The Role of Marine Bacteria in the Dinoflagellate Bloom 1. Distribution of Marine Bacteria and Dinoflagellate in Chinhae Bay

해양세균이 적조형성 생물에 미치는 역할 1. 진해만의 해양세균과 과편모조류의 분포

To provide essential information of the role of marine bacteria on the dinoflagellate blooms, distribution of marine bacterial flora and dinoflagellate species was investigated in Chinhae Bay located in southern part of Korea from August 1989 to April 1990. Two hundred and fifty one strains of marine bacteria were isolated from seawater samples collected from the study area. Among them, Flavobacterium spp. and Acinetobacter spp. were the most dominant in bacterial flora. Another 32 strains which comprised 13 percent of total strains were Erythrobacter spp.. Based on the physiological character, Erythrobacter spp. were identified as Erythrobacter longus, Erythrobacter sp.(J-2) and Erythrobacter sp. (J-8). From the phytoplanktonic community, fourteen genera and twenty nine taxa of dinoflagellate species were identified. Based on the spatio-temporal frequence and abundance Gymnodinium sanguneum, Prorocentrum micans and Prorocentrum minimum were the aestival dominent species. However, Heterocapsa triquetra was appeared as predominant species in April. Cell density of about 2,000 cells/ml was prevailed in the bloom of August, but it developed into more intensive bloom of above 500 cells/ml in September. The water quality showed eutrophic or hypereutrophic condition, which was proved by high concentration of dissolved inorganic nitrogen, ortho-phosphate and chemical oxygen demand. Oxygen deficient water mass was found in the bottom overlying waters in August and September. High relationship between abundant bacterial flora and persistent dinoflagellate blooms in eutrophic condition would be approvable.

해양세균이 적조형성 생물에 미치는 역할을 알기 위하여, 일차적으로 진해만에 분포하고 있는 세균을 분리동정함과 동시에 과편모조류의 군집 조사한 결과는 다음과 같다. 분리동정한 총균주수는 251균주로 Flavobacterium spp.가 26균주, Ainetobacter spp.가 18균주였으며 우점종은 계절별로 다르게 나타났다. 한편 광합성세균은 약 $13\%$인 32균주가 분리되었으며, 이들은 Erythrobacter longus, Erythrobacter sp.(J-2) 및 Erythrobarter sp.(J-8)의 3종으로 동정되었다. 과편모조류 군집은 14속 29taxa로 구성되었으며, 출현양은 9월에 4,699cells/m1로 가장 많고 4월에 36cells/ml로 가장 적었다. 우점종으로 8월에 Gymnodinium sangurneum, 9월에는 Prorocentrum micans, P. minimu, 10월에는 Ceratium fussus 그리고 4월에는 Heterocapsa triquetra였다. 한편 8, 9월에는 주로 마산만과 진해만 서부연안에서 적조현상이 발생하였다. 수질부영양지표성분인 DIN과 DIP는 적조발생조건(수질2급기준에 해당)인 $7.14{\mu}g/-at/\iota$와 $0.48{\mu}g/-at\iota$를 대부분 초과하였으며, COH는 부영양 또는 과영양수역에 해당되었고 하계 저층수에서는 빈산소상태를 나타냈다.