彭水水库蓄水初期乌江下游浮游甲壳动物群落结构特征

2008年4月、7月和10月,在乌江下游彭水水库库区、坝下江段和库尾以上江段设16个采样断面对浮游甲壳动物进行了调查;共检出浮游甲壳动物29属、49种;其中,枝角类13属、21种,桡足类16属、28种;枝角类年均密度1.89个/L,生物量37.70μg/L,桡足类年平均密度0.78个/L,生物量5.49μg/L。浮游甲...     

彭水水库蓄水初期乌江下游浮游甲壳动物群落结构特征

2008年4月、7月和10月,在乌江下游彭水水库库区、坝下江段和库尾以上江段设16个采样断面对浮游甲壳动物进行了调查;共检出浮游甲壳动物29属、49种;其中,枝角类13属、21种,桡足类16属、28种;枝角类年均密度1.89个/L,生物量37.70μg/L,桡足类年平均密度0.78个/L,生物量5.49μg/L。浮游甲壳动物的季节变化比较明显,种类数以春季最多,秋季最少;水平分布呈现库区种类数相对较多,库尾及以上江段种类数相对较少,坝下江段受水库下泄水影响显著。     

三道河水库浮游甲壳动物群落结构特征的初步研究

研究了湖北省三道河水库2007年8月至2008年4月浮游甲壳动物的群落结构及现存量的时空变化。三道河水库6个采样点(Ⅰ～Ⅵ)共鉴定出浮游甲壳动物8科、13属、21种,其中枝角类5科、9属、14种,优势种为简弧象鼻溞(Bosmina coregoni)、短尾秀体溞(Diaphanosoma brachyurum)和透明溞(Daphnia hyalin);桡足类3科、4属、7种,优势种为广布中剑水蚤(Microcyclops leuckarti)和汤匙华哲水蚤(Sinocalanus dorrii)。浮游甲壳动物年平均密度为92.6个/L,枝角类和桡足类分别为36.9个/L和55.7个/L;平均生物量为1.126mg/L,枝角类和桡足类分别为0.737mg/L和0.389mg/L。浮游甲壳动物现存量的季节变化明显,密度和生物量由高到低依次为秋季>夏季>冬季>春季。浮游甲壳动物密度的水平分布差异明显,采样点的密度和生物量由高到低为Ⅱ>Ⅵ>Ⅲ>Ⅰ>Ⅳ>Ⅴ。     

白洋淀浮游甲壳动物的生物多样性研究

基于2006年4月至2006年12月对白洋淀浮游甲壳动物进行采样调查,分析了白洋淀浮游甲壳动物的群落结构及多样性。本次调查共记录到浮游甲壳动物34种,隶属于9科19属,其中枝角类（Cladocera）19种,桡足类（Copepoda）16种。物种多样性季节性明显：枝角类优势种在春、夏和秋冬季依次为微型裸腹溞（Moina micrura）、长额象鼻溞（Bosmina longirostris）、长肢秀体溞（Diaphanosoma leuch）;而桡足类优势种在冬春季为英勇剑水蚤（Cyclopidae strenuus）,在夏秋季为锯缘真剑水蚤（Eucyclopinae macruroides）和台湾温剑水蚤（Thermocyclops tsihokurnsis）。物种多样性春秋季较高,夏季和冬季较低。浮游甲壳类个体密度以春季最高,冬季最低。根据生物多样性指数综合判定白洋淀的水质为中营养化水平。     

尤溪街面水库浮游甲壳动物的初步研究

2008年8月对尤溪街面水库的浮游甲壳动物进行了调查,共采集到浮游甲壳动物8科13属16种,其中枝角类5科7属8种,桡足类3科6属8种。枝角类优势种为突额湖仙达溞和长肢秀体溞,桡足类优势种为广布中剑水蚤。浮游甲壳动物平均密度为43.58ind/L,平均生物量为477.43μg/L。浮游甲壳动物种数由蓄水前的8种增加到16种,广布中剑水蚤和透明温剑水蚤在蓄水后仍然存在。     

沙颍河阜阳段浮游甲壳动物的群落结构与季节变化

从2011年4月至2012年1月,分季节在3个采样点对沙颍河阜阳段的浮游甲壳动物进行了调查。结果表明,沙颍河阜阳段共记录浮游甲壳动物20种,其中枝角类11种,桡足类9种;枝角类中各季节均为优势种的有蚤状溞(Daphnia pulex)和大型溞(D.magna);桡足类中各季节均为优势种的有近邻剑水蚤(Cyclops vicinus)和广布中剑水蚤(Mesocyclops leuckarti);浮游甲壳动物密度在春季(4月)最高,冬季(1月)最低。Shannon-Wiener多样性指数在1.30~2.13,初步评价表明沙颍河阜阳段水质处于轻度-中度污染状态。     

武汉南湖的浮游甲壳动物

通过周年4次采样,在南湖5个采样站一共鉴定出浮游甲壳动物14种,年平均密度为119.7ind./L,平均生物量为1.67mg/L。其中枝角类8种,优势种为短尾秀体Diaphanosomabrachyurum和微型裸腹Moinamicrura;桡足类6种,优势种为近邻剑水蚤Cyclopsvicinusvicinus。浮游甲壳动物现存量的季节变化明显,密度由高到低依次为冬季>春季>秋季>夏季;生物量由高到低则依次为秋季>冬季>夏季>春季。浮游甲壳动物密度的水平分布差异明显,密度由高到低为Ⅳ>Ⅲ>Ⅴ>Ⅰ>Ⅱ站;生物量由高到低为Ⅴ>Ⅳ>Ⅲ>Ⅱ>Ⅰ站。     

三道河水库浮游甲壳动物群落结构特征的初步研究

研究了湖北省三道河水库２００７年８月至２００８年４月浮游甲壳动物的群落结构及现存量的时空变化。三道河水库６个采样点（Ⅰ ～Ⅵ）共鉴定出浮游甲壳动物８科、１３属、２１种,其中枝角类５科、９属、１４种,优势种为简弧象鼻蟤（Ｂｏｓｍｉｎａｃｏｒｅｇｏｎｉ）、短尾秀体蟤（Ｄｉａｐｈａｎｏｓｏｍａｂｒａｃｈｙｕｒｕｍ）和透明蟤（Ｄａｐｈｎｉａｈｙａｌｉｎ）;桡足类３科、４属、７种,优势种为广布中剑水蚤（Ｍｉｃｒｏｃｙｃｌｏｐｓｌｅｕｃｋａｒｔｉ）和汤匙华哲水蚤（Ｓｉｎｏｃａｌａｎｕｓｄｏｒｒｉｉ）。浮游甲壳动物年平均密度为９２．６个／Ｌ,枝角类和桡足类分别为３６．９个／Ｌ和５５．７个／Ｌ;平均生物量为１．１２６ｍｇ／Ｌ,枝角类和桡足类分别为０．７３７ｍｇ／Ｌ和０．３８９ｍｇ／Ｌ。浮游甲壳动物现存量的季节变化明显,密度和生物量由高到低依次为秋季＞夏季＞冬季＞春季。浮游甲壳动物密度的水平分布差异明显,采样点的密度和生物量由高到低为Ⅱ ＞Ⅵ ＞Ⅲ ＞Ⅰ ＞Ⅳ ＞Ⅴ。     

尤溪街面水库浮游甲壳动物的初步研究

２００８年８月对尤溪街面水库的浮游甲壳动物进行了调查,共采集到浮游甲壳动物８科１３属１６种,其中枝角类５科７属８种,桡足类３科６属８种。枝角类优势种为突额湖仙达蟤和长肢秀体蟤,桡足类优势种为广布中剑水蚤。浮游甲壳动物平均密度为４３．５８ｉｎｄ／Ｌ,平均生物量为４７７．４３μｇ／Ｌ。浮游甲壳动物种数由蓄水前的８种增加到１６种,广布中剑水蚤和透明温剑水蚤在蓄水后仍然存在。     

小龙虎泡浮游动物组成与环境因子相关性分析

嫩江下游小龙虎泡为大水面绿色渔业水体,为查明小龙虎泡生态系统基本情况,更好地对其进行渔业管理,于2017年2、4、6、8、10、12月对小龙虎泡浮游动物季节变化及相关水环境因子进行了调查。调查结果显示,共检出浮游动物22属36种,其中轮虫7属15种,枝角类9属12种,桡足类6属9种。优势种19种,其中枝角类8种,轮虫7种,桡足类4种。浮游动物年均密度为356.7个/L,年均生物量为5.45 mg/L,其物种数量、密度和生物量最高值均出现在8月,最低值在2月。Shannon-Wiener多样性指数和Margalef丰富度指数年均值分别为1.99和2.88,多样性季节差异显著。多样性指数法和优势种指示法评估结果显示,小龙虎泡在2017年基本处于中营养化状态。浮游动物物种数、密度、生物量与水环境因子的Pearson相关性分析表明,水温是影响小龙虎泡浮游动物种类、密度和生物量的决定性正相关因子,总磷和氨氮含量是影响浮游动物密度的重要正相关因子,pH和总氮是影响物种数的负相关因子。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

The optimal dietary protein level of juvenile silver sillago Sillago sihama at three dietary lipid levels

A 5 × 3 factorial growth trial was conducted to evaluate optimal dietary protein and lipid levels (dietary protein level, DP; dietary lipid level, DL) for juvenile Sillago sihama (S. sihama) (2.0 ± 0.02 g, initial weight). Fish were fed 15 diets containing 5 DPs (350, 400, 450, 500 and 550 g/kg) and 3 DLs (60, 90 and 120 g/kg) for 8 weeks. The interaction between proteins and lipids significantly influenced the feed conversion ratio, condition factor, body composition, antioxidant indices and lipase activity (p < .05). DP 450 g/kg showed the highest average final body weight. DPs 500 and 550 g/kg significantly decreased the protein efficiency ratio (p < .05). DL 120 g/kg showed the highest percentage weight gain. The low feed conversion ratio was found in diets P45L12, P55L9 and P55L12. Diet P45L12 showed high superoxide dismutase activities. DP 450 g/kg showed the lowest average malondialdehyde content. Lipase activity was increased by increasing DP (p < .05) with a fall at DP 550 g/kg. Under the present experimental conditions, the optimal DP for S. sihama was 450 g/kg under the DL 120 g/kg.     

Vitamin D3 and the renal handling of phosphate in American eels

Cholecalciferol (Vitamin D₃) increased plasma inorganic phosphate concentration in American eels,Anguilla rostrata, in a dose-dependent fashion. This response was more marked in phosphate loaded fish. In control as well as phosphate loaded eels the hyperphosphatemic response to D₃ was associated with a sharp reduction in renal phosphate clearance relative to¹⁴C-polyethelene glycol (PEG) clearance. Glomerular filtration and urine flow rates were not affected by D₃. As renal phosphate clearance, even in phosphate loaded eels, never significantly exceeded that of PEG, it is suggested that D₃ reduced the relative clearance rate of phosphate by increasing renal phosphate reabsorption rather than by reducing the tubular secretion of phosphate.