Mixotrophy in the marine red-tide cryptophyte Teleaulax amphioxeia and ingestion and grazing impact of cryptophytes on natural populations of bacteria in Korean coastal waters |
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| Institution: | 1. Department of Marine Biotechnology, College of Ocean Science and Technology, Kunsan National University, Kunsan 54150, Republic of Korea;2. School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea;3. Nakdonggang National Institute of Biological Resources, Sangju, 37242, Republic of Korea;1. School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea;2. Advanced Institutes of Convergence Technology, Suwon, Gyeonggi-do 16229, Republic of Korea;3. Department of Marine Biotechnology, College of Ocean Science and Technology, Kunsan National University, Kunsan 54150, Republic of Korea;1. Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791, South Korea;2. Research Institute for Natural Sciences, Hanyang University, Seoul 133-791, South Korea;3. School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000, USA;4. Korea Institute of Ocean Science and Technology/South Sea Institute, Geoje 656-830, South Korea;1. Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000, Helsingør, Denmark;2. Alfred-Wegener Institute for Polar and Marine Research, Chemical Ecology, Am Handelshafen 12, Bremerhaven, 27570, Germany;1. Graduate School of Science and Engineering, Yamagata University, 1-4-12 Kojirakawa, Yamagata 990-8560, Japan;2. Biological Institute, Section of Phycology, University of Copenhagen, Universitetsparken 4, DK-2100, Copenhagen K, Denmark;3. Faculty of Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata 990-8560, Japan;4. Asian Natural Environmental Science Center, the University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-8657, Japan;1. Department of Biology, Kongju National University, Kongju 314-701, Republic of Korea;2. Converging Research Division, National Marine Biodiversity Institute of Korea, Seocheon 325-902, Republic of Korea;3. Department of Biology, Chungnam National University, Daejeon 305-764, Republic of Korea;4. Southwest Sea Fisheries Research Institute, National Fisheries Research & Development Institute, Yeosu 556-823, Republic of Korea;5. Department of Oceanography, Kunsan National University, Gunsan 573-701, Republic of Korea |
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| Abstract: | Cryptophytes are ubiquitous and one of the major phototrophic components in marine plankton communities. They often cause red tides in the waters of many countries. Understanding the bloom dynamics of cryptophytes is, therefore, of great importance. A critical step in this understanding is unveiling their trophic modes. Prior to this study, several freshwater cryptophyte species and marine Cryptomonas sp. and Geminifera cryophila were revealed to be mixotrophic. The trophic mode of the common marine cryptophyte species, Teleaulax amphioxeia has not been investigated yet. Thus, to explore the mixotrophic ability of T. amphioxeia by assessing the types of prey species that this species is able to feed on, the protoplasms of T. amphioxeia cells were carefully examined under an epifluorescence microscope and a transmission electron microscope after adding each of the diverse prey species. Furthermore, T. amphioxeia ingestion rates heterotrophic bacteria and the cyanobacterium Synechococcus sp. were measured as a function of prey concentration. Moreover, the feeding of natural populations of cryptophytes on natural populations of heterotrophic bacteria was assessed in Masan Bay in April 2006. This study reported for the first time, to our knowledge, that T. amphioxeia is a mixotrophic species. Among the prey organisms offered, T. amphioxeia fed only on heterotrophic bacteria and Synechococcus sp. The ingestion rates of T. amphioxeia on heterotrophic bacteria or Synechococcus sp. rapidly increased with increasing prey concentrations up to 8.6 × 106 cells ml−1, but slowly at higher prey concentrations. The maximum ingestion rates of T. amphioxeia on heterotrophic bacteria and Synechococcus sp. reached 0.7 and 0.3 cells predator−1 h−1, respectively. During the field experiments, the ingestion rates and grazing coefficients of cryptophytes on natural populations of heterotrophic bacteria were 0.3–8.3 cells predator−1 h−1 and 0.012–0.033 d−1, respectively. Marine cryptophytes, including T. amphioxeia, are known to be favorite prey species for many mixotrophic and heterotrophic dinoflagellates and ciliates. Cryptophytes, therefore, likely play important roles in marine food webs and may exert a considerable potential grazing impact on the populations of marine bacteria. |
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| Keywords: | Bloom Flagellate Grazing impact Predator-prey relationship Red tide |
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