Interactions between common heterotrophic protists and the dinoflagellate Tripos furca: implication on the long duration of its red tides in the South Sea of Korea in 2020

Abstract

The mixotrophic dinoflagellate Tripos furca causes red tides in the waters of many countries. To understand its population dynamics, mortality due to predation as well as growth rate should be assessed. Prior to the present study, the heterotrophic dinoflagellates Noctiluca scintillans, Polykrikos kofoidii, Protoperidinium steinii, and mixotrophic dinoflagellate Fragilidium subglobosum were known to ingest T. furca. However, if other common heterotrophic protists are able to feed on T. furca has not been tested. We explored interactions between T. furca and nine heterotrophic dinoflagellates and one naked ciliate. Furthermore, we investigated the abundance of T. furca and common heterotrophic protists in coastal-offshore waters off Yeosu, southern Korea, on Jul 31, 2020, during its red tide. Among the tested heterotrophic protists, the heterotrophic dinoflagellates Aduncodinium glandula, Luciella masanensis, and Pfiesteria piscicida were able to feed on T. furca. However, the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium jinhaense, Gyrodinium moestrupii, Oblea rotunda, Oxyrrhis marina, and the naked ciliate Rimostrombidium sp. were unable to feed on it. However, T. furca did not support the growth of A. glandula, L. masanensis, or P. piscicida. Red tides dominated by T. furca prevailed in the South Sea of Korea from Jun 30 to Sep 5, 2020. The maximum abundance of heterotrophic dinoflagellates in the waters off Yeosu on Jul 31, 2020, was as low as 5.0 cells mL-1 , and A. glandula, L. masanensis, and P. piscicida were not detected. Furthermore, the abundances of the known predators F. subglobosum, N. scintillans, P. kofoidii, and Protoperidinium spp. were very low or negligible. Therefore, no or low abundance of effective predators might be partially responsible for the long duration of the T. furca red tides in the South Sea of Korea in 2020.

Comparative Transcriptome Analysis of the Phototrophic Dinoflagellate Biecheleriopsis adriatica Grown Under Optimal Temperature and Cold and Heat Stress

“…Dinoflagellates are ubiquitous and major components of marine ecosystems (Sherr and Sherr, 2007;Taylor et al, 2008;Kang et al, 2020b;Jeong et al, 2021a). They have all three trophic modes (i.e., autotrophy, mixotrophy, and heterotrophy) and play diverse roles as primary producers, prey, predators, symbionts, and parasites, which contribute to active biological interactions and material cycling in the ocean (Hansen, 1991;Coats, 1999;Jeong et al, 2010;Davy et al, 2012;Stoecker et al, 2017;Kang et al, 2018Kang et al, , 2019aKang et al, , 2020bSpilling et al, 2018;Eom et al, 2021). They sometimes cause red tides or harmful algal blooms, resulting in large-scale marine organism mortality and considerable economic loss to marine industries (Shumway, 1990;Landsberg, 2002;Flewelling et al, 2005;Jeong et al, 2021a;Sakamoto et al, 2021).…”

Phytoplankton Bloom Dynamics in Incubated Natural Seawater: Predicting Bloom Magnitude and Timing

“…The dominant phototrophic protists in the seawaters used in this study, S. costatum, C. curvisetus, C. closterium, P. pungens, and T. furca, and the photosynthetic ciliate, M. rubrum, are commonly found in the seawater of many other regions (e.g., Tilstone et al, 1994;Marshall and Nesius, 1996;Zhang et al, 2015). Furthermore, they are known to often cause blooms in the study region and many other regions (e.g., Lips and Lips, 2017;Eom et al, 2021;Jeong et al, 2021). The naked ciliate Strobilidium spp.…”

Interactions Between the Kleptoplastidic Dinoflagellate Shimiella gracilenta and Several Common Heterotrophic Protists

“…The cell volumes of A. glandula, G. jinhaense, G. dominans, O. rotunda, O. marina, P. kofoidii, P. piscicida, and Rimostrombidium sp. were estimated following the method described by Jang et al (2016), Kang et al (2020), Jeong et al (2001bJeong et al ( , 2007aJeong et al ( , 2008, Ok et al (2017), andEom et al (2021). The cell volume of S. gracilenta was also measured in the present study.…”

“…Typically, to identify predators of specific dinoflagellates, mixotrophic and/or heterotrophic organisms, which are abundant during or after the bloom of the target dinoflagellate (Yoo et al, 2013a;Lim et al, 2017;Eom et al, 2021), are selected as the potential predators. Alternatively, predators of the target dinoflagellate can be identified by observing the feeding behavior under a microscope after mixing the target dinoflagellate cells with potential predators commonly found in many marine environments (Yoo et al, 2010(Yoo et al, , 2015Potvin et al, 2013;Ok et al, 2017;Kim et al, 2019).…”