Plankton and Benthos Research
Online ISSN : 1882-627X
Print ISSN : 1880-8247
ISSN-L : 1880-8247
Original Papers
Photoautotrophic growth of Noctiluca scintillans with the endosymbiont Pedinomonas noctilucae
Haruna SaitoKen FuruyaThaithaworn Lirdwitayaprasit
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2006 Volume 1 Issue 2 Pages 97-101


Photosynthesis and respiration of a heterotrophic dinoflagellate Noctiluca scintillans that contained Pedinomonas noctilucae as an endosymbiont, were examined on cultures and natural populations in Manila Bay, Philippines, using a Clark-type oxygen electrode. The cultures isolated from the inner Gulf of Thailand were of two types: one required external supply of Dunaliella tertiolecta as food (feeding strains) and the other did not (non-feeding strains). The non-feeding strains grew photoautotrophically for generations, but they also fed on D. tertiolecta, indicating phagotrophy was facultative. Gross photosynthesis was at the same level in both types, but net photosynthesis was significantly higher in the non-feeding strains than the feeding ones. The difference was due to high respiration activity in the feeding strains. This was consistent with observations in the natural population of Manila Bay, where net photosynthesis was significantly higher in cells lacking food vacuoles than those with food vacuoles. The relationship of photosynthesis with irradiance was characterized by low intensity of light saturation and absence or weak photoinhibition, showing efficient utilization of a wide range of light intensities. P. noctilucae likely assures a supply of organic matter to the host, and facilitates survival of N. scintillans during shortages of food particles.

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© 2006 The Plankton Society of Japan, The Japanese Association of Benthology
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