Effect of nutritional condition on photosymbiotic consortium of cultured Globigerinoides sacculifer (Rhizaria, Foraminifera)

Haruka Takagi, Katsunori Kimoto, Tetsuichi Fujiki, Kazuyoshi Moriya

    Research output: Contribution to journalArticle

    Abstract

    Several foraminifers found in warm and low-nutrient ocean surface water have photosynthetic algae as endosymbionts (photosymbiosis). To understand the trophic interactions, we studied Globigerinoides sacculifer, a spinose planktic foraminifer that has a dinoflagellate endosymbiont. We controlled two nutritional factors, feeding and inorganic nutrients in the seawater. The growth of the host and the symbionts and the photophysiological parameters were monitored under four experimental conditions. The results demonstrated that the holobionts primarily relied on phagotrophy for growth. The foraminifers grew considerably, and the chlorophyll a content per foraminifer, which is an indicator of the symbiont population, increased in the fed groups, but not in the unfed groups. The nutrient-rich seawater used for some of the cultures made no difference in either the growth or photophysiology of the holobionts. These observations indicated that the symbionts mainly utilized metabolites from the hosts for photosynthesis rather than inorganic nutrients in the seawater. Additionally, we observed that the symbionts in the starved hosts maintained their photosynthetic capability for at least 12 days, and that the hosts maintained at least some symbionts until gametogenesis was achieved. This suggests that the hosts have to retain the symbionts as an energy source for reproduction. The symbionts may also play an indispensable role in the metabolic activities of the hosts including waste transport or essential compound synthesis. Overall, our results revealed a novel mode of photosymbiosis in planktic foraminifers which contrasts with that found in benthic photosymbiotic foraminifers and corals.

    Original languageEnglish
    Pages (from-to)1-15
    Number of pages15
    JournalSymbiosis
    DOIs
    Publication statusAccepted/In press - 2017 Dec 9

    Fingerprint

    Rhizaria
    Foraminifera
    symbionts
    Seawater
    Food
    seawater
    endosymbionts
    nutrients
    algae
    Growth
    Gametogenesis
    Dinoflagellida
    Anthozoa
    Photosynthesis
    Oceans and Seas
    gametogenesis
    Reproduction
    Retaria
    corals
    surface water

    Keywords

    • Growth
    • Nutrition
    • Photophysiology
    • Photosymbiosis
    • Planktic foraminifers
    • Symbiotic algae

    ASJC Scopus subject areas

    • Agricultural and Biological Sciences(all)

    Cite this

    Effect of nutritional condition on photosymbiotic consortium of cultured Globigerinoides sacculifer (Rhizaria, Foraminifera). / Takagi, Haruka; Kimoto, Katsunori; Fujiki, Tetsuichi; Moriya, Kazuyoshi.

    In: Symbiosis, 09.12.2017, p. 1-15.

    Research output: Contribution to journalArticle

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