太子河流域底栖动物群落结构及其与环境因子的关系

2012年9月对太子河流域39个采样点的底栖动物群落和水体环境因子特征进行野外调查,并运用香农威纳指数、均匀度指数和典范对应分析等方法分析底栖动物的群落结构。结果表明:在太子河流域共采集到底栖动物61种,以双翅目、蜉蝣目为主,各采样点底栖动物平均密度为0.64×10~3ind/m~2,平均生物量为20.03g/m~2,香农威纳指数和均匀度指数平均值分别为2.14和0.52。典范对应分析表明:影响太子河流域底栖动物群落的主要水体环境因子是总氮、流量和氨氮。综合分析得出:太子河流域受到了轻度污染。     

沙湖大型底栖动物群落特征及其水环境评价

为掌握宁夏沙湖大型底栖动物群落状况,于2013年春季、夏季、秋季调查沙湖8个采样点的大型底栖动物群落结构,并评价沙湖水质状况。结果表明:3个季节在沙湖共采集了17种大型底栖动物,隶属6科,主要由水生昆虫、软体动物、节肢动物组成,且随季节与空间变化显著;沙湖大型底栖动物优势类群为水生昆虫幼虫;大型底栖动物生物指数较低,Shannon-Wiener生物多样性指数和Pielou均匀度指数平均值分别为0.91和0.51;依据多样性指数和大型底栖动物数量分布对沙湖水质进行综合评价,沙湖水域属重度污染,夏季沙湖污染最严重,秋季沙湖受污染状况略好于春季。     

海浪河水产种质资源保护区大型底栖动物群落结构及多样性

2011年8月,对海浪河大型底栖动物群落结构进行了调查研究。本次调查共采集到了大型底栖动物14目31科56种,其中水生昆虫43种,分属7目21科,占总数75.44%。海浪河特有鱼类国家级水产种质资源保护区境内大型底栖动物共计13目30科51种,依群落数量看,蜉蝣目、毛翅目、双翅目为优势类群。海浪河大型底栖动物平均密度为180.19 ind.m-2、生物量为3.20 g.m-2。在各功能摄食生态类群中,捕食者最多,为25种,收集者15种,撕食者10种,刮食者6种。角锥毛石蚕(Brachycentinao)、泥苞虫(Setodes)、小划蝽(Siga substraia-ta)、Epeorus uenoi和Stenpsyche griseipennis是目前海浪河大型底栖动物的优势种。采用Shannon-Weiner生物指数、BI生物指数和Simposon生物指数对海浪河水质评价表明,各生物指数水质评价结果相似,洁净度排序趋势基本一致,均表明海浪河特有鱼类水产种质资源保护区境内水质比较清洁。     

济南流域秋季底栖动物多样性研究

于2014年秋季对济南地区水域的底栖动物的进行设点采样调查,并利用底栖动物香农维纳多样性指数和均匀度指数对水质进行评价。结果表明:济南地区水域共鉴定出底栖动物3门10目33种,以节肢动物门和软体动物门为主。底栖动物平均密度为865.42个/m2,底栖动物香农维纳指数和均匀度指数较低,平均值分别为1.28和0.67。综合各项指标评价认为济南流域秋季水质污染较为严重,为中度污染,应加大保护力度。     

海南省文澜江底栖动物群落结构及其水质生物学评价

为了解海南省临高县文澜江流域底栖动物群落结构特征,探索适宜的水质生物学评价方法,为文澜江流域环境监测、环境评价和科学管理提供数据参考。于2014年11月对文澜江流域17个点位底栖动物群落结构进行调查,并采用5种生物指数对水质现状进行了评价。结果表明,文澜江流域共采集底栖动物56种,隶属4门、7纲、29科,其中水生昆虫占绝对优势,共38种,占总数的67.86%;底栖动物密度和生物量分别为376.11个/m~2和200.79 g/m~2;多足摇蚊属(Polypedilum sp.)、米虾属(Caridina sp.)和环棱螺属(Bellamya sp.)为优势种,优势度分别为0.16、0.04和0.03。采用Goodnight-Whitley修正指数(GBI)和生物指数(BI)对文澜江流域水质整体评价结果均为清洁;采用Shannon-Wiener多样性指数、Margalef丰富度指数和生物学污染指数(BPI)的流域水质整体评估结果均为轻污染,3种水质生物指数评估结果基本相似,并与常规水质监测结果基本吻合。以水产养殖为主的水库出水口和流经临高县县城河道的水质处于中度污染程度,表明水产养殖废水、城市生活污水等对底栖动物的物种组成和群落结构造成了一定影响。     

瓯江干流“玉溪电站～开潭大坝”段底栖动物现状及水质生物评价研究

2009年,对瓯江干流"玉溪电站~开潭大坝"段底栖动物的种类和数量进行了调查,并应用Hilsenhoff生物指数和理化指标对此干流段水质状况进行了评价。结果显示:本次调查共采集到底栖动物30种(属),隶属于19科。底栖动物平均密度为(1126±630)ind./m2,平均生物量为(42.183±10.645)g/m2,底栖动物的密度和生物量随站位变化明显。生物评价显示,3、5、7、8号采样点水体已污染或轻度污染;化学评价显示,大多数采样点水质基本处于Ⅲ类至Ⅴ类水水质水平。结果表明,"玉溪电站~开潭大坝"段水质已有一定程度的污染,且正处于富营养化状态。     

白洋淀底栖动物多样性调查及水质评价

底栖动物对环境变化反应敏感,当水体受到污染时,底栖动物群落结构及多样性会发生改变。为了解白洋淀的底栖动物组成及水质状况,于2006年12月、2007年3～11月对白洋淀9个采样点的底栖动物进行了采样调查。共鉴定出底栖动物23种,其中,软体动物17种、环节动物2种、水生昆虫幼虫4种,与1958年的调查结果对比,发现物种种类数呈降低趋势。其中,中国圆田螺、中华圆田螺、绘环棱螺、羽摇蚊幼虫为全年分布种。应用Shannon-Wiener多样性指数对水质进行分析,可以看出白洋淀水质为中污染。     

黑龙江中游底栖动物群落结构与水质生物评价

2010—2011年对黑龙江中游底栖动物群落结构进行调查研究,共采集到底栖动物16目49科117种,其中水生昆虫种类最多,为79种,分属7目34科,占总数67.52%。黑龙江中游底栖动物平均密度为58.37 ind/m2,生物量为34.62 g/m2。2010年平均密度以春季最高,秋季次之,夏季最低,平均生物量以秋季最高,夏季次之,春季最低。2011年秋季平均密度和平均生物量均高于夏季。黑龙江短沟蜷(Semisulcospira amurensis)、东北田螺(Viviparuschui)、圆顶珠蚌(Unio douglasiae)、截口土蜗(Galba truncatula)和生米蜉(Ephemera shengmi)是现阶段黑龙江中游底栖动物的优势种。聚类分析将7个调查断面分为3组,多维标度分析结果支持了聚类分析结果。多样性分析结果表明,Shannon-Weiner指数、Pielou均匀度指数、Simpson指数均以2010年春季最高,2010年秋季最低。功能摄食类群以刮食者占优,共计为41种。采用BI生物指数和FBI生物指数对黑龙江中游水质的评价结果基本一致,黑龙江中游水质处于清洁轻度污染等级。     

白洋淀底栖动物多样性调查及水质评价

底栖动物对环境变化反应敏感，当水体受到污染时，底栖动物群落结构及多样性将会发生改变。为了解白洋淀的底栖动物组成及水质状况，作者于2006年12月、2007年3月至11月对白洋淀9个采样点的底栖动物进行了采样调查。共鉴定出底栖动物23种，其中软体动物17种，环节动物2种，水生昆虫幼虫4种，与1958年的调查结果对比可以发现物种种类数呈降低趋势。其中中国圆田螺、中华圆田螺、绘环棱螺、摇蚊幼虫为全年分布种。应用香农-威纳多样性指数对水质进行分析，可以看出白洋淀为重、中污染。     

红旗河夏季大型底栖动物群落结构及水质生物学评价

为系统了解红旗河大型底栖动物群落结构和水质现状,2017年和2018年夏季采用常规方法对红旗河流域进行2次调查。共采集大型底栖动物66种,隶属于10目30科,其中水生昆虫6目26科62种,占总数的93.94%。按照功能摄食类群划分,红旗河大型底栖动物包括收集者30种(最多,占总数的45.45%),撕食者19种,刮食者12种,捕食者5种。调查期间,红旗河大型底栖动物平均密度为73.1 ind/m~2,平均生物量为4.93g/m~2,2017年夏季红旗河大型底栖动物密度和生物量高于2018年,但差异不显著(P0.05)。相对重要性指数、K-优势曲线与Shannon-Weiner指数、Pielou均匀度指数和Simpson指数分析表明:红旗河底栖动物群落的相对重要性指数较高的种类均为水生昆虫,弯握蜉Drunella sp.1和瘤石蚕Goera sp.为2个调查年度共有的优势种;2018年K-优势曲线、Shannon-Weiner指数、Pielou均匀度指数和Simpson指数略高于2017年(P0.05);BI生物指数和Shannon-Weiner指数结果表明:红旗河水质基本处于清洁状态,水质条件较好。     

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.     

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.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.