| Title |
Occurrence and Succession Pattern of Cyanobacteria in the Upper Region of the Nakdong River : Factors Influencing Aphanizomenon Bloom |
| Authors |
류희성 ( Hui Seong Ryu ) ; 박혜경 ( Hae Kyung Park ) ; 이혜진 ( Hae Jin Lee ) ; 신라영 ( Ra Young Shin ) ; 천세억 ( Se Uk Cheon ) |
| DOI |
https://doi.org/10.15681/KSWE.2016.32.1.52 |
| Keywords |
Aphanizomenon bloom; Cyanobacteria; Nakdong River; Nostocales |
| Abstract |
This study investigated the occurrences and succession patterns of harmful cyanobacteria, as well as environmental factors, during a 3-year period (September 2012 to August 2015) in the upper region of the Nakdong River around Sangju weir. A total of 27 cyanobacterial taxa were observed in this study, and classified into 26 species and 1 variety belonging to 11 genera, 5 families, and 3 orders. Cell density ranged from 24 to 42,001 cells/ml, with a geometric mean of 33 cells/ml, during the survey period. The dominant orders differed depending on the survey year; order Oscillatoriales in 2013, Chroococcales in 2014 and Nostocales in 2015. An Aphanizomenon bloom occurred in June 2015 at which time the highest cell density of 36,873 cells/ml was detected in the upper region of the Nakdong River, where as the Aphanizomenon spp. cell density (190-1,704 cells/ml) had been low prior to that time. An Aphanizomenon bloom also occurred at around the same time downstream in the Young River, a major inflow branch of the Nakdong River. The Aphanizomenon cell density along the Nakdong River increased markedly after joining of the YoungRiver, indicating that the Aphanizomenon bloom in the YoungRiver caused a bloom in the Nakdong River. Meteorological and environmental parameters, such as very low precipitation, higher water temperature, pH, and TP concentration, and lower TN/TP ratio, in May and June of 2015 than in 2013 and 2014 exerted marked effects on the Aphanizomenon bloom in June 2015 in the Young River. |