Relationships between occurrences of toxic Dinophysis species (Dinophyceae) and small phytoplanktons in Japanese coastal waters

Goh Nishitani, Mineo Yamaguchi, Akira Ishikawa, Satoshi Yanagiya, Tadashi Mitsuya, Ichiro Imai

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Fluctuations of the genus Dinophysis, which contained several toxic species of diarrhetic shellfish poisoning (DSP), were investigated during blooms in Hiroshima Bay, Mutsu Bay and Ise Bay, Japan. The co-occurrences of small phytoplanktons (cryptophytes, other nanophytoplanktons, cyanobacteria and eukaryotic picophytoplanktons) were investigated to search for relationships with mixotrophic Dinophysis. Cryptophytes were divided into three size-groups based on length of their chloroplasts (>10, 5-10 and <5 μm) during counting by epifluorescence microscopy. Clear relationships were not found between the occurrences of Dinophysis spp. and nanophytoplanktons, cyanobacteria and eukaryotic picophytoplanktons. However, the fluctuations of small-sized cryptophytes (<5 μm) showed a close relationship with that of D. acuminata in Hiroshima Bay. In Mutsu Bay, small-sized cryptophytes also accompanied the first occurrence peak of Dinophysis spp. In Ise Bay, peaks of the occurrences of middle- and small-sized cryptophytes were observed 2-3 weeks before the peak of D. acuminata. These cryptophytes decreased rapidly with increase in D. acuminata. These results suggest the possibility that small-sized cryptophytes may be food organisms for mixotrophic Dinophysis, with the abundance of Dinophysis dependent on these cryptophytes.

Original languageEnglish
Pages (from-to)755-762
Number of pages8
JournalHarmful Algae
Issue number4
Publication statusPublished - 2005 Jun
Externally publishedYes


  • Dinophysis species
  • Mixotrophy
  • Small-sized cryptophytes

ASJC Scopus subject areas

  • Aquatic Science
  • Plant Science


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