title: The newly described heterotrophic dinoflagellate Gyrodinium moestrupii, an effective protistan grazer of toxic dinoflagellates.
abstract: Few protistan grazers feed on toxic dinoflagellates, and low grazing pressure on toxic dinoflagellates allows these dinoflagellates to form red-tide patches. We explored the feeding ecology of the newly described heterotrophic dinoflagellate Gyrodinium moestrupii when it fed on toxic strains of Alexandrium minutum, Alexandrium tamarense, and Karenia brevis and on nontoxic strains of A. tamarense, Prorocentrum minimum, and Scrippsiella trochoidea. Specific growth rates of G. moestrupii feeding on each of these dinoflagellates either increased continuously or became saturated with increasing mean prey concentration. The maximum specific growth rate of G. moestrupii feeding on toxic A. minutum (1.60/d) was higher than that when feeding on nontoxic S. trochoidea (1.50/d) or P. minimum (1.07/d). In addition, the maximum growth rate of G. moestrupii feeding on the toxic strain of A. tamarense (0.68/d) was similar to that when feeding on the nontoxic strain of A. tamarense (0.71/d). Furthermore, the maximum ingestion rate of G. moestrupii on A. minutum (2.6 ng C/grazer/d) was comparable to that of S. trochoidea (3.0 ng C/grazer/d). Additionally, the maximum ingestion rate of G. moestrupii on the toxic strain of A. tamarense (2.1 ng C/grazer/d) was higher than that when feeding on the nontoxic strain of A. tamarense (1.3 ng C/grazer/d). Thus, feeding by G. moestrupii is not suppressed by toxic dinoflagellate prey, suggesting that it is an effective protistan grazer of toxic dinoflagellates.
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-747, R.O. Korea.
authors.forename: Yeong Du
authors.initials: YD
authors.lastname: Yoo
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Yoon
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Kyung Ha
authors.initials: KH
authors.lastname: Lee
authors.forename: Yeong Jong
authors.initials: YJ
authors.lastname: Hwang
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Seong
authors.forename: Jae Seong
authors.initials: JS
authors.lastname: Kim
authors.forename: Jae Yeon
authors.initials: JY
authors.lastname: Park
mesh_terms: D059001:Aquatic Organisms; D004141:Dinoflagellida / Q000254:growth & development / Q000502:physiology*; D020387:Food Chain; D010933:Plankton; D056910:Republic of Korea; D013045:Species Specificity