Spatio-temporal Characteristics of Cyanobacterial Communities in the Middle-downstream of Nakdong River and Lake Dukdong

Abstract

Temporal and spatial characteristics of cyanobacterial communities at the monitoring stations for Harmful Algal Bloom Alert System (HABAS) in Nakdong River and Lake Dukdong were investigated for two years (2013 to 2014). A total of 30 cyanobacterial species from 14 genera were found at the survey stations. Microcystis sp. showed maximum cell density in the total cyanobacterial community in August, 2014 at ND-2 and in September, 2013 at ND-3 station. Lynbya limnetica and Geitlerinema sp., non-target species for alert criteria showed maximum cell density at ND-1 (August, 2013) and Dam station of Lake Dukdong (September, 2014), respectively. Total cyanobacterial cell density and the relative abundance of four target genera (Microcystis, Anabaena, Aphanizomenon and Oscillatoria spp.) for alert criteria was relatively lower in the mesotrophic Lake Dukdong than at the eutrophic riverine stations of Nakdong River, indicating cyanobacterial density and the RA of target genera is affected by the trophic state of the monitoring stations. Simulating the alert system using phycocyanin concentration as an alert criterion resulted in the longer period of alert issued compared to the period of alert issued using the current criterion of harmful cyanobacterial cell density due to the influence of phycocyanin concentration from non-target cyanobacterial species.

Morphology and taxonomy of the Aphanizomenon spp. (Cyanophyceae) and related species in the Nakdong River, South Korea

“…and Anabeana spp. and the major component of the water bloom in the Nakdong River (Park et al 2015;Yu et al 2014). Whereas Aph.…”

“…8; John et al 2002, p. 96, pl. 18g-j;Rajanieimi et al 2005b, Fig This species was common in Asian freshwater not only in South Korea (Park et al 2015;Ryu et al 2016) but also in China (Wu et al 2010;Ma et al 2015) and in Japan (Takano and Hino 2009;Yamamoto 2009). Studied samples were collected from all stations.…”

Molecular Verification of Bloom-forming Aphanizomenon flos-aquae and Their Secondary Metabolites in the Nakdong River

“…However, large cities as well as various agricultural industrial complexes in the basin have polluted the Nakdong River, and there have been reports of cyanoHAB in the downstream section of the Nakdong River since the 1990s [ 6 , 7 ]. After the construction of the eight weirs along the river in 2012, there has been cyanoHAB formation every summer [ 8 , 9 ]. In addition, cyanoHAB, which has been known to only occur during seasons with high water temperature, was recently observed to persist even during the winter, and the nostocalean cyanobacteria, Aphanizomenon spp., were the most dominant [ 10 ].…”

“…The occurrence of the Aphanizomenon spp. cyanoHAB, which has the potential to produce harmful substances such as cyanobacterial toxins or off-flavor metabolites, in drinking water sources such as the Nakdong River [ 8 , 9 , 10 ], does not only call for an urgent response but also call for the critical verification of the harmful substances-producing potential of cyanoHAB-causing cyanobacteria. However, the identity of toxin producers can only be confirmed by isolating and identifying strains and by analytically confirming the presence of both the harmful metabolites and the genetic identity of the monoculture [ 11 ].…”

Occurrence and Succession Pattern of Cyanobacteria in the Upper Region of the Nakdong River : Factors Influencing Aphanizomenon Bloom

“…상주보가 위치한 낙동강 상류 수역은 낙동 강에 위치한 보 구간 수역 중에 비교적 수질이 양호하고, 수환경이 청정한 것으로 알려져 있다 (NRERC, 2014). 낙동 강에서 식물플랑크톤의 종조성 및 군집구조, 녹조현상에 대 한 연구는 주로 중 하류를 중심으로 이루어져왔으며 (Park et al, 2015;Son, 2013;Yu et al, 2014), 상류수역에서의 식물플랑크톤 특히 녹조현상 유발 남조류를 중심으로 한 연구는 매우 미비한 실정이다 (Hur et al, 2013). 녹조현상을 유발하는 남조류의 발생과 천이, 감소의 원리 에 대한 이해는 남조류에 의한 녹조현상을 관리하는 측면 에서 필수적이라 할 수 있다 (Ma et al, 2015 Fig.…”