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Induced phagotrophy in the photosynthetic dinoflagellate Heterocapsa triquetra

1998; Inter-Research Science Center; Volume: 15; Linguagem: Inglês

10.3354/ame015065

1616-1564

Catherine Legrand, E Granéli, Per Carlsson,

Aquatic Ecosystems and Phytoplankton Dynamics

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 15:65-75 (1998) - doi:10.3354/ame015065 Induced phagotrophy in the photosynthetic dinoflagellate Heterocapsa triquetra Catherine Legrand*, Edna Granéli, Per Carlsson Department of Natural Sciences, University of Kalmar, Box 905, S-39129 Kalmar, Sweden *E-mail: catherine.legrand@ng.hik.se Mixotrophy by the photosynthetic dinoflagellate Heterocapsa triquetra was investigated using fluorescently labelled algae (FLA) (size 1, 3, 6 μm). Experiments were conducted in nitrogen- and phosphorus-replete/depleted medium under light and dark conditions. Incubations ranged from several hours to several days. The dinoflagellate was capable of phagotrophy when exposed to light and dark periods in nutrient-depleted medium. H. triquetra showed similar ingestion rates in the light (range: 0.1 to 0.4 FLA dino-1 d-1) and in the dark (range: 0.06 to 0.4 FLA dino-1 d-1). The dinoflagellate was able to selectively ingest the different FLA. The cyanobacterium Synechococcus sp. was not ingested, whereas a small round flagellate and the diatom Thalassiosira pseudonana were observed inside the cells. The flagellate was ingested at higher rates than the diatom in both the light and the dark. About 40% of the labelled flagellate was removed from the suspension by H. triquetra in the light and 22% in the dark. The diatom was removed from the suspension at the same rate (27 to 30%) in both light and dark treatments.After 5 d incubation in nutrient-depleted medium and no addition of FLA, the proportion of small H. triquetra cells ( 2000 μm3) increased from 6 to >20 during long incubations in the light and the dark. Since the frequency of observed cells with ingested FLA varied from 3 to 20% for the same period, the proportion of larger cells may be the phagotrophic proportion of the population. However, only 8 (dark) to 12% (light) of the observed H. triquetra cell volume increase can be explained in terms of carbon from the ingestion of fluorescently labelled phytoplankton. We conclude that phagotrophy in H. triquetra may be important in maintaining the population in environments of low nutrient concentration and low light intensity. Phagotrophy · Mixotrophy · FLA · Nutrient limitation · Light limitation · Peridiniales · Heterocapsa triquetra Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 15, No. 1. Publication date: May 22, 1998 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1998 Inter-Research.