Abstract
The pennate diatom Neosynedra provincialis bloomed prominently on the surface of plastic plates which were placed in a seawater tank to grow diatoms for the primary food of abalone larvae in 1982. The electron micrographs are shown to inform the morphological features.
Propagation of this diatom in the maricultural tank might be caused by excessive aeration of seawater flowing in the tank. The growth of threadlike colonies of this diatom looked unfavorable for abalone larvae, because the individuals living on the plates tended to get out of their feeding beds. Localities on the Japanese coast where N. provincialis has been found are noted.
