Different life cycle strategies of the dinoflagellates Fragilidium duplocampanaeforme and its prey Dinophysis acuminata may explain their different susceptibilities to the infection by the parasite Parvilucifera infectans |
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| Affiliation: | 1. Norwegian Institute for Water Research, Gaustadallèen 21, 0349, Oslo, Norway;2. Norwegian Veterinary Institute, P.O. box 750 Sentrum, 0106, Oslo, Norway;3. University of Oslo, Department of Biosciences, P. O. box 1066 Blindern, 0316, Oslo, Norway;4. Marine Biological Association of the UK, The Citadel, Plymouth, Pl1 2PB, United Kingdom;1. Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Alte Fischerhuette 2, D-16775 Stechlin, Germany;2. Sugadaira Montane Research Center, University of Tsukuba, 1278-294, Sugadaira-Kogen, Ueda, Nagano 386-2204, Japan;3. Universidad Latina de Costa Rica, Campus San Pedro, Apdo. 10138-1000, San Jose, Costa Rica;4. Department of Environmental Sciences, Faculty of Science, Toho University, Funabashi, Chiba, Japan;5. Institute of Biochemistry and Biology, Potsdam University, Maulbeerallee 2, 14476 Potsdam, Germany;1. Library of Marine Samples, Korea Institute of Ocean Science and Technology, Geoje, 656-830, Republic of Korea;2. Marine Ecosystem and Biological Research Center, Korea Institute of Ocean Science and Technology, Ansan, 425-600, Republic of Korea;3. Marine Ecology Research Center, Yeosu, 59697, Republic of Korea;4. National Institute of Fisheries Science, Busan, 619-705, Republic of Korea;1. Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390 Vigo, Spain;2. Centro i∼mar & CeBiB, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile;3. Instituto Español de Oceanografía (IEO), Centro Oceanográfico de A Coruña, Paseo Marítimo Alcalde Francisco Vázquez 10, 15001 A Coruña, Spain;4. Departamento de Ecología y Biología Animal, Universidad de Vigo, Campus Universitario As Lagoas-Marcosende, E-36310 Vigo, Spain;5. Instituto de Investigaciones Marinas (IIM-CSIC), Eduardo Cabello 6, 32208 Vigo, Spain;1. Department of Life Science, Hanyang University, Seoul 04763, South Korea;2. Marine Science Institute, The University of Texas at Austin, Port Aransas, TX 78373, USA;3. Department of Oceanography, Pukyong National University, Busan 48513, South Korea;4. Water Source Management Division, Han River Basin Environmental Office, Hanam, 12902, South Korea;5. Risk Assessment Research Center, KIOST (Korea Institute of Ocean Science and Technology), Geoje, 53201, South Korea;6. Research Institute for Natural Sciences, Hanyang University, Seoul 04763, South Korea;1. School of Biological Sciences, F07, University of Sydney, NSW 2006, Australia;2. Department of Environmental Sciences, Faculty of Agriculture and Environment, University of Sydney, NSW 2006, Australia;3. Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA, Scotland, UK;4. LMGE, Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Université Blaise Pascal, BP 80026, 63171 Aubière Cedex, 9, France;5. Culture Collection for Algae and Protozoa, Scottish Marine Institute, Scottish Association for Marine Science, Oban PA37 1QA, UK;6. Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034, Russian Federation;7. St. Petersburg State University, St. Petersburg 199034, Russian Federation;8. CNRS, UMR 7144, Laboratoire Adaptation et Diversité en Milieu Marin, Place Georges Teissier, CS90074, 29688 Roscoff Cedex, France;9. Sorbonne Universités, Université Pierre et Marie Curie – Paris 6, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, CS90074, 29688 Roscoff cedex, France |
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| Abstract: | Some marine dinoflagellates form ecdysal cyst (=temporary cysts) as part of their life cycle or under unfavorable growth conditions. Whether the dinoflagellates form ecdysal cysts or not may influence susceptibility to parasitism. In this study, parasite prevalence relative to inoculum size of the parasitoid Parvilucifera infectans zoospores for two dinoflagellate hosts (i.e., Fragilidium duplocampanaeforme and Dinophysis acuminata), which have different life cycle strategies, was examined. Further, susceptibility of cysts to parasitism, encystment signal, duration of encystments, and effects of induced encystment on diel periodicity, using ecdysal cyst-forming F. duplocampanaeforme were explored. The percent hosts infected by P. infectans plotted as a function of inoculum size showed a sharp increase to a maximum in D. acuminata, but a gradual linear rise in F. duplocampanaeforme: while the parasite prevalence in D. acuminata increased to a maximum of 78.8 (±2.4%) by a zoospore:host ratio of 20:1, it in F. duplocampanaeforme only reached 8.9 (±0.3%), even at a zoospore:host ratio of 120:1. In F. duplocampanaeforme, infections were observed only in the vegetative cells and not observed in ecdysal cysts. When exposed to live, frozen, and sonicated zoospores and zoospore filtrate, F. duplocampanaeforme formed ecdysal cysts only when exposed to live zoospores, suggesting that temporary cyst formation in the dinoflagellate resulted from direct contact with zoospores. When the Parvilucifera zoospores attacked and struggled to penetrate F. duplocampanaeforme through its flagellar pore, the Fragilidium cell shed all thecal plates, forming a ‘thecal cloud layer’, in which the zoospores were caught and immobilized and thus could not penetrate anymore. The duration (35 ± 1.8 h) of ecdysal cysts induced with addition of zoospores was significantly longer than that (15 ± 0.8 h) of normally formed cysts (i.e., without addition of zoospores), thereby resulting in delayed growth as well as influencing the pattern of diel periodicity. The results from this study suggest that in addition to the classical predator-prey interaction and allelopathic interaction, parasitism and its accompanying defense can make the food web dynamics much more complicated than previously thought. |
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| Keywords: | Dinoflagellate Defense mechanism Parasite Cyst formation Food web dynamics |
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