高温季节蟹塘不同水生植物对水质净化和温室气体排放的影响

    Effects of Different Aquatic Plants on Water Purification and Greenhouse Gas Emission in Crab Pond in High Temperature Season

    • 摘要: 蟹塘水生植物不仅是河蟹(Eriocheir sinensis)的天然饵料和栖息蜕壳场所,还可净化蟹塘水体。蟹塘原有植物伊乐藻(Elodea nuttdlii)在炎热的夏季会生长不良甚至死亡,致使河蟹生境恶化。因此,筛选具有耐高温特性的水生植物对生态养蟹有重要意义。分别以蕹菜(Ipomoea aquatica)、水稻(Oryza sativa)和伊乐藻作为蟹塘水生植物,通过比较其对河蟹产量、养殖尾水水质和温室气体排放的影响,筛选出更为适宜蟹塘的水生植物,以期达到河蟹稳产和环境友好的目标。结果表明,3个处理间河蟹产量均无显著差异,3种水生植物的氮磷同化量从大到小依次为蕹菜、伊乐藻和水稻。与伊乐藻相比,7-9月蕹菜和水稻对蟹塘水体总氮有明显的削减作用,且多数时间点差异显著,对总磷的削减作用则无显著差异。同时,不同处理蟹塘均表现为CH4和N2O排放源。蕹菜和水稻处理CH4累积排放量均显著高于伊乐藻处理,而3个处理N2O累积排放量无显著差异。与蕹菜和水稻处理相比,伊乐藻处理全球增温潜能(GWP)增加。考虑到8月中下旬水稻结实死亡,因此在炎热的夏季,蕹菜可以作为伊乐藻和水稻的替代品,以改善河蟹养殖尾水水质。

       

      Abstract: Aquatic plants are not only natural bait and molting habitat for the crabs (Eriocheir sinensis), but also play an important role in purifying the water body of Chinese crab ponds. Elodea nuttallii, as the traditional plants in rearing ponds, usually performed poor growth or even death in hot summer, which lead to the deterioration of the crab habitat. Thus, screening candidate plants with high temperature resistance has great significance in ecological crab rearing. In this comparative study in high temperature period, three different aquatic plants, Ipomoea aquatic, Oryza sativa and Elodea nuttallii, were employed to assess their related effects on crab yields, water quality and greenhouse gas emissions for achieving stable yield as well as friendly environment for crab pond. The results show that there was no significant difference of crab yields in the three different treatments. Considering the amount of assimilated nitrogen or phosphorus, the three types of aquatic plants displayed as I. aquatic > E.nuttallii > O. sativa. Compared to E.nuttallii, O. sativa and I. aquatic treatments significantly reduced the water nitrogen concentrations from July to September whereas no significant difference was found for the phosphorus concentrations. Meanwhile, different aquatic plants changed CH4 and N2O emission fluxes. The accumulated CH4 emissions of the O. sativa and I. aquatic treatments were both significantly higher than that of the E.nuttallii treatment, while no significant difference of accumulated N2O emissions was found forthe three treatments. The E.nuttallii treatment had higher global warming potential (GWP) than the O. sativa and I. aquatic treatments. Considering the decay after grain-filling stage of O. sativa in late August, I. aquatic can be a great alternate of E.nuttallii in hot summer to improve water quality in crab rearing.

       

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