Feeding by common heterotrophic protist predators on seven &lt;italic&gt;Prorocentrum&lt;/italic&gt; species

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Water temperature is known to affect the growth and feeding of marine dinoflagellates. Each dinoflagellate species grows well at a certain optimal temperature but dies at very cold and hot temperatures. Thus, changes in water temperatures driven by global warming and extremely high or low temperatures can affect the distribution of dinoflagellates. Yihiella yeosuensis is a mixotrophic dinoflagellate that can feed on only the cryptophyte Teleaulax amphioxeia and the chlorophyte Pyramimonas sp. Furthermore, it grows fast mixotrophically but rarely grows photosynthetically. We explored the direct and indirect effects of water temperature on the growth and ingestion rates of Y. yeosuensis feeding on T. amphioxeia and the growth rates of T. amphioxeia and Pyramimonas sp. under 7 different water temperatures (5-35°C). Both the autotrophic and mixotrophic growth rates of Y. yeosuensis on T. amphioxeia were significantly affected by temperature. Under the mixotrophic and autotrophic conditions, Y. yeosuensis survived at 10-25°C, but died at 5°C and ≥30°C. The maximum mixotrophic growth rate of Y. yeosuensis on T. amphioxeia (1.16 d-1) was achieved at 25°C, whereas the maximum autotrophic growth rate (0.16 d-1) was achieved at 15°C. The maximum ingestion rate of Y. yeosuensis on T. amphioxeia (0.24 ng C predator-1 d-1) was achieved at 25°C. The cells of T. amphioxeia survived at 10-25°C, but died at 5 and ≥30°C. The cells of Pyramimonas sp. survived at 5-25°C, but died at 30°C. The maximum growth rate of T. amphioxeia (0.72 d-1) and Pyramimonas sp. (0.75 d-1) was achieved at 25°C. The abundance of Y. yeosuensis is expected to be high at 25°C, at which its two prey species have their highest growth rates, whereas Y. yeosuensis is expected to be rare or absent at 5°C or ≥30°C at which its two prey species do not survive or grow. Therefore, temperature can directly or indirectly affect the population dynamics and distribution of Y. yeosuensis.

Section: Introductionmentioning

confidence: 99%

Effects of temperature on the growth and ingestion rates of the newly described mixotrophic dinoflagellate Yihiella yeosuensis and its two optimal prey species

Kang¹,

Jeong²,

Lim³

et al. 2020

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“…Cells of L. masanensis and P. piscicida are known to feed on dinoflagellate prey species of ≤9.7 µm in the equivalent spherical diameter (ESD) and athecate dinoflagellates such as Margalefidinium polykrikoides, Akashiwo sanguinea, and Gymnodinium catenatum, but they did not feed on thecate dinoflagellates ≥12.1 µm (Jeong et al 2007). You et al (2020) reported that P. piscicida fed on larger sized thecate dinoflagellates, but only on motionless cells. Thus, the present study is the first to report that L. masanensis and P. piscicida are able to feed on a moving thecate dinoflagellate ≥12.1 µm because the ESD of T. furca is approximately 29 µm (Jeong et al 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Using the same calculation, the carbon contents of all predator species in the present study were also evaluated from the cell volume. The cell volumes of the heterotrophic predators were assessed using the methods of Jang et al (2016) for A. glandula; Ok et al 2017for G. shiwhaense; Kang et al (2020) for G. dominans, G. jinhaense, and G. moestrupii;Jeong et al (2007) for L. masanensis and P. piscicida; You et al (2020) for O. rotunda and O. marina; and this study for Rimostrombidium sp. (Table 1).…”

Section: Introductionmentioning

confidence: 92%

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

Eom¹,

Jeong²,

Ok³

et al. 2021

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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.

“…Gjin Gmoe Chl-a T S highest abundance of each species was found during the study period was 127.0, 6.8, and 0.9 ng Chl-a mL -1 for G. dominans, G. jinhaense, and G. moestrupii, respectively. Assuming that the ratio of carbon to Chl-a was 40 (Peterson and Festa 1984) and all Chl-a were attributed to P. donghaiense, using the equation of You et al (2020), the calculated growth rate of G. dominans on P. donghaiense at 127 ng Chl-a mL -1 (5,080 ng C mL -1 ) would be 1.09 d -1 . Similarly, if all Chl-a belonged to D. salina, using the equation of Kang et al (2020), the calculated growth rate of G. jinhaense on D. salina at 6.8 ng Chl-a mL -1 (270 ng C mL -1 ) would be 0.20 d -1 .…”

Section: Species Gdomentioning

confidence: 99%

Comparison of the spatial-temporal distributions of the heterotrophic dinoflagellates Gyrodinium dominans, G. jinhaense, and G. moestrupii in Korean coastal waters

Lee¹,

Jeong²,

Kang³

et al. 2021

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Heterotrophic dinoflagellates Gyrodinium spp. are one of the major grazers of phytoplankton in many coastal waters. Gyrodinium dominans, G. jinhaense, and G. moestrupii have similar morphologies but different edible prey species. To explore the variations in the ecological niches of these three species, we investigated their spatial-temporal distributions in Korean waters. Because of the high similarity in morphology among these three Gyrodinium species, we used real-time polymerase chain reactions to quantify their abundance in water samples that were seasonally collected from 28 stations along the Korean Peninsula from April 2015 to October 2018. Cells of G. dominans were found at all sampling stations, G. jinhaense at 26 stations, and G. moestrupii at 22 stations, indicating that all three species were widely distributed in Korea. Furthermore, all three species displayed strong seasonal distributions. The largest numbers of the stations where G. dominans and G. jinhaense cells were present were found during the summer (26 and 23 stations, respectively), but that for G. moestrupii was found in the autumn (15 stations). The abundance of G. dominans was positively correlated with that of G. jinhaense, but not with that of G. moestrupii. The highest abundances of G. dominans (202.5 cells mL-1) and G. jinhaense (20.2 cells mL-1) were much greater than that of G. moestrupii (1.2 cells mL-1). The highest abundances of G. dominans and G. jinhaense were found in July, whereas that of G. moestrupii was found in March. The abundances of G. dominans and G. jinhaense, but not G. moestrupii, were positively correlated with water temperature. Therefore, the spatial-temporal distributions of G. dominans and G. jinhaense were closer than those of G. moestrupii and G. dominans or G. jinhaense. This differs from results based on the relative differences in ribosomal DNA sequences and the types of edible prey reported in the literature. Thus, the variations in spatial-temporal distributions and prey species of these three Gyrodinium species suggest that they may have different ecological niches in Korean coastal waters.