Population Dynamics and the Toxin of Anabaena in the Lower Naktong River

다국어 초록 (Multilingual Abstract)

Population dynamics of Anabaena and the anatoxin-a concentration were monitored with physicochemical parameters
at 3 sites in the lower Naktong River from May to September in 2000. Total 4 species of Anabaena (A. flosaquae,
A. smithii, A. ucrainica and A. mucosa) were identified with morphological characteristics. Anabaena flos-aquae
was most abundant among the populations. The standing crop of Anabaena ranged from 10 to 11,220 cells ·ml–1 and
biomass of Anabaena more 1,000 cells ·ml–1 was observed once at St. Mulgeum and St. Seonam, twice at St. Hagueon
out of total 9 samplings. There were not significant correlations between the standing crop of Anabaena and other
physicochemical parameters such as temperature, nitrate, total nitrogen, phosphate, total phosphorus and N/P
ratios. The frequency of trichomes with akinetes was low and ranged from 0 to 4% in the total Anabaena population
and A. smithii showed highest frequency of 2.8% among all species. The population at St. Seonam showed highest
frequency of 1.4% among all sampling sites. The population in September showed the highest frequency of 3.0%
among all sampling period. The frequency of trichomes with heterocysts was low and ranged from 1 to 87% in the
total Anabaena population and A. smithii showed highest frequency of 55.1% among all species. The population at St.
Mulgeum showed highest frequency of 17.6% among all sampling sites. The population in August showed the highest
frequency of 21.4% among all sampling period. The frequency of trichomes with akinetes and/or heterocysts
was not related to all the physicochemical parameters of temperature, nitrate, total nitrogen, phosphate, total phosphorus
and N/P ratios. The anatoxin-a concentrations were determined in algal materials dominated by Microcystis
and Anabaena from June though August by derivatization using 7-fluoro-4-nitro-2, 1, 3-benzoxadiazole (NBD-F) and
HPLC analysis with fluorimetric detection. All the concentrations were below the detection limit of 0.1 μg · l–1 in the
present study.