光裸方格星虫(Sipunculus nudus)对3种不同底质的适应能力

Adaptability of Sipunculus nudus to Three Types of Different Sediments

中文关键词: 方格星虫  底质  存活率  适应能力

英文关键词: Sipunculus nudus  Sediments  Survival  Adaptability

中文摘要:

      在室内养殖系统中开展光裸方格星虫(Sipunculus nudus)对3种不同底质适应能力的研究。3个底质处理组分别为海沙组(S-s)、对虾池塘底质组(S-sp)和鱼塘底质组(S-fp)，各设5个重复；方格星虫[(2.58±0.23) g]的养殖密度为5条/缸。结果显示，3个处理组中，方格星虫的存活率均高于90%；3个处理组中，方格星虫的排泄物主要由粒径(R)小于0.4 mm的物质组成，其中R<0.224 mm的物质占较大比例，在S-s、S-sp和S-fp组中分别达到47.70%、85.95%和69.99%。试验结束时，S-fp组的方格星虫表现出一定程度的生长，而S-s和S-sp组体重稍有下降。研究结果表明，方格星虫成体对于底质的还原状态具有较大的耐受范围，而对于较小粒径(R<0.224 mm)的物质具有较高摄食需求；同时，底质中的有机质含量也是影响其生长的因素之一。

英文摘要:

      To study the adaptive capability of Sipunculus nudus to three different types of sediments, we carried out a rearing experiment of S. nudus under the laboratory conditions. Treatments in quintuplicate were the sea sand (S-s), shrimp-pond sediment (S-sp) and fish-pond sediment (S-fp), respectively, with different oxidation reductive potential value, organic material content and different grain sizes. After sunlight exposure, all types of sediments were paved onto the bottom of the tanks (31 cm × 20 cm × 30 cm) to 10 cm thick, and the same water was put into each tank. Five individuals with mean weight of (2.58±0.23) g were stocked in each tank and cultured with a normal ration supply. DO content in the water was above 6.0 mg/L and no water change during the experiment. The results showed that the survival rate of S. nudus was up to 96%, 92% and 92% in S-s, S-fp and S-fp (P>0.05), respectively. Main component of the excrement of S. nudus was fine particles smaller than 0.4 mm, especially the 0.224 mm particles reached 47.70%, 85.95% and 69.99% in the treatments of S-s, S-sp and S-fp, respectively. At the end of the experiment, S. nudus presented growth to some extent in S-fp, while a little weight loss in other two groups. These results suggest that S. nudus has strong adaptive capability to the reductive condition and different grain size of sediment, while it has a higher need for the smaller size of particles (R<0.224 mm) for the restriction of its feeding organs. Meanwhile, the organic material of the sediment was a key factor to the growth of S. nudus, including the quality (source) and quantity of the food. Therefore, based on its strong adaptive capability to the different sediments, the culturing of S. nudus in the suitable ponds/beaches was an ecological-economical model with potential development.