辽东湾水体交换能力模拟及保守水质模型应用

通过建立与垂向平均的二维非恒定和谐型水动力模式相耦合的保守型水质跟踪预报模型,模拟了辽东湾海域的水体交换能力及无机磷和化学耗氧量的平面实时分布状况。给出不同典型时刻下辽东湾海域的潮流场、水体半交换时间及浓度场的计算结果,据此对辽东湾的水体交换性能和污染物的对流输运状况进行分析评价。最后,将其保守型水质预报模型应用于普兰店湾海域的典型渔业污染事故中,验证了该模型处理实际问题的有效性。     

辽东湾水体中石油类的时空分布特征和污染状况

根据2013-2014年春、夏、秋、冬季对辽东湾海域8个航次的调查资料,研究了水体中石油类的空间分布特征及季节变化趋势,分析了其污染状况,探讨了其污染来源.结果显示,辽东湾海域海水石油类含量范围为(0.003-0.239) mg/L,平均为0.027 mg/L,随着季节周期性变化波动,整体呈下降的变化趋势;春、秋、冬季各航次均存在不同程度的海水水质超标准现象,表底层石油类含量存在显著相关性,具有秋季＞冬季＞春季＞夏季的季节变化趋势,石油类含量呈沿岸高于远岸,开放海域大于海洋保护区的平面分布特征.深入分析发现,石油类含量范围为0.030-0.032 mg/L,分布区域面积最广,为6960 km2,占调查海域的27.0％;集中分布在辽东湾北部沿岸和西部近岸海域.石油类含量低于0.024 mg/L的区域分布面积为2806 km2,占辽东湾调查面积的10.9％,分布区域主要集中在大连斑海豹国家级自然保护区范围内.石油类含量高于0.032 mg/L,区域分布面积为1170 km2,仅占辽东湾调查面积的4.5％,集中分布在辽东湾西部沿岸港口区海域.季节变化主要受机动渔船海上作业污染影响;陆源输入和人类海上活动的输入为辽东湾海域石油类主要来源.     

污染物对海洋生态环境的影响

根据《2003年中国海洋环境质量公报》:2003年,全国海域未达到清洁海域水质标准的面积约为14.2万平方公里,其中轻度污染海域面积约为2.2万平方公里,中度污染海域面积约为1.5万平方公里,严重污染海域面积约为2.5万平方公里。海水中的主要污染物是无机氮、活性磷酸盐和铅。严重污染海域主要分布在鸭绿江口、辽东湾、渤海湾、长江口、杭州湾、珠江口和部分大中城市近岸局部水域。2002年,全国七大水系741个重点监测断面中,29.1%的断面满足Ⅰ～Ⅲ类水质要求,30.0%的断面属Ⅳ、Ⅴ类水质,40.9%的断面属劣Ⅴ类水质。河流污染物质和沿海城市污水、工业…     

辽东湾北部海域表层水体夏季油类的污染状况

监测结果表明:2001—2004年辽东湾北部调查海域海油含量为0.002~0.709 mg/L。6月油的含量高于8月,2004年6月污染最为严重,其次是2002年6、8月;而2003年8月、2004年8月油含量较低。从区域变化趋势看,大凌河口海域污染最为严重,其次是双台子河口下游海域、辽河口海域与小凌河口海域;而锦州湾与大凌河口下游海域水质含量较低,均未超过一类国家油类海水水质标准。     

乌伦古湖水质污染的空间分布特征

评价湖泊水质并探究其空间分布规律对于湖泊管理具有重要意义。通过对乌伦古湖2017年7-8月采样点(S1~S8)的8个水质指标(矿化度、pH值、透明度、总氮、总磷、高锰酸盐指数、溶解氧、五日生化需氧量)监测,运用主成分分析法(PCA)评价乌伦古湖水质现状,采用空间插值法分析其空间分布特征,并基于聚类分析法(CA)识别水质污染驱动因素。结果表明,乌伦古湖水体呈弱碱性,水质污染以氮、磷有机污染为主;8个采样点主成分综合得分排序结果为:骆驼脖子>小海子>码头>中海子>农十师渔政点>湖中心>吉力湖中心>吉力湖入水口,呈现出小湖区水质优于大湖区、湖中心区水质优于湖岸区、距离进水口越远水质越差的显著空间差异特征。骆驼脖子采样点(S1)水质污染最严重,吉力湖采样点(S7、S8)水质相对最好;基于湖区水质空间分布特征将乌伦古湖湖区分为3类,Ⅰ类湖区水质最差,Ⅱ类湖区水体呈咸化趋势,Ⅲ类湖区水质相对最好;水体矿化度、营养盐与有机污染物是乌伦古湖污染的主要来源,主要原因可归结为自2000年来乌伦古河常态化断流以及湖区渔业养殖、周边农业面源污染导致的盐分与营养成分及有机污染物由河道不断向湖泊的迁移富集。     

夏季和冬季辽东湾海域水体中叶绿素a含量分布特征

为研究辽东湾海域水体中叶绿素a含量的分布特征,于2013年8月(夏季)和12月(冬季)在辽东湾设置38个站位,分别采集了表、中、底层的海水样品,检测夏季和冬季两个航次水体中叶绿素a的含量,分析该海域叶绿素a的季节分布与空间变化特征。同时利用相关性统计分析的方法,将各水质因子对叶绿素a含量影响的差异显著性进行了分析。结果显示,调查海域夏季的叶绿素a平均质量浓度为6.90μg/L,冬季为1.26μg/L,时间分布上夏季质量浓度明显高于冬季;空间水平分布上,夏季辽东湾湾口的平均叶绿素a质量浓度明显高于湾内的平均质量浓度,而冬季则越靠近湾口处叶绿素a的平均质量浓度越低,与夏季规律正好相反;空间垂直分布上,夏季表层叶绿素a的质量浓度最高,10m层次之,底层的质量浓度最低;而冬季的叶绿素a质量浓度则呈现10m层最高,底层次之,表层质量浓度最低的趋势。说明辽东湾叶绿素a含量存在明显的时间和空间分布特征;结合同期的温度、盐度、溶解氧等环境因子的调查结果,统计分析结果表明调查海域中环境因子温度、盐度、溶解氧和营养盐的季节性变化是导致叶绿素a含量趋势变化的最可能原因之一。     

辽东湾海域典型营养盐指标分布规律的统计与评价

在详细了解辽东湾海域自然地理和水动力分布状况的基础上,对实际采样测站的营养盐检测资料进行统计,分析了辽东湾海域的水体环境质量状况,并利用单因子标准指数法评价了辽东湾海域的污染现状。通过利用各监测站位的铵盐、硝酸盐及亚硝酸盐(无机氮)和磷酸盐的采样检测结果值,给出各典型营养盐指标的浓度分布趋势图,可见,辽东湾海域海水中无机氮和活性磷酸盐分布有明显的季节性,各个季节表现出不同的特点;而且辽东湾海域的无机氮超标四季均比较明显,活性磷酸盐污染除冬季较重外,其他季节较轻。     

环渤海主要城市近岸海域水质状况综合评价

为评价环渤海13个城市近岸海域水质状况,基于渤海195个监测站位2020年3月和5月的实测水质数据,选取化学需氧量、无机氮、总氮、活性磷酸盐、总磷和石油类物质作为评价因子,采用雷达图指数、内梅罗指数和主成分指数对环渤海主要城市近岸海域水质状况进行了综合评价和等级划分。结果显示,渤海近岸海域主要污染物为无机氮和总磷,其次为石油类物质;葫芦岛、秦皇岛、大连和烟台的近岸海域水质状况较好,而位于辽东湾北岸辽河口附近的盘锦、锦州、营口以及位于莱州湾西侧的滨州近岸海域水质状况较差;3类水质综合指数对海水中盐度和悬浮物浓度敏感性较强,且相互之间及其与水质优良面积比例存在显著相关性,表明所选择的3类水质指数能够真实反映渤海近岸海域水质状况。研究结果可为渤海水质评价与综合治理成效评估提供借鉴。     

葫芦岛市五里河排污口及邻近海域水质状况与评价

依据2017年葫芦岛市五里河排污口及其邻近海域水质监测结果,采用单因子评价方法确定该排污口和邻近海域水质超标污染物,然后通过等标污染负荷评价、超标率评价和污染程度的评价得出该排污口的排污状况综合评价,并采用E指数法对该邻近海域进行富营养化状况评价。结果表明:该排污口主要污染物有粪大肠菌群、COD、石油类和镉,存在着高排污负荷、高污染程度的主要排污特征,对海洋环境造成的危害或潜在的危害很大;五里河入海口邻近海域水质污染状况季节性差异较大,5月份水体未呈富营养化状态,8月份主要污染物为无机氮,水体呈轻度富营养化状态。     

辽东湾近岸表层海水重金属污染分析与评价

根据2013年春季、夏季和秋季对辽东湾近岸表层海水重金属的调查数据,分析了该调查区域海水重金属浓度的季节变化,并运用内梅罗(Nemerow)指数法和综合质量指数法对该海域海水重金属污染状况进行了综合评价.结果显示,辽东湾调查海域表层海水中重金属浓度夏季最高,仅Pb超过第一类海水水质标准,且Pb的站位超标率为66.67％.按照美国国家海洋与大气管理局(National Oceanic and Atmospheric Administration,NOAA)推荐的海水中重金属生物慢性安全浓度下限,仅Cu在个别站位的浓度高于NOAA推荐的生物慢性安全浓度下限,其余所有元素的浓度均未超出,不会对生物体产生显著影响.内梅罗指数法和综合质量指数法评价结果显示,辽东湾调查海域属于清洁-轻污染等级,水环境分级属于尚清洁-允许级别,重金属污染较重的区域主要有3个,分别是绥中近岸海域、辽东湾北部河口区、复州湾和金州湾近岸海域.     

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.     

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.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.