Spatial distribution and temporal variation of Microcystis species composition and microcystin concentration in Lake Biwa

Abstract

Spatial and temporal variation in Microcystis species composition and microcystin concentration, quantified by enzyme-linked immunosorbent assay and high-performance liquid chromatography, were investigated during a 3-year period (1998-2000) in the Northern Basin of Lake Biwa. The Northern Basin generally had a concentration of 5 microg L(-1) or less, except at station 1 (Nagahama Bay) from July to October during the study period. The maximum concentration at station 1 was 22.7, 35.9, and 22.0 microg L(-1) in October of 1998, 1999, and 2000, respectively. Eleven species of cyanobacteria were observed: Microcystis aeruginosa, M. ichthyoblabe, M. novacekii, M. wesenbergii, Oscillatoria raciborskii, Anabaena oumiana, A. affinis, A. flos-aquae, A. ucrainica, A. smithii, and A. crassa. Of these, M. aeruginosa and M. wesenbergii were the main components observed. A high concentration of microcystin in the lake water was mostly a result of variation in the relative amount of toxic M. aeruginosa rather than of the total Microcystis cell number. This was supported by the analytical results for isolated strains. Microcystis spp. cell density in the Northern Basin appeared to increase gradually over the course of the study. This is the first study to have surveyed the Northern Basin of Lake Biwa, which supplies drinking water to 14 million people and is the largest lake in Japan.

Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake

“…M. viridis dominated almost throughout the study, and the proportion of total Microcystis varied between 35% and 87%. Even though M. viridis was predominant, the amounts of MCs it produced were low (Harada et al, 2001;Ozawa et al, 2005), and our results generally were consistent with observations from above studies.…”

“…The study above had indicated the dominant Microcystis species were identified as M. wesenbergii, M. ichthyoblabe and M. viridis. M. wesenbergii was one of the most dominant waterbloom-forming microcystis morphospecies from May to December (ranged between 25% and 42%), but were not shown to contain MC synthesis gene or MC by both molecular and chemical methods (Xu et al, 2008a(Xu et al, , 2008bOzawa et al, 2005). M. viridis dominated almost throughout the study, and the proportion of total Microcystis varied between 35% and 87%.…”

“…High concentration of MCs in the blooms was always associated with M. flos-aquae and M. aeruginosa, whereas when M. wesenbergii was the dominant colonial type, the MC production was low. Meanwhile, most colonies (> 75%) of M. aeruginosa and M. botrys contained the mcy genes, whereas < 20% of the colonies identified as M. ichthyoblabe and M. viridis gave a PCR product of the mcy genes or MCs oligopeptide (Kurmayer, 2002;Ozawa et al, 2005;Fastner et al, 2001). However, the most common M. aeruginosa in other aquatic environment was not the dominant species during the study period.…”

Cyanobacteria and their toxins in Guanting Reservoir of Beijing, China

“…On September 13, 2006, cell numbers were much more than that of on August 28, but the maximum MC value occurred on August 28. Heresztyn and Nicholson [19] reported the toxin concentration followed the general trend of cyanobacterial cell numbers, whereas other studies found no relationship between Microcystis cell numbers and MC concentrations with changes in MC concentrations related to the dominant species of Microcystis [20]. However, in the present study, the MC content within the cyanobacteria and in water sample was consistent.…”

Numerical simulation of the vertical migration of Microcystis (cyanobacteria) colonies based on turbulence drag

“…In summary, it is reasonable to ignore the effect of turbulence on colony viability and size in simulation process, and simulated results are suitable for field. The phenomenon has been found that water blooms occurred under poor weather or nutrient conditions (Ozawa et al, 2005;Ma et al, 2015). The reason may be explained as the effect of water motion.…”