Resting stages of freshwater algae from surface sediments in Paldang Dam Lake, Korea
Li, Zhun; Shin, Hyeon Ho; Lee, Taehee; Han, Myung-Soo
Although the studies on marine cysts are quite frequent, information on resting stages of freshwater algae are rather scarce. The present study focused on the identification of resting-stage algae from freshwater sediments in Paldang Dam Lake, an important source of water for South Korea. We examined the morphological characteristics of resting-stage specimens and identified them by germination experiments or DNA analysis. Surface sediment samples were collected from 12 sites in Paldang Dam Lake from July 2009 to June 2010. Thirty-five resting stage morphotypes were identified: 19 chlorophytes, 6 dinoflagellates, 5 diatoms, 2 cyanobacteria, 2 euglenoids and 1 cryptophyte. Resting-stage and vegetative cells of five chlorophyte morphotypes could not be identified by morphology. These specimens were identified by molecular sequence analysis based on the nuclear-encoded SSU rDNA sequences of Polyedriopsis, Oogamochlamys and Chlamydomonas. Our samples included resting-stage of the potentially toxic species Cylindrospermum stagnale, the first recorded sighting in Korea. Resting-stage assemblages were dominated by diatoms, which ranged from 560 to 2750 cells g–1. Resting-stage of diatoms and cyanobacteria were abundant along the eastern shore toward the southern part of Paldang Dam Lake, where there have been periodic algal blooms.