Linking spatial pattern of bottom fish assemblages with water masses in the North Sea

Understanding the links between large scale spatial structuring of fish assemblages and shaping factors is essential to develop comprehensive ecosystem-based fisheries management. In this study, we investigated spatial patterns of bottom fish assemblages in the North Sea in relation to prevailing water masses in the region. We based our analysis on catch data from the German Small-Scale Bottom Trawl Survey conducted between 1987 and 2005 and used both ordination techniques and Mantel tests. Spatial variability of bottom fish assemblages was larger than inter-annual variability. Five significantly different bottom fish assemblages were associated with the following prevailing hydrographical regimes: i) the English Channel, ii) Continental Coastal, iii) central North Sea, iv) northern North Sea, and v) northern Atlantic water masses. Associations were generated by gradients in relative proportions of abundant species such as grey gurnard ( Eutrigla gurnardus ), dab ( Limanda limanda ), whiting ( Merlangius merlangus ), haddock ( Melanogrammus aeglefinus ) and Norway pout ( Trisopterus esmarki ). Taking into account large scale spatial structuring of catch data Mantel tests confirmed significant correlation between the fish assemblages and hydrographical variables. In summary, our results strongly support the hypotheses that hydrographical features such as water masses, fronts, and residual currents could shape bottom fish associations in the North Sea. Spatial demarcations of bottom fish assemblages indicated by this study can be used to support ecosystem-based fisheries management strategies.     

澜沧江源区浮游植物群落特征及其对水质的指示作用

为了探究澜沧江源区水生态现状与变化趋势,在干流囊谦段布置多昌、扎曲大桥及香达3个监测点,支流选择子曲的下拉秀、尕麻和野吉尼玛3个监测点,共计6个监测点位,于2016年7月(夏季)和10月(秋季)对澜沧江源区干流及其支流浮游植物进行了调查,以期为三江源区水生态保护与管理提供科学依据。结果表明:(1)记录浮游植物7门、47种,其中硅藻(21种)和绿藻(14种)为主要成分,分别占总种类数的45%和30%;时空差异明显,夏季较秋季种类丰富,支流较干流种类丰富;优势种以硅藻为主,其中针杆藻(Synedra sp.)为两季度绝对优势种;(2)澜沧江源区浮游植物密度为5.4×10~4～230×10~4个/L,平均密度为79×10~4个/L,硅藻贡献最大;时空差异明显,秋季高于夏季,支流高于干流;(3)浮游植物Shannon-Wiener多样性指数(H)夏季为2.32,秋季为2.72,Pielou均匀度指数(J)夏季为0.73,秋季为0.70。研究显示,澜沧江源区水质介于极贫营养至中营养之间,处于轻度污染至无污染状态,水生态状况整体优良。     

北运河浮游植物调查及水质评价

北运河水系是北京和天津的主要纳污水系,关乎着京津区域发展的供水安全和生态安全。为了合理开发利用水资源,保护生态环境,2009-2010年对北运河水系浮游植物和水质进行了4次调查,对浮游植物种类组成、密度、生物量和群落多样性指数等以及理化性状进行了分析。结果表明,北运河浮游植物有41种;其中,蓝藻门14种,占34.1%;绿藻门14种,占34.1%;硅藻门7种,占17.1%;裸藻门5种,占12.2%;其它种类2种,占2.5%。夏季以蓝藻为主,秋季、冬季和春季均以绿藻为主,整体表现为蓝藻-绿藻型,主要优势种为蓝藻门、绿藻门的耐污种;北运河的CODMn、NH3-N、NO3-N、TP和TN含量大于我国地表水环境质量V类标准的2.12～9.79倍,主要污染物为总氮、氨氮和总磷。北运河的水质普遍较差,大部分为中污染,部分断面为重污染,水体质量在中-重污染之间。     

牡蛎壳在水质改良中的应用

牡蛎壳能有效减少水体中多种污染物的含量,具有良好的水质改良能力。本文综述了牡蛎壳的主要成分、结构,以及牡蛎壳改良水质的原理,介绍其在水处理中用来脱磷、除重金属、去染料及其他污染物的研究、应用现状,并对其开发应用前景进行了展望。     

赤水河鱼类资源量的初步估算

为了解赤水河的鱼类资源现状,于2010年5～6月和9～10月在赤水河赤水镇、赤水市和合江县的3个江段进行了渔获物调查工作。通过统计各江段的渔业捕捞情况,计算年捕捞量。采用体长股分析的方法,对云南光唇鱼（Acrossocheilus yunanensis）、大鳍鳠（Mystus macropterus）和张氏歺鱼又（Hemiculter tchangi）的资源量进行了估算,并以此推算各江段鱼类的总资源量。结果显示,赤水镇江段的鱼类年总资源量为10.76t,其中云南光唇鱼为1.23t;赤水市江段的年总资源量为     

水温对不同规格细鳞鲑摄食和生长的影响

为探讨水温对不同规格细鳞鲑(Brachymystax lenok)摄食和生长的影响,采用自制饲料在不同温度(6℃、10℃、14℃、18℃和22℃)下对小(7 g)、中(68 g)、大(169 g)三种规格的细鳞鲑进行饲养实验。研究结果表明,小规格细鳞鲑在18℃时获得最大摄食率,中规格细鳞鲑在14℃和18℃获得最大摄食率,而大规格细鳞鲑在14℃时获得最大摄食率(P0.05)。小、中规格细鳞鲑在14℃和18℃时的特定生长率最高,而大规格细鳞鲑特定生长率在14℃时有最大值(P0.05)。相同水温条件下,细鳞鲑的最大摄食率随体重的增加而增加,特定生长率随体重的增加而降低,鱼体能值随体重的增加而升高。多元回归分析显示,水温和体重对细鳞鲑最大摄食率(C_(max))的影响可以用下式模拟:lnC_(max)=–6.8282+1.1603ln W+0.3729T–0.0095T~2–0.0157Tln W;水温和体重对细鳞鲑湿重特定生长率(SGR_w,%/d)的影响可用下式拟合:ln SGRw=–1.9390–0.2184ln W+0.4376T–0.0147T~2,水温和体重对细鳞鲑能值E_t(k J/fish)的影响可用如下方程进行较好拟合:ln Et=1.0012+1.2070ln W–0.0002T~2–0.0021Tln W。逐步回归分析表明,水温和体重对细鳞鲑最大摄食率和鱼体能值的影响存在显著的交互作用(P0.05),而对湿重特定生长率的影响不存在交互作用(P0.05)。综合上述研究结果可以认为细鳞鲑养殖的适宜水温范围是14~18℃。     

Use of treated mine water for rainbow trout (Oncorhynchus mykiss) culture: a production scale assessment

In previous proof-of-concept work, it was shown that the use of treated coal mine water for rainbow trout (Oncorhynchus mykiss) culture in a cage was technically feasible, though only a 50-fish bioassay was grown and no work on production-related issues was conducted. To further advance the use of treated mine water, an under-utilized water resource throughout Mid Appalachia, work was conducted to assess the effects of using treated coal mine water for the intensive production of rainbow trout in a flow-through system. During this study, comprehensive water quality data were collected to supplement fish weight and length data taken during routine monthly sampling events. The 8000 fish grew well in the raceway system over the 9 months of production, where a feed conversion ratio of 1.4 and a condition factor of 5.1 × 10⁻⁴ were measured with stocking and harvest densities of 26.4 and 50.2 kg/m³, respectively. Further, total net production was 3275 kg (7220 lb) with 98.6% survival. Throughout the study, dissolved ion concentrations (Fe, Al, Mg, Ca, and SO₄) often exceeded recommended tolerance limits. Further, elevated ammonia nitrogen concentrations generated from a component of the mine water-treatment process were identified as a potential limiting factor for aquaculture development. However, when the non-ideal effects of high ionic strength and the speciation of dissolved metal–ligand complexes were taken into account, the concentrations of free metal ions were within recommended tolerance limits.     

逆流运动训练对多鳞四须鲃摄食、生长和体营养成分的影响

在室内条件下［水温(28?1) ℃］,设置0.7 BL/s和2.0 BL/s 2个流速组以及一个静水对照组,研究了不同逆流运动训练对多鳞四须鲃幼鱼［体质量(75.21?2.82) g］摄食、生长和体营养成分的影响。实验分1~23 d和23~45 d两个阶段,共进行45 d。实验结果表明,多鳞四须鲃平均日摄食率随流速增加而增大,但体长特定生长率、体质量特定生长率和食物转换率均以0.7 BL/s组最高,静水组次之,2.0 BL/s组最低,且三者间差异显著(P<0.05)。不同流速下多鳞四须鲃肌肉水分和灰分含量差异不显著(P>0.05),但随流速增大,多鳞四须鲃肌肉中蛋白质含量增加,而脂肪含量却显著下降。在实验末期,2.0 BL/s流速组的氨基酸总含量(82.63%)、必需氨基酸总含量(34.34%)和鲜味氨基酸总含量(33.50%)均显著高于静水对照组(78.27%,32.6%,30.63%)(P<0.05)。研究表明,较低流速(0.7 BL/s)的运动训练明显促进多鳞四须鲃的生长,提高食物转化率和增加肌肉蛋白质含量,高流速(2.0 BL/s)的运动训练不利于生长,但却能显著提高肌肉必需氨基酸和鲜味氨基酸含量。     

水泥池悬挂毛刷丛养殖罗非鱼试验

在水泥池中悬挂毛刷丛,利用其附着的微生物藻类形成的生物膜净化养殖水体水质,进行奥尼罗非鱼(T.aureus♀×T.nilotica♂)养殖试验。试验从2011年5月6日开始,在4口露天水泥池中共投放全长2～3 cm奥尼罗非鱼苗2 400尾,经182 d的养殖,2口试验池共收获1 179尾,平均体重197g/尾,成活率98.25%,总产量232.25 kg;2口对照池共收获906尾,平均体重197.6 g/尾,成活率75.50%,总产量179.02 kg。试验结果表明,试验池能提高水体透明度、维持水温相对稳定和净化水质,实现不换水或少量换水的目的,达到健康养殖的功效。     

应用浮游动物群落结构评价扎龙自然保护区的水质现状

2011年在扎龙自然保护区设置七个站点,调查鉴定出3门27属44种浮游动物,其中轮虫的种类最多,占62%;原生动物的丰度最多,占总数的58%;桡足类生物量最多,占总数的75%。采用Shannon-Weaver指数（H’）和Margalef丰富度指数（d）评价水质,它们的年平均值分别为2.56和1.74。生物多样性指数最高的站点是5#站点扎龙湖,最低的是6#站点龙湖,对水质的综合评价结果均为中度污染。