open access

https://doi.org/10.14943/bull.fish.66.3.121

https://hdl.handle.net/2115/64176

Iron requirements of Heterosigma akashiwo(Raphidophyceae), Heterocapsa circularisquama(Dinophyceae) and two common centric diatoms

英語

maximum growth rate

2016-12-27

北海道大学大学院水産科学研究院

北海道大学水産科学研究彙報

66(3)

121-128

Iron is increasingly recognized to play a key role in the growth of microalgae in various marine systems, but there is a paucity of knowledge about the physiological iron requirements of harmful algal species. This study aimed to elucidate the halfsaturation constant for growth(Ks) and the maximum growth rate(μmax) of four phytoplankton species with regard to iron concentrations. The four species were the fish-killing raphidophyte Heterosigma akashiwo, the bivalve-killing dinoflagellate Heterocapsa circularisquama, and the centric diatoms Ditylum brightwellii(large sized) and Chaetoceros didymus(small sized). We conducted incubation experiments with axenic cultures of the four species using a chemically defined synthetic medium. Compared with Heterocapsa circularisquama(0.59 day-1) and Heterosigma akashiwo(0.50 day-1), the two diatom species exhibited high μmax values(0.68 day-1). The smaller diatom had the lowest Ks value of 7.5×10-9M, while the larger diatom had the highest Ks value of 2.1×10-7M. The Ks values of Heterosigma akashiwo and Heterocapsa circularisquama were 5.1×10-8 and 3.1×10-8M, respectively. Smaller-sized phytoplankton showed better affinity to lower concentrations of iron in the sea.

紀要論文

Version of Record

1346-1842

AA11547977