添加碳源提高卤虫生物量和改善水质

摘要

在零换水养殖系统中，研究不同碳源及碳氮比(C/N)对高盐水体中卤虫生物量产出、营养质量和水质的影响．实验一在正常(NF，100%)、较低(LF，60%)和极低(VLF，30%)3个杜氏盐藻(Dunaliella salina)投喂水平下，分别添加蔗糖和淀粉两种碳源，C/N为20．实验二杜氏盐藻投喂水平为 LF，分别添加蔗糖和淀粉两种碳源，C/N 分别为20和40．单位养殖水体积1,000,mL，初始卤虫密度1.5,mL-1，养殖盐度50，温度24～25,℃，养殖周期14,d．结果表明，在相同单胞藻投喂水平下，添加碳源显著提高卤虫生物量(P＜0.05)；水体中总氨氮(TAN)、2NO−、3NO−和总氮(TN)水平大幅度减少，pH 有所降低，黏度保持稳定；脂肪酸 C16：1n7含量有所增加，而 C20﹕5n3含量有所降低．碳源对卤虫生物量的促进作用与卤水中生物絮团的形成密切相关，这一点可由相同单胞藻投喂水平下，添加碳源显著提高卤虫生物量和降低水中氮浓度等得到证明．比较蔗糖与淀粉两种碳源，分子结构简单的蔗糖作用效果较好．提高C/N对卤虫生物量的影响不显著．%Effects of carbon sources and C/N ratio on the output and nutritional quality of Artemia biomass and water qual-ity were studied in zero-water exchange culture system. In Experiment I,microalgae Dunaliella salina were fed to Artemia at 100% normal feeding(NF),60% low feeding(LF)and 30% very low feeding(VLF)of the feeding levels,respectively. Su-crose and starch were supplemented in the culture area at a C/N ratio of 20. In Experiment Ⅱ,sucrose and starch were sup-plemented at a C/N ratio of 20,and 40,respectively,and D. salina was fed at low feeding level(LF). Artemia were cultured in 1 L brine water with an initial density of 1.5 mL-1 for 14 days;the salinity was 50 and temperature 24-25,℃. The results showed that the supplementation of sucrose and starch in culture medium significantly enhanced Artemia biomass output at the same microalgae feeding levels(P<0.05),and improved water quality by remarkably reducing the content of total am-monia(TAN),nitrite,nitrate and total nitrogen(TN)in the culture medium. Carbon supplementation slightly decreased pH, whilst the viscosity remained stable. Carbon supplementation also resulted in higher fatty acid C16:1n7 content,but de-creased C20:5n3 in the Artemia biomass. The improvement of Artemia biomass output in the presence of extra carbon source is closely related to the bioflocs formed in the culture system,which has been justified by the fact that supplementary carbon can reduced microalgae requirement and lower the level of various nitrogen in the culture medium. Compared with starch, sucrose with simple molecular structure has better effect on Artemia biomass output. Increasing C/N ratio has no remarkable effect on it.