Diel Changes in Biochemical Components of Particulate Matter, and Uptake Activities of Carbon and Nitrogen by Phytoplankton in August in Lake Nakanuma, Japan.

Abstract

We measured diel changes in neutral sugars, amino acids and fatty acids of particulate matter in Lake Nakanuma in August 1988. We also measured uptake of carbon and nitrogen during the day and night. During the diel cycle, chlorophyll at 1 m varied little. Neutral sugars and glucose at 1 m increased during the day and decreased at night. Amino acids did not show such changes. Carbon uptake at 1 m was 2.06 μg-at C⋅l-1⋅h-1 during the day and almost zero at night. The uptake increase during the day corresponded to the diurnal increase of neutral sugars. Ammonium uptake under light conditions during the day at 1m was 1.84×10-1 μg-at N⋅l-1⋅h-1, whereas the night uptake was 59% of that. The change in ammonium uptake did not necessarily correspond to the amino acid changes. We discuss the. relationship between the biochemical components and uptake activities of phytoplankton.