Algae. 1996; 11(1): 23-34.

Morphological Variations of the Marine Diatom Thalassiosira weissflogii under Culture Conditions

Jae-Shin Kang, Hyung-Sun Kim, Jin Hwan Lee

Department of Biology, Sangmyung University, Department of Biotechnology, Korea
Ocean Research & Development Institute

The diatom Thalassiosira weissflogii was cultured under different nitrate-nitrogen, phosphate-phosphorus and silicate-silica concentrations, salinity and water temperature. Specific growth rate was obtained for each group, and specimens were taken from each group while in the stationary phase and were observed with a scanning electron microscope to detect morphological variations. The result showed that the tendency for the average diameter to decrease with a higher specific growth rate was more distinct than the direct influence of nutrient concentration on cell diameter. There were variations in the number of central strutted processes under limited N, P and Si conditions. The number of central strutted processes showed variations according to culture temperature showing from no central strutted process at a low temperature of 10℃ to one central strutted process at a high temperature of 30℃. A variation of number central strutted processes occurred at a low salinity (5-10‰), also. Under limited phsphate-phosphorus conditions, a variation in which the central strutted process moved toward the margin occurred. Also, seashell-shaped areolation was found. When the central strutted process shifted toward the margin, areolation changed to scallop-shaped, also. When silicate-silica was limited, the girdle of the cells elongated 3-10 times their normal length. Under low temperature conditions, a variation of the areolation to the scallop-shaped form occurred, mostly in cells with no central strutted process.

Keywords : diatom, nutrients, culture, morphology, variations