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.

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.

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.

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.

Genetic Differences of Mitten Crabs Based on RFLP Analysis on Mitochondrial Cytochrome Oxidase Subunit I(COI) Gene

The genetic differences of 15 mitten crab populations from 6 river systems in China's Mainland and 1 population from Russia were studied based on RFLP analysis of mitochondrial cytochrome oxidase subunit I （CO I）. The results showed that Tas I-RFLP pattern could be used as a genetic marker to distinguish Eriocheir hepuensis from Eriocheir sinensis, Eriocheirjaponica and Eriocheir leptognathus; genetic distances among 13 populations of Eriocheir sinensis range from 0 to 0.015, indicating that they were different geographic strains; the subspecies status of Eriocheir sinensis and Eriocheir hepuensis （population from Nanliujiang） were considered owning to their genetic distances of 0.02-0.044, indicating that genetic divergence between them was low; Eriocheir leptognathus （population from Nanpaihe, Tianjin） was the most distant taxon with genetic distances value of 0.147-0.195, which could be defined as genetic distances between species in genus Eriocheir.

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.

Evolutionary relationship of three mitten crabs(Eriocheir sp)revealed by mitogenome and 5S ribosomal DNA analysis

To reveal the evolutionary relationship of three mitten crabs(Eriocheir sinensis,E.hepuensis,and E.japonica),complete mitogenomes and nuclear 5S rDNA sequences were analyzed.Sequencing revealed that the mitogenomes analyzed shared conserved organization of the coding and non-coding regions but genetic variation was identified.Among the three mitten crabs distinct tandem repeats were identified in the mitochondrial D-loop region.The 5S gene(5S rDNA)sequence was highly conserved across the three species,whereas non-transcribed spacer(NTS)region exhibit high levels of variation including insertions,deletions and point mutations.Cluster analysis suggested that the three mitten crabs had their own independent 5S rDNA sequence variation and evolutionary pattern.Both mitogenome and 5S rDNA sequence analysis revealed significant genetic variation across the mitten crabs species.Phylogenetic analysis using mitogenome and 5S rDNA sequences demonstrated that E.japonica was relatively more distant from E.sinensis and E.hepuensis.This study extended our previous knowledge and confirmed that the three mitten crabs are likely to be genetically differentiated species.In addition,our study also provided insights into the conservation of pure natural resources of E.sinensis,an important aquaculture species.

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。

崇明清水蟹产业特点、主要问题与发展建议

崇明是上海河蟹产业的主产区,占上海市河蟹养殖总面积的78.2%,占全市河蟹总产量的86.3%。文章通过梳理崇明清水蟹2017—2022年的发展脉络,总结了其发展特点及存在问题。分析发现,近年来崇明加强政企联合宣传,促使“崇明清水蟹”知名度逐步提高,2022年崇明清水蟹示范养殖面积基本稳定在269 hm^(2),良种覆盖范围不断扩大,全区良种覆盖率达73.3%。但受种草品种单一和持续高温的影响,2022年成蟹单位产量、单位产值和单位效益相比2021年分别减少了10.0%、8.3%和18.5%。建议未来崇明清水蟹发展定位于高品质的种源、领先的养殖技术,逐步形成三产融合的发展格局。

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%。

基于宏基因组学的中华绒螯蟹养殖池塘水体微生物群落结构和功能组成分析

养殖水体中的微生物群落结构及功能组成对养殖生态系统具有重要作用。为了全面系统评估中华绒螯蟹(Eriocheirsinensis)养殖中后期水体微生物群落结构和功能组成,于2022年6―10月逐月监测上海市崇明区中华绒螯蟹养殖池塘内水质指标,同时基于宏基因组学技术分析了养殖期内水体中微生物物种组成及功能结构特征,并探讨了二者与环境因子的关系。结果显示,该养殖池塘在养殖中后期主要超标水质指标为p H、高锰酸盐指数、总磷和总氮。在养殖期水体中,6―8月的微生物群落多样性以及7―8月的微生物群落丰富度处于较高水平,优势门为细菌中的变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、疣微菌门(Verrucomicrobia)、蓝细菌门(Cyanobacteria)和病毒中的尾噬菌体门(Uroviricota),而在属水平上,丰度占比前10的优势属在多组之间均存在显著差异,如7月蓝藻门微囊藻属(Microcystis)细菌和8―10月的有尾噬菌体目(unclassified_o_Caudovirales)病毒丰度明显高于其他月份。微生物的主要功能为代谢功能包括能量代谢、全局和概览图、氨基酸代谢等,不同月份的功能组成存在显著差异,尤其是6―7月代谢途径丰度明显高于8―10月,而优势细菌变形菌门、放线菌门和拟杆菌门是上述功能的主要贡献者。环境因子对微生物群落结构和功能组成的影响趋势一致,叶绿素a和pH是影响最显著的环境因子,溶解氧、总磷的影响作用稍弱。在养殖水体中,丰度占比较大的致病菌为肠道沙门氏菌(Salmonella enterica)、爱德华氏菌(Edwardsiella ictaluri)和金黄色葡萄球菌(Staphylococcus aureus)。研究结果可为中华绒螯蟹养殖池塘水体微生物群落结构和功能组成研究提供基础数据,并可为养殖水质调控及生态系统构建提供理论依据。

水华对中华绒螯蟹(Eriocheir sinensis)池塘养殖系统细菌群落及潜在致病菌的影响

近年来,水华频发制约着中华绒螯蟹养殖业的发展,环境微生物群落响应水华发生与消退机制是预防与治理水华的重要组成部分。为了解析中华绒螯蟹养殖系统细菌群落对水华的响应特征,采用16S rRNA基因扩增测序技术对拟浮丝藻水华下中华绒螯蟹养殖池塘细菌群落的组成、结构和潜在病原菌的变化进行了研究。结果显示,水体中的优势细菌类群为伯克霍尔德菌科(Burkholderiaceae)和微杆菌科(Microbacteriaaceae),底泥中的优势类群为Steroidobacteraceae菌科和Burkholderiaceae等;科水平下的蓝细菌门类群和其他大部分细菌群落呈显著正相关。养殖水体中潜在病原菌的丰度与水华的生消呈现出相反的趋势,OTU365和OTU1614(均属于Candidatus Similichlamydia epinepheli)是其主要的潜在病原菌,而在底泥中潜在致病菌表现出富集的特征,以OTU1280(大肠杆菌,Escherichia coli)为主。CCA结果显示,蓝藻暴发过程中,Tem、NO3--N、NO2--N及NH4+-N驱使水体蓝藻门细菌类群的变异,NO2--N是驱动养殖水体潜在致病菌群落变异的主导因子。研究结果为防治中华绒螯蟹养殖水华发生提供了宝贵的数据支撑。

碳酸盐碱度对中华绒螯蟹仔蟹耐受性和 抗氧化物酶活性的影响

为研究不同碳酸盐碱度对中华绒螯蟹(Eriocheir sinensis)仔蟹成活率和抗氧化酶活性的影响,在不同碱度条件下(7.00、9.49、12.86、17.42、23.61、32.00 mmol/L)对中华绒螯蟹新品种“江海21号”仔蟹进行96 h急性碱度胁迫实验,探讨仔蟹对碳酸盐碱度的适应性。结果显示:中华绒螯蟹仔蟹随着碱度的升高,死亡率增加,在24、48、96 h时的碳酸氢钠碱度半致死浓度LC 50分别为62.32、46.77、34.22 mmol/L,安全浓度SC为7.90 mmol/L;对照组7.00 mmol/L超氧化物歧化酶活性无显著差异,9.49、12.86、17.42、23.61 mmol/L实验组SOD活性均呈现先显著升高后降低的趋势,在24 h达到峰值,而32.00 mmol/L呈现显著增加的趋势;各实验组过氧化氢酶(CAT)活性显著低于对照组,9.49、12.86、17.42 mmol/L浓度碱度组CAT活性随胁迫时间的变化呈现下降趋势。23.61、32.00 mmol/L高浓度碱度组总体呈先降低后升高的趋势;各实验组组织液总抗氧化能力(T-AOC)活性均呈现先显著升高再降低的趋势;32.00 mmol/L浓度组谷胱甘肽过氧化物酶(GSH-Px)活性呈现显著增加的趋势,其它实验组均出现先显著升高再降低的趋势并在24 h时达到峰值。不同碱度对中华绒螯蟹仔蟹生存有较大的影响,中华绒螯仔蟹可以通过激活抗氧化系统来适应一定程度的碱度胁迫。

基于注意力机制和深度神经网络的中华绒螯蟹品级快速鉴定方法研究

提出一种基于注意力机制和深度神经网络(YOLO-v7)的中华绒螯蟹品质快速预测的新方法。首先,蟹在自然环境中生长会形成背部花纹特征,根据形态测量学将其划分为侧齿、龙骨脊、额突、疣突、颈沟、复眼6种特征,提出基于对称度的特征定量计算方法,并根据视觉注意力机制可视化YOLO-v7模型中对分类精准度较高的区域,采用LabelImg图像标记软件分别对差异较大的前5种组合特征进行活力品级标记,然后基于YOLO-v7模型对标记好的数据进行训练和推理,得到最优中华绒螯蟹品级鉴定和预测模型。结果显示,疣突+颈沟的蟹背纹理组合特征可实现中华绒螯蟹品级的快速识别,总体训练准确率可以达到95.0%,总体推理准确率可以达到96.2%,且每只河蟹活力品级的推理时间不超过0.5 s。该方法具有较大的应用前景和市场价值,为开发大规模中华绒螯蟹在线品质的无损检测装备提供关键技术。

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。

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。

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。