Abundance and composition of the summer phytoplankton community along a transect from the Barguzin River to the central basin of Lake Baikal

Abstract

The abundance and composition of phytoplankton were investigated at six stations along a transect from the Barguzin River inflow to the central basin of Lake Baikal in August 2002 to clarify the effect of the river inflow on the phytoplankton community in the lake. The water temperature in the epilimnion was high near the shore at Station 1 (17.3°C), probably due to the higher temperature of the river water, and gradually decreased offshore at Station 6 (14.5°C). Thermal stratification developed at Stations 2-6, and a thermocline was observed at a 17-22-m depth at Stations 2-4 and an 8-12-m depth at Stations 5 and 6. The concentrations of nitrogen and phosphorus nutrients in the epilimnion at all stations were \1.0 lmol N l -1 and \0.16 lmol P l -1 , respectively. Relatively high concentrations of nutrients (0.56-7.38 lmol N l -1 and 0.03-0.28 lmol P l -1 ) were detected in the deeper parts of the euphotic zone. Silicate was not exhausted at all stations ([20 lmol Si l -1 ). The chlorophyll a (chl. a) concentration was high ([10 lg l -1 ) near the shore at Station 1 and low (\3 lg l -1 ) at five other stations. The\2 lm fraction of chl. a in Stations 2-6 ranged between 0.80 and 1.85 lg l -1 , and its contribution to total chl. a was high ([60%). In this fraction, picocyanobacteria were abundant at all stations and ranged between 5 9 10 4 and 5 9 10 5 cells ml -1 . In contrast, chl. a in the[2 lm fraction varied significantly (0.14-11.17 lg l -1 ), and the highest value was observed at Station 1. In this fraction, the dominant phytoplankton was Aulacoseira and centric diatoms at Station 1 and Cryptomonas, Ankistrodesmus, Asterionella, and Nitzschia at Stations 2-6. The present study demonstrated the dominance of picophytoplankton in the pelagic zone, while higher abundance of phytoplankton dominated by diatoms was observed in the shallower littoral zone. These

Asynchrony of spring phytoplankton response to temperature driver within a spatial heterogeneity bay of Three-Gorges Reservoir, China

“…Iriarte and Purdie, 2004;Jasprica and Hafner, 2005;Henson et al, 2006;Miller and Harding, 2007;Peeters et al, 2007a) or on the effect of nutrient on phytoplankton biomass (e.g. Hunt and Matveev, 2005;Beamud et al, 2007;Ç elik and Ongun, 2008;Kasprzak et al, 2008;Katano et al, 2008 Tirok and Gaedke (2007) investigated the individual and combined effects of three physical variables (irradiance, temperature and water stability) on algal dynamics using descriptive statistics, multiple regression models and a process-oriented dynamic simulation model, few studies has tried to reveal the relative importance of local (e.g. spatial heterogeneity) and regional (e.g.…”

Lake Baikal Ecosystem Faces the Threat of Eutrophication

“…In the same year in the southern part of Lake Baikal in the west bank (Bolshie Koty village) mineralization amounted to 98.5 mg/L; that is, it almost corresponds to the value registered here 50 years ago. Few literature data also indicate the supply of nutrients from the river Barguzin to the bay, which affects the composition of phytoplankton in the shallow zone [5].…”