Eco-physiological studies on Chinese integrated fish culture

在上海淀山湖周边进行的中国综合养鱼中，草鱼(Ctenophyngon Idella)和其他一些具有不同食物习性的鲤科鱼类被水生植物圈养，以获得极高的鱼类产量。在这个系统中，大量悬浮在养殖池中的草鱼排泄物似乎在直接或间接为其他鱼类提供食物物质方面发挥了重要作用。事实上，在鲫鱼和鲤鱼的肠道内容物中发现了相当数量的分解草鱼面。本研究在好氧实验室条件下对从池塘中采集的草鱼面(苦草的碎片)进行分解，以揭示草鱼面在这个池塘生态系统的食物网中的作用。在分解的16天内，面孔中的碳含量以恒定的速度下降到原始含量的50%，而氮含量在实验的前8天几乎没有下降。单位干重的氮素和氨基酸含量在实验第8天达到最大值，但在进一步分解过程中变化不大。加入孵育液的NH_4~+和~3H-胸腺嘧啶核苷被活跃地掺入各种大小的粪便片段中。研究表明，分解草鱼鱼面(包括生成的细菌及其代谢产物)为无脊椎动物以及浮游生物和底栖生物提供了一种新的食物来源。

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.