Validation,use, and disadvantages of enzyme-linked immunosorbent assay kits for detection of cortisol in channel catfish,largemouth bass,red pacu,and golden shiners

Measurement of cortisol response is an important tool to asses stress in fisheries research. Radioimmunoassay (RIA) is a common method for the measure of cortisol in fish. Use of enzyme-linked immunosorbent assays (ELISA) to detect cortisol would eliminate health hazards, costs of handling radioisotopes, and the short stability time associated with RIA. Enzyme-linked immunosorbent assays have been used for the determination of cortisol in several fish species. However, the ELISA method of cortisol determination in fish lacks proper validation testing. We conducted validation procedures for multiple commercial cortisol ELISA kits and compared the results to RIA. The assays were tested for four species: (1) channel catfish Ictalurus punctatus, (2) largemouth bass Micropterus salmoides, (3) red pacu Piaractus brachypomus, and (4) golden shiners Notemigonus crysoleucas. We evaluated the ELISA methods against RIA, and determined that at least one kit is suitable (accuracy: mean recovery of spiked samples, 102.8%; reproducibility: interassay coefficient of variation < 10.5% for all species; precision: intra-assay coefficient of variation < 16.8% for all species; linearity: R ² > 0.96 for all species) for the measurement of cortisol response in fish and comparative determination of stress. All of the ELISA assay results varied by more than 10% from the cortisol concentrations detected by the RIA. The high variability of the kit results indicates that commercial ELISA kits could be utilized for qualitative determination of cortisol in fish, but should be fully validated in each laboratory for each species before being used for research.     

Cryopreservation effects on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier 1818)

The effects of straws volume, cryoprotectants and thawing temperatures were evaluated on the sperm quality of cachama blanca Piaractus brachypomus (Cuvier), an important Colombian fish species. Sexually mature fish were induced to ovulation or spermiation with a carp pituitary extract. A pool of suitable sperm samples was diluted in glucose, egg yolk, dimethyl sulphoxide (DMSO‐10%), methanol (MET‐10%) or ethylene glycol (ETG‐5%) and packed in 0.5, 2.5 or 5.0 mL straws and frozen in nitrogen vapour. The thawing process was performed in a 35 or an 80 °C water bath. The fertility was evaluated after 6 h post fertilization. The highest motility percentage (33 ± 3%) was observed with sperm cryopreserved with DMSO, packed in 5 mL straws and thawed at 35 °C. The treatments with DMSO and MET packed in 0.5 and 5.0 mL straws and thawed at 35 °C showed the highest fertility (higher than 71%) and the lowest fertility was obtained with MET‐2.5 mL (9 ± 5%). In all the treatments, a significant decrease in the sperm quality was observed at 80 °C. Sperm cryopreserved with DMSO‐10% or MET‐10%, packed in 2.5 or 5.0 mL straws are suitable to achieve acceptable fertilization and to fertilize high amounts of eggs.     

Analysing the growth of turbot (<Emphasis Type="Italic">Psetta maxima</Emphasis>) in a commercial recirculation system with the use of three different growth models

The growth data of a commercial aquaculture recirculation system were analysed to investigate the growth performance of reared turbot (Psetta maxima). Three common growth models (von Bertalanffy, Gompertz and Schnute) were fitted to the growth data documented over a time period of 6 years. To determine the most suitable model, three different criteria were used: (1) the Akaike index criterion, (2) the sum of squared residuals and (3) the average daily deviation between the estimated final weight and the observed final weight. The evaluation of the growth models showed that the Schnute model had the lowest Akaike index, the lowest sum of squared residuals and the lowest daily deviation between estimated and real weight of all tested growth models. The Schnute model produced sigmoid growth curves. The estimated growth coefficients were the most realistic ones in regard to biological interpretation. In contrast, the von Bertalanffy growth model and the Gompertz model estimated inaccurate exponential growth curves and are therefore unable to simulate the growth data as well as the Schnute model. The results indicate that the von Bertalanffy growth model is not the optimal model to simulate the present growth data and that the growth potential of reared turbot has probably not yet been fully exploited in the aquaculture system(s) examined (so far).     

河湖水生态系统服务价值核算研究及应用展望

科学有效地界定河湖水生态系统服务价值评估体系与评估指标,可以促进河湖水生态的可持续发展、合理制定水资源价格、为河湖水生态系统服务价值评估提供参考,同时也为河湖水资源纳入国民经济核算体系提供借鉴,为绿色经济核算提供有力的依据。从河湖水生态系统服务功能、评估体系和评估方法等方面总结了国内外研究进展,分析了现有河湖水生态系统服务体系和评估方法的优缺点。对河湖水生态系统服务评估体系进行了优化,优化后的评估体系包括供给服务、调节服务、文化服务和支持服务4大类以及水资源供给、水质净化、科研教育和固碳能力等19项指标,优化了水资源供给、提供水产品、水质净化、防洪减灾、休闲娱乐、生物多样性保护等6个指标的评估方法。对河湖水生态系统服务价值核算在生态文明建设考核、生态产品价值实现机制、自然资源资产审计以及新时期河湖长制考核实施方面的应用进行了展望。下一步要制订GEP核算技术标准,建设市场化、多元化的生态产品交易体系,将水资源开发、利用及保护情况、水资源管理生态环境效益等指标纳入审计范围,建立以水生态系统为整体、以维护河湖生态系统健康为总目标、以定量评判和可操作性为抓手的新的河湖长制考核体系。     

Effect of dietary vitamin B6 supplementation on growth and intestinal microflora of juvenile golden pompano (Trachinotus ovatus)

In order to investigate the dietary vitamin B₆ (VB₆) requirement for juvenile golden pompano, an experiment of six different diets with six dietary VB₆ levels (0, 3.75, 7.47, 10.6, 13.7 and 18.5 mg/kg) was conducted. The results indicated that the content of dietary VB₆ significantly increased weight gain rate (WGR), specific growth rate (SGR) and feed conversion ratio (FCR; p < 0.05). Golden pompano fed diet containing 7.47 mg/kg VB₆ achieved the maximum ALT, AST, GPx, hepatic VB₆ concentrations as well as the minimum MDA, however, the ALT, AST, GPx and hepatic VB₆ concentrations decreased while MDA increased with a further increase in dieatry VB₆. The highest values of GR and POD occurred at the 10.6 and 13.7 mg/kg dietary VB₆ (p < 0.05) respectively. A diet supplemented with 7.47 mg/kg VB₆ increased intestinal Na⁺, K⁺‐ATPase, Chymotrypsin, γ‐glutamyl transpeptidase, creatine kinase and amylase activities (p < 0.05). The relative abundance of Tenericutes and Bacteroidetes decreased while Proteobacteria and Firmicutes improved with an increase in dietary VB₆ levels up to 7.47 mg/kg. Quadratic regression analysis on WGR, hepatic VB₆ concentrations, AST and ALT indicated that the optimum dietary VB₆ levels for juvenile golden pompano were 8.84–9.28 mg/kg.     

Comparison of early life history stages of the bay scallop, Argopecten irradians: Effects of microalgal diets on growth and biochemical composition

The culture of bay scallops, Argopecten irradians, is limited by a reliable and affordable supply of spat and the ability to ensure that animals attain market size within a single growing season. The main goals of our study were thus: (1) to develop growth-optimizing algal diets for implementation in hatcheries, and (2) to identify and compare bay scallop postlarval and juvenile dietary requirements, especially of lipids and fatty acids, which if met may enhance production. Nutritional needs of postlarval bay scallops (present study) are compared with those of sea scallops, Placopecten magellanicus, offered the same diets in a previous companion study. To this end, postlarval (initial shell height, SH = 240 μm) and juvenile (initial SH = 10 mm) bay scallops were offered 6–7 microalgal diet combinations at 20 °C, for 3 weeks. A similar growth ranking among diets was observed between the two developmental stages. A combination diet of Pavlova sp. (CCMP 459) and Chaetoceros muelleri was far superior to any other diet tested, yielding growth rates of 58 and 357 μm day^− 1 which were 65% and 25% higher than the next highest performing diet of Tetraselmis striata/C. muelleri in postlarvae and juveniles, respectively. The T. striata/C. muelleri diet, which is limited in the n-3 fatty acid docosahexaenoic acid (DHA), yielded very poor growth of sea scallop postlarvae in a prior study, indicating that bay scallops may have less stringent requirements for DHA than sea scallops. The Pav 459/C. muelleri diet, which also supported the highest growth of sea scallop postlarvae, is characterized by elevated levels of the n-6 fatty acids, arachidonic (AA) in C. muelleri and 4,7,10,13,16-docosapentaenoic (DPA) in Pav 459. The two diets deficient in AA and n-6 DPA, Pavlova lutheri/Thalassiosira weissflogii and P. lutheri/Fragilaria familica, yielded the lowest growth rates in both bay scallop postlarvae and juveniles. Tissue enrichment of these two fatty acids relative to the diet, as well as overall enrichment in ∑n-6 fatty acids was observed across developmental stages and dietary treatments. A similar pattern has previously been observed in sea scallop postlarvae, suggesting a dietary requirement for n-6 fatty acids in pectinids that has often been overlooked in the past.     

Effect of l‐ascorbyl‐2‐polyphosphate supplementation on growth performance,body composition,antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp,Litopenaeus vannamei

An 8‐week feeding trial was conducted to evaluate the effects of ascorbic acid (AsA), in the form of l ‐ascorbyl‐2‐polyphosphate (LAPP) on growth performance, body composition, antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei. Five practical diets (46% crude protein and 7.6% lipid) supplemented with graded levels of AsA (14.64, 48.55, 84.98, 308.36 and 639.27 mg kg^?1 diet) were fed to five replicate groups of L. vannamei (mean initial wet weight 0.57 g). No significant differences were found on growth performance among all treatments. However, whole body lipid content significantly decreased with dietary AsA levels increasing. Activities of total antioxidant capacity, glutathione reductase and glutathione peroxidase were significantly affected by dietary AsA levels. Shrimp fed LAPP‐free diet had higher malondialdehyde content than those fed the diets supplemented with LAPP. Dietary AsA levels higher than 308.36 mg kg^?1 diet increased the survival of shrimps after 1, 2 and 3 h of acute salinity change. Broken‐line regression analysis on survival after 3 h of salinity stress and second‐degree polynomial regression analysis on glutathione reductase data indicated that the optimal dietary AsA requirement of L. vannamei was estimated to be 306.39, 319.75 mg kg^?1 diet respectively.     

池塘养殖刺参腐皮综合征发病环境因素分析

通过对2014年7—8月山东省青岛市红岛邵哥庄(SGZ)和宿流(SL)两个社区的发生刺参腐皮综合征和未发病刺参养殖池的环境因子跟踪监测和对比,解析发病的原因。从发病前至发病后,分别监测了两地多个池塘水体中的4类可培养细菌(总异养菌、弧菌、硝化细菌和硫化细菌)和6项理化参数(温度、p H、盐度、溶解氧、无机氮、COD),以及沉积环境中6类可培养细菌(总异养菌、弧菌、硝化细菌、硝酸盐还原菌、硫化细菌、硫酸盐还原菌)和4项理化参数(pH、氧化还原电位、硫化物、有机碳)。结果表明,刺参发病时,邵哥庄发病池(SGZ-1~#)环境中细菌数量与未发病对照池(SGZ-2~#)无显著差异,但温度高达25.94℃,盐度低至24.47,均超过刺参耐受限度。水体NO_2-N含量为79.56μg/L,沉积物中硫化物含量为221.1 mg/g,均高于对照池;宿流发病池SL-南2弧菌数量(1.85×10~4 CFU/mL)在发病当日明显升高,高于对照池SL-北1和邵哥庄社区的发病池,而发病池的理化指标反而好于对照池。由此推断,邵哥庄社区的刺参发病与池塘理化指标突变有密切关系,而宿流的刺参发病与病原菌数量激增有密切关系。因此,应从理化指标和病害生物两方面对刺参病害进行预警及采取防治措施。     

点带石斑鱼对盐度适应性的初步研究

通过对体长10.4～8.0cm、平均体长8.6cm;体重19.5～12.2g平均体重16.63g的点带石斑鱼的淡化试验,分别采用盐度突变及渐变淡化两种方式,在水温27.5～29.0℃,经过30d的试验,结果是：将点带石斑鱼鱼苗从盐度（‰）30的自然海水中直接投放至盐度2.6的水体中时,其成活率100%;直接投放至盐度1.3的水体中的成活率80%。而渐变淡化,在盐度降至0.3时的成活率100%,进入纯淡水时的3d后才有逐渐死亡现象出现,10d后的成活率55%。点带石斑鱼的生长速度从纯海水至盐度5.2,随着盐度的降低其生长速度加快。研究结果证明,点带石斑鱼对盐度变化具有很强的适应能力,不但能在海水中养殖而且也可以在河口及低盐地区进行养殖。     

全过程安全评估体系在浙江省水库型水源地的应用

国内的水源地评价主要是采用水质指标的单因子评价,缺乏考虑水源地环境质量、水生态系统状况的综合因子,不能有效识别水源地的安全状况。为此,本研究按照水源产生过程、蓄水过程分析的水污染环节和各种危害因素,从环境特征、人类活动、水质状况和生态完整性4个方面构建水源地全过程评估指标体系。并选择浙江省4座水库型水源地,开展全过程评估指标体系应用。评估结果表明:全过程评估体系较好地反映水源地水在不同阶段的安全状况,发现存在的问题,并能针对性地提出污染控制和预防改进措施,能够切实可行的运用于水库型水源地安全评估的实际工作,为水资源管理提供技术支撑。