以皖南山区的河源溪流为研究区域, 根据2016年7月和11月两次的调查数据, 在区分土著物种和本地入侵物种的基础上, 初步比较研究了低水头坝的坝上蓄水区和冲刷区鱼类群落的季节动态及所受水坝大小和功能的影响。共采集鱼类24种, 隶属4目10科, 其中土著鱼类13种, 本地入侵鱼类11种。尽管坝下冲刷区的鱼类群落无显著季节变化, 但坝上蓄水区的鱼类群落季节动态显著, 其中11月的鱼类个体数显著高于7月。水坝大小对鱼类群落的影响相对较小, 仅冲刷区入侵鱼类群落结构随水坝大小显著变化; 水坝功能对鱼类群落的影响较大, 蓄水区土著鱼类群落及冲刷区入侵鱼类群落等都随水坝功能显著变化——同蓄水坝相比, 引渠坝的蓄水区中宽鳍鱲较少但中华花鳅和吻虾虎鱼较多, 且引渠坝的冲刷区中高体鳑鲏和泥鳅具有更高多度。研究表明, 在研究区域内, 低水头坝对鱼类群落分布的影响视水坝蓄水功能而不同, 而水坝大小的相对重要性较低。研究也进一步证实, 因亲流性土著鱼类与广布性入侵鱼类对低水头坝干扰的响应不同, 在开展有关人类活动对溪流鱼类多样性的影响评价时, 有必要区分土著物种和入侵物种来进行, 以确保研究结论的科学性。
β2-微球蛋白(β2-microglobulin, β2m)作为MHCⅠ类分子的亚基, 在鱼类的免疫系统中发挥重要作用。实验采用直接测序法从P0代尼罗罗非鱼(Oreochromis niloticus)的β2m基因组序列中筛选到30个SNPs, 其中1个SNP位于5ʹUTR, 16个SNPs位于外显子区域(15个非同义突变位点, 1个同义突变位点), 9个SNPs位于内含子区域, 4个SNPs位于3ʹUTR。利用snapshot分型法对F1代的102尾易感群体和102尾抗病群体进行基因分型, 并通过Popgen32和PIC-CALC软件统计分析尼罗罗非鱼β2m基因序列的SNPs的He、Ho、Ne和PIC等遗传参数, 表明易感群体中7个SNPs属于中度多态水平(0.25<PIC<0.5), 抗病群体中25个SNPs属于中度多态水平(0.25<PIC<0.5)。采用SPSS 23.0软件分析了30个SNPs在F1代2个群体中的基因型频率和等位基因频率, 分析其与链球菌抗性或易感性状之间的相关性。结果表明: 24个SNPs的基因型和等位基因频率与无乳链球菌(Streptococcus agalactiae)抗性/易感性状显著相关(P<0.05)。通过连锁不平衡分析发现30个SNPs构成4个单倍块和14种单倍型。其中, 4个单倍型与无乳链球菌抗性性状显著相关(P<0.05), 4个单倍型与易感性状显著相关(P<0.05)。标签SNP分析发现, 单倍块2中的4个SNPs和单倍块3中的13个SNPs彼此之间高度连锁(r2>0.9), 这意味着我们在β2m基因中发现2个htSNPs。研究筛选到的与链球菌抗性/易感性状相关的SNP位点及单倍型具有辅助尼罗罗非鱼抗链球菌病品种选育的潜力。
Myxobolus haichengensis Chen, 1958 forms numerous small plasmodia on the gill filaments of wild cyprinid Abbottina rivularis Basilewaky. The species described originally was lacking important characters, which made the accurate identification difficult. Here, we supplemented its characteristics with morphological and molecular data. Plasmodia of M. haichengensis are oval. Mature spores are ellipsoidal-shaped in frontal view and fusiform-shaped in lateral view, measuring (10.8±0.7) μm (10.1—11.5 μm) long, (8.1±0.5) μm (7.5—9.0 μm) wide, and (5.7±0.4) μm (5.2—9.0 μm) thick; two unequal polar capsule are pyriform with tapering anterior, large polar capsule averaging (4.7±0.5) μm (4.8—6.7 μm) long and (2.5±0.2) μm (3.2—4.3 μm) wide; small polar capsule averaging (4.4±0.2) μm (4.1—4.8 μm) long and (2.2±0.1) μm (2.0—2.5 μm) wide; polar filaments coil with four to five turns. The nuclear 18S rDNA sequence was obtained and deposited in GenBank (KY965936), and sequences alignment analyses revealed that M. haichengensis was most similar with the actinosporean Hexactinomyxon type 2 (AY162272, 97%) released from the freshwater tublificid oligochaete Limnodrilus hoffmeisteri.
G蛋白偶联受体54(GPR54, G protein-coupled receptor 54)是kisspeptin (Kiss)的受体蛋白。Kisspeptin/GPR54系统通过调节促性腺激素释放激素(GnRH)的活性来参与鱼类生殖调控。为了研究Kisspeptin/GPR54系统对达氏鲟(Acipenser dabryanus)GnRH的调控功能, 克隆得到达氏鲟2个gpr54基因的全长cDNA序列, 命名为dsgpr54-1及dsgpr54-2, 分别编码379和368个氨基酸。氨基酸序列比对及进化树分析表明, 达氏鲟Gpr54与四足动物Gpr54序列一致性较高, 亲缘关系较近。荧光定量PCR研究发现, dsgpr54-1的转录本在精巢、卵巢、下丘脑、垂体、中脑及端脑等组织中均有表达, 且在下丘脑中转录水平最高; 而dsgpr54-2仅在脑组织中转录, 且在垂体、中脑及下丘脑中表达丰度均较高。为了研究Gpr54是否可以与其配体Kisspeptin结合调控下丘脑中gnrh基因的表达, 分别合成了达氏鲟Kiss-1和Kiss-2的核心十肽(10 nmol/L、1000 nmol/L), 腹腔注射到9月龄达氏鲟。结果表明, 不同浓度Kiss-1、Kiss-2注射均引起gpr54基因表达量升高, 并且10 nmol/L Kiss-2注射能够显著促进dsgpr54-2的表达(P<0.05)。另外, 不同浓度Kiss-1注射均造成了gnrh转录水平的下降; 而10 nmol/L Kiss-2注射使得gnrh1表达量上升, 而gnrh2的表达量下降, 1000 nmol/L Kiss-2注射则引起gnrh1表达量的下降, gnrh2的表达量没有显著变化。上述研究结果表明, 达氏鲟gpr54基因均能与其配体kiss-1、kiss-2相结合, 但表现出一定的受体-配体选择性差异。Kiss-1、Kiss-2通过激活Gpr54的活性, 调控下丘脑中gnrh基因的表达, 且其调控功能存在差异。
研究通过组织病理分析、超微结构观察以及分子特征分析对石斑鱼(Epinephelus spp.)苗种肠道微孢子虫病病原进行了鉴定。其为一肠孢虫属新种, 命名为石斑鱼肠孢虫(Enterospora epinepheli sp. n.), 专性寄生于细胞核内, 发育过程与肠孢虫属模式种黄道蟹肠孢虫(Enterospora canceri)一致。早期单核裂殖体通过一层简单的电子薄膜与宿主细胞核质隔离。随后, 单核裂殖体发育形成多核裂殖原质团。此时, 细胞核出现明显肥大, 有的甚至被裂殖子胀破。裂殖原质团进一步发育形成多核产孢体, 并开始出现许多高电子密度的囊泡状结构。这些与极丝及锚状盘有关的囊泡状结构聚集在藕核周围, 并组装形成微孢子虫特征性结构(挤出装置)前体。随后, 产孢体原生质团通过连续分裂形成一个个孢子母细胞。孢子母细胞与细胞核直接接触, 并直接发育形成成熟孢子。成熟孢子椭圆形, 孢子长(1.56±0.31) μm (1.07—1.96 μm), 宽(1.08±0.98) μm (0.93—1.28 μm)。 孢壁分为3层, 外壁电子密度高, 厚(15.51±0.95) nm (9.87—26.18 nm), 内壁为电子透明层, 较外层更厚(81.13±2.71) nm (57.16—110.81 nm), 最里面为孢质膜。极丝为同型极丝, 共5—6圈, 分2排排列。组织病理学分析发现该微孢子虫寄生于肠道上皮杯状细胞核内, 肠壁脱落的内容物中也发现大量的微孢子虫。序列比对发现该种与之前报道的石斑鱼肠道微孢子虫待定种(Microsporidium sp.)序列基本一致, 与其他相似性较高的种类的遗传距离在0.162—0.225。系统发育关系分析显示肠胞虫科的种类明显分为两支, 石斑鱼肠孢虫和肠孢虫属其他种类及毕氏肠胞虫聚为一个独立分支, 但不与该分枝中任何种类形成姊妹支。
以紫球藻(Porphyridium purpureum)为供试材料, 研究了5个不同浓度的Cd2+对紫球藻的细胞密度、叶绿素a含量、藻红蛋白含量及ATP含量的影响, 以及对紫球藻的最大光量子产额(Fv/Fm)、实际光量子产额(YII)、相对电子传递效率(ETR)及非光化学淬灭(NPQ)的影响, 探讨了各荧光参数在不同浓度的Cd2+胁迫下的变化规律。研究结果表明, 在Cd2+胁迫的6d内, 紫球藻的生长速度显著下降, 且Cd2+的浓度越高, 生长速度下降越快; Cd2+胁迫显著的减少叶绿素a、藻红蛋白及ATP含量, 且浓度越高, 减少的幅度越大; 在Cd2+浓度低于200 μmol/L时, 紫球藻的叶绿素荧光参数Fv/Fm、YII及ETR呈现先下降后上升的趋势,而且随着胁迫时间的延长, 下降幅度逐步增大; NPQ在低浓度下(<200 μmol/L)呈现显著上升趋势, 高浓度下(>500 μmol/L)呈现显著下降趋势。因此, 水体中浓度超过50 μmol/L的Cd2+就会显著影响紫球藻的生长及光化学活性, 水生环境中不断累积的Cd2+将会对紫球藻的生态平衡产生影响。
目前黄颡鱼(Pelteobagrus fulvidraco Richardson)生产上使用的母本非常混杂, 成为影响黄颡鱼产业发展的一个突出问题。建立一个优良性状稳定的全雌家系对于全雄黄颡鱼和杂交黄颡鱼的生产尤为重要, 而将XX雌性黄颡鱼逆转为XX雄性黄颡鱼是创制全雌家系中的关键一步。黄颡鱼性染色体连锁分子标记的开发为鉴定XX雄鱼提供了技术支撑。研究使用不同浓度的17α-甲基睾酮(MT)和芳香化酶抑制剂来曲唑(LZ)处理黄颡鱼鱼苗54d (7—60日龄)。61日龄测量并统计各组鱼的存活率、体长及体重。解剖观察性腺结构, 结合性腺组织切片和性别分子标记分析各组实验鱼中XX鱼性腺发育情况。结果显示: 2种药物对黄颡鱼的存活率影响较小, 与对照组没有显著差异; MT处理的XX性腺为空腔状精小囊结构, 不能逆转为功能性精巢; 适当剂量的LZ可以将XX雌性黄颡鱼性逆转成正常的XX雄鱼, 诱导效果随着剂量的增加而增强。用完全逆转的XX生理雄鱼分别与XX雌鱼和YY雌鱼交配, 能够正常繁殖并具备较好的繁殖能力。研究建立了一种使用芳香化酶抑制剂来曲唑创制黄颡鱼XX雄鱼的方法, 为全雄黄颡鱼的品种改良及新品种的培育奠定了基础。
以雨生红球藻Haematococcus pluvialis LUGU株为研究对象, 研究在高光照和缺氮胁迫条件下, 添加不同浓度褪黑素(melatonin, MLT)对雨生红球藻生长、虾青素积累、活性氧(ROS)、信号分子及dxs基因表达量的影响。结果表明, 外源添加10 μmol/L MLT可有效提高藻细胞中虾青素的含量, 最高可达31.32 mg/g, 是对照组(13.27 mg/g)的2.36倍; 抑制了细胞内ROS水平, 上调了信号分子一氧化氮(NO)和水杨酸(SA)的含量; 此外, dxs基因表达水平比对照组明显提高, 最高达11.3倍。研究表明, 在非生物胁迫条件下, 雨生红球藻中虾青素的大量积累可能与外源MLT调控细胞内ROS、信号分子及基因表达有关。
试验旨在研究饲粮添加α-酮戊二酸(α-ketoglutarate, α-KG)对氨氮胁迫下草鱼(Ctenopharyngodon idellus)鳃Na+/K+-ATP酶活性及血液生化指标的影响。选取初始体重为(24.79±0.11)g的健康草鱼, 随机分为3个处理组(对照组, 养于曝气后氨氮浓度为1.51 mg/L的自来水中并饲喂基础饲粮; 氨氮组, 养于氨氮浓度为18.37 mg/L的水中并饲喂基础饲粮; α-KG组, 养于氨氮浓度为18.37 mg/L的水中并饲喂添加0.75% α-KG的饲粮)。每处理组设3个重复, 每个重复30尾鱼, 养殖试验为期42d, 分别于第1、第14、第28和第42天采样。结果表明:在饲料中添加α-KG能够有效缓解氨氮胁迫导致的草鱼血浆氨含量(1d)、谷草转氨酶(Aspartate transaminase, AST)活性(14d)、碱性磷酸酶(Alkaline phosphatase, ALP)活性(28d)的显著升高和鳃Na+/K+-ATP酶活性(28d)、血浆谷丙转氨酶(Alanine aminotransaminase, ALT)(28d和42d)活性、血浆尿素(UREA)含量(28d)的显著降低, 显著增加氨氮胁迫下草鱼血浆球蛋白(Globulin, GLB)含量(28d)。即饲粮α-KG的适量添加能够有效缓解草鱼氨氮胁迫所致的血氨含量升高, 维持氨氮胁迫下草鱼鳃Na+/K+-ATP酶、血浆谷丙转氨酶、谷草转氨酶、碱性磷酸酶的活性和血浆球蛋白、尿素含量的稳定, 从而有利于草鱼缓解氨氮胁迫。
以洱海微囊藻水华为研究对象, 借鉴生态毒理学风险评估思路对藻类水华的水生态风险进行评价。研究通过暴露实验以及查阅文献获取了微囊藻水华对底栖动物、浮游动物、鱼类和沉水植物的效应数据, 采用毒性百分数排序法推导了洱海微囊藻水华的急性和慢性效应藻密度, 用风险商值评估微囊藻水华密度的水生态风险。进一步结合水华盖度和持续时间制定了微囊藻水华的急性、慢性生态风险评价表。研究结果表明, 微囊藻水华的急性生态风险分为低中高三级, 分别为微囊藻藻密度小于3.4×106 cells/L为低风险，微囊藻藻密度在3.4×106—3.4×107 cells/L之间为中风险，微囊藻密度大于3.4×107 cells/L为高风险。慢性生态风险同样分为低中高三级, 分别为微囊藻藻密度小于1.1×106 cells/L为低风险，微囊藻藻密度在1.1×106—1.1×107 cells/L为中风险，微囊藻密度大于1.1×107 cells/L为高风险。实际应用中需综合微囊藻水华密度、面积和持续时间, 制定洱海微囊藻水华水生态风险评价标准。当微囊藻水华处于中风险状态时, 应启动预警、强化水质管理和生物抑制措施, 当处于高风险状态时, 应采取水华的应急处理措施。研究结果有助于洱海微囊藻水华的科学管理。
饵料对鱼类生长发育和繁殖具有重要影响。为了筛选稀有鲫(Gobiocypris rarus)幼鱼和成鱼阶段最适投喂方式, 实验将出膜5周末(日龄为35 day after hatching)的幼鱼随机分为5个组: A组投喂丰年虫; B组每周前6d (days)投喂丰年虫, 后1d投喂商业化微颗粒S3饲料; C组每周前3.5d投喂丰年虫, 后3.5d投喂饲料; D组每周前1d投喂丰年虫, 后6d投喂饲料; E组一直投喂饲料; 各组均采用饱食投喂策略。每2周统计生长、存活指标, 直至第21周(147 dah), 在17周(119 dah)取材用于观察性腺发育程度。在产卵后统计各组产卵量、孵化率和子代畸形率。结果显示: (1)E组存活率和特定生长率显著低于其他组(P<0.05); (2)从产卵量、孵化率和子代畸形率上看, B组产卵量显著高于其他组(P<0.05); (3)从性腺组织学上看, 不同投喂方法对精巢的成熟度无显著影响, 但投喂过丰年虫的稀有鲫卵巢发育成熟度显著优于E组。研究结果提示:适量加入丰年虫比单一投喂活饵或饲料更有利于稀有鲫的生长和繁殖。建议在标准化养殖过程中, 幼鱼和成鱼期的稀有鲫采取丰年虫与饲料投喂频次比值为6﹕1的方式最佳。
为进一步确认及掌握鲤浮肿病毒(Carp Edema Virus, CEV)目前的流行现状和流行特点,于2017年重点调查了我国北方地区5省市26个正发生或曾经发生“鲤急性烂鳃病”的养殖场, 随机监测了9个省市的97家鲤和锦鲤养殖场。样品采用实时荧光定量PCR(Quantitative real time PCR,qPCR)法和套式PCR(Nest PCR)方法进行检测, nest PCR法扩增出的产物进行测序和基因分析。结果重点调查的26家养殖场中有20个为CEV阳性, 1个为锦鲤疱疹病毒(Koi Herpes Virus, KHV)阳性, 1个为孢子虫感染。随机调查的97家养殖场中有50家为CEV检测阳性, 阳性率高达52%; 可测序的CEV毒株均属于Genogroup Ⅱa型; 样品按不同地区、不同采样水温、不同品种、不同规格鱼等划分, 各组均有CEV阳性检出, 但检出率均无显著差异。以上结果表明CEV感染是多省市“鲤急性烂鳃病”暴发的主要病因。另外, 该病毒病的流行水温在12—27℃。
根据2013—2014在皎平渡圆口铜鱼产卵场的定点亲鱼收集(n=206)和2006—2014年在金沙江中下游金安桥至巧家干流江段的流动亲鱼采集(n=70), 对圆口铜鱼的繁殖生物学进行了初步研究。定点亲鱼收集的结果显示: 圆口铜鱼雌性最小性成熟个体全长330 mm, 体质量441.0 g, 年龄4龄; 雄性最小性成熟个体全长352 mm, 体质量396.6 g, 年龄3龄; 50%个体达到性成熟的年龄和全长分别为雌性4.32龄 406 mm, 雄性4.44龄 412 mm; 繁殖群体雌雄性比为1.37﹕1, 繁殖群体中雌性年龄为4—7龄, 雄性年龄为3—7龄; 雌雄个体的性成熟系数平均值均以6龄个体最高, 分别为10.55%和3.45%; 平均卵径为0.16 cm, 卵径分布呈双峰型。定点和流动亲鱼收集的雌性性成熟个体的结果表明: 圆口铜鱼绝对繁殖力变动范围为4055—137900粒/尾, 平均值为22817粒/尾; 相对繁殖力变动范围为5—73粒/g, 平均值为20粒/g, 75.68%个体的绝对繁殖力在10000—30000粒/尾之间, 70.27%个体的相对繁殖力在15—20粒/g之间; 绝对繁殖力和相对繁殖力均随着体长和体质量的增加而增加, 其中全长、体质量与绝对繁殖力呈指数分布函数正相关, 而与相对繁殖力呈二次项函数正相关。研究结果可为长江流域圆口铜鱼资源的保护提供重要的基础数据支撑。
研究以裂片石莼(Ulva fasciata)、肠浒苔(Ulva intestinalis)、龙须菜(Gracilaria lemaneaformis)、坛紫菜(Pyropia haitanensis)为实验材料, 分析了不同温度(15、20、25、30℃)下4种大型海藻对海水中N、P元素的吸收效率和光合特性的特点。结果显示: (1)4种大型海藻对水体N、P均有明显的吸收效果, 吸收能力高低依次为肠浒苔>裂片石莼>坛紫菜>龙须菜; (2)温度过高或过低都会限制藻类对N、P的吸收和正常生长, 同时降低4种藻的相对电子传递速率及光化学效率; (3)裂片石莼与肠浒苔的N、P吸收能力强, 且光合系统对温度耐受性高, 是实施养殖污水生物净化的良好材料; (4)4种海藻对水体中N、P营养盐的吸收在48h内基本完成, 实地应用中可考虑24—48h周期换水或采用流通循环式的培养模式, 以达到既促进藻类的生长又提高营养盐吸收效率的目的, 以避免藻体因营养缺乏引起负生长而造成二次污染。
对厦门沿海6个代表性站位砂壳纤毛虫进行了为期1年的采集, 共分离鉴定了27种砂壳纤毛虫, 其中拟铃虫属Tintinnopsis 20种, 薄铃虫属Leprotintinnus 3种, 类铃虫属Codonellopsis 2种, 领细壳虫属Stenosemella 1种以及网纹虫属Favella 1种。对该5属27种砂壳纤毛虫进行形态学描述, 并提供了显微照片, 其中侧胀拟铃虫Tintinnopsis ventricosoides Meunier, 1910为中国新记录种。
对广东省珠海市每年6—10月池塘养殖的眼斑拟石首鱼(Sciaenop socellatus)暴发不明原因疾病进行了研究。通过对该病的流行病学调查，结合症状观察、病原分离鉴定、病理学变化，结果显示：该病具有明显的传染性，解剖病鱼可见鳃丝贫血、脾脏和肾脏肿大、出血，通过镜检未检测到大量的寄生虫；从发病鱼的肝、脾、肾脏和肠中未分离到致病菌；在病鱼肝、脾和肾组织病理切片中观察到有大量肿大细胞；通过使用OIE 推荐的虹彩病毒特异性引物进行PCR扩增出570 bp左右的目的片段，MCP基因序列比对显示扩增获得的基因序列与真鲷虹彩病毒(RSIV)的基因序列同源性高达99.2%。综合以上结果表明导致眼斑拟石首鱼发病死亡的原因是感染了细胞肿大属虹彩病毒而引起的虹彩病毒病。
采用扫描电镜、透射电镜和蛋白银染色等方法研究了海蜇胚胎发育和变态过程中细胞超微结构变化。结果显示: (1)海蜇自受精卵至原肠期阶段细胞均等分裂, 细胞间存在大量连接, 细胞形态相近, 未出现显著分化; (2)海蜇自早期浮浪游虫阶段, 其外胚层细胞开始出现空泡化, 至4触手螅状体阶段外胚层细胞空泡体积逐渐增大, 而内胚层细胞仅在4触手螅状体阶段才出现空泡化。伴随着外胚层细胞空泡化比例的增大, 杯状体和4触手螅状体阶段出现疑似凋亡小体结构; (3)刺细胞分化于早期浮浪游虫期的外胚层近中胶层区域, 而后逐渐向外转移, 至4触手螅状体阶段发育成熟并转移至表面; (4)纤毛形成于早期浮浪幼虫, 在杯状体阶段逐渐退化, 并于4触手螅状体阶段完全消失; (5)在海蜇早期发育各个阶段, 其内部均发现大量着色较深的卵黄体, 且在浮浪游虫阶段首次发现了海蜇外层细胞主动吞噬细菌现象, 表明海蜇早期发育营养来自内源性和外源性两部分。研究结果可为阐明刺胞动物早期发育模式提供依据。
为了明确我国海域拟菱形藻属(Pseudo-nitzschia)物种的产毒特征, 从中国沿海建立了15个拟菱形藻单克隆培养株系, 利用高效液相色谱-质谱联用法对其多莫酸特征进行检测, 在10个株系中检测到多莫酸。结合光学显微镜下的群体特征和透射电镜下的超微形态学特征, 以及基于核糖体转录间隔区的分子系统学数据, 确认上述10个产毒株系分别隶属于3个物种：尖细拟菱形藻P. cuspidata、伪柔弱拟菱形藻P. pseudodelicatissima、伪善拟菱形藻P. fraudulenta, 其中伪善拟菱形藻是我国的新记录种。建立尖细拟菱形藻的11个尖细拟菱形藻株系, 其中3个株系未检出多莫酸, 其余8个株系有检出, 单细胞产毒水平为0.4—5.5 fg。建立伪柔弱拟菱形藻株系2个, 1个未检出多莫酸, 另1个株系的单细胞产毒量为1 fg。建立伪善拟菱形藻株系2个, 纯种培养株系均未检出多莫酸。利用卤虫(Artemia salina)对部分藻株进行混培诱导, 其中尖细拟菱形藻(MC4049)和伪柔弱拟菱形藻(MC3015)的产毒水平略有下降, 单细胞产毒水平分别由2、1 fg降至0.2、0.4 fg, 而伪善拟菱形藻(MC4074)的产毒能力则有显著改变, 单细胞产毒水平由未检出上升至17.5 fg。研究丰富了我国产毒拟菱形藻的物种多样性, 明确了其物种信息和产毒水平, 可为后续深入研究提供基础数据。
研究以线粒体细胞色素氧化酶Ⅰ(COⅠ) 部分序列(614 bp)为分子标记, 对捞刀河浏阳段河蚬Corbicula fluminea (n=40)的种群遗传多样性进行评价, 并分别从性腺组织学和精子形态学两方面分析其生殖特征, 以期丰富河蚬的繁殖生物学信息, 为开展其人工繁殖及资源保护提供参考。结果显示, 40条河蚬COⅠ基因序列共检出4种单倍型, 17个变异位点, 平均单倍型多样性、平均核苷酸多样性和平均核苷酸差异数分别为 0.664±0.042、0.014±0.006和8.595。捞刀河浏阳段河蚬存在雌雄同体和雌雄异体2种性别系统, 雌雄同体、雄性和雌性的性比约为6﹕3﹕1。雌雄同体个体生殖滤泡存在滤泡混合型和滤泡并存型2种类型。23个雌雄同体和8个雄性个体的精子均为双鞭毛。结果表明, 捞刀河浏阳段河蚬种群的遗传多样性相对较低, 生殖方式多样且以雄核生殖为主。
以鱼粉和小麦蛋白粉为蛋白源, 配制成6种等氮等脂(粗蛋白45%; 粗脂肪10%)的饲料, 研究其对大黄鱼(Larimichthys Crocea)幼鱼生长、肠道组织结构及肠道微生物菌群的影响。这6种饲料是以发酵豆粕分别替代基础饲料(含40%鱼粉)中0 (FSM0, 对照组)、15% (FSM15)、30% (FSM30)、45% (FSM45)、60% (FSM60)和75% (FSM75)的鱼粉制作而成。经过56d的生长实验, 结果表明, 饲料中随着发酵豆粕替代比例的升高, 各处理组大黄鱼幼鱼(10.49±0.03) g的存活率无显著性差异(P>0.05), 但FSM60和FSM75组有下降趋势; 相比FSM0组, FSM60和FSM75组的特定生长率(SGR)和增重率(WGR)显著降低(P<0.05), 饲料系数(FCR)显著升高(P<0.05); 摄食率(FI) FSM 60和FSM 75组显著高于FSM0、FSM15、FSM30和FSM45组(P<0.05)。肠道组织结构研究发现, 各处理组肠道组织结构后肠黏膜、皱襞高度、固有膜宽度和杯状细胞个数均无显著性差异(P>0.05)。Illumina-Mi Seq高通量测序技术分析发现, FSM0 (TC对照组)、FSM45 (TB最佳生长组)和FSM75 (TW最差生长组)组Chao1、香农指数(Shannon)、辛普森指数(Simpson)和覆盖率(Good coverage)均无显著性差异(P>0.05); 基于门水平, TC、TB和TW组大黄鱼幼鱼肠道优势菌群为厚壁菌门(Firmicutes); 而在属水平, 类芽孢杆菌(Paenibacillus)占绝对优势。从属水平差异菌属研究发现, 发酵豆粕对大黄鱼幼鱼肠道菌群有一定的影响: 与最差生长组(TW)相比, 最佳生长组(TB)和对照组(TC)均显著增加了类芽孢杆菌(Paenibacillus)和嗜碱菌属(Alkaliphilus)的物种丰度(P<0.05); 与TW组相比, TB组水栖菌属(Enhydrobacter)和TC组副球菌属(Paracoccus)的物种丰度均显著降低(P<0.05)。结果表明, 发酵豆粕替代鱼粉达45%时对大黄鱼幼鱼的生长、肠道组织结构及肠道优势菌群没有负面影响, 即发酵豆粕替代饲料(含40%鱼粉)中45%的鱼粉较为适宜。
为了解人工选育对华南鲤(Cyprinus carpio rubrofuscus)选育群体遗传结构的影响, 采用微卫星技术分析了华南鲤4个连续选育世代(F1、F2、F3和F4)的遗传多样性和遗传结构。结果显示：在4个选育群体中, 16对微卫星引物共扩增得到99个等位基因, 每个微卫星座位检测到的等位基因数为3—10个, 平均为6.1875个。随着人工连续选育的进行, F1到F4的平均等位基因数(Na)从5.6875下降到4.6755, 平均观测杂合度(Ho)从0.7943下降到0.7135, 平均多态信息含量(PIC)从0.6577下降到0.5834。F1与其后各代的遗传距离逐代增加(从0.1486上升到0.2181), 遗传相似系数逐代减小(从0.8619下降到0.8041), 而相邻世代间的遗传分化指数(Fst)逐代变小(F1与F2为0.062, F2与F3为0.058, F3与F4则为0.051), 遗传相似性逐步升高。世代间Fst值配对比较结果显示4个世代间的遗传分化处于中等水平, 表明人工选育已对华南鲤选育群体的遗传结构产生了影响。实验结果表明, 华南鲤经过4代选育后, 虽然遗传杂合度和遗传多样性存在下降的现象, 但遗传多样性水平依然较高, 还具有进一步选育的潜力。研究结果为下一步制定华南鲤新品种选育计划提供基础遗传数据。
通过脑室注射异亮氨酸, 探究短期内异亮氨酸对鳜(Siniperca chuatsi)雷帕霉素靶蛋白(Mammalian target of rapamycin, mTOR)信号通路及氮代谢影响。结果显示: 脑室注射异亮氨酸后, (1)促进鳜氨氮排泄; (2)谷氨酸脱氢酶基因(Glutamate dehydrogenase, GDH)、谷草转氨酶基因(Glutamic oxaloacetic transaminase, GOT)和腺苷酸脱氨酶基因(Adenosine monophosphate deaminase, AMPD)氮代谢基因相对表达量显著性上调(P<0.05); (3)鳜血糖含量在0.5h显著性降低(P<0.05); (4)激活了鳜肝脏mTOR信号通路, 促使下游分子核糖体蛋白S6磷酸化(P<0.05)。结果表明: 异亮氨酸能够激活鳜肝脏mTOR信号通路, 介导氨基酸代谢, 提高鳜氮代谢基因的转录水平, 促使氨氮排泄增多。
植物是人工湿地的重要组成部分, 但大多数湿地植物在低温环境下不能生存, 微生物活性受到抑制, 导致人工湿地低温应用受到限制。研究将辐照育种的手段应用于湿地植物, 以提高其抗寒性。研究采用25 Gy、45 Gy、60 Gy和80 Gy的γ射线对美人蕉(Canna indica L.)种子进行辐照, 剂量率为6 Gy/min, 待幼苗长出后进行阶段性降温培养, 并评价各组抗寒性。结果表明: 在低温下, 辐照幼苗的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均高于对照组。对照组丙二醛(MDA)在低温下大量积累, 且含量显著高于辐照组。在低温条件下, 幼苗脯氨酸、可溶性糖、蛋白质含量高于对照组。辐照组抗寒性得分高于对照组, 45 Gy组得分最高。随后将最佳辐照处理的美人蕉种植于人工湿地, 对其冬季净化效果进行评估, 评价指标包括: 总磷(TP)、总氮(TN)、化学需氧量(COD)。结果发现, 45 Gy辐照组人工湿地的冬季TP去除率显著高于对照组(P<0.05)。由此可见, 辐照处理能够有效提高美人蕉的抗寒性, 并提高人工湿地冬季净化效果。
为研究长江口水生动物食物网营养结构及其变化, 运用胃含物分析法研究了2016—2017年长江口及其邻近水域捕获的43种水生动物的食性类型与营养结构, 并与20世纪90年代和2006年文献数据进行了比较, 结果表明, 长江口及其邻近水域捕获的水生动物分为4种食性类型: 浮游生物食性、底栖生物食性、游泳生物食性、混合食性, 其中浮游生物食性消费者占绝对优势, 为39.53%; 游泳生物食性消费者所占比例最少, 为11.63%。所分析样品的营养级可分为3级, 其中植食性消费者占优势, 为76.75%; 中级肉食性消费者所占比例最少, 为4.65%; 与20世纪90年代相比, 12种常见鱼类的平均营养级由3.80下降到2.87。长江口水生动物食物网结构较为复杂, 生产者类型包括底栖藻类、浮游植物、有机碎屑3种, 主要由牧食食物链和碎屑食物链构成复杂的食物网。
为了考察力竭追赶训练对中华倒刺鲃(Spinibarbus sinensis)和岩原鲤(Procypris rabaudi)幼鱼呼吸循环系统和力竭运动后代谢特征的影响, 在(25±0.5)℃条件下, 将2种实验鱼各60尾 [体重分别为(28.36±0.08)g和(19.53±0.13)g]随机等分成对照组和训练组, 训练组进行1次/d共21d的力竭追赶训练。随后测定各组实验鱼的心脏和鳃指数、血液指标以及力竭运动后过量耗氧(Excess post-exercise oxygen consumption, EPOC)。结果发现: 2种鱼心脏指数、鳃指数、血红蛋白含量和红细胞数目在各自对照组和训练组之间都没有显著性差异; 岩原鲤对照组的鳃指数显著低于中华倒刺鲃对照组(P<0.05), 但心脏指数、血红蛋白含量和红细胞数目与中华倒刺鲃对照组无显著性差异。中华倒刺鲃训练组的运动前代谢率、运动代谢峰值、峰值比率、代谢恢复速率与其对照组没有显著差异, 但运动后恢复时间和过量耗氧显著大于对照组(P<0.05); 岩原鲤训练组的运动前代谢率显著低于其对照组(P<0.05), 但运动代谢峰值、峰值比率、运动后恢复时间、过量耗氧、代谢恢复速率与其对照组没有显著性差异。岩原鲤对照组的运动前代谢率、运动代谢峰值、过量耗氧和代谢恢复速率分别显著低于中华倒刺鲃对照组(P<0.05), 但峰值比率和运动后恢复时间与中华倒刺鲃对照组无显著性差异。研究表明: (1)力竭追赶训练对中华倒刺鲃和岩原鲤幼鱼的呼吸和循环系统参数没有产生显著性影响; (2)力竭追赶训练显著提高了中华倒刺鲃幼鱼的无氧代谢能力; (3)中华倒刺鲃幼鱼力竭运动前后代谢率显著高于岩原鲤幼鱼, 这可能与其较为活跃的习性有关。
外源性激素在中华鳖(Pelodiscus sinensis)性别决定有重要作用, 为给中华鳖性别决定机制研究提供生物学信息, 首次克隆和分析了中华鳖Foxl2 cDNA部分序列。为研究其在遗传和生理水平的差异, 以10 mg/kg剂量17α-甲基睾酮(MT)和17β-雌二醇(E2)分别对中华鳖雌雄个体注射, 检测0、6h、12h、24h、48h、7d和14d性腺Foxl2 mRNA表达水平。获得中华鳖Foxl2基因(GenBank登录号: KP734210)部分 cDNA长903 bp, 共编码300个氨基酸, 属于叉头框转录因子家族, 参与卵巢发育和功能维持; 多重序列比对显示, Foxl2具有典型的FH结构域, 与红耳龟的同源性最高, 达到99%; 系统进化树分析显示, 中华鳖Foxl2基因与爬行动物Foxl2基因聚为一个亚支, 且与西部锦龟Foxl2基因距离最近。荧光定量PCR结果显示, 与对照组相比, 注射E2后24h, 卵巢Foxl2 mRNA表达水平被极显著上调(P<0.001), 7d和14d后, 精巢Foxl2 mRNA表达水平极显著上升(P<0.001); 注射MT后24h, 精巢和卵巢Foxl2 mRNA的表达水平均极显著升高(P<0.001)。结果表明, E2和MT促进Foxl2表达, E2促进其表达的性别差异比MT明显。研究可为了解Foxl2的功能及明确外源性激素调控中华鳖Foxl2的分子机制提供基础资料。
There is limited information available on effects of aquaculture on lake ecosystems. Community structure and biodiversity of phytoplankton were investigated from July to September, 2015 in 23 lakes in the middle reach of the Yangtze River Basin, which include four groups: reservoir group (A), aquaculture ban group (B), low stocking aquaculture group (C) and high stocking aquaculture group (D). The analysis showed that dominant genera of the four groups were different. Group A was dominated by Pseudanabaena (Y=0.642) and Planktolyngbya (Y=0.064). Group B was dominated by Merismopedia (Y=0.428), Planktolyngbya (Y=0.118), Pseudanabaena (Y=0.133), and Scenedesmus (Y=0.066). Group C was dominated by Pseudanabaena (Y=0.395), Merismopedia (Y=0.097), and Planktolyngbya (Y=0.122). Group D was dominated by Merismopedia (Y=0.308), Microcystis (Y=0.118), and Pseudanabaena (Y=0.077). The phytoplankton abundance in group A was significantly lower than those in other lake groups (P<0.05). There was no significant difference in Shannon-Wiener index, Margalef index and Pielou index of phytoplankton among the four lake groups. The study indicated that fish culture could affect the abundance and dominant genera of phytoplankton, which may provide some implications for lake ecosystem management.
The histology of gonadal development in Ptychobarbus dipogon was studied by using conventional paraffin sections and HE staining, in order to obtain information on its reproductive systems useful for its artificial breeding. The results showed that the development of oocytes can be divided into five phases, and ovarian development can be divided into six stages. In stage V ovaries, ovum worship was found to occur, indicated by the 1.38:1 ratio of small ova to large ova. Phase 3 oocytes were characterized by appearance of yolk granules and follicles; phase 4 oocytes by rapid increase of yolk granules, and the movement of the nucleus toward the animal poles; phase 5 by the fusion of yolk granules, and the separation of oocytes from follicular membranes to float in the ovarian cavity. Male P. dipogen had lobular testes, and their germ cells can be categorized into spermatogonia, spermatocytes; spermatids; and spermatozoa. Their testes also developed in six stages. The species followed a batch-synchronous spawning pattern.
Knowledge of the vulnerability of different species and size groups to various types of fishing methods is vital to the development of optimal harvesting strategies and rational exploitation of fish resources. In this study, the selectivity of four types of fishing methods (weir nets, gill nets, electrofishing, and cormorants) used simultaneously in a typical multi-species shallow lake (Lake Niushan, China) within the Yangtze River basin, was compared for catch composition, efficiency, and size selection. Species selectivity was evaluated with the index of relative importance (IRI). Potential fishing effects on the trophic structure of fish community were analyzed by calculating the mean trophic level (MTL) of the catches and the weight ratio between prey and predator fishes. Results indicated the use of weir nets and electrofishing should be reduced or eliminated, because they were relatively unselective and caught many species, including juvenile individuals. Fishing efforts of cormorants should be restricted due to their high fishing efficiency, especially on piscivorous fishes. Gill nets with appropriate mesh size are likely to be a more sustainable fishing method since they were more selective in capturing larger individuals and could balance the prey-predator relationship. We suggest shifting from single-species approaches toward multi-species management, and taking trophic interactions into account to better manage fishery resources.
The yellow perch, Perca flavescens, is an economically significant freshwater fish species in the Midwest of the United States. TypeⅠ markers are useful for comparative mapping and other genetic analyses, but limited quantities in yellow perch. In the present study, EST containing microsatellite sequences were identified and characterized for yellow perch by data mining from updated public EST databases. Out of 21,968 EST sequences of yellow perch, about 14.4% of ESTs contain repeat motifs of various types and length. CA repeat was the most abundant dinucleotides. Out of the 62 EST-SSRs for which PCR primers were designed, 15 loci showed polymorphic in a yellow perch population with the alleles per locus ranging from 4 to 19 (average 9). The observed (HO) and expected (HE) heterozygosity of these EST-SSRs were 0.103—0.929 and 0.116—0.934, respectively. Four EST-SSR loci significantly deviated from the Hardy-Weinberg equilibrium (HWE) expectation, and the remaining 11 loci were in HWE. These new EST-SSR markers should provide sufficient polymorphism for population genetic studies and genomic mapping of yellow perch.
To assess possible bias of different fishing methods is essential to appropriate fisheries management. In the current study, fish assemblage structure of a shallow Yangtze River lake was assessed by combining one international standard sampling gear (multi-mesh gillnet), and one traditional Chinese gear (the dense-mesh weir). Using Lake Biandantang as a case study, a total of 27 fish species were collected from the two gears combined, including 2 new species that had not been recorded previously in this lake. Results suggested that fish assemblages had changed greatly compared to a previous study conducted in the 1990s. Specifically, differences were found in species composition, abundance, biomass, and length distributions collected from the two gears. Difference in total length (TL) distributions of fishes caught was the most conspicuous change. Fishes collected from the weir ranged from 40—70 mm TL, whereas fishes collected from gillnets ranged from 90—140 mm TL. Multivariate ordinations based on relative abundance and biomass data also indicated fish assemblage structural differences between the two gears. The comparative results showed that the multi-mesh gillnet was effective at assessing fish assemblages in shallow lakes, such as those found along the middle and lower reaches of the Yangtze River. Additionally, assessments using only one gear could have some limitations with respect to interpreting fish assemblage changes over time.
Asian carp are expanding their range throughout the Mississippi River; however, abundance is thought to be highest in reaches within close proximity to the Illinois River. In the Mississippi River, Lock and Dam 19 (L&D 19) at Keokuk, Iowa is the primary barrier to slow the expansion upstream. As Asian carp abundance increases below L&D 19, it is important to investigate potential means of control (i.e., reduction through harvest and barriers) that will prevent complete invasion of the Mississippi River above L&D 19. Silver Carp and Bighead Carp were collected below L&D 19, a subsample were implanted with ultrasonic transmitters to evaluate passage through the lock chamber and the remainder were used to determine population dynamics at the leading edge of invasion. Although the dam portion of the structure poses a complete barrier to upstream expansion, we documented lock chamber passage demonstrating the lock chamber has the capability to provide passage upstream. Based on the results of the population assessment, in order to induce recruitment overfishing at this leading edge of invasion, Asian carp will need to be intensively harvested at 300 mm and larger. The combination of commercial fishing efforts and research investigating ways to prevent passage upstream must be employed.
Our study examined spatial distribution differences of rotifer resting eggs (RRE) in lakes of the Poyang Lake Wetland Area during dry season, January 2015. Field sampling was conducted in both Nanshen Lake and Baisha Lake. We found that densities of RRE in different habitats were significantly different (P<0.05), and their distribution had an obvious gradient. The highest mean density was in the marshland vegetation area of Nanshen Lake, where it was (3.34±1.28) ind./cm3. The density of resting eggs in the Zizania latifolia area was up to 5.45 ind./cm3. The density of RRE was different spatially, with the greatest in the vegetation area, then in the muddy area, and then the lowest in the water area. ANOVAs results showed that water depth, vegetation, and sediment had significant effects on RRE (P=0.001, 0.007, <0.001, respectively). The trend of resting egg densities in different aquatic habitats was: emergent aquatic plant > marshland vegetation > floating-leaf plants > submerged plants. The distribution of RRE in areas of different water depths was inconsistent. The density of RRE was higher in the hard than soft sediment.
Sexual dimorphism refers to the morphological differentiation between males and females in the same population, such as sizes, morphological features, and colors. Cold water fish Glyptosternum maculatum, is an endemic teleost species of notable economic importance and with high potential for controlled rearing of the species in Tibet Autonomous Region. In this study, morphological measurements and related analysis were conducted on sexually mature G. maculatum to investigate their morphological differences in Tibet Autonomous Region. Results indicated the sexually mature populations indeed display really displayed significant sexual dimorphism: males exhibited significantly greater body length, weight, and males also exhibited in addition to greater tail length while females exhibited significantly greater eye diameter, body depth, trunk length, and lengths of dorsal, pectoral, pelvic, anal, and caudal fins at a given body length. Principal components analysis on 16 morphological parameters showed that the differences were largely due to features of the body shape (including lengths of body parts and fins) and the head, and differences in the above features differences contributed 76.7%. The t-statistic test on the allometry index b in the total length-weight function showed that during the breeding season, the total lengths and weights of G. maculatum females developed proportionally, while the male specimens were allometrical.
Silver carp Hypophthalmichthys molitrix were introduced into the U.S. to control water quality in aquaculture ponds. From this point of origin, silver carp escaped into nearby rivers through multiple flood events. Because of their documented negative effects on native biota, silver carp have been labeled as problematic. Therefore, evaluating the biology and ecology of these non-indigenous species is critical. Multiple parameters are needed to evaluate silver carp populations (length, weight, age, and sex). Furthermore, developing methods for rapidly acquiring these data are needed. In relation to sex determination, sexual dimorphism was observed where males exhibit distinct pectoral fin ray features. Specifically, males have pronounced ridges or a " rough patch” on the dorsal surface of pectoral fins. Therefore, to test if this was an applicable way of determining silver carp gender; silver carp were collected from Midwestern U.S. rivers (N=2,015) in the fall of 2011 (N=870), spring of 2012 (N=645), winter of 2013-2014 (N=202) and summer 2015 (N=323) via electrofishing. For each silver carp collected, presence (e.g., rough patch) or absence (e.g., smooth) of pronounced ridges on the top side of the pectoral fins was recorded, and an incision was made in the body cavity to identify gender. Based on the results of our evaluation, gender was correctly identified over 99% of the time (2,006 out of 2,015) based on the pectoral fin dimorphism. In the samples taken in the winter of 2013—2014 and summer of 2015, accuracy for silver carp shorter than 300 mm and longer than 800mm was 53.7% (19 out of 41) while accuracy for silver carp between 300 mm and 800mm total length was 98.9% (289 out of 292). This study provides a rapid assessment approach for evaluating silver carp gender.
A tag-release-recapture study was conducted to evaluate effects of size at release on survival, growth and yield of hatchery-reared mandarin fish Siniperca chautsi fingerlings stocked in a shallow Yangtze lake. In May and June 2012, a total of 2,400 juvenile mandarin fish were graded into three size groups, identified with coded wire tags and tail fin, and released into Xiaosai Lake. Mandarin fish were collected after the lake drained in December 2012. Overall, a total of 973 mandarin fish individuals were captured, with an average survival rate of 40.5%. Survival rate of large sized group (63%) is more than three times higher than that of small sized group (19.5%) and 1.5 times higher than that of middle sized group (39.1%). The mean final length and weight of mandarin fish increased with the increase of release size and showed significant difference among groups. Yield was significantly affected by release size, which was the highest in large sized group and the lowest in small sized group. The net income of stocked mandarin fish increased with the increase of fish size at release. Our results indicated that mandarin fish size at release can have a major impact on success of hatchery releases, and it is suggested that the optimum release size of mandarin fish should not be less than 50 mm in Xiaosai Lake.
We analysed spatial pattern in the fish assemblage structure along a longitudinal gradient of the Upper Yangtze River and the Three Gorges Reservoir. We tested the hypothesis that shifts from lotic to lentic environment affect the richness and structure of the fish assemblage. Samplings were carried out from 2005 to 2012 in four zones: 1) Hejiang reach, river upstream from the reservoir; 2) Mudong reach, upper part of the reservoir; 3) Wanzhou reach, middle part of the reservoir, and 4) Zigui reach, lower part of the reservoir. A total of 368706 fish representing 132 native species of 17 families were collected during the study period with Cyprinidae as the dominant group. The results showed that the native species richness decreased while the non-native species increased from river (Hejiang reach) to reservoir (Zigui reach). Patterns in fish assemblage ordination evaluated by correspondence analysis reflected a clear division of the riverine and reservoir zones. Uppermost sampling stations were characterized by species characteristic of flowing waters, whereas in the lowland most lentic species were captured. Further, 22 species, three functional groups (rheophilic, equilibrium, insectivorous) were identified for the upper reach and 16 species, three functional groups (herbivorous, planktivorous, stagnophilic) for the lowland reach by indicator species analysis (P<0.05). Therefore, it is evident that impoundment of the Three Gorges Reservoir is the major driving factor to structuring the fish assemblage structure along the longitudinal gradient from river to the reservoir. Different fisheries management actions should be made to conserve or rehabilitate native fish assemblages and control invasive non-native species.
The establishment of a highly efficient planktivore, Silver Carp (Hypophthalmichthys molitrix), in the Mississippi River Basin has been documented as having negative impacts on native planktivore populations. Silver Carp have the potential, to alter the trophic food web through negative interactions with native planktivores in large river systems. Due to increasing Silver Carp ranges, interactions between Silver Carp and other native planktivores is likely to increase. One abundant native planktivore that is often found in similar habitats as Silver Carp is Gizzard Shad (Dorosoma cepedianum). Potential competition for resources exists because of overlapping habitat use and forage. Given the similarities between these two planktivores, we sought to evaluate daily growth rates and determine hatch dates of age-0 Silver Carp and Gizzard Shad in the Middle Mississippi River. Silver Carp and Gizzard Shad were collected from the Middle Mississippi River using an electrified surface trawl from June through September with sizes ranging from 21—65 mm total length for Gizzard Shad and 24—85 mm total length for Silver Carp. A sample of age-0 fish (n=697) was collected at the end of the growing season including 292 Gizzard Shad and 405 Silver Carp. Size structure (total length in mm) of Silver Carp (49.05±0.41; X ̅ ± SE) was significantly greater (T=-16.43, df=695, P<0.001) than Gizzard Shad (38.95 ± 0.45). Hatch dates were similar between Silver Carp (July 26th to August 18th) and Gizzard Shad (July 28th to August 19th). Growth of Silver Carp (2.24 mm per day) was significantly greater (P<0.001, T=-11.1, df=82) than Gizzard Shad (1.72 mm per day). Mortality was similar between Silver Carp (28.1%) and Gizzard Shad (25.1%) at this early life stage. The faster growth rates in Silver Carp result in Silver Carp entering the winter season larger in size with likely an increased capacity to consume plankton and decreased predation ultimately leading to higher recruitment. Knowing that there exists an overlap between Silver Carp and Gizzard Shad diets and habitat could alone call cause for concern. Adding that spawning occurs at a similar time and Silver Carp have the ability to outgrow Gizzard Shad early in life leads to major concerns about food web balance. Knowing that invasive planktivores have already shown to alter food webs in aquatic systems in North America, extra caution should be taken.
A comprehensive investigation on macrophyte community in Hongze Lake was conducted seasonally from May 2010 to February 2011. Overall, twelve species representing eight families of macrophytes were identified in Hongze Lake, including nine species of submerged plants, two species of floating-leaved plants, and one species of emerging plant. In general, Potamogeton malaianus, P. maackianu, P. pectinatus and P. crispus were the four dominant species throughout the whole year, the highest biomass of macrophytes was presented in autumn, followed by summer and winter, while spring had the lowest biomass of macrophytes. Based on field data, we used kriging interpolation in ArcGis to map the spatiotemporal distribution of the entire macrophyte community as well as each of the four dominant species. From the GIS maps we observed that the northern area of the lake, namely the Chengzihu region, had the highest biomass of macrophytes potentially as a result of better water quality and greater transparency. Potential factors that affected the community structure, biomass, and distribution patterns of macrophytes considerably were then discussed. The results of this study illuminate the need for more information on the role and importance of aquatic macrophytes in shallow lake ecosystems. Conservation of macrophytes should be taken to maintain the lake ecosystem health.
Schizothorax macropogon and Ptychobarbus dipogon are important economic fishes in the Yarlung Zangbo River. Both are Schizothoracinaes containing a variety of essential fatty acids with high nutritional values. As food products, the textural characteristics of their meat determine important factors like taste or methods of treatment. To explore the preservation and utilization of fish resources in the Tibet Autonomous Region, China, the texture profile analysis (TPA) method was used to analyze 12 textural parameters. Fish were captured from the Yarlung Zangbo River in Shigatse and Nyingchi City. Principal component analysis showed that the texture of P. dipogon captured from the Nyingchi segment was different from the same species captured in the Shigatse segment, and different from S. macropogon captured from both segments. Factorial analysis indicated that the textural characteristics of Schizothoracinae fishes in Tibet Autonomous Region can be summarized as hardness indices, overcome attraction indices and contractility indices, of which the accumulated variance contribution rate of the first four principal component factors was 81.472%. The three categories of the four principal component axes could be the main deciding parameters of the textural characteristics of Schizothoracinae fishes in Tibet Autonomous Region. This provides scientific data for subsequent development and utilization of Schizothoracinae fishes from the Yarlung Zangbo River in different geographical areas.
To investigate the influence of artificial substrates (AS) on the growth performance of fish in pond poly-culture systems, a feeding experiment was conducted in six individual earthen ponds, which were divided into two groups. The ponds with AS in the water were labeled as the " AS group” and that without the use of AS were labeled as the " control group” (three ponds per group). A total of 3867 common carp [Cyprinus carpio, (310±11) g], being artificial-feeds feeding fish, and 370 bighead carp (Aristichthys nobilis) and silver carp [Hypophthalmichthys molitrix, (810±15) g], being plankton filter feeding fish, were divided into six groups and cultured in the ponds respectively. The common carp in each pond were fed with commercial particle feeds three times a day and the feeding period was 62 days. Water quality, concentration of plankton and the bacterial community presenting in the water and sediment were monitored during the experiment. At the end of the experiment, all fish were harvested and the growth of the fish and feed efficiency ratio were determined. Results showed that the weight gain rate and feed efficiency ratio of common carp in AS group was significantly higher than that of the control group. Final body weights of bighead carp and silver carp in the AS group were significantly lower than that of the controls. Water transparency and diversity indices of the bacterial community in the AS group were significantly higher than that of the control (P<0.05) and the concentration of plankton in the AS group was lower than that of the control. Results showed that the application of AS in poly-culture ponds was beneficial for the growth of common carp, being artificial-feeds feeding fish, while it was not beneficial for the growth of bighead carp and silver carp, being plankton filter feeding fish.
Many efforts have been devoted to developing, constructing and refining fishways or fish passage facilities to facilitate the target fish species to pass barriers in fluvial systems. Once dominated by an engineering-focused approach, fishways science nowadays involves a wide range of disciplines from fish behaviour to socioeconomics, and to complex modeling of passage prioritization options in river networks. Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovations. After the completion of fishways construction, corresponding management systems usually need to be improved as well. In the current study, we first reviewed international fishways adaptive management systems (e.g., aspects of development, construction, and management) from 1991 to 2017 reporting on " fishway”, " fish passage”, " fish” and " dam”. The functions of fishways gradually transferred from conservation of economic stocks to overall biodiversity conservation, from facilitating upwards to both upwards and downwards passages, from developing a single project to considering the entire river basin, from fish passing function to habitats restorations as well, and from pure engineering construction to considering adaptive management. Finally, we discussed adaptive management systems and management prospects of fishways for China.
This study examined anesthetic behaviors of Schizothorax o’connori Llord in two size ranges as induced by MS-222, to acquire useful information on anesthesia of said highland fish species in out-of-water activities (surgery, labeling, measurement, etc.). Test results indicated that for both large (25.0±1.5) cm and small-sized (14.8±2.3) cm specimens, respiration rates showed no significant change in anesthetic stages I to III, and only begun to significantly decline after entering stage IV. The effective concentrations of MS-222 were 150—180 mg/L and 150 mg/L for two sizes, respectively. The 150—180 mg/L caused large specimens to enter anesthetic stage IV within 5min, and recovered within 5min; the 150 mg/L caused small specimens to enter stage IV within 5min, and recovered within 7min; both doses ensured a 100% survival rate after immersion for 20min. For large specimens anesthetized at 180 mg/L for 5min and exposed to air for 0—15min, there was no significant difference in recovery times (P>0.05); for small specimens anesthetized at 150 mg/L for 5min and exposed to air for 0—15min, there were significant differences in recovery (P<0.05).
The lower Mississippi River (LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to " notch” wing-dike structures that close secondary (side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer (rkm) 628 (Louisiana-Mississippi, U.S.A.) upstream to rkm 1504 (Missouri-Kentucky, U.S.A.). Four secondary channels were termed " permanent” (i.e., with notched dikes) while three secondary channels were termed " temporary” (i.e., without notched dikes). Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from 1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad (Dorosoma cepedianum), threadfin shad (D. petenense), and white bass (Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish (Ictalurus furcatus), flathead catfish (Pylodictis olivaris), and freshwater drum (Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However, temporary secondary channels also contain unique fish species, and also appear to be important sites of riverine primary production. Restoration strategies should consider a balance of both secondary channel types, which should support the greatest biodiversity for the LMR ecosystem.
This study is based on monthly sampling (from April 2013 to April 2015) of 18 fish species representing three families. Samples were obtained using benthic fyke-nets, block nets, and multi-mesh gillnets in Lake Kuilei, a shallow lake of the Yangtze River basin, China (N 31º24', E 120º51'). Using ordinary least-squares linear regression, length-weight relationships of these fish species were estimated, with equations for 3 species reported for the first time. The maximum total length records of the 15 species exceeded those reported in FishBase. This paper provides new LWR equations for these species to be included in FishBase.