伊乐藻环境中克氏原螯虾适宜养殖密度的筛选

为探究伊乐藻（Elodea nuttallii）环境中克氏原螯虾适宜的养殖密度，在伊乐藻覆盖率约为60%的环境中，采用不同养殖密度（10、15、20、25、30尾/ m2）养殖初始体质量为（4.35 ± 0.95）g的克氏原螯虾45 d，比较了各密度组的克氏原螯虾的生长性能、食源贡献度及非特异性免疫酶活力。结果显示：（1）10尾/ m2密度组的克氏原螯虾的终末体质量、终末体长及增重率最高，其余各组间无显著差异（P > 0.05）；当养殖密度高于15尾/ m2时，小规格虾（10g ~ 15g）的占比明显增多。（2）伊乐藻对克氏原螯虾的平均食源贡献度范围为12.8% ~ 26.9%，且对大规格虾（20g ~ 25g）的食源贡献度高于小规格虾；（3）各组超氧化物歧化酶（SOD）和溶菌酶（LZM）的活力均无明显差异（P > 0.05），仅10尾/ m2密度组的克氏原螯虾丙二醛（MDA）的含量显著低于其他四组（P < 0.05）。说明保障一定的伊乐藻覆盖度能有效降低密度带来的胁迫，并且摄食伊乐藻对克氏原螯虾的非特异性免疫具有积极作用。综上表明，伊乐藻（约60%的覆盖率）环境中，克氏原螯虾的适宜养殖密度为15尾/ m2。

Selection of suitable stocking densities of Procambarus clarkii in the environment of Elodea nuttallii

To investigate the suitable stocking density of red swamp crayfish (Procambarus clarkii) in an environment with about 60% Elodea nuttallii coverage rate, a 45-day rearing experiment was conducted. The initial weight of juvenile crayfish was 4.35 ± 0.95g, the growth performance, food source contribution and non-specific immune enzyme activity of red swamp crayfish were compared under different stocking densities (10, 15, 20, 25 and 30 ind / m2). The results showed that: (1) The final body weight, terminal body length and weight gain rate of crayfish in the density group of 10 ind / m2 were the highest, and there was no significant difference among the other groups (P > 0.05); When the culture density was higher than 15 ind / m2, the proportion of small-sized crayfish (10g ~ 15g) increases significantly. (2) The average food source contribution of Elodea nuttallii to crayfish ranged from 12.8% to 26.9%, and its contribution to large-scale crayfish (20g-25g) was higher than that of small-sized crayfish; (3) There was no significant difference in the activities of superoxide dismutase (SOD) and lysozyme (LZM) among all groups (P > 0.05), the malondialdehyde (MDA) content of crayfish of only 10 ind /m2 was significantly lower than the other four groups (P <0.05). It indicated that ensuring certain coverage rate of Elodea nuttallii can effectively reduce the negative effects of density stress, and the intake of Elodea nuttallii could have a positive effect on the non-specific immunity of crayfish. In conclusion, the suitable stocking density of crayfish was 15 ind / m2 in the environment of Elodea nuttallii (about 60% coverage).