Eco-physiological studies on Chinese integrated fish culture

在上海淀山湖一带进行的中国综合养鱼试验中，草鱼（Ctenopharyngon idella）和其他一些具有不同食性的鲤科鱼类与水生植物共同饲养，获得了极高的产量。在该系统中，养殖池中悬浮的大量草鱼排泄物似乎对其他鱼类直接或间接提供食物物质起着重要作用。事实上，在鲫鱼（Carassius auratus）和鳙鱼（Aristichthys nobilis）的肠道内容物中发现了相当数量的腐烂草鱼脸。本研究在实验室有氧条件下，对池塘中收集的草鱼面（Vallisneria spiralis的碎片）进行分解，以探索草鱼面在该池塘生态系统食物网中的作用。在16 d的分解过程中，表层碳含量以恒定速率下降至原始含量的50%，而氮含量在试验的前8天几乎没有下降。在试验第8天，面氮含量和单位干重氨基酸含量达到最大值，但在进一步分解过程中变化不大。^<15>NH_4^+和^ 3h -胸腺嘧啶加入培养液后，在不同大小的粪便碎片中被积极掺入。由此可见，草鱼表面的分解（包括生成菌及其代谢产物）为该池塘生态系统中的无脊椎动物以及浮游生物和底栖鲤科动物提供了新的食物资源。

In a Chinese integrated fish culture conducting around Dianshan Lake in Shanghai, Grass carp (Ctenopharyngon idella) and some other cyprinid fishes with different food habits are coreared with water plants to give extremely high fish yields. In this system, a large amounts of grass carp excreta suspended in the culture pond seem to play an important role in providing food material directly or indirectly to other fishes. In fact, considerable quantities of decomposing grass carp faces were found in the intestinal contents of Carassius auratus and Aristichthys nobilis.In the present study, grass carp face (fragments of Vallisneria spiralis) collected from the pond were decomposed under aerobic laboratory condition, in order to discover the role of grass carp faces in the food-webs of this pond ecosystem. During 16 days of decomposition, carbon contents in the faces decreased at a constant rate to 50% of original contents, while nitrogen contents hardly decreased for the first 8 day periods of the experiment. The nitrogen as well as amino acid contents per unit of dry weight of faces increased up to the maximum level on the 8th day of the experiment, but changed little during further decomposition. ^<15>NH_4^+ and ^3H-thymidine added the incubation medium were actively incorporated into various sized fecal fragments. It is suggested that decomposing grass carp faces (including resultant bacteria and their metabolic products) make a new food resource available to invertebrates as well as to the plankton and benthos cyprinid feeders in this pond ecosystem.