Feeding by the newly described heterotrophic dinoflagellate Gyrodinium jinhaense : comparison with G. dominans and G. mo
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ORIGINAL PAPER
Feeding by the newly described heterotrophic dinoflagellate Gyrodinium jinhaense: comparison with G. dominans and G. moestrupii Hee Chang Kang1 · Hae Jin Jeong1,2 · Sang Ah Park1 · Se Hee Eom1 · Jin Hee Ok1 · Ji Hyun You1 · Se Hyeon Jang1 · Sung Yeon Lee1 Received: 11 June 2020 / Accepted: 16 September 2020 / Published online: 1 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Heterotrophic dinoflagellates are major grazers of microalgae in marine food webs. The feeding of the newly described heterotrophic dinoflagellate Gyrodinium jinhaense was explored by providing 19 common microalgal prey species and the ciliate Mesodinium rubrum as prey. Furthermore, the specific growth and ingestion rates of G. jinhaense feeding on the chlorophyte Dunaliella salina were determined as a function of prey concentration. Cells of G. jinhaense were able to feed on microalgae of sizes ≤ 26 μm with the exception of the dinoflagellate Karenia mikimotoi. In contrast, G. jinhaense did not feed on microalgae > 26 μm with the exception of the dinoflagellate Lingulodinium polyedra. With increasing mean prey concentration, both the specific growth and ingestion rates of G. jinhaense feeding on D. salina rapidly increased at mean prey concentrations 30 G. jinhaense cells were tracked to examine physical contact, attack (attempt to capture), and successful capture (ingestion) with a dissecting microscope at a magnification of 10–63 × . Cells of G. jinhaense containing the ingested cells were photographed at a magnification of 1000 × using the EVOS M5000 Imaging System (Thermo Fisher Scientific, Bothell, WA, USA). Expt 2 was designed to investigate whether G. dominans could feed on each of 7 target prey species (Tables 3, 4). In addition, data on feeding occurrence by G. dominans on 13 target prey species were obtained from the literature (Table 4). The initial concentration of each prey species offered to G. dominans was similar to that offered to G. jinhaense in Expt 1. A dense culture of G. dominans growing by feeding on living cells of Amphidinium carterae was transferred to a 250-mL PC bottle containing freshly filtered seawater. Three 1-mL aliquots were then removed from the bottle and examined using a light microscope to determine the concentration of G. dominans. The procedures for establishing the initial concentrations of G. dominans and each target prey species; setting up the experimental, prey-only control, and predator-only control bottles; incubating the bottles; tracking predators; and photographing predators ingesting prey cells were the same as in Expt 1. Expt 3 was designed to investigate whether G. moestrupii could feed on each of 14 target prey species (Tables 3, 4). Data on feeding occurrence by G. moestrupii on 6 target prey species were obtained from the literature (Table 4). The initial concentration of each prey species offered to G. moestrupii was also similar to that offered to G. jinhaense in Expt 1. A dense culture of G. moestrupii growing by feeding on living
