水蕹菜和罗莎生菜对麦穗鱼养殖系统水质的影响

Purification Effect of Aquatic Plants Ipomoea aquatica and Lactuca sativa on Water Quality in Topmouth Gudgeon Pseudorasbora parva Culture

将9个40 cm×24 cm×16 cm泡沫箱放在实验室靠窗处,每个箱中放养12尾体长(7.3±0.56)cm,体质量(3.88±0.78)g的麦穗鱼(Pseudorasbora parva),搭建占水体面积35%的水蕹菜(Ipomoea aquatica)和罗莎生菜(Lactuca sativa)浮床,菜根裹海绵固定防止其松动,用纱布裹住菜根防止麦穗鱼啃食。试验设水蕹菜-麦穗鱼和罗莎生菜-麦穗鱼2个处理组和1个单养麦穗鱼的对照组,每组设3个重复。每隔7 d取一次水样,检测水体pH、溶氧(DO)、总氨氮(TAN)、亚硝酸盐氮(NO_(2)^(-)-N)、硝酸盐氮(NO_(3)^(-)-N)和总氮(TN)含量等指标,研究水蕹菜和罗莎生菜对麦穗鱼养殖系统水质的影响。结果显示,水蕹菜和罗莎生菜能维持麦穗鱼养殖水体pH及DO浓度稳定,使水体TAN浓度降至较低水平;水蕹菜组和罗莎生菜组水体NO_(2)^(-)-N和NO_(3)^(-)-N浓度显著低于对照组(P<0.05);水蕹菜组降低水体TN的能力优于罗莎生菜组,吸收NO_(3)^(-)-N的效率显著高于罗莎生菜(P<0.05)。在浮床覆盖率为35%的条件下,水蕹菜和罗莎生菜均能有效吸收麦穗鱼养殖水体中的无机氮盐,促进有害氮盐向可吸收利用氮盐转化,起到净化水质的作用。本研究结果可以为鱼菜共生养殖提供理论参考。

Topmouth gudgeon Pseudorasbora parva with body length of(7.3±0.56)cm and body weight of(3.88±0.78)g were monocultured(as control group)and co-cultured with water spinach(Ipomoea aquatic)or rosa lettuce(Lactuca sativa)in floating beds with coverage area of 35% of the water area in nine 40 cm×24 cm×16 cm foam boxes placed near the window in a laboratory at stocking density of 12 fish per box for 6 weeks. The vegetable roots were wrapped in a sponge to prevent them from loosening, and the vegetable roots were wrapped with gauze to prevent the fish from eating. The experiment set up two treatment groups and a control group of water spinach-wheat ear fish and rosa lettuce-wheat ear fish, and a control group of monoculture wheat ear fish, each with 3 replicates. The water pH, and levels of dissolved oxygen(DO), total ammonia nitrogen(TAN), nitrite nitrogen(NO_(2)^(-)-N), nitrate nitrogen(NO_(3)^(-)-N)and total nitrogen(TN)and other indicators were determined to investigated the influence of water spinach and rosa lettuce on the water quality of the topmouth gudgeon culture system every 7 days. The results showed that water spinach and Rosa lettuce led to the stability of pH and DO concentration in water,and to decrease in the TAN concentration to a low level. There was significantly lower concentration of NO_(2)^(-)-N and NO_(3)^(-)-N in water of water spinach and rosa lettuce treatment group than that in the control group(P < 0.05). In the two treatment groups,water spinach had higher capacity of reducing TN than the rosa lettuce did, with significantly higher efficiency of absorbing NO_(3)^(-)-N than the rosa lettuce(P < 0.05). Under the condition of floating bed coverage rate of 35%both water spinach and rosa lettuce effectively absorbed inorganic nitrogen salts in topmouth gudgeon culture water,promoting the transformation from harmful nitrogen salts to absorbable nitrogen salts and playing a role in water purification. The findings provide theoretical reference for future aquaponics farming.