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Inorganic carbon pools in the bloom‐forming dinoflagellate Peridinium gatunense
Author(s) -
BermanFrank Ilana,
Erez Jonathan
Publication year - 1996
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1996.41.8.1780
Subject(s) - bloom , dinoflagellate , photosynthesis , total inorganic carbon , isotopes of carbon , fractionation , carbon dioxide , carbon fibers , chemistry , carbon cycle , dissolved organic carbon , assimilation (phonology) , environmental chemistry , carbonic anhydrase , botany , biology , total organic carbon , ecology , biochemistry , chromatography , materials science , linguistics , philosophy , ecosystem , composite number , composite material , enzyme
Peridinum gatunense, the main bloom‐forming species in Lake Kinneret, acquires a carbon‐concentrating mechanism (CCM) during the progression of the annual winter–spring bloom. Previous indications for CCM activity in P. gatunense were based on decreased carbon isotope fractionation and higher activity of carbonic anhydrase (both external and internal). In the present study, CCM activity in low‐density, natural, and cultured P. gatunense populations was demonstrated by cells showing higher internal inorganic carbon (C i ) concentrations than those in the external medium. The presence, size, and dynamics of these C i pools were measured using pulse‐chase experiments of 14 C uptake into photosynthetic acid‐stable products under varying C i , pH, CO 2 (aq), and light regimes. Internal C i levels in P. gatunense were higher by a factor of ∼20–80 relative to the ambient C i . The time required to reach isotopic equilibration of the pool ranged from 30 to 90 min, whereas the time required for the assimilation of the pool into cellular carbon ranged from 10 to 50 min. These long timescales are attributed to the larger vol: surface area ratio of this organism. Induction of the CCM was triggered by CO 2 (aq) rather than C i and was evident at CO 2 (aq) concentrations <15 M. Preincubation in either the dark or with high CO 2 (aq) levels diminished the C i pool. The data we report represent the steady‐state carbon metabolism of the species since the cells were not deprived of C i prior to the measurements. The CCM in P. gatunense is an important adaptation mechanism contributing to the high primary production observed in the lake at the peak of the bloom under CO 2 ‐limiting conditions [pH >9.5 and CO 2 (aq) <5 µ M].