1997 Volume 34 Issue 2 Pages 185-194
A field study was carried out to make clear the pattems of flow and water quality changing in a nursery aquaculture pond (30mx 40mxlm) for juvenile flounders, Paralichthys olivaceus, constructed on a sandy beach to utilize wave energy for water exchange. Current velocity, water temperature, salinity, and dissolved oxygen (DO) were measured and a dye diffusion experiment to visualize the flow pattem was conducted. The inflow rate varied according to the sea level and wave height, and the sea water coming from the inlet to the outlet generally created a recirculating flow pattem in the pond. Therefore,.the time, when the maximum values of water temperature and DO concentration occurred, varies with respect to the location in the pond. The DO concentration fell to 60% saturation as a minimum at around 6 a.m., when the inlets were closed. estimated from the DO budget, it was found that the DO consumption rate by all processes in the pond was calculated at 0.162mg/l/hr. About 60% of the consumption was due to the organisms and chemicals which were suspended in the water, about 20% was due to the flounders, and the rest 20% was due to the sediment. The inflow rate of groundwater was relatively small when compared with that of sea water, judging from the salinity budget in the pond.
