Composition and Some Ecological Features of Winter Zooplankton in Deep Stratified Lakes

Abstract

For the first time, zooplankton and environmental factors have been studied in winter in the deep stratified lakes Siverskoe, Borodaevskoe, and Vydogoshch. The zooplankton consists of 18-22 species of rotifers, copepods, and cladocerans, including 15-18 specifically winter, cryophilic and eurythermic forms. The populations of zooplankters reproduce actively: males and egg-bearing females (in copepods), females with embryos and eggs in brood pouches (in cladocerans), and females with attached eggs (in rotifers) are present. In lakes Siverskoe and Borodaevskoe (depth 20-24 m), where oxygen deficiency is observed only in the bottom water layer, the zooplankton populates the greater part of the water column and forms a large aggregation in the oxycline and near the bottom. The abundance of bacteria in these zones is high (up to 4-6 × 10 6 cells/ml). In Lake Vydogoshch (depth 16 m), oxygen deficiency extends to the middle layers, and all zooplankton is distributed above the oxycline. The biomass of winter zooplankton in Lake Siverskoe in 1983 averaged 1.26 g/m 3 , with a maximum of 4 g/m 3 ; in 1993, 1.4 and 8.04 g/m 2 ; the respective values in Lake Borodaevskoe were 0.98 and 3.1 in 1983 and 0.14 and 1.6 in 1993; in Lake Vydogoshch, 0.15 and 0.24 in 1983 and 1.25 g/m 3 in 1993. The development of winter zooplankton is limited by the size of the zone of oxygen deficiency and depends on the amount of food (bacterioplankton). The distribution of zooplankton in the water column and its biomass in individual layers is determined by the rate of methane formation and oxidation.

Winter Limnology: How do Hydrodynamics and Biogeochemistry Shape Ecosystems Under Ice?

“…portant food source to zooplankton in humic lakes with anoxic hypolimnia (Bastviken et al, 2003;Kankaala et al, 2006), and have been isotopically traced to higher species (Jones & Grey, 2011), including fish (Sanseverino et al, 2012). Under ice, zooplankton abundance can coincide with regions of high bacterial biomass (Rivier, 2005) while other studies indicate bacteria make up only a small part of the diet of zooplankton in winter (Grosbois et al, 2017) (Section 5.3). The increasing abundance of highly reactive reduced chemicals (Gammons et al, 2014;Joung et al, 2017) as well as methanotrophs (Samad & Bertilsson, 2017) with depth in winter implies either that ciliates and other microzooplankton cannot make immediate use of food sources at or below the chemocline, or that the rate increase of methanotrophs outpaces grazing rates.…”

Effect of winter conditions on spring nutrient concentrations and plankton in a large shallow Lake Peipsi (Estonia/Russia)

“…The species composition and low abundance of winter zooplankton in L. Peipsi are generally comparable with temperate lakes in Russia: L. Siverskoe, L. Borodaevskoe, L. Vydokoshch (Rivier 2005), L. Nero (Rivier et al 1992) and in Rybinsk Reservoir (Rivier 1986(Rivier , 1996. The main difference is quite rare occurrence of adult Cyclops kolensis Lilljeborg in L. Peipsi.…”

Small peatland with a big story: 600-year paleoecological and historical data from a kettle-hole peatland in Western Russia

“…The species Ch. sphaericus occurs in a wide range of pH and temperatures from 2°C to 4°C – functioning without reproduction (Rivier, 1992, 2005) to 36°C (Gorobey, 1974; Verbitsky and Verbitskaya, 2011). Laboratory tests show that at temperatures above 25°C the mortality of individual Chydorus sp.…”