ABSTRACT: A method for estimating the in situ growth rate from the nuclear position of the pelagic diatom Pseudosolenia calcar-avis is proposed. The algal cells were seento exhibit characteristic positioning of the nucleus during each cell cycle. Nucleus movement in the first several hours after cell division was consistent in this algalpopulation. The position of the nucleus can be regarded as the quantitative index of duration time after cell division. Applying this index to the method proposed by McDuff & Chisholm (1982; Limnol Oceanogr 27:783-788) has been shown to give an estimation for the daily averaged specific growth rate of the P. calcar-avis population. This method could be useful for the estimation of the in situ growth rate of other Rhizosoleniacea species in the ocean without the need for bottle incubations.

KEY WORDS: In situ growth rate . Large pelagic diatom . Rhizosoleniacea

Published in MEPS Vol. 131 (1996) on February 8
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996