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INTERSPECIFIC VARIATION IN DARK NITROGEN UPTAKE BY DINOFLAGELLATES 1
Author(s) -
Paasche Eystein,
Bryceson Ian,
Tangen Karl
Publication year - 1984
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1984.00394.x
Subject(s) - dinoflagellate , biology , dcmu , nitrogen , interspecific competition , nitrate , photosynthesis , nitrogen assimilation , botany , ammonium , darkness , nitrogen cycle , ecology , photosystem ii , chemistry , organic chemistry
Seven species of marine dinoflagellates were grown in nitrogen‐sufficient media under a 12:12 h L:D cycle, and then tested for their ability to take up nitrate and ammonium in the light and in the dark in short‐term experiments with 15 N‐labelled substrate. The effect of the N substrate chosen, and the effect of sampling time in the L:D cycle, on the relative nitrogen content (the C:N ratio) was investigated at the same time. The physiological extremes in the material were represented by Prorocentrum minimum (Pav.) J. Schiller, which took up and presumably assimilated nitrate equally fast in the light and in the dark, and Gyrodinium aureolum Hulburt, which did not take up nitrate in the dark when in a state of nitrogen sufficiency. A strong coupling between nitrate assimilation and photosynthetic carbon assimilation in the latter species was suggested by the close similarity of the light saturation curves of 15 NO 3 − and 14 CO 2 incorporation, and by a complete blocking of 15 NO 3 − incorporation by 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU). Nitrogen starvation for 24 h induced a capacity in G. aureolum for taking up nitrate in the dark, or in the light in the presence of DCMU, a phenomenon that might be useful for identifying nitrogen limitation in this species in the field. Our study emphasizes the variability of dinoflagellate nitrogen nutrition and illustrates the difficulty of associating mass occurrences of dinoflagellates in nature with any particular nutritional mode.