The black rockfish,Sebastes schlegelii,is the main marine fish species produced via offshore cage culture in China.Moreover,it is essential to select a convenient,safe,and harmless anesthetic that can effectively reduce the physiological stress response of juveniles during land-sea relay transport.MS-222 has been widely used in fish and other aquatic creatures during handling and transportation because of its secure induction and rapid recovery.In this study,the anesthetic effect of MS-222(tricaine methanesulfonate;anesthetic effect:20-130 mg/L,interval of 10 mg/L,total of 12 concentration gradients;simulated transportation:30-60 mg/L,interval of 10 mg/L)on three specifications of juvenile black rockfish(W10,W40,and W80;average body weight of(10.11±2.13)g,(42.38±5.19)g,and(80.79±6.65)g,respectively)was investigated.The times to deep sedation(A2)and anesthesia(A4)under different concentrations of MS-222 and the optimal sedation and anesthetic concentrations of MS-222 were determined.The results showed that in water with a temperature of(14.5±0.5)℃,pH of 7.85,salinity of 30 and dissolved oxygen concentration above 7.5 mg/L,the time required for W10,W40,and W80 juveniles to reach the A2 and A4 stages decreased with an increase in anesthetic concentration and increased with an increase in body weight at the same anesthetic concentration.Quadratic regression analysis was performed to analyze the relationship between the A2 and A4 stage effect times and the concentrations of MS-222.The equations describing the relationship between the A2 stage effect time(y)and anesthetic concentration(x)in W10,W40,and W80 groups were y=0.210 7x2-21.207x+602.6(R2=0.95),y=0.202 1x2-21.501x+642.6(R2=0.98)andy=0.089 3x2-14.153x+606(R2=0.91),respectively.Those for A4 stage effect time and the concentration of MS-222 werey=0.043 1x2-10.755x+813.57(R2=0.97),y=0.062 1x2-16.221x+1 205.6(R2=0.97)andy=0.059 6x2-15.954x+1 229.9(R2=0.92),respectively.Therefore,the optimal sedative and anesthetic concentrations of MS-222 for juvenile W10,W40,and W80 black rockfish were 27.38,29.94,and 40.39 mg/L(A2),and 95.32,107.32,and 116.58 mg/L(A4),respectively,according to the optimal effect time of 180 s.No significant difference was observed between the respiratory rates of juvenile fish in the A2 stage and those in the control group;however,the respiratory rates of juvenile fish in the A4 stage gradually decreased with an increase in anesthetic concentration and were significantly lower than those of the control group(P＜0.05).The results of simulated transport over 8 h demonstrated that the survival rate of all fish remained at 100％within a concentration range of 30-50 mg/L for MS-222.However,when the concentration reached 60 mg/L,the survival rate decreased to approximately 60％for the W10 group and 80％for the W40 group,though it was still maintained at 100％for the W80 group.Therefore,suggested transport concentrations for juvenile W10,W40,and W80 black rockfish are in the ranges of approximately 27.38-50.00,29.94-50.00,and 40.39-60.00 mg/L,respectively.These findings provide valuable guidance for the safe transportation of juvenile black rockfish during stock enhancement and offshore cage land-sea transportation.Moreover,the optimal anesthetic concentration can serve as a reference point for biological experiments involving measurement,labeling,or sample collection with juveniles of varying sizes.

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微藻是一类含有叶绿素.并能进行光合作用的微观的以个体、链状或群体形式存在的单细胞藻类,能够利用水体中的C、N、P增殖并合成自身所需的蛋白质、核酸等细胞成分.近年来,国内外发展了藻类水处理技术,因其高效、安全等优势被广泛用于水产养殖水质调控和尾水处理,微藻与细菌的共生和抑制也是目前的研究热点.本文综述了微藻在水质净化中的应用及其影响因素,为进一步研究微藻在水产绿色养殖的应用提供参考.

为研究异养培养的蛋白核小球藻(Chlorella pyrenoidosa)去除对虾池塘养殖尾水氮、磷营养盐的效果,本实验通过对异养藻种的光自养转换、盐度驯化,并以不同初始密度接种入养殖尾水,定期检测水体中氨氮、磷酸盐、硝酸盐氮和亚硝酸盐氮等指标,分析其对营养盐的吸收利用规律.结果表明:光照强度6600 lx、光照周期16 h:8 h(L/D)、温度25±0.5℃条件下,接种细胞密度为1.0×105个/mL、5.0×105个/mL、1.0×106个/mL的蛋白核小球藻均在接种初期快速进入指数生长期,10 d后进入生长平台期,20 d藻细胞生物量分别增加39.25、7.98和4.07倍;蛋白核小球藻能明显降低养殖水体中氮、磷营养盐浓度,起到去氮除磷的净化作用,磷酸盐的去除率随藻细胞的生长持续上升,21 d去除率分别为58.8％±0.72％、72.9％±1.7％、81.4％±9.86％;对氮盐的利用规律依次为氨氮、硝酸氮和亚硝酸氮,氨氮6 d的去除率达81.9％±6.0％,96.2％±1.16％,95.4％±1.24％,硝酸氮21 d去除率达82％±1.35％、93.3％±4.41％、91.8％±2.77％,亚硝酸氮21 d去除率分别为84.3％±3.52％、23.5％±2.53％、3.4％±2.16％.相关结果可为异养蛋白核小球藻在海水池塘养殖尾水水质净化的应用提供参考.

The mass production of triploid turbot Scophthalmus maximus is expected to enhance the economic benefits of aquaculture due to its sterility, growth, and survival advantages. Among the methods for inducing triploidy in teleost, pressure shock has been considered a more consistent and reliable approach. In this study, the optimal parameters for inducing triploidy in turbot through hydrostatic pressure shock were investigated in a series of trials, including the intensity (55–75 MPa), timing (3.5–8.5 min after fertilization, maf) and duration (4–12 min). The ploidy level was determined by flow cytometry analysis. Under a water temperature of 14.5 ± 0.5 °C, treatment optima for pressure shock were determined to be 4.5–5.5 maf with 60 MPa for 6 min, resulting in 100% triploidy rate. A comparison of induction efficiency between pressure shock using this combination and cold shock initiated at 6.5 maf in −2 °C sea water for 25 min was carried out using eggs from three females. The higher hatching rates and triploidy rates, and lower abnormality rates were investigated with pressure shock treatment compared with cold shock treatment. The optimized parameters were successfully applied to three large batches of eggs (∼ 250, 300 and 330 mL) for mass production of triploid turbot. The total length and body weight of triploids were significantly lower than those of diploid counterparts at 2 months after hatching (mah), however, they exhibited a significant increase at 8 and 11 mah, respectively, and maintained this higher level thereafter. Additionally, the survival rates remained similar from 2 to 12 mah. The results of this preliminary study indicate that pressure shock rather than cold shock is more beneficial for the commercial production of triploid turbot under farming conditions.