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PHOTOSYNTHESIS OF TWO MORPHOLOGIES OF NOSTOC PARMELIOIDES (CYANOBACTERIA) AS RELATED TO CURRENT VELOCITIES AND DIFFUSION PATTERNS 1
Author(s) -
Dodds Walter K.
Publication year - 1989
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.1529-8817.1989.tb00121.x
Subject(s) - biology , midge , botany , photosynthesis , larva , nitrogenase , diffusion , cyanobacteria , metamorphosis , nitrogen fixation , bacteria , physics , genetics , thermodynamics
Colonies of the stream‐inhabiting cyanobacterium Nostoc parmelioides Kützing often contain a single endosymbiotic dipteran larva Cricotopus nostocicola (Wirth), which induces a morphological change from small, spherical colonies to larger, ear‐shaped colonies. At a current velocity of 0 cm · s −1 , whole colonies containing the midge showed overall rates of 14 CO 2 uptake and nitrogenase activity that were higher than those when the midge was absent (sphere‐shaped colonies). Spherical colonies incubated at current velocities of 5‐10 cm · s −1 did not show higher rates of 14 CO 2 or 15 N 2 incorporation than those with the larvae (ear‐shaped colonies). Ear‐shaped colonies extended well into regions of higher current velocity, whereas spherical colonies did not. Photosynthesis of ear‐shaped colonies was stimulated by increased current velocity, increased inorganic C and decreased O 2 concentrations. Moreover, levels of O 2 at the surface of midge‐inhabited colonies decreased with increased current velocity. The morphological change induced by the larva is detrimental (lowers photosynthesis and N 2 fixation) in quiescent water but not at current velocities above 10 cm · s −1 . This is probably a result of higher diffusion of O 2 and CO 2 associated with the midge‐induced morphology.