Temperature, salinity, COD, DIN (Dissolved Inorganic Nitrogen), DIP (Dissolved Inorganic Phosphorus), and Chlorophyll a obtained from the southern coastal waters during the period of 2003 to 2005 were analyzed. Variability in temperature was not found between groups in southern coastal waters, but significantly different depending on sampling sites (p<0.05). The average temperature in 2003 estimated at 18.33℃ that was annually increased by 2005 and significantly different based on statistics (p<0.05). Unlikely to temperature, salinity was significantly different depending on sampling sites, as well as monthly variations (p<0.05). Likewise to temperature, the value of salinity was annually increased. COD estimated at the average of >1.7 mg l-1 for three years, indicating optimal water quality. The fluctuations of nutrients were extremely shown in different sampling sites and monthly variations. Chlorophyll a recorded above 2.0 μg l-1 which was associated with high primary phytoplankton, whereas it showed much fluctuations in temporal and spatial, In particular, Tongyong, Jaranman, Jinjuman, and Samcheonpo located in the southeast were the highest fluctuations in water quality than any other regions. The correlation between salinity/COD and nutrients/chlorophyll a was strongly negative or positive, which was possibly associated with much the introduction of run-off water as well as rainfall in summer.

이 연구는 남해안 중부해역의 여름철 전 후 단계를 나누어서 6월부터 10월까지의 2004-2006년 장기간 해양환경 모니터링 및 식물플랑크톤 군집구조를 파악함과 아울러, Cochlodinium 적조발생에 관한 해석에 이용되고자 하는 것이다. 조사해역은 득량만, 고흥연안, 여자만, 가막만, 광양만, 여수연안, 남해연안으로 총 16개 정점이다. 수온은 19−29℃ 범위로 여름철 여자만에서 두 정점 모두 가장 높은 29℃C, 27℃ 를 나타내었다. 그러나 8월을 제외한 6월, 7월, 9월, 10월에는 조사정점에 관계없이 큰 차이를 보여주지 않았다. 염분도는 7월과 8월에 여자만과 광양만에서 다른 조사해역에 비하여 약 5-6 정도 낮은 25-27를 나타내었다. 클로로필의 경우도 7월과 8월에 각 조사해역별 큰 차이를 보이고 있다. 특히 광양만은 최고 5배 정도 많은 15μgl−1 까지 보였다. 투명도는 수온, 염분도, 클로로필과 다르게 조사기간 동안 해역에 관계없이 거의 비슷한 수준인 2-5m 정도로 보여주고 있다. 용존무기질소도 조사해역 중 광양만의 경우 7월과 8월에 가장 높은 0.53mgl−1 까지 보여 10배 정도까지 차이를 보였으나, 용존무기인 상대적으로 큰 차이를 나타내지 못하고 있다. 용존무기질소와 클로로필의 관계를 보면 7월에는 임의 상관성을 보여 클로로필의 증가에 따른 용존무기질소가 급속히 소모됨을 알 수 있지만, 8월에는 거의 오히려 양의 상관성을 보여주고 있다. 식물플랑크톤의 평균 세포수는 7월과 8월에 500 cells ml−1 까지 나타내었고, 대부분 규조류의 비율이 60% 이상 출현되었으나, 8월에 와편모조류의 점유율이 20-30%까지 보였다. 우점종으로는 Skeletonema costatum이 2004년부터 2006년까지 전 해역에 걸쳐 가장 많이 출현되었다. 각 해역별에 출현하는 식물 플라크톤의 집괴분석에 따르면 상호 혼잡되어 분포 되는 것으로 나타났다. 이상의 결과를 보면 여름철에 가장 큰 해양환경 변화를 보였고, 식물플랑크톤 중 S. costatum은 남해연안의 대표적인 기초생산 종으로 간주된다. 특히 여름철 Cochlodinium 적조는 득량, 가막, 고흥, 여수, 남해해역에서 3년 동안 계속해서 발생된 반면, 여자만과 광양만은 전혀 나타나지 않았다. 뚜렷한 차이점은 용존무기질소 Cochlodinium 적조 형성을 위한 요구량은 수중에 풍부하게 존재하고 있기보다는, 미량이라도 충분히 적조를 유발시키고, 외해역에서도 발생될 수 있다는 뒷받침을 하고 있다.

The clarification of spatial-temporal patterns of phytoplankton from southern coastal waters during the period of March to November in 2004 was carried out. Total cell numbers were shown in 5,286 cells ml−1 on March and reached to encounter a peak of 27,775 cells ml−1 on July. Mean cell number was also shown in maximum of 1,587 cells ml−1 on July, which recorded approximately two times higher than on June. The cell number of phytoplankton from southmiddle waters attained an abundance of ≥35 regardless of months, which was the highest the abundance of phytoplankton in 2004 than any other waters in this study. Southwestern waters were lower the cell number of 2-5 times than those of southmiddle and southeastern waters. In particular, Prorocentrum occurred in southeastern waters on June and the highest cell number of 8,200 cells ml−1 around Tongyeong region on July, which was recorded to occupy the value of 60.9% in southeast waters. The abundance of Skeletonema costatum as a dominant taxa in southwest was shown in ≥60 on March, July, September, and October, whereas was also recorded to achieve the abundance of above 80% in southmiddle waters on March, July, and September. The majority of the taxa in southeastern waters was diatom: Eucampia zoodiacus, and Chaetoceros spp.. They occupied above 45%. On November, most of southern waters were abundant to Chaetoceros spp. On the basis of cluster analysis using SPSS ver 10.0, phytoplankton occurring on March showed somewhat no correlation with all of southern waters. In contrast to on March, the relationship between southwestern and southmiddle waters was shown on August and November, indicating a distinction from southeastern waters. However, the distance between southwestern/middle and southeastern waters appeared to be less than 5. Consequently, the abundance of phytoplankton in southern waters showed much fluctuations in temporal and spatial assays. In particular, southwestern and southmiddle waters during the periods of summer and winter appeared to be a similar to environmental characteristics.

In order to study the temporal variations of nutrients and chlorophyll-a in the Bottol Bada, three field observations were carried out on 20, 23 and 26 July, 2004. The low N:P values exhibit nitrogen deficiency during the periods of observation. This result is not representative of typical summer environment in the southern coast of Korea. The possible mechanisms are as follows: 1) The freshwater inflow was not sufficient for the supply of nitrogen because the total precipitation was 11.9 mm in July, 2004. This amount is no more than 5% in normal precipitation in July. 2) There was an inflow of oceanic water under the subsurface into the Bottol Bada. Even though the oceanic water comprises more nutrients, it produces the stratification between the surface and the subsurface water and seems to prevent the supply of nutrinets to the surface layer. 3) The high chlorophyll-a concentration of 1.2 μg/L was shown near the narrow channel between Gae-do and Geumo-do. This seems to be resulted from the inflow of water from Gamak Bay.

Based on the observation on 20, 23 and 26 July 2004, the distributions of temperature, salinity and stratification was investigated in relation to ebb, turn of tide and flood. The results are as follows: 1) The high temperature and low saline water with 23.5～24.0℃ and 32.4～33.0psu existed at Naro Island. 2) The cold surface water below 21.0℃ and 33.0～33.4psu appeared in the area near Gae Island and Geumo Island. 3) The cold and saline water, below 24.0℃ at the surface and 17.0℃ near the bottom, 32.8～33.8psu at the surface and 33.8～34.0psu near the bottom, existed in Sori Island. These waters were more saline compared to the South Sea Coastal Water with about 31.8psu. This suggests that the oceanic saline water intruded into the Bottol Bada through the area near Sori Island. The stratification appeared during all the observation periods due to a high solar radiation of 22MJ/m2, and a weak wind speed of 2.9m/s on the average while the mean speed of wind in July is around 3.9 m/s. It qualitatively suggested that the stratification was maintained during the observation periods because of a high solar radiation, a weak wind speed and intrusion of saline oceanic water.