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LIGHT RESPIRATION IN SIX ESTUARINE PHYTOPLANKTON SPECIES: CONTRASTS UNDER PHOTOAUTOTROPHIC AND MIXOTROPHIC GROWTH CONDITIONS 1
Author(s) -
Lewitus Alan J.,
Kana Todd M.
Publication year - 1995
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.0022-3646.1995.00754.x
Subject(s) - respiration , biology , irradiance , mixotroph , phytoplankton , photosynthesis , cellular respiration , botany , respiration rate , heterotroph , ecology , bacteria , nutrient , physics , genetics , quantum mechanics
The photoresponse of respiration was examined in six estuarine phytoplankton species grown at a limiting irradiance in the presence or absence of glucose. Cellular respiration rates in the dark, at the growth irradiance, and at saturating light levels were higher in glucose‐grown cultures than in photoautotrophic cultures. Glucose uptake also affected the relationship between incident irradiance and gross respiration rate, and the specific respiratory pathways that contributed to the respiration versus irradiance (R vs. I) response. The energy‐conseming Mehler reaction contributed largely to light‐stimulated respiration in photoautotrophic (energy‐limited) cultures. However, the energy‐dissipating alternative pathway was the predominant form of respiration measured in mixotrophic (energy‐sufficient) cultures. Based on these and previous observations, a model of phytoplankton R us. I response is presented, in which the relative contributions of different light respiratory processes (cytochrome pathway respiration, alternative pathway respiration, chlororespiration, Mehler reaction) are dependent on the incident irradiance and cellular energy content .