Modeling of dissolved oxygen of aquaculture grounds in a semi-enclosed bay

Abstract

SAMMARY: Coastal aquaculture has been increased and developed in a semi-enclosed bay. In Sido Bay, located northeast side of Kagawa Pref., could produce marine aquaculture productions to supply the population demands. The feeding rate of fish farming is approximately 12,378 tones a year, with the highest rate in summer. Therefore, the pollution from floating aquaculture cage can affect the environment via fecal waste, dissolved waste and excess feed settles. After the field experiments, it was found the tidal current, bottom topography and DO consumption rate by sediment are important factors to evaluate the carrying capacity of aquaculture grounds. The authors proposed a more appropriate evaluation method for DO by using 3-dimensional numerical model taking the effect of oxygen consumption by the fish in the aquaculture cage and bottom sediment into consideration.

Diffusive Fluxes across Sediment–Water Interface in the Seto Inland Sea, Japan

“…Mid-bay stations (S and N25) showed moderate fluxes of all species. Surprisingly, fluxes of NH 4 + and PO 4 3- were not high in this study, because of the low organic matter content (14.0 mg-C g -1 , 1.95 mg-N g -1 and 0.67 mg-P g -1 ; Table II), which is influenced by the outflow of the relatively strong tidal current of the Seto Inland Sea [6].…”

“…The area is characterized by a macrotidal regime (ca. 2 m), and the current velocity at the mouth varies from 15 to 20 cm s -1 , which is higher than in the inner part (less than 10 cm s -1 ) [6]. The annual temperature ranges from 9.6 to 26.7 °C, and salinity varies between 30.5 and 32.4 psu [3].…”

“…All of them are directed from sediments to the overlying waters. The lowest NH 4 + , PO 4 3-and Si(OH) 4 were characterise Stn.T18, where was the deepest and the sediment was characterised by low porosity and organic matter content, thus suggesting that this site is exposed to resuspension events due to strong the tidal current at the mount of the bay [6]. Mid-bay stations (S and N25) showed moderate fluxes of all species.…”