title: Differential interactions between the nematocyst-bearing mixotrophic dinoflagellate Paragymnodinium shiwhaense and common heterotrophic protists and copepods: Killer or prey.
abstract: To investigate interactions between the nematocyst-bearing mixotrophic dinoflagellate Paragymnodinium shiwhaense and different heterotrophic protist and copepod species, feeding by common heterotrophic dinoflagellates (Oxyrrhis marina and Gyrodinium dominans), naked ciliates (Strobilidium sp. approximately 35μm in cell length and Strombidinopsis sp. approximately 100μm in cell length), and calanoid copepods Acartia spp. (A. hongi and A. omorii) on P. shiwhaense was explored. In addition, the feeding activities of P. shiwhaense on these heterotrophic protists were investigated. Furthermore, the growth and ingestion rates of O. marina, G. dominans, Strobilidium sp., Strombidinopsis sp., and Acartia spp. as a function of P. shiwhaense concentration were measured. O. marina, G. dominans, and Strombidinopsis sp. were able to feed on P. shiwhaense, but Strobilidium sp. was not. However, the growth rates of O. marina, G. dominans, Strobilidium sp., and Strombidinopsis sp. feeding on P. shiwhaense were very low or negative at almost all concentrations of P. shiwhaense. P. shiwhaense frequently fed on O. marina and Strobilidium sp., but did not feed on Strombidinopsis sp. and G. dominans. G. dominans cells swelled and became dead when incubated with filtrate from the experimental bottles (G. dominans+P. shiwhaense) that had been incubated for one day. The ingestion rates of O. marina, G. dominans, and Strobilidium sp. on P. shiwhaense were almost zero at all P. shiwhaense concentrations, while those of Strombidinopsis sp. increased with prey concentration. The maximum ingestion rate of Strombidinopsis sp. on P. shiwhaense was 5.3ngC predator-1d-1(41 cells predator-1d-1), which was much lower than ingestion rates reported in the literature for other mixotrophic dinoflagellate prey species. With increasing prey concentrations, the ingestion rates of Acartia spp. on P. shiwhaense increased up to 930ngCml-1(7180cellsml-1) at the highest prey concentration. The highest ingestion rate of Acartia spp. on P. shiwhaense was 4240ngC predator-1d-1(32,610 cells predator-1d-1), which is comparable to ingestion rates from previous studies on other dinoflagellate prey species calculated at similar prey concentrations. Thus, P. shiwhaense might play diverse ecological roles in marine planktonic communities by having an advantage over competing phytoplankton in anti-predation against potential protistan grazers.
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea; Advanced Institutes of Convergence Technology, Suwon, Gyeonggi-do, 16229, Republic of Korea. Electronic address: hjjeong@snu.ac.kr.
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Jeong
authors.affiliation: Water and Eco-Bio Corporation, Kunsan National University, Kunsan 54150, Republic of Korea. Electronic address: kimjs90@kunsan.ac.kr.
authors.forename: Jae Seong
authors.initials: JS
authors.lastname: Kim
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Kyung Ha
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Marine Biotechnology, Kunsan National University, Kunsan 54150, Republic of Korea.
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Seong
authors.affiliation: Department of Marine Biotechnology, Kunsan National University, Kunsan 54150, Republic of Korea.
authors.forename: Yeong Du
authors.initials: YD
authors.lastname: Yoo
authors.affiliation: Marine Biodiversity Institute of Korea, Seochun-gun, Chungchungnam-do, 33662, Republic of Korea.
authors.forename: Nam Seon
authors.initials: NS
authors.lastname: Kang
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Kim
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Jae Yoon
authors.initials: JY
authors.lastname: Song
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Kwon
mesh_terms: D000818:Animals; D016798:Ciliophora / Q000254:growth & development / Q000502:physiology*; D033342:Copepoda / Q000254:growth & development / Q000502:physiology*; D004032:Diet; D004141:Dinoflagellida / Q000254:growth & development / Q000502:physiology*; D004435:Eating; D020387:Food Chain; D010839:Phytoplankton / Q000254:growth & development / Q000502:physiology; D011235:Predatory Behavior
keywords: Acartia; Growth; Gyrodinium; Ingestion; Oxyrrhis; Strobilidium; Strombidinopsis