抄録
In the season of Microcystis bloom in Lake Suwa, both the horizontal and vertical distributions of dissolved oxygen around a floating net (9×9×1.5m) with about 7000 carps were studied. Oxygen concentration in the upper waters at the edge of the net or inside it was always lower than that at the control stations at a distance of 100 or 200m from the net, and the presence of nets caused the decrease of oxygen concentration up to the distance of about 50m from the net. The decrease in oxygen concentration was more prominent in the layer of 0 to 2m (32% saturation on Sept. 17), especially when the net was set in the windward direction. Oxygen consumption of bottom deposits around the net, up to a distance of about 20m, was much larger than that at the other stations located far away.
