Phytoplankton complexes monitoring results at the final stage of the vegetation cycle in the Rybinsk reservoir (2020-2021)

• A.V. Anisimova

  Water Problems Institute of the Russian Academy of Sciences, 3, Gubkina str., 119333, Moscow, Russian Federation

  Автор

• L.V. Razumovsky

  Water Problems Institute of the Russian Academy of Sciences, 3, Gubkina str., 119333, Moscow, Russian Federation

  Автор

The work is devoted to the study of the phytoplankton complexes
structure in the Rybinsk reservoir at the final stage of their vegetation cycle. The
report highlights the vulnerability of freshwater to anthropogenic impacts and the
need to assess its quality through monitoring. Rybinsk reservoir is used as an example
for such scientific research. This is stipulated by the presence of the Papanin Institute
for Biology of Inland Waters Russian Academy of Sciences in its coastal zone and
regular observations by the staff of this institute of the ecosystem transformations
taking place in the reservoir. Those works have been carried out since the mid-1950s
and up to the present. The article provides a brief description of the object of research
– the Rybinsk reservoir (area, average depth, etc.). It is emphasized that
phytoplankton and its species structure belong to one of the major bioindication
groups during routine monitoring. The main purpose of the research was to evaluate
the transformation of the phytoplankton complexes structure at the final stage of
vegetation activity, as well as the variability of these processes. For this purpose,
phytoplankton samples from all horizons of the water column were collected at 6
stationary monitoring stations in August and October 2020 and 2021. The obtained
integral samples of phytoplankton complexes were studied in detail. The systematic
composition, the number of identified taxa, and the taxonomic proportions of
phytoplankton complexes were determined. The following is a brief description of
the methods of sampling, processing and viewing phytoplankton samples. The
location of 6 standard monitoring stations is given. The main part of the article
contains a detailed description of the species composition of phytoplankton
complexes observed in August and October 2020 and 2021. As a result of the
conducted studies, representatives of 7 systematic groups of phytoplankton were
identified: green algae (Chlorophyta); diatoms (Bacillariophyta); dinophytic algae
(Dinophyta); cyanobacteria (Cyanobacteria); Euglenophyta; yellow-green
(Xanthophyta) and golden (Chrysophyta) algae. Based on the results of
phytoplankton studies, the spatial and temporal variability of the saprobicity index

(S) was estimated. Significant variability in the taxonomic structure of phytoplankton
complexes and the calculated saprobicity index was established.

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