Control of the harmful alga Cochlodinium polykrikoides by the naked ciliate Strombidinopsis jeokjo in mesocosm enclosures |
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Authors: | Hae Jin Jeong Jae Seong Kim Yeong Du Yoo Seong Taek Kim Jae Yoon Song Tae Hoon Kim Kyeong Ah Seong Nam Seon Kang Mi Seon Kim Jong Hyeok Kim Shin Kim Jina Ryu Hee Mahn Lee Won Ho Yih |
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Institution: | aSchool of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea;bDepartment of Oceanography, College of Ocean Science and Technology, Kunsan National University, Kunsan 573-701, Republic of Korea;cMarineBio Co., Myrongdong San 68, Kunsan 573-701, Republic of Korea |
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Abstract: | Red tides dominated by the harmful dinoflagellate Cochlodinium polykrikoides have caused annual losses of USD $5–60 million to the Korean aquaculture industry annually since 1995 and a loss of USD $3 million during a 1999 net-pen fish mortality event in Canada. In order to evaluate the potential to control C. polykrikoides red tides dominated by using mass-cultured heterotrophic protistan grazers, we monitored the abundance of Strombidinopsis jeokjo (a naked ciliate) and C. polykrikoides after mass-cultured S. jeokjo was introduced into mesocosms (ca. 60 l) deployed in situ and containing natural red tide waters dominated by C. polykrikoides. Water temperature, salinity, and pH, as well as the abundance of co-occurring other protists and metazooplankton were measured concurrently. To compare the growth and ingestion rates of S. jeokjo feeding on cultured versus natural populations of C. polykrikoides, we also monitored the abundance of cultured C. polykrikoides and S. jeokjo in bottles during laboratory grazing experiments. S. jeokjo introduced into the mesocosms grew well, effectively reducing natural populations of C. polykrikoides from approximately 1000 cells ml−1 to below 10 cells ml−1 within 2 days. The growth and ingestion rates of cultured S. jeokjo on natural populations of C. polykrikoides in the mesocosms for the first 30 h (0.72 day−1 and 51 ng C grazer−1 day−1) were 84% and 44%, respectively, of those measured in the laboratory during bottle incubations with similar initial prey concentrations. The calculated grazing impact of S. jeokjo on natural populations of C. polykrikoides suggests that large-scale cultures of this ciliate could be used for controlling red tides by C. polykrikoides in small areas. |
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Keywords: | Cochlodinium polykrikoides Growth Harmful algal bloom Ingestion Management Mitigation Red tide |
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