饲料维生素C对急性降温后花鲈免疫、抗氧化及抗应激的影响

为研究饲料维生素C(Vc)对急性降温后花鲈(Lateolabrax maculatus)免疫、抗氧化及抗应激的影响,以含有不同水平Vc (6.85、46.90、88.24、167.43、329.21和658.69 mg/kg)的饲料饲养花鲈56 d后,进行急性降温(从33℃水体转入27℃水体)处理24 h和48 h。结果显示,降温24 h和48 h时,各组血清补体3(C3)水平高于0 h,而补体4(C4)水平低于0 h。饲料Vc在6.85~167.43 mg/kg时,血清免疫球蛋白M(IgM)水平随降温时间的增加,在24 h和48 h显著高于0 h (P<0.05);当饲料Vc含量高于167.43 mg/kg时,各时间点IgM差异不显著。血清溶菌酶(LZM)活性在降温48 h后显著低于降温前(P<0.05),而各Vc添加组显著高于对照组(P<0.05)。肝脏丙二醛(MDA)含量在降温后显著高于降温前,但在降温后随着饲料Vc水平的升高而显著降低(P<0.05)。肝脏总超氧化物歧化酶(T-SOD)含量随降温时间的增加,先增加后降低。在各时间点,花鲈肝脏谷胱甘肽(GSH)含量都随着饲料Vc水平的升高而升高。当饲料Vc为6.85 mg/kg时,肝脏血红素氧合酶(HO-1)活性在降温后显著高于降温前(P<0.05);当饲料Vc为88.24~167.43 mg/kg时,肝脏HO-1活性在降温后显著低于降温前(P<0.05)。花鲈血清热休克蛋白(HSP70)水平在降温后显著高于降温前(P<0.05),而当降温时间达到48 h时,各Vc添加组HSP70含量显著低于对照组。研究表明,饲料中适量的Vc (46.90~167.43 mg/kg)能提高花鲈肝脏的抗氧化能力,减轻脂质过氧化水平,缓解花鲈急性降温引起的应激反应。     

Winter monsoon promotes the transport of Japanese temperate bass Lateolabrax japonicus eggs and larvae toward the innermost part of Tango Bay,the Sea of Japan

Northwesterly cold winds characteristic of the East Asian Winter Monsoon (EAWM) dictate winter climatic conditions over the Japanese Archipelago. Japanese temperate bass Lateolabrax japonicus is a commercially important coastal fish that spawns offshore in winter and uses shallow waters as nursery habitats. To investigate the effects of EAWM on the planktonic period of L. japonicus, eggs, larvae, and juveniles were quantitatively collected in Tango Bay on the Sea of Japan side in winter and spring from 2007 to 2017. Although eggs occurred close to the mouth of the bay, planktonic larvae occurred further inside as they developed. The horizontal distribution of planktonic larvae, combined with water velocity data obtained from mooring observations, indicated that planktonic larvae are transported south‐ to westward through Ekman current and an anticyclonic circulation, which are driven by northwesterly winds. To evaluate survival during the planktonic period in each year class, the abundance of benthic larvae/juveniles was divided by winter total landings of Lateolabrax spp. (proxy of the spawning stock size). This survival index exhibited a positive correlation with the northwesterly component of winter winds, and a negative correlation with winter air temperature (average from December to February, Spearman's correlation, p < .05). There was, however, no significant correlation with winter water temperature or winter freshwater discharge in the bay. We conclude that northwesterly cold winds of EAWM play a critical role in transporting L. japonicus eggs and larvae toward nursery habitats, specifically beaches and estuaries fringing the innermost part of Tango Bay.     

Survival and serum biochemical responses of spotted sea bass Lateolabrax maculatus during simulated waterless live transportation

Waterless live fish transportation is an alternative and promising transport strategy, which may reduce shipping costs, increase stocking density and improve survival of some species. Spotted sea bass is one of the most economically important marine fish in China. However, waterless transportation has not yet been studied on spotted sea bass. To explore the possibility of waterless transportation of spotted sea bass and its sublethal stress responses, the survival rate and dynamics of blood biochemical parameters were evaluated in the present study by preserving it under no water, less water and water (control) conditions for 9 hr. The serum biochemical parameters including total protein, cortisol, glucose, lactate, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total carbon dioxide (TCO₂), creatinine, blood urea nitrogen (BUN), ammonia, superoxide dismutase (SOD) activity and malonaldehyde (MDA) were investigated. Results showed that the survival rates of fish in all groups gradually declined with time increasing. At the end of transportation, the survival rates in the control group, less‐water group and no‐water group decreased to 49.11%, 15.60% and 23.96% respectively. Significant changes were observed in several selected serum biochemical parameters, including glucose, lactate, ALT, TCO₂, BUN and ammonia during simulated waterless transportation, which might negatively affect the physiological homeostasis of fish, leading to the high mortality in present study. In general, waterless transportation of spotted sea bass was possible, but it might be rather suitable for short time than long time.     

Understanding the life histories of amphidromous fish by integrating otolith‐derived growth reconstructions,post‐larval migrations and reproductive traits

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