Impact of three different processing methods on the digestibility and allergenicity of Chinese mitten crab(Eriocheir sinensis)tropomyosin

The tropomyosin(TM)fractions of crab protems may cause allergic reactions in mdividuals susceptible to allergies;however,efficient and safe methods by which to reduce such allergenicity are not currently available.Therefore,in this study,the effects of three different processing methods,i.e.,microwave,ultrasound,and high temperature-pressure(HTP)treatments,on the digestion stability of TM from Chinese mitten crab muscle and the allergenicity of TM digestion products were explored.sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that microwaving had little effect on the digestion stability of TM.In contrast,ultrasound and HTP treatments facilitated the degradation of TM.Similarly,Western blotting and inhibition ELISA indicated that the IgE-binding activity of TM was significantly reduced after treatment with ultrasound or HTP.Among the three different proces sing methods,HTP was the most effective method for improving digestibility of TM and reducing immunoreactivity.This finding provides new insights into treatments for crab allergies.

Using Sr isotopes to trace the geographic origins of Chinese mitten crabs

Identifying the geographic origins of Chinese mitten crabs is important for food safety and fair market competition.In this study,we used strontium(Sr) isotopes as a tool to trace the geographic origins of Chinese mitten crabs.Chinese mitten crabs,water,and different types of crab feed were collected from four different lakes for Sr isotope analyses.The results showed that the Sr isotope compositions of the different parts from one single crab were consistent within error,indicating that any piece of a crab could be used to represent the Sr isotope characteristics of the whole crab.The Sr isotope compositions of Chinese mitten crabs from the same lake were consistent within the analytical error,and the values were similar to the Sr isotope composition of the water from the same lake.However,the Sr isotope compositions of water and crabs from different lakes are significantly different.Therefore,the Sr isotope compositions of Chinese mitten crabs are mainly controlled by lake water composition,while the impact of feed is limited.This study provides an effective method for tracing the geographic origins of Chinese mitten crabs.

Identification and Genetic Diversity Analysis of Chinese Mitten Crab(Eriocheir sinensis) in the Liao River Area

Chinese mitten crab （Eriocheir sinensis） is an indigenous and ecologically and economically important species in the Liao River area, but its identification and genetic diversity remain poorly understood. To evaluate the germplasm resources of this species, samples were collected from these locations： four sub-populations from the Liao River area and one population from the Yangtze River area; one primer was used to distinguish between the Liao River and the Yangtze River crabs. Thirteen loci were used for crab genetic diversity analysis, and basic statistics showed that the collecting samples were purebred in the Liao River area. The average observed heterozygosity （H0） of the Liao River population was 0.5931, and the expected heterozygosity （He） was 0.8064. The polymorphism information content （PIC） was 0.7753, which showed that the Liao River population had high genetic diversity. The genetic differentiation index （FST） averaged 0.0342, meaning a low degree of differentiation; cluster analysis indicated that Hujia （HJ）, Xinli （XL） and Chenjia （CJ） sub-populations were allocated to the same cluster, while Baqiangzi （BQZ） sub-population was isolated. In summary, these data demonstrated that the crabs in the Liao River had high genetic diversity, but low genetic differentiation. Thus, the Liao River population had the potential for breeding selection. Furthermore, this study also provided valuable genetic information for the conservation of Chinese mitten crab.

Sustainable fisheries in shallow lakes:an independent empirical test of the Chinese mitten crab yield model

Next to excessive nutrient loading,intensive aquaculture is one of the major anthropogenic impacts threatening lake ecosystems.In China,particularly in the shallow lakes of mid-lower Changjiang(Yangtze) River,continuous overstocking of the Chinese mitten crab(Eriocheir sinensis) could deteriorate water quality and exhaust natural resources.A series of crab yield models and a general optimum-stocking rate model have been established,which seek to benefit both crab culture and the environment.In this research,independent investigations were carried out to evaluate the crab yield models and modify the optimum-stocking model.Low percentage errors(average 47%,median 36%) between observed and calculated crab yields were obtained.Specific values were defined for adult crab body mass(135 g/ind.) and recapture rate(18%and 30%in lakes with submerged macrophyte biomass above and below 1 000 g/m^2)to modify the optimum-stocking model.Analysis based on the modified optimum-stocking model indicated that the actual stocking rates in most lakes were much higher than the calculated optimum-stocking rates.This implies that,for most lakes,the current stocking rates should be greatly reduced to maintain healthy lake ecosystems.

Microsatellite analysis of genetic diversity and population structure of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab （Eriocheir sinensis） has higher commercial value as food source than any other species of Eriocheir in China. To evaluate the germplasm resources and characterize the genetic diversity and population structure of the crabs in different water systems, two stocks and two farming populations were assessed with 25 polymorphic microsallite loci available in public GenBank. Basic statistics showed that the average observed heterozygosity （Ho） amongst populations ranged from 0.5789 to 0.6824. However, a remarkable presence of inbreeding and heterozygote deficiencies were observed. To analyze population structure, pairwise FST coefficients explained only -10.3% variability from the subdivision of mitten crab populations, the remaining variability stems from the subdivision within subpopulations. Although the four populations had slight differentiation, different allelic frequencies resulted in distinct population structures. Two stocks and one farming population were clustered together to the phylogenetic branch of Yangtze crab, with an approximate membership of 95%. Whereas, another farming population was clustered singly to the phylogenetic branch of the Liaohe crab, with a membership of 97.1%. The tests for individual admixture showed that Yangtze crab had probably been contaminated with individuals from other water systems. Genetic relationships between populations also supported the conclusion that Yangtze crab and Liaohe crab had different gene pools in spite of the origins of the same species.

Water quality, nutrient budget, and pollutant loads in Chinese mitten crab (Eriocheir sinensis) farms around East Taihu Lake

To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.

An Experimental Study on the Gait Patterns and Kinematics of Chinese Mitten Crabs

Despite the many studies on eight-legged animals and the importance of their mechanics of terrestrial locomotion, the mechanical energy of crabs in voluntary locomotion on uneven, unpredictable terrain surfaces has received little attention thus far. In this paper, motion video images of Chinese mitten crab （Eriocheir sinensis Milne-Edwards） locomotion on five types of terrains were recorded using a high-speed three-dimensional （3D） recording video system. The typical variables of locomotion such as gait patterns, duty factor, mechanical energy of the mass center, mass-specific write of the total mechanical power of the mass center, and percentage recovery, were analyzed. Results show that the Chinese mitten crab uses random gaits instead of the alternating tetrapod gait with the increasing terrain roughness. The duty factors of the rows of the leading legs are greater for all terrains than those of the rows of the trailing legs. On smooth terrain, the duty factors of the rows of the trailing legs are greater than that on rough terrains. Kinematic measurements and calculations reveal that similar to mammals, birds, and arthropods, the Chinese mitten crab uses two fundamental gaits to save mechanical energy： the inverted pendulum gait and the bouncing gait. The bouncing gait is the main pattern of mechanical energy conservation. The low probability of injury and energy expenditure due to adaptations to various terrains induce the Chinese mitten crab to modify the mass-specific rate of the total mechanical power of the mass center. The statistical results of percentage recovery also reveal that the Chinese mitten crab has lower energy recovery efficiency over rough terrains compared with smooth terrains.

池塘养殖“六月黄”中华绒螯蟹肝胰腺的滋味特征

为揭示“六月黄”中华绒螯蟹食用部分(几乎全部为肝胰腺)的滋味品质特征,利用味觉分析系统,研究昆山市养殖池塘产雌、雄“六月黄”中华绒螯蟹肝胰腺的滋味特征。结果表明,新鲜蒸制的“六月黄”中华绒螯蟹肝胰腺的基本味味觉指标中,鲜味非常突出,其次是苦味和涩味。而其回味味觉指标中苦味回味最高,其次是涩味回味和鲜味回味。“六月黄”雌、雄蟹个体间,苦、涩味和苦味回味等味觉强度指标均有极显著差异(P<0.01)。相关线性判别分析的初始验证判别和交互验证回判的正确率均可达到100%。池塘养殖“六月黄”中华绒螯蟹肝胰腺滋味具有显著性别差异性,雄蟹的滋味特征显示出较雌蟹更为美味的趋势。

上海河蟹主产区良种采纳意愿分析

种源是河蟹产业发展的关键,论文以上海河蟹主产区-崇明为例,对河蟹养殖户进行十年追踪调查,收集成蟹养殖生产和经营信息,共获得151份有效数据,分析河蟹养殖户采纳良种的意愿,并比较采纳良种与未采纳良种的上海主产区崇明河蟹养殖户在生产与经营水平上的差异,利用二元logit回归分析良种采纳率不高的主要原因。实证结果显示,成为体系示范点、获得生产补贴,更好的销售价格是影响良种采纳意愿的主要驱动力。对此,得出三方面的启示:一是吸引农户加入产业技术体系;二是提供生产补贴;三是提高河蟹品质,带动提高成蟹的售价。

基于AlexNet模型的大闸蟹自动分级系统设计与实现

针对目前大闸蟹人工分级方法的局限性,设计基于Matlab图像处理的大闸蟹分级系统。首先,在湖州市太湖养殖基地采集不同等级大闸蟹背部和腹部图像,对采集的图像进行灰度化、阈值分割、形态学等预处理。然后利用卷积神经网络AlexNet模型提取大闸蟹公母特征,利用面积法计算其大小。通过选取的10只大闸蟹的重量和系统计算得到的像素转化为面积参数,分析得到大闸蟹背部图像像素占比与其重量成近似正比例关系,因此可根据背部图像的计算值得到其大小特征。根据大闸蟹公母、大小特征完成分级。实验结果表明,系统在大闸蟹公母识别方面平均准确率达到92.655%,大小分级方面平均准确率达到95%。

褶皱臂尾轮虫（BrachionusplicatilisOFMüller）人工半海水的培养及利用

本文通过正交试验研究了人工半海水中主要生态因子与褶皱臂尾轮虫繁殖、生长的关系，得出了培养褶皱臂尾轮虫的生态因子最佳水平组合，并初步摸索出培养大个体轮虫的外界条件，在自然条件下，褶皱臂尾轮虫的繁殖生长周期为９ｄ；它们的种群生长曲线呈逻辑斯谛曲线。通过生化分析，褶皱臂轮虫体内Ｖｃ含量为４５．１μｇ／ｇ湿重。作为河蟹苗期二、三期幼体的饵料，可使河蟹幼体顺利地变态，且有较高的变态率，是河蟹苗期二、三期幼体理想的适口饵料。

中华绒螯蟹“长荡湖1号”选育第二代扣蟹阶段养殖性能研究

为探究中华绒螯蟹(Eriocheir sinensis)“长荡湖1号”A系和B系选育第二代扣蟹的生长性能和养殖效果,在相同养殖条件下,以未选育的养殖群体扣蟹为对照进行了网箱养殖试验。结果表明:(1)大眼至豆蟹阶段,不论是平均体质量、增重倍数还是成活率,“长荡湖1号”B系均显著高于对照组(P<0.05),“长荡湖1号”A系较对照组具有一定的优势,但差异不显著。(2)扣蟹阶段,“长荡湖1号”B系的平均体质量均显著高于对照组(P<0.05),“长荡湖1号”A系9月份体质量与对照组接近,其他月份均显著高于对照组(P<0.05)。就生长速度而言,在6—7月期间,“长荡湖1号”A系和B系的生长速度显著快于对照组(P<0.05)。(3)“长荡湖1号”B系养殖效果最佳,具体表现在养殖产量和成活率最高,显著高于其他两个组,且1龄早熟率和饲料系数最低(P<0.05)。(4)就规格分布而言,“长荡湖1号”A系和B系的体质量在3.00~5.99 g和6.00~8.99 g两个区间内的比例低于对照组,在12.00~14.99 g和≥15.00 g两个区间内显著高于对照组(P<0.05),即A系和B系大规格蟹所占的比例相对更高。综合评价,“长荡湖1号”A系和B系选育第二代在扣蟹阶段成活率高,平均规格大,其余生长性能也优于未经选育的对照组。

配合饲料糖脂比对中华绒螯蟹生长、体组成和性腺发育的影响

探究配合饲料不同糖脂比替代冰鲜鱼对中华绒螯蟹生长、体组成和性腺发育的影响。在为期6周的饲养试验中,采用5种不同糖脂比(4.09、3.00、1.93、1.40、1.05)的中华绒螯蟹配合饲料(各配合饲料分别命名为:diet 1、diet 2、diet 3、diet 4、diet 5组)替代冰鲜鱼,观察不同糖脂比下的配合饲料对中华绒螯蟹[初始平均体重(98.36±8.17)g]的生长性能、体组成、性腺指数及性腺脂肪酸的营养成分等的影响。结果显示:存活率方面,冰鲜鱼组的中华绒螯蟹成活率(63%)显著低于配合饲料组(P<0.05)。增重率方面,diet 3组(糖脂比1.93)中华绒螯蟹增重率最高[(0.89±0.07)%]。体组成和性腺发育方面,diet 3组(糖脂比1.93)中华绒螯蟹的肝胰腺中总脂肪含量[(21.11±6.14)%]显著低于其他组(P<0.05),性腺中的总脂肪含量[(38.45±6.78)%]显著高于其他组(P<0.05),性腺指数[(14.67±2.35)%]显著高于除diet 4组外的其他组(P<0.05);性腺不饱和脂肪酸含量方面,各处理组中华绒螯蟹性腺中的花生四烯酸、二十碳五烯酸和二十二碳六烯酸等脂肪酸含量存在差异,其中diet 3组(糖脂比1.93)的花生四烯酸含量显著高于其他组、二十碳五烯酸和二十二碳六烯酸含量显著高于除diet 4组以外的其他组(P<0.05)。在中华绒螯蟹初始平均体重为(98.36±8.17)g,饲养6周的试验条件下,相比冰鲜鱼组,配合饲料diet 3组(糖脂比1.93)中华绒螯蟹具有更高的存活率、增重率及性腺指数。配合饲料性腺指数的提高可能与配方中更适宜的糖脂比有关,这为营养物质从肝脏中积累进而转移到性腺中提供了物质基础和能量基础。

水质因子对阳澄湖大闸蟹生态养殖的影响

在昆山市巴城镇武神潭村设立观测试验点,对水温、溶解氧、pH、氨氮及大闸蟹生长动态情况进行监测,讨论适宜大闸蟹生长的水质环境。结果表明,水温对于大闸蟹的影响最大,温度突然变化或者超过30℃易造成大闸蟹的死亡;溶解氧白天呈单峰型,藻类对于溶解氧贡献最大;7月中旬后pH逐步下降且趋于平稳,氨氮总体较低,利于大闸蟹生长。水温28℃左右、溶解氧维持4 mg/L以上、pH 7.5~8.5是阳澄湖大闸蟹适宜生长的水质环境。

黄河口中华绒螯蟹成蟹形态性状与体质量的相关性及通径分析

为确定影响黄河口地区养殖中华绒螯蟹(Eriocheir sinensis)成蟹体质量的重要形态性状,为品种选育提供参考,测定随机采集的247只黄河口中华绒螯蟹成蟹的头胸甲长(X1)、头胸甲宽(X2)、体高(X3)、第三步足长节长(X4)和体质量(Y),通过相关分析、多元回归分析及通径分析建立其形态性状与体质量间的多元线性回归方程。研究显示各形态性状与体质量的相关程度均达到极显著水平(P<0.01)。通过回归分析,剔除偏回归系数不显著的性状,排除共线性自变量,建立了最优多元线性回归方程Y=-328.06+5.43X2+2.43X4。拟合度检验表明达到极显著水平(P<0.01)。通径分析结果显示,头胸甲宽对体质量的直接影响最大,直接作用大于间接作用,表明头胸甲宽是影响黄河口中华绒螯蟹成蟹体质量的主要性状。在对黄河口中华绒螯蟹成蟹以体质量为目标性状进行选育时,可以头胸甲宽(X2)为主要间接选择指标,第三步足长节长(X4)为辅进行选育。

浙江地区中华绒螯蟹中甲基汞分布特征与食用风险

为了研究浙江地区中华绒螯蟹中甲基汞的分布特征与食用风险,在浙江主要养殖地区的养殖场设点抽样,利用LC-AFS6000液相色谱原子荧光联用仪检测样品可食部分中的甲基汞含量。结果表明,中华绒螯蟹的蟹肉中甲基汞含量明显高于蟹黄中的甲基汞含量,蟹肉中的甲基汞含量远小于0.5 mg/kg,吴兴乔溇采样点的蟹肉中甲基汞含量最高达到0.043 mg/kg。综上所述,浙江地区中华绒螯蟹符合国家相关要求,可以放心食用,同时建议对甲壳类动物中重金属甲基汞限量作更细的区分和说明。

崇明地区河蟹与罗氏沼虾生态高效混养技术探究

为充分挖掘河蟹养殖池塘潜能和利用养殖水体空间,增加单位面积内的经济效益,在崇明地区传统河蟹养殖模式的基础上,开展不同密度的罗氏沼虾混养试验。结果表明:在河蟹蟹种放养量为250 kg/hm^(2)时,罗氏沼虾放养1.8万尾/hm^(2)较为适宜,罗氏沼虾销售价格为200元/kg,总产值比放养2.4万尾/hm^(2)高出5.985万元/hm^(2),较未混养罗氏沼虾的河蟹精养池塘增加6.195万元/hm^(2)。

不同品系中华绒螯蟹群体单性化养殖对生长性能及水质的影响

近年来,中华绒螯蟹单性化养殖技术逐渐受到养殖者的青睐,其不同品系单性化养殖技术对环境影响尚不清晰。本研究通过试验比较了中华绒螯蟹早上市新品系、长江蟹这2类群体在雌雄分养和雌雄混养模式下成蟹规格、成活率、增重率、产量等生长性能、饵料模式、效益情况和养殖尾水情况。结果表明:长江蟹平均产量明显高于早上市新品系,同一品系内雄蟹组的平均产量均最高,早上市新品系的成活率及增重率普遍低于长江蟹,但在两种品系内不同组别表现不同;以冰鲜鱼为主的饵料模式,不同品系中华绒螯蟹均表现雌蟹组饵料系数最低、饵料转化效率最高,且早上市新品系的雌蟹组优于长江蟹雌蟹组;早上市新品系的平均投入低于长江蟹,且以早上市新品系雌蟹组最低,上市时间早晚的差异导致早上市新品系单价比长江蟹高,平均利润也明显高于长江蟹;中华绒螯蟹不同品系、不同养殖模式下,尾水所有指标均达到DB 32/4043—2021的二级标准,总磷、高锰酸盐指数达到一级标准,两种品系高锰酸盐指数趋势一致,雌蟹组养殖池塘高锰酸盐指数较低。

Effects of fermented protein feed on the growth performance of pond-raised crab

This study aimed to elucidate the effect of a pellet feed containing fermented proteins on pond-raised Chinese mitten crabs,Eriocheir sinensis in a 7-month crab feeding experiment in Gucheng Lake,Jiangsu province,China.The results showed that fermented protein could significantly increase mean weight gain,crab size and total yield compared with control group.Moreover,the mean weight of male crabs and the number of large-sized male crabs improved over those of the control group.However,feed efficiency ratio did not differ significantly between the two groups.The amino acid content in the muscles of the female crabs of both the groups was higher than that in the muscles of the male crabs.The present study suggests that fermented compound protein may be one kind of potential protein sources for E.sinensis.

梯形透空丁坝局部水动力特性对底栖动物生境演替的影响机制

针对因梯形透空丁坝局部水动力特性对底栖动物栖息地的影响机制尚不明确,限制了此类结构的大范围推广应用的问题,依托长江深水航道建设的示范应用工程,构建三维水动力数值模型,选择中华绒螯蟹为指示物种,研究了不同径流条件下梯形透空丁坝局部水动力特性及其对指示物种栖息地的影响;结合梯形透空丁坝不同时期沉积物和底栖动物的监测数据,分析了梯形透空丁坝对底栖动物生境演替的影响机制。结果表明:梯形透空丁坝迎流面产生的上升流将主流引导至丁坝后上方,在汛期为中华绒螯蟹提供了避洪场所;坝内及坝后较小的流速和丰富的流场结构为中华绒螯蟹提供了索饵场和越冬场。