大鹏澳网箱养殖海域水质评价及因子分析

根据2001年6月至2002年6月对大鹏澳网箱养殖海域6个航次的水质监测数据,采用有机污染评价指数法对养殖区水质状况进行了评价,同时应用因子分析方法对T(水温)、DO、SS(悬浮物)、CoDMn、BOD5、NO2-N、NO3-N、NH3-N、TIN(总无机氮)、PO4-P等10个水质成分的监测数据进行了分析。结果表明,(1)2001年9月和2002年3月海水出现轻度污染,前者主要是由NO3-N、CoDMn和BoD5所引起,后者是由NH3-N、PO4-P引起的。(2)水质监测数据的总体方差主要来源于T、Do、SS、NO3-N及TIN等5个成分,其次是NO2-N、NH3-N、PO4-P,再次是CODMn和BOD5。(3)因子分析结果表明,各水质成分之间存在一定的相关关系。其中,T、Do、SS、NO3-N及TIN同时载荷于第1主因子上,说明此5个水质成分之间具有较好的相关性;NO2-N、NH3-N、PO4-P同时载荷于第2主因子上,则此3个水质成分之间的相关程性较好;CODMn和BOD5同时载荷于第3主因子上,二者之间具有较好的相关性。     

大亚湾大鹏澳网箱养殖海域沉积物中Pb的分布特征

通过4个航次的调查,研究了大鹏澳海水网箱养殖海域沉积物中铅(Pb)的时空分布特征。网箱养殖区沉积物中的Pb含量明显高于贝类养殖区和对照区;网箱养殖区0～15cm层沉积物的Pb含量明显受到环境扰动的影响,呈垂直梯度减少趋势,而对照区沉积物的Pb含量垂直变化不明显;网箱养殖区,贝类养殖区和对照区沉积物的Pb含量均以春、夏季较高,秋季最低;网箱养殖区沉积物的Pb含量高于其它区域。大鹏澳网箱养殖区沉积物中的Pb含量主要受到网箱养殖活动的影响。     

大鹏澳网箱养殖区沉积物中Cu的分布特征

研究了大鹏澳网箱养殖海域表层沉积物中Cu的平面分布特征,并对采集的沉积物柱状样进行垂直分层分析,以探讨Cu在沉积物中的垂直分布特征。结果表明:(1)网箱养殖区表层沉积物中Cu的含量(范围20.63~78.53mg.kg-1,均值55.08mg.kg-1)明显高于对照区表层沉积物中Cu的含量(范围20.68~23.68mg.kg-1,均值21.87mg.kg-1);(2)垂直方向上,网箱养殖区0~15cm段沉积物中Cu的含量变化幅度很大,15cm后Cu的含量变化则相对平缓,而对照区从表层往下Cu的含量变化一直都很平缓,说明网箱区新沉积层的Cu含量受环境扰动的影响较大;(3)与相关水域比较,Cu的含量高于大亚湾的而与具有类似养殖背景的日本Ka-sumigaura湖养殖区的相吻合;(4)污染评价的结果显示网箱养殖区沉积物Cu的含量劣于我国海洋沉积物一类标准,污染有增加的趋势。根据研究结果,初步推测网箱养殖可能输入Cu元素,造成Cu污染。     

大鹏澳网箱养殖区沉积物耗氧的初步研究

2005年5月对大鹏澳海水网箱养殖海域的沉积物进行密闭培养实验,并进行了水温、DO、BOD5、CODMn、pH等环境因子的现场测定。结果表明:研究海域的沉积物SOD20(在20±2℃下培养)达到3·73(网箱区平均值)、2·70(贝类养殖区)和1·24g·(m2·d)-1(对照区)。t检验表明,在95%的置信水平上网箱区SOD20明显高于对照区。回归分析表明沉积物需氧量随培养时间呈非线性变化,沉积物需氧量与底层海水DO的相关系数达到-0·900(P=0·05)。     

大鹏澳养殖水域溶解氧的变化及其与生态结构的关系

根据2001年6月至2002年6月大鹏澳网箱养殖水域周年的溶解氧(DO)水平监测数据,阐述网箱养殖区水体DO的水平、季节的变化、垂直变化和网箱养殖水体DO质量评价以及DO与水环境因子的相关性。结果表明,大鹏湾网箱养殖水域DO周年水平为3 86～8 01mg/L,氧饱和度为51 6%～103 6%,养殖水域DO水平低于非养殖水域的;冬、春季DO水平较高,均符合我国渔业水质标准要求。夏季DO水平普遍较低,超标率为95%;表层水DO水平略高于底层水,DO水平超标率分别为46%和66 7%;DO水平(全年)与pH值、盐度、叶绿素水平均呈显著性正相关(P<0 02,n=32),与水温、无机磷和无机氮水平呈显著性负相关(P<0 02,n=32)。其中,在春季相关最为明显。     

黑龙滩水库网箱养鱼对水环境的影响

水库面积１６９３ｈａ，１９９３年伴随养鱼饲料进入水体的ＴＮ９６．２７ｔ，ＴＰ３４．０４ｔ，成为水库的污染源。一年沉积库底的残饵、粪便经推算为１６２５ｔ，构成内、荷二次污染源。对网箱区内外水体ＳＤ、ＴＮ、ＴＰ、Ｃｈｌａ，Ｈ２Ｓ、浮游植物和底栖动物的测定结果表明，网箱养鱼已促进了网箱区水质富营养化。ＤＯ减少、缺氧层增厚晃环境变化的一个重要标志，并直接影响网箱养鱼效果。为保证库多功能的正常发挥，在保持网     

网箱养殖对水环境的影响

网箱养殖是一种精养模式，采取高密度放养并大量投喂外源性饵料、肥料。排泄物和残饵增加，成为网箱养殖污染物的主要来源，由此改变了水体的物质组成和理化性质。分析了网箱养殖对水环境影响的原因和机理，同时就实现网箱养殖的可持续发展，降低网箱养殖造成的污染提出了相应的对策。     

网箱养殖与水环境相互作用关系的研究进展

1 网箱养殖对水体所产生的影响 网箱养鱼增加了水体中营养物的浓度,对水体会产生一定的影响.影响程度的大小决定于水体对营养物的敏感性.水体对营养物的敏感性取决于三个方面:水体的形态特征、底质类型和水体交换率.水体的形态特征在一定程度上决定了水体的生态功能,决定水体形态特征的参数可分为两种类型:一是大小参数,如沿岸线长度,最大深度,水面积,横切面积,水体积等.二是由大小参数所决定的形态参数,如平均深度,平均宽度,平均坡度及沿岸线的不规则性等.     

浅析网箱养鱼对乌江流域水环境的影响

网箱养鱼于19世纪末起源于柬埔寨等东南亚国家，网箱箱体用竹子或木头等编制而成，20世纪20年代初传人印度尼西亚，50年代引入日本，开始采用金属或化学合成网片架构网箱进行养殖，随后在挪威、苏格兰等国也相继开展了网箱养殖。我国网箱养鱼于20世纪70年代开始发展，     

网箱养殖对水环境的影响

根据网箱水产养殖特点,分析了养殖过程各种因素对水环境的影响。就实现淡水网箱养殖健康发展,降低水产养殖对水环境的污染,提出了相应对策。     

大亚湾鱼类深水网箱养殖对环境的影响

2016年5月(养殖开始前)和2016年8月(养殖投饵高峰期)对大亚湾大碓鱼类深水网箱区、外围区(网箱外0.1 km)和非养殖区(网箱外10~15 km)的海水和沉积环境进行了调查,采用有机污染指数(A)法、营养状态质量指数(NQI)法对水环境进行评价,用潜在生态危害指数(RI)法对表层沉积物重金属潜在生态危害进行评价。结果显示,与传统网箱养殖化学需氧量(COD)由网箱区中心向四周递减的趋势不同,深水网箱养殖CODMn浓度在3个区域间无显著性差异。深水网箱养殖海域水质较好(A1),水质处于贫营养水平(NQI2)。深水网箱养殖海域表层沉积物重金属铅(Pb)和锌(Zn)含量均符合第一类海洋沉积物质量标准,但铜(Cu)和镉(Cd)含量轻微超标。沉积环境处于轻微生态危害状态(Eir30,RI100),与中国同类型海区相比,污染危害程度相对并不严重。深水网箱养鱼对周围海域环境的影响较小。     

Technical efficiency of cage fish farming in Peninsular Malaysia: a stochastic frontier production approach

The study estimates technical efficiency and investigates the factors affecting the technical inefficiency of cage fish farming in Peninsular Malaysia. The study employs the stochastic frontier function to estimate a production frontier and technical inefficiency model. The data were collected using standard structured questionnaires completed by sample cage fish farmers in the study area. The result reveals an estimated mean technical efficiency score of 0.79, implying that the sample fish farmers are operating 21% below the production frontier and thus, there is room for improvement. The production function involves the use of one output and four inputs, which are stocking density, feed, labour and other relevant production costs. The coefficients of all the inputs have positive signs and statistically significant impacts on the output. The output elasticity associated with stocking density is the highest (0.634), followed by feed (0.317). The null hypotheses that the technical inefficiency effects are absent from the model and that the combined exogenous variables do not influence inefficiency are strongly rejected. The individual's null hypotheses of no age effect, no experience effect, no education effect, no species effect, no extension services effect, no workshop attended effect and no diseases effect on technical inefficiency are all rejected at different levels of statistical significance.     

Carrying capacity and potential environmental impact of fish farming in the cascade reservoirs of the Paranapanema River,Brazil

The objective of this study was to simulate changes in water quality standards caused by the installation of aquaculture parks for caged fish farming in the eight large artificial reservoirs in the Paranapanema River according to the different scenarios of technical and legal limitations: (i) occupancy of 1% of the total surface of the reservoirs and (ii) occupancy according to the environmental carrying capacity. For water quality modelling, these two scenarios were simulated to determine the trophic state index (TSI) of each reservoir. Based on the total area of all reservoirs in the first scenario, the fish farm facilities would occupy 18.3 km² and have an annual fish production of an estimated 513 thousand MT. However, because of limitations in the carrying capacity, the annual production in the second scenario would be 98 thousand MT and the fish farm facilities would occupy 3.5 km². Simulating the TSI for the first scenario, approximately 75% of the total area of all reservoirs was estimated to change from oligo or mesotrophic conditions to eutrophic, supereutrophic and hypereutrophic conditions, and four reservoirs may become completely eutrophic (Canoas 2, Canoas 1, Taquaruçu and Rosana). For the second scenario, however, eutrophic areas accounted for less than 30% of the total, although the Taquaruçu and Rosana reservoirs were still at risk of total eutrophication. These results indicate as well‐intentioned legislation can have unintended environmental consequences in dynamic social–ecological aquaculture systems as in the case of large reservoirs in the Paranapanema River.     

The benthic environmental footprint of aquaculture in the Eastern Mediterranean: Organic vs conventional fish farming

A field experiment was carried out in a fish farm of the Eastern Mediterranean in order to evaluate the benthic environmental footprint of the organic versus the conventional fish farming. The highest values of chl α were recorded at the conventional culture during both studied seasons. The organic matter and organic carbon rates recorded at the conventional culture were significantly higher than those observed at the organic culture in both studied seasons (p < .05). Furthermore, in all cases the quality characteristics of benthic community variables were optimum at the organic culture compared to the conventional one and similar to those of the control. SIMPER analysis showed that the maximum average dissimilarity occurred between organic and conventional culture, while the main contributor species for this dissimilarity was the polychaete Capitella capitata. Multidimensional scaling (MDS) ordination plot indicated clearly a separation of the organic and conventional fish farming during both studied seasons. K‐dominance curves revealed a clear difference in elevation, mainly during summer. M‐AMBI index showed a poor to moderate environment for conventional culture, while organic one was good to high and similar to the control site (high). The results indicated the lower environmental footprint of the organic fish farming compared to the conventional, demonstrating its potential as an important management tool, which could play a significant ecological role for the sustainability of aquaculture in the Mediterranean region.     

Effect of fish farming on the water column nutrient concentration in a semi-enclosed gulf of the Eastern Mediterranean

The spatial and seasonal impact of fish farming on the water column of two fish farms in the Eastern Mediterranean was investigated, between July 2004 and April 2005. In the area of each fish farm, three stations were sampled. One was located at the centre of the fish farm, the other at a distance of 50 m from the centre and the last one at a distance of 300 m from the fish farm centre. At each sampling station, water samples were collected at the surface, at 5 m and at every further 10‐m depth from the surface to the bottom, for nutrient analysis (ammonium, nitrite, nitrate, phosphate, silicate). Statistical analysis showed significant differences between seasons for all nutrients, with the exception of nitrite in one of the farms. Furthermore, ammonium, nitrite, phosphate and silicate values showed significant differences among sampling stations. The maximum concentrations of the above nutrients (1.64, 0.10, 2.57, 0.28 and 4.89 μM respectively) were recorded at the sampling stations located at the centre of each fish farm and they were gradually reduced with increasing distance from the cages. The concentrations of nutrients did not appear to exceed permitted levels for the appearance of eutrophication. The maximum concentrations were considerably lower than those observed previously in the study area.     

蛋白质分离器中的不同臭氧浓度对工厂化养殖净水效果的试验

近几年,国外的工厂化循环水养鱼系统中普遍采用了一种新型的水处理设备——蛋白质分离器（protein skimmer）。国内的一些单位已开始从德国、美国等引进小型的蛋白质分离器,并应用在水族馆及宾馆、饭店的观赏鱼的养殖中,使用效果较好。     

大亚湾鱼卵、仔稚鱼种群特征与环境因子的相关关系

为了解大亚湾鱼卵、稚仔鱼种群动态变化及其与环境因子的关系, 2015年采用浅水I型浮游生物拖网对大亚湾鱼卵、仔稚鱼进行了4个季度的调查,结果表明,4个季度共采获鱼卵31361粒,仔稚鱼244尾。经鉴定分析共有27种,其中鱼卵19种,隶属于6目16科18属;仔稚鱼18种,隶属于5目15科16属;鱼卵、仔稚鱼共有种11个。鱼卵平均丰度为614.55 ind/1000 m^3,稚仔鱼的平均丰度为3.69 ind/1000 m^3。鱼卵丰度季节变化由高到低依次为夏季、春季、冬季、秋季;空间分布显示,丰度由高到低依次为中央列岛、人工鱼礁区、湾口东岸。鱼卵多样性指数(H￠)范围为0.05～2.26,平均值为0.86,稚仔鱼多样性指数(H?)范围为0～2.53,平均值丰度0.82;鱼卵均匀度指数(J)范围为0.02～0.99,平均值为0.50;稚仔鱼均匀度指数(J)范围为0～1.00,平均值为0.52。根据Pearson相关性结果分析表明,与种群关系最密切的环境因子为温度和溶解氧(P<0.01)。研究结果显示,春夏季是大亚湾海域鱼类产卵的重要时期,中央列岛海域是大亚湾鱼类繁殖的关键区域。     

大鹏湾深水网箱养殖区的污损生物研究

大鹏湾位于南海北部,属半封闭海湾,目前有各种类型网箱60多个。本试验于大鹏湾的深水抗风浪网箱养殖区投放试验挂板,以测定污损生物的附着状况,并利用Shannon—Wiener指数进行群落的多样性分析,试验周期为1年。共记录污损生物53种,月平均附着生物量为277．37g／m^2,最高在9月份;季度平均生物量为4497．18g／m^2,最高在冬季;垂直分布方面,最高生物量在1～2m水层。全年各月均有污损生物附着,优势种是网纹藤壶,其次是多室草苔虫、翡翠贻贝和变化短齿蛤。种类的多样性指数(H′)和均匀度(J)均以春季为最高,冬季最低;种类丰度(d)则以秋季最高,春季最低;优势度(I)则以冬季最大,春季最小。     

Effects of cage fish farming on phytoplankton community structure,biomass and primary production in an aquaculture area in the middle Adriatic Sea

In this study, we investigated the physical, chemical and biological parameters of the water column at two stations under different trophic conditions during a 1‐year period (from September 2005 to September 2006) in an aquaculture area. The investigation was performed monthly at a station inside the fish farm in Maslinova Bay (middle Adriatic Sea, Croatia) and at a control station located in the Hvar Channel in the vicinity of the farm. The results showed that the concentrations of dissolved nutrients were slightly enhanced at the farm station in comparison with the control station, although those differences were not statistically significant, nor were the differences in oxygen saturation recorded during the investigation period. As opposed to the chemical parameters, considerably higher deviations were recorded for biological parameters as demonstrated by a significant increase in phytoplankton biomass and primary production (measured in situ) at the farm station, particularly during the summer season. Phytoplankton community structure analysis showed that the phytoplankton composition at the farm was mostly determined by seasonal changes rather than by the influence of fish farming. In Maslinova Bay, no causal links were identified between increased biomass and the appearance of toxic species.