Estimation of Phosphorus Release Rate by Bacterivorous Flagellates in Lake Biwa.

概要

論文の詳細を見る
In situ phosphorus release rates of bacterivorous flagellates were estimated in Lake Biwa to clarify their contribution to P cycling. Density of the flagellates ranged from 0.67 to 11×106 cells I-1, and their community ingestion rate, which was determined by the fluorescently labeled bacteria method, varied seasonally from 0.20 to 23×108 bacteria-I-1⋅d-1. Bacterial carbon content showed seasonal variation (0.53 to 15 fmol C cell-1), but bacterial C: P molar ratio was relatively invariant (106 ±25, n=24). In situ P release rate by the flagellates was estimated, based on these data and a stoichiometric model. The validity of the estimates was confirmed by incubation experiments using bacteria with C : P ratios of 30 to 103. In four of five experiments, P release rates estimated from the model coincided well with those from another method. In situ P release rate ranged from 0.11 to 59 nmol P⋅-1⋅d-1, accounting for 4.2 to 31% of P required for phytoplankton primary production. This result suggests that bacterivorous flagellates are important, if not major, P suppliers in the lake, and that other P sources are needed for the lake phytoplankton.
日本陸水学会の論文