Carbon to nitrogen to phosphorus ratios of seston in lake biwa japan as indicators of nutrient deficiency in phytoplankton and decomposition process of hypolimnetic particulate matter
Tezuka, Y.
Japanese Journal of Limnology 46(4): 239-246
1985
ISSN/ISBN: 0021-5104
Accession: 004878143
In an attempt to diagnose the nutritional status of phytoplankton and decomposition process of hypolimnetic particulate matter, C:N:P ratios of seston collected from various depths were determined in Lake Biwa in four seasons of 1983. The results of a preliminary experiment, where laboratory cultures inoculated with natural phytoplankton from Lake Biwa were grown in media with different N:P ratios, showed that C:N:P ratios of phytoplankton were good indicators of N or P deficiency. C:N:P ratios of seston from the euphotic zone indicated that phosphorus limited phytoplankton growth throughout almost all seasons. In addition, nitrogen was also a limiting factor in late summer. This result agreed well with the prediction obtained by the chemical analysis of lake water. Comparisons of C:N:P ratios of seston collected from the trophogenic and tropholytic layers suggested that among the three elements, carbon is most and phosphorus is least rapidly mineralized during sedimentation of particulate matter.