Sediment metabolism associated with a fish cage facility within a shallow embayment (Eastern Mactan Island, Central Philippines): an initial study
2000
Dy, D.T. (University of San Carlos, 6000 Cebu City (Philippines). Marine Biology Section)
Sediment metabolism around a small fish cage facility located within a shallow embayment was studied to determine any measurable impacts to the surrounding water body and underlying sediments. Laboratory analysis of oxygen uptake of sediments showed no significant difference between the control (i.e., 25 m away from the fish cage facility) and impact station (i.e., beneath the fish cage facility). However, the % organic matter in the sediments at the fish cage facility was significantly higher (mean % TOM=4.3; P=0.049) than that of the control station (mean % TOM = 3.8). There was only slight difference in sediment grain size distribution between the fish cage facility and the nearby control station. The net photosynthesis of the sediments at the control station, using in-situ bell jar incubation, ranged from 36 to 118 mg O2/sq m/h and the respiration rate during the night (i.e., dark oxygen uptake) ranged from 38 to 62 mg O2/sq m/h. Initial results also showed no significant differences in pH, total suspended solids (or TSS), total organic matter (or TOM) and temperature of water. Implementing a long term monitoring protocol is suggested to include key parameters such as biological oxygen demand or BOD, dissolved inorganic nutrients, particulate organic carbon and coliform count of the water body. Lowering the fish stocking density and installing artificial aeration devices are also suggested in minimizing fish mortality
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