Seasonal changes in the phytoplankton taxonomic structure and photosynthetic pigments in pelagial and littoral of two interconnected lakes in Belarus

Zh F Buseva,D Ozolins,E A Sysova,N N Sushchik,Yu K Veras,Sh G Farahani,A A Kolmakova

doi:10.29235/1029-8940-2020-65-3-310-318

Abstract

The seasonal pattern of phytoplankton taxonomical composition and phytoplankton chlorophyll а content from pelagial and littoral locations with and without macrophyte beds in two interconnected lakes (north-west of Belarus) under contrasting trophic conditions were studied. We estimated influence of hydrochemical parameters on phytoplankton in studied lakes. There was “a clear water phase” in pelagial and low phytoplankton abundance in littoral of mesotrophic Lake Obsterno but we revealed a brief pulse of Chrysophyta and “a late spring bloom” with high total phytoplankton abundance in shallow macrophyte-covered low trophic state Lake Nobisto. It was found some prominent differences in total phytoplankton abundance and taxonomic composition in littoral and pelagial locations of both lakes. We used Phyto-Pam phytoplankton analyser for analysis of algae pigments. Phyto-Pam method allowed roughly identify two types of pigments - pigments of green algae and diatoms and revealed differences in concentrations of pigments between littoral locations and pelagial in both lake types. Results indicated that total chlorophyll a content has a pronounced seasonal cycle with high values during the early fall and low values throughout the late spring in mesotrophic lake and have shown differences in phytoplankton pigments between lakes littoral locations.

Highlights

Clear differences exist in algal species composition, both between lakes and within a single lake over time, but the relative importance of nutrient competition among different taxa and purely physical processes among variable taxa in different seasons have not been clarified yet [1, 2] in the literature, a large number of methods are available to measure chlorophyll from phytoplankton [3]
We are aware that the chlorophyll a content generally differs between pelagic and littoral zones in the lakes and that the shallow areas are more influenced by the benthic processes than the pelagic zones [12, 13]
Water temperature varied from 21.4 °C in May with maximum of 23.6 °C in littoral location to September 14.3 °C in Lake Obsterno

Summary

Introduction

Clear differences exist in algal species composition, both between lakes and within a single lake over time, but the relative importance of nutrient competition among different taxa and purely physical processes among variable taxa in different seasons have not been clarified yet [1, 2] in the literature, a large number of methods are available to measure chlorophyll from phytoplankton [3]. The so far available instrumentation has been limited by the fact that it cannot distinguish between different groups of phytoplankton, like green algae, diatoms and blue-green algae. In principle, such distinction is possible on the basis of the specific fluorescence excitation properties of differently pigmented phytoplankton groups [11]. We are aware that the chlorophyll a content generally differs between pelagic and littoral zones in the lakes and that the shallow areas are more influenced by the benthic processes than the pelagic zones [12, 13]

Objectives

Results

Conclusion