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

作者：Katano Toshiya^*; Nakano Shin ichi; Ueno Hiroyuki; Mitamura Osamu; Anbutsu Kaori; Kihira Masayuki; Satoh Yasuhiro; Satoh Takeshi; Drucker Valentin V; Tanaka Yuji; Akagashi Yuki; Sugiyama Masahito

来源：Limnology, 2008, 9(3): 243-250.

DOI：10.1007/s10201-008-0252-6

• Lake Baikal
• Phytoplankton
• Summer
• Transect

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 degrees C), probably due to the higher temperature of the river water, and gradually decreased offshore at Station 6 (14.5 degrees 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 mu mol N 1(-1) and < 0.16 mu mol P 1(-1), respectively. Relatively high concentrations of nutrients (0.56-7.38 mu mol N 1(-1) and 0.03-0.28 mu mol P 1(-1)) were detected in the deeper parts of the euphotic zone. Silicate was not exhausted at all stations (> 20 mu mol Si 1(-1)). The chlorophyll a (chl. a) concentration was high (> 10 mu g 1(-1)) near the shore at Station 1 and low (< 3 mu g 1(-1)) at five other stations. The < 2 lm fraction of chl. a in Stations 2-6 ranged between 0.80 and 1.85 mu g 1(-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 x 10(5) cells m1(-1). In contrast, chl. a in the > 2 mu m fraction varied significantly (0.14-11.17 mu g 1(-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 larger phytoplankters in the littoral zone probably depend on nutrients from the Barguzin River.

• 出版日期2008-12