The Relation between the Red Tide Occurrence and the Sea Water Temperature in South Sea of Korea

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1 , pp The Relation between the Red Tide Occurrence and the Sea Water Temperature in South Sea of Korea Do-Hyun Hwang 1, Su-Ho Bak 1, Heung-Min Kim 1, Hong-Joo Yoon 1, Don-Hyug Kang 2 and Yong-Hyun Chung 3* 1 Division of Earth Environmental System Science, Pukyong National University, Yongso-ro 45, Nam-gu, Busan, 48513, South Korea yoonhj@pknu.ac.kr 2 Maritime Security Research Center, Korea Institute of Ocean Science & Technology, Ansan, 15627, South Korea 3 Department of Ecological Engineering, Pukyong National University, Yongso-ro 45, Nam-gu, Busan, 48513, South Korea chungyh@pknu.ac.kr Abstract. Red tide blooming causes the serious fisheries damages. This study investigated the relation between the characteristics of red tide occurrence and the sea water temperature. The red tide occurrence data from National Institute of Fisheries Science(NIFS) and sea water temperature data from the Korea Hydrographic and Oceanographic Agency. In Tongyeong, the most of red tide occurred in August. The highest number of red tide occurrence was in Cochlodinium polykrikoides concentration more than 1000 cells/ml in 2013 was 29 times in August. For the red tide occurrence, the best sea water temperature is between 22 and 25 which starts from the end of June to the beginning of the July and the red tide is expected to occur about after one month. It would be concluded more accurate results by using the satellite climate data for the further study. Keywords: Red tide, Sea water temperature, Cochlodinium polykrikoides. 1 Introduction Phytoplankton is the most common plankton causing red tide. Since the red tide caused by Cochlodinium polykrikoides was the first encountered in Jinhae Bay in the South Sea of Korea in 1982, it occurred the most of the Korean coasts in The red tide blooming caused serious fisheries damage of US $67 million in In the South Sea of Korea, the red tide occurs three times higher than the East Sea of Korea[1]. Because of rising the sea water temperature, the first day of red tide blooming is gradually being advanced, and the duration days are also longer. The amount of the fisheries damage caused of the red tide is also increasing, which is similar to the length of the red tide duration[2]. * Corresponding Author ISSN: ASTL Copyright 2017 SERSC

2 In particular, Tongyeong is the highest occurrence of the red tide for 551 times between 1998 and 2015[3]. There are various factors in the occurrence of red tide, sea water temperature is the most important factor for the red tide occurrence in Korea[4],[5]. Most of studies are focused when the red tide occurred and the distribution of the red tide. In this study, it is investigated the characteristics of the marine environment before the red tide occurrence. 2 Data and Methods The C(NIFS) s Red Tide Information System[6]. It shows the date, occurrence area, sea water temperature, density, latitude and longitude. Sea water temperature data were obtained from the Korea Hydrographic and Oceanographic Agency(KHOA)[7]. Each data were between 2011 and 2015 because the reference of GOCI image for the future study. For the red tide occurrence, the best sea water temperature for the occurrence of the red tide is 22~25 [5]. To use the water temperature data, the number of days are taken from the beginning of the best sea water temperature(22 ) to the occurrence of the red tide. 3 Results Table 1 shows the number of the monthly red tide occurrence in Tongyeong. It is different for each observation area, it could be occurred more than one places for one day. Red tide did not occurred in Table 1. The number of monthly red tide occurrence in Tongyeong from 2012 to July Aug Sep Oct Total Most of red tide occurred in August, and the red tide occurred in October in 2012 as well. Most of red tide occurred from July to August in In 2014, it occurred from July to October which was the highest for 81. Red tide occurred in August and September in Table 2 shows the number of red tide occurrence according to the concentration of the Cochlodinium polykrikoides. It was classified by referring the red tide forecast of the NIFS. In 2012, August is the highest number of the red tide appearance. More Copyright 2017 SERSC 133

3 than 100 cells/ml appeared 11 times and more than 1000 cells/ml appeared 7 times in that time. In 2013, more than 1000 cells/ml accounted 45 times for about 87%, it classified Yellow type when the red tide warned. More than 1000 cells/ml in August 2013 is the highest number of the red tide appearance from 2012 to In 2014, more than 1000 cells/ml in August and September appeared 20 times. Compared with 2012 and 2015, the number of red tide occurrence is similar, however, the concentration of 1000 cells/ ml is more than three times of difference. Table 2. The number of red tide occurrence according to the concentration of the Cochlodinium polykrikoides from 2012 to 2015 Cochlodinium polykrikoides (cell/ml) < > > > Total Figure 1 shows the mean sea water temperature between 2012 and Blue line is 2012, green line is 2013, yellow line is 2014, and orange line is Grey box shows the 22~25. In 2012, the sea water temperature is almost 30 in August which shows the highest. In 2013, the sea water temperature between July and August almost remain between 22 and 25 and it increases in September. In 2014 and 2015, most of the sea water temperature was highest in August. By using sea water temperature data, it is investigated that how long does it takes from the beginning of the best sea water temperature(22 ) to the occurrence of the red tide. Figure 2 shows the sea water temperature from the day of 22 to the end of the red tide occurrence in each year. In 2012, the sea water temperature was enough to cause the red tide from middle of June, and it occurred in 27th July, which is after 39 days. In 2013, it started from the beginning of July, the red tide occurred in 17th July, after 16 days. In 2014, it was reached from the end of June, the red tide started in 25th July, after 28 days. In 2015, it started from the beginning of July, and it started in 2nd August, after 31 days. 134 Copyright 2017 SERSC

4 Fig. 1. Mean sea water temperature from 2012 June to 2015 October. Blue line is 2012, green line is 2013, yellow line is 2014, and orange line is Grey box shows the 22~25. Fig. 2. Sea water temperature from the best sea water temperature to the end of the red tide occurrence. (a) shows the sea water temperature in 2012, which takes 39 days from 22 to red tide occurrence, (b) takes 16 days in 2013, (c) takes 28 days in 2014, and (d) takes 31 days in Copyright 2017 SERSC 135

5 For the red tide occurrence, the best sea water temperature starts from the end of June to the beginning of the July and the red tide is expected to occur about one month later. In 2013, the density of the Cochlodinium polykrikoides is high, however, red tide occurrence was short. It is considered that the best sea water temperature started earlier, and the sea water temperature in August was for 3~5 lower than other years which is between 22 and Conclusion In Tongyeong, the most of red tide occurred in August. The highest number of red tide occurrence was 2014 for 37 times. Cochlodinium polykrikoides concentration more than 1000 cells/ml in 2013 were 29 times. The red tide occurrence, the best sea water temperature is 22~25 which starts from the end of June to the beginning of the July and the red tide is expected to occur about one month later. This study only compared the sea water temperature data for the red tide occurrence. The sea water temperature does not cover the all of red tide occurrence area. It would be concluded more accurate results by using the satellite data for the wide area and meteorological data such as air temperature, wind, and sun shine duration for the further study. Acknowledgments. This work was supported by a Research Grant of Pukyong National University(2017 year). References 1. Lee, M. O., Kim, B. K., Kim, J. K.: Marine Environmental Characteristics of Goheung Coastal Waters during Cochlodinium polykrikoides Blooms. J. of the Korean Society for Marine Environment and Energy. 18(3), (2015) 2. Park, B.Y.: A study on satellite image and numerical model for the drift diffusion of red tide. Sungkyunkwan University, Seoul (2015) 3. Korea Institute of Science and Technology Information: A Study on the Detection and Likelihood Assessment of HAB outbreaks using Big Satellite Databases. Korea Institute of Science and Technology Information, Seoul (2014) 4. Yoon, H.: Meteorological Information for Red Tide.: Technical Development of Red Tide Prediction in the Korean Coastal Areas by metrological Factors. The Korean Institute of Maritime Information and Communication Sciences. 9(4), (2005) 5. Oh, S., Park, J., Yoon, H.: Prediction of Red Tide Occurrence by using Oceanic and Atmospheric Data by Satellite. J. of the Korea Institute of Electronics Communication Sciences. 10(2), (2015) 6. National Institute of Fisheries Science, 7. The Korea Hydrographic and Oceanographic Agency, Copyright 2017 SERSC