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Uptake kinetics of nitrate, ammonia and phosphate by the dinoflagellate Heterocapsa circularisquama isolated from H iroshima B ay, J apan
Author(s) -
Yamamoto Tamiji,
Kishigami Tomoko,
Nakagawa Hikaru
Publication year - 2017
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/pre.12193
Subject(s) - phosphate , dinoflagellate , nitrate , ammonia , biology , bloom , kinetics , ammonium , nutrient , botany , biochemistry , food science , chemistry , ecology , physics , quantum mechanics , organic chemistry
SUMMARY Heterocapsa circularisquama is a harmful dinoflagellate whose first bloom in H iroshima B ay, J apan, appeared in 1992. As suggested by the authors’ group, in the S eto I nland S ea including H iroshima B ay, oligotrophication particularly the reduction of phosphate starting 1980 is severe. The bloom caused serious damage to the bay's extensive oyster culture. In the present study, the uptake kinetics of nitrate, ammonia, and phosphate by this species were experimentally investigated. The maximum uptake rate (ρ max ) and the half‐saturation constant ( K s) were 0.41 pmol cell −1 h −1 and 4.45 μM, respectively, for nitrate, 2.02 pmol cell −1 h −1 and 11.1 μM for ammonium, and 0.079 pmol cell −1 h −1 and 1.79 μM for phosphate. The maximum specific uptake rates ( V max ) for nitrate, ammonia, and phosphate were estimated to be 8.95, 44.1, and 21.3 day −1 , respectively. A comparison of V max / K s, which is also an index of affinity to nutrients, between this species and others suggested that H. circularisquama can utilize nitrate and ammonia efficiently, but not phosphate. Considering both reports describing that H. circularisquama has the ability to utilize dissolved organic phosphorus ( DOP ) and the DOP concentration is higher than phosphate in H iroshima B ay, it was concluded that H. circularisquama became dominant due to the phosphate reduction measure.