Energy Conversion Efficiency in Three Ecological Types of Pond in Pearl River Delta in China
The energy conversion efficiencies of three pond types in the Pearl River Delta were measured: a still-water pond, 0.247 ha in size, with no water-exchange or other oxygen increasing equipment; a renewal-water pond, 0.193 ha in size, with daily water-renewal of 2, 700 to 3,000 m3/ha; and a tidal-flow pond, 0.193 ha in size, with a daily tidal-water flow of 30,255 to 42,480 m3/ha. The conversion of biological plus industrial energy inputs into net fish production ranged from 10.1% in the stagnant pond to 12.8% in the tidal-flow pond. The objective was to stock each pond to its maximum fish carrying capacity, determined by past experience with the ponds, and to determine the maximum production rate as well as the energy conversion efficiency for each type of pond. The effect of water exchange rate on the efficiency of energy conversion in the ponds however, appeared to be minimal.