ENERGY CONVERSION EFFICIENCY IN THREE ECOLOGICAL TYPES OF POND IN THE PEARL RIVER DELTA IN CHINA

本文研究了珠江三角洲三种不同生态类型池塘的能量转换效率。三种不同类型的池塘分别是：１）静水塘，面积０．２４７ｈａ，试验期间不换水，也没有其它增氧设施；２）加水塘，面积０．１９３ｈａ，每天加水２，７００－３，０００Ｍ３／ｈａ；３）微流水塘，面积０．１９３ｈａ，每天由潮汐自然进水３０，２５５－４２，４８０Ｍ３／ｈａ。另外，加水塘和微流水塘各配一台３千瓦的叶轮式增氧机，在鱼浮头时使用。结果表明增加池塘的换水量可以增加鱼产量，提高池塘的能量转换效率。还表明换水量大的池塘其生物能占的比例较大，而光合能占的比例则较小。为提高池塘的能量转换效率和鱼产量，必须增加“直食性”鱼类的放养量、减少“滤食性”鱼类的放养量。

ENERGY CONVERSION EFFICIENCY IN THREE ECOLOGICAL TYPES OF POND IN THE PEARL RIVER DELTA IN CHINA

The energy conversion efficiencies of three pond types in the Pearl River Delta were measured: 1) a still-water pond, 0.247 ha. in size, without water renewing nor other oxygen increasing equipment; 2)a renewing-water pond, 0.193 ha. in size, with a daily water-renewing of 2,700-3,000 m 3/ha; and 3) a slight-flow pond, 0.193 ha, in size, with a daily flow of 30,255-42, 480 m 3/ha, of tide-water. In addition, 3 kilo-watt lobe aerators were installed in the renewing-water and slight-flow ponds. These aerators were used when fishes were surfacing. The increased water exchange in two ponds permitted increased loading rates of fish and feeds, and resulted in a marked increase in net fish production, from 10.8 tonnes/ha in the still-water pond to over 40tonnes/ha in the slight-flow pond. The results showed that the energy conversion efficiencies and the percentage of biologidal energy were higher in those ponds with higher water exchange, while the percentage of photosynthetic energy dropped. So it is necessary to stock more direct-feeding species and apply much supplementary feed in order to achieve higher energy conversion efficiency and fish production.