Seasonal Cycles of Vitamin B12, Thiamine and Biotin in Lake Sagami. Patterns of Their Distribution and Ecological Significance

Abstract

AbstractSeasonal cycles of vitamin B12, thiamine and biotin in the water and sediment of Lake Sagami have been studied for two years in 1970 and 1971 at monthly intervals. They were compared with other biological and chemical factors. Sediments were very rich in the three vitamins during the period of study and they were considered to be a vitamin source for the Jake water. In the surface water, fluctuations both of dissolved and particulate forms of the vitamins were found to correspond fairly with the succession of phytoplankton during these years. Particularly, the dissolved vitamin B12 concentration decreased remarkably at the same time that the particulate form increased considerably in the surface water during periods of dominance by diatoms such as Cyclotella sp., Nitzschia acicularis, N. paleacea, N. actinastroides, N. palea, N. sp. and Synedra acus. From the results, the possible importance of vitamin B12 as one of the ecological factors in Lake Sagami was suggested and discussed.