Maximum algal biomass at this depth was at sites close to settlements and popular tourist destinations: 125.0 +/- 59.0 and 70.5 +/- 39.0 g m(-2) (both n= 8) (Bol'shoye Goloustnoye village and 2 km south of the Tyya River) in the southern and northern basins, respectively. Based on morphology of fertile specimens, we identified 15 taxa, including one intraspecific form of Spirogyra from 37 lake sites and five streams. Eight taxa were new for Lake Baikal; nine were previously unknown for the region. Eight morphological species were reported for East Siberia for the first time. The species richness of the genus was higher in shallow-water bays with sandy bottoms in areas presumably influenced by organic pollution. The most common was S. cf. fluviatilis that developed year-round in the rocky Baikal littoral at 0.5-17.0-m depths and in one of the tributaries as well as in the Angara River. This study provides the first detailed account of the mass development of Spirogyra in Lake Baikal under conditions of an unfolding ecological crisis and the first data regarding species richness and distribution of Spirogyra in the Lake Baikal region.