Ingestion of cryptophyte cells by the marine photosynthetic ciliate Mesodinium rubrum

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 36:165-170 (2004) - doi:10.3354/ame036165 Ingestion of cryptophyte cells by the marine photosynthetic ciliate Mesodinium rubrum Wonho Yih1,*, Hyung Seop Kim1, Hae Jin Jeong2, Geumog Myung1, Young Geel Kim1 1Department of Oceanography, Kunsan National University, San 68, Miryong-dong, Kunsan 573-701, RO Korea 2School of Earth and Environmental Science, College of Natural Sciences, Seoul National University, Seoul 151-747, RO Korea *Email: ywonho@kunsan.ac.kr ABSTRACT: We investigated the mechanism of capturing and ingesting cryptophyte cells by a laboratory strain of the marine photosynthetic ciliate Mesodinium rubrum Lohmann 1908 (= Myrionecta rubra Jankowski 1976), a cosmopolitan red tide species. When offered cryptophytes as food, M. rubrum, originally grown photosynthetically for 2 wk, used its bifurcated oral tentacles to instantly seize prey cells when encountered. Immediately after capturing a prey cell, M. rubrum swam in a zigzag pattern (30 to 60 μm long linear paths) for >4 s, without showing the large jumps (with ca. 2000 μm long linear paths) that were usually observed when the predator was not feeding. M. rubrum with a cryptophyte attached to its tentacles became motionless while the prey cell was moved to the oral surface of the predator, a process that took <10 s. Engulfment of a captured prey cell by M. rubrum occurred through a cytostome-like structure and took ca. 15 s. Once engulfed, the prey was slowly delivered to the posterior end of the ciliate over a period of ca. 63 s. The whole feeding process lasted approximately 92 s. With increasing mean prey concentration, specific growth rates of M. rubrum feeding on the cryptophyte increased, with saturation at a mean prey concentration of 44 cells ml-1. The maximum specific growth rate (mixotrophic growth) of M. rubrum feeding on the cryptophyte was 0.521 d-1, under continuous illumination of 60 μE m-2 s-1, while its growth rate (phototrophic growth) under the same light conditions without added prey was 0.357 d-1. The ingestion rate of M. rubrum feeding on cryptophytes increased continuously with increasing prey concentration. The maximum ingestion rate was 8.9 cryptophytes ciliate-l d-1. M. rubrum may sometimes exert considerable impact on prey populations. KEY WORDS: Feeding · Growth rate · Grazing · Life cycle · Phagotrophy · Red tide Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 36, No. 2. Online publication date: July 21, 2004 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2004 Inter-Research.