Phytoplankton of the middle course of the Kostroma River and its tributaries (Kostroma Oblast, Russia)

Abstract

This study was undertaken in the summer and fall of 2009–2013 to investigate phytoplankton in the middle reaches of the Kostroma River and its first-order Koryoga and Tyobza tributaries. Based on the analysis of floral and species diversity, the ratio of large taxonomic groups (divisions), dominant species, abundance, biomass and phytoplankton cell size, as well as chlorophyll а content and water saprobity, both similarities and differences were found in the phytoplankton of the rivers and the quality of their waters. It was also found that the diversity and abundance of the river phytoplankton was determined by green algae, diatoms and cyanoprokaryotes. It was shown that in the tributaries (small rivers) the diversity and abundance of phytoplankton, as well as the level of water trophy, decreased. The latter was accompanied by an increase in the proportion of mixotrophic phytoflagellates in the potamoplankton of the Koryoga and Tyobza rivers. At the same time, the algae cell size in the tributaries increased. The water saprobity in all the rivers corresponded to the β-mesosaprobic zone of organic pollution. The water quality assessment based on various indicator parameters of phytoplankton showed that the rivers under study belonged to two classes: clean and satisfactory clean, with higher water quality in the tributaries.

Keywords

• planktonic algae
• diversity
• biomass
• abundance
• chlorophyll a
• saprobity
• water quality
• koryoga river