浙江乐清湾海域冬季颗粒有机碳的分布特征及影响因素

依据2014年2月浙江乐清湾海域调查的资料,研究了浙江乐清湾海域颗粒有机碳(POC)的分布特征及其与主要环境因子的相关性分析。结果表明,表层POC的质量浓度范围为0.1 596~3.4 117 mg/L,平均质量浓度为(0.9 540±0.7 012)mg/L;底层POC的质量浓度范围为0.759~6.2 107 mg/L,平均质量浓度为(2.1 556±1.4 668)mg/L。相关性分析表明,POC与化学需氧量极显著正相关,与硝酸盐氮极显著负相关,与亚硝酸盐氮显著负相关。     

五垒岛湾海域COD分布特征及动态变化

根据2012年—2014年5月、8月、10月对五垒岛湾的调查数据,分析了该海域COD的分布特征及动态变化。结果表明:该海域近3年COD含量介于0.49~2.57mg/L,平均值为1.22mg/L;空间分布上,呈现出由北向南逐渐递减以及近岸水域含量大于远岸的变化趋势;年际间表现出逐渐增加的趋势。污染指数评价表明,COD污染指数介于0.16~0.93,平均0.41,均达到国家II类海水标准,未出现超标现象。     

乳山湾及邻近海域化学需氧量的分布特征及影响因素

根据2011年春季(5月)和秋季(10月)乳山湾及邻近海域调查资料,对海水中的化学需氧量的时空分布特征进行研究,并分析了化学需氧量与环境因子之间的关系以及对区域富营养化的贡献率。结果表明,乳山湾及邻近海域海水中的化学需氧量质量浓度春、秋季均表现为湾内高于湾外、近岸高于远岸的趋势,且春季化学需氧量平均质量浓度高于秋季。乳山湾及邻近海域海水中的化学需氧量在春、秋季与温度、盐度均呈显著负相关关系(P0.01),与无机氮呈显著正相关关系(P0.05)。化学需氧量对富营养化的贡献值为39.53%~67.18%,化学需氧量是影响乳山湾及邻近海域富营养化的重要因素,但并非决定性因子。     

泉州湾表层海水和沉积物中油类的分布特征

本文以2008年泉州湾海域表层海水、沉积物油类含量调查数据为依据,对泉州湾海域表层海水和沉积物油类的分布进行分析、讨论。结果表明,泉州湾水体油类含量范围为0.006～0.216 mg/L,平均值为0.068mg/L,含量分布呈湾内向湾外逐渐降低,以晋江入海口海域含量最高,夏季含量最高,冬季含量最低。泉州湾表层沉积物油类含量范围为42.4～1290mg/kg,平均含量为615mg/kg,蚶江海域含量最高,表层沉积物油类含量与底质类型密切相关。     

黄岛区南部海域营养水平和有机污染状况分析与评价

利用2008-2013年水质调查资料,分析了青岛市黄岛区南部海域营养盐分布与变化特征,并采用营养指数(E)法和有机污染综合指数(A)法对该海域海水的营养状况和有机污染状况进行了评价。结果显示,(1) 2012-2013年调查期间,无机氮含量范围为20.82-197.62 µg/L,活性磷酸盐为4.52-52.91 µg/L,COD为0.39-1.25 mg/L。除个别站点活性磷酸盐含量超标外,其余站点活性磷酸盐含量以及全部站点无机氮和COD含量均符合二类海水水质标准要求。(2) 调查海域无机氮以春季最高(86.42 µg/L),秋季次之,夏季最低(38.59 µg/L);活性磷酸盐以秋季最高(18.68 µg/L),春季次之,夏季最低(9.10 µg/L);COD以夏季最高(0.962 mg/L),秋季次之,春季最低(0.682 mg/L)。(3) 调查海域无机氮和COD含量2008-2011年呈逐年降低的变化趋势,2012年又有所增高;活性磷酸盐含量2008-2010年呈逐年降低的变化趋势,2010–-2012年呈逐年增高的变化趋势。研究表明,调查海域海水的营养水平较低,未达到富营养化水平,发生赤潮的可能性较小。调查海域水质状况良好,未受到有机污染。     

乳山湾表层海水COD与氮、磷营养盐的分布及其营养状况

调查结果表明,乳山湾东流区化学需氧量(COD)浓度较低,均低于2mg／L。无机氮浓度较高,5月和8月无机氮的平均值分别为0．32、0．39mg／L,5月无机氮组成以硝酸氮(NO3-N)为主,8月则以氨氮(NH4-N)为主。5月和8月无机磷的平均值分别为0．015、0．035mg／L,IN／IP比值较高,平均值分别为74和25。乳山湾东流区处于富营养化水平。     

抚宁扇贝养殖区营养盐及浮游植物变化研究

为探明河北抚宁海湾扇贝养殖海域营养盐、浮游植物变化特征,及两者相关性,2020年5—11月,每月监测离岸0、0.3、4.6、11.1 km的常规水质指标及浮游植物。调查结果表明,各站位水温变化趋势一致;0 km的化学需氧量、活性磷酸盐、亚硝态氮、硝态氮、氨氮、活性硅酸盐含量均高于其他站位,盐度、pH低于其他站位。5—11月,化学需氧量质量浓度为0.260～3.460 mg/L;活性磷酸盐和活性硅酸盐均在7月出现峰值,最高质量浓度分别为0.044 mg/L、7.174 mg/L;亚硝态氮、硝态氮、氨氮质量浓度分别为0～0.101 mg/L、0.052～1.578 mg/L、0～0.096 mg/L。共鉴定浮游植物56属102种,包括硅藻门、甲藻门、绿藻门、蓝藻门、隐藻门、裸藻门、金藻门藻类,0、0.3 km站位浮游植物密度高于4.6、11.1 km,各站位密度变化为8.3×10⁴～445.6×10⁴个/L。优势种为中肋骨条藻、条纹小环藻、舟形藻、丹麦细柱藻等,调查海域中绿藻优势种与硝态氮呈显著正相关(P<0.05)。本调查结果可为河北省海...     

天津周边海域表层水体理化要素分布特征和水质评价

通过对天津周边海域表层水体的一些理化要素进行调查,得到化学需氧量(CODMn)、活性磷酸盐(PO34--P)、氨氮(NH4+-N)、亚硝酸盐氮(NO2--N)及硝酸盐氮(NO3--N)含量从离岸近的海域向外海方向递减。水温、pH值、盐度的变化趋势则正好相反;在此次调查期间,天津周边海域海水中无机氮的主要存在形式为NO3--N和NO2--N;相关性分析表明,盐度与化学需氧量、活性磷酸盐、无机氮、亚硝酸盐氮在p=0.01水平上均呈极显著负相关;活性磷酸盐与无机氮、NO2--N和NH4+-N含量均在p=0.01水平上呈极显著正相关;由N/P比和E值的平面分布图可以得到,沿岸N/P比最低,离岸越远的地方N/P比越高。E值的平面分布恰恰相反。北塘附近海域依然是富营养化最严重的区域;本调查海域主要是磷限制,无机氮仍然是此海域的首要污染因子,其次是化学需氧量。     

东山湾水体和沉积物中有机碳的春夏季分布特征

为了解东山湾水体和沉积物中有机碳的分布特征、影响因子及其污染状况,研究分析了TOC的含量分布特征,并讨论了TOC与叶绿素a、盐度、化学需氧量、重金属及粒度等环境因子之间的关系.结果表明,东山湾水体中TOC的浓度范围为1.24～2.33 mg·L-1,平均值为1.78 mg·L-1.其浓度的分布特征呈湾内高于湾外的格局;春季东山湾水体中TOC浓度高于夏季;表底层水体中TOC浓度变化不明显.沉积物中有机碳含量的变化范围为0.02％ ～0.78％.其含量的分布趋势呈现湾中部高湾口低的格局.东山湾水体中有机碳与叶绿素a及COD值之间呈显著正相关关系,与盐度值之间呈负相关关系.沉积物中有机碳与粘土及重金属（Hg、Cu、Zn和Cr）含量之间呈显著正相关关系.     

三峡水库试验性蓄水后小江沿岸水质研究

根据2010年3月－12月对三峡水库小江沿岸水体的水质监测数据,分析总氮、总磷、化学需氧量和叶绿素a等水质因子的时空变化规律,以及叶绿素a与水质因子之间的相互关系,评价水体富营养化水平。结果表明：总氮、总磷、化学需氧量和叶绿素 a含量分别为1.980±0.119mg/L、0.114±0.018mg/L、9.520±1.748 mg/L和23.342±8.810 mg/L,小江沿岸水体呈现中度富营养化水平。叶绿素a与水质因子间的相关关系分析发现,叶绿素a含量与温度、pH、溶解氧、亚硝酸氮和化学需氧量显著相关,与总氮、总磷不具有显著相关性。这说明小江沿岸水体叶绿素a含量与总营养盐无关,而主要与水体所含的有机质含量有关。     

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.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

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).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

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.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.