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COMPARATIVE LABORATORY AND FIELD STUDIES OF PHOTOSYNTHESIS BY A MARINE PLANKTONIC DIATOM 1
Author(s) -
Tailing J. F.
Publication year - 1960
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.1960.5.1.0062
Subject(s) - photosynthesis , plankton , algae , phytoplankton , diatom , chlorophyll a , biology , botany , bicarbonate , saturation (graph theory) , environmental chemistry , oceanography , ecology , chemistry , nutrient , geology , mathematics , combinatorics , endocrinology
A study is described of the factors affecting measurements of phytoplankton photosynthesis by the much used field method, based upon changes of oxygen concentration in clear and darkened bottles as determined by the Winkler method. Unialgal cultures of a marine plankton diatom, Chaetoceras affinis , were used with short exposures of 1–3 hours in both laboratory and sea. Indications of a limitation of photosynthetic rate by inadequate CO 2 supply were only found for culture media with pH raised by prolonged photosynthesis. Otherwise photosynthetic rates were unaltered by the bicarbonate concentration over a wide range, including that of unenriched sea‐water, or by cell sedimentation in unshaken cultures. A comparison of the Winkler and manometric methods of measuring oxygen production gave very similar results. High rates of photosynthesis were well maintained over the main period of each exposure, despite the development of oxygen supersaturation. Lower rates were however always found during an initial induction phase. Photosynthetic characteristics deduced from exposures in laboratory and sea, carried out almost simultaneously and with the same algal material, were in general agreement. Data from the experiments as a whole indicated the development of unusually high photosynthetic capacities at light saturation, assessed per unit content of chlorophyll a. The onset of light saturation, and the development of photo‐inhibition, occurred at intensities similar to those recorded for many other plankton algae. Some ecological implications of the findings are discussed.