Effects of stocking density, periphyton substrate and supplemental feed on biological processes affecting water quality in earthen tilapia–prawn polyculture ponds

The technical and economic potentials of tilapia, Oreochromis niloticus (L.), and giant river prawn, Macrobrachium rosenbergii (de Man), polyculture in periphyton-based systems are under investigation in an extensive research programme. This article is a combined analysis of data from four experiments exploring the effects of periphyton, fish, prawn and feed on water quality. Factor analysis and ancova models applied to the combined dataset allowed to identify the underlying ecological processes governing the system, and construct conceptual graphic models of the periphyton–environment relationships observed. With the first factor, variability in water quality was due to autotrophic (photosynthesis and nutrient uptake) and heterotrophic (respiration and decomposition) processes affecting water quality in opposite directions. With the second factor, variability was related to decomposition on the bottom and nutrient release into the water column, algae production and sedimentation. The analysis of the relationships between both factors and the growth rates of tilapia and prawn in the different systems allowed a better understanding of the functioning of tilapia–prawn ponds, and indicates that their joint culture is technically feasible and economically viable. Therefore, this technology is recommended for poverty alleviation and nutritional security in rural Bangladesh as well as in other countries of the region.     

南海港湾(海陵湾)浮游植物与赤潮生物研究

根据2015—2016年4个航次的调查数据,对海陵湾口海水温度、盐度、pH、溶解氧(DO)、化学需氧量(COD)、无机氮(DIN)、无机磷(DIP)、叶绿素a (Chl-a)、石油类、硫化物和重金属质量浓度等16项水质指标进行分析,并通过综合污染评价指数(P)、富营养状态(E)和质量评价指数(NQI)对该区域渔业环境质量进行综合评价。结果显示,对海陵湾海域污染贡献率最高的因子依次是石油类、DIN、COD和DO,不同季节海水受污染程度和主要污染物水平存在显著差异(P<0.05);春季海水中DIN污染贡献率最高(0.27~0.69 mg·L^–1),仅达到国家四类海水标准;夏季水质清洁,达到国家二类海水标准,但DO质量浓度(4.69~5.93 mg·L^–1)显著低于其他三季;秋冬两季海水均受到一定程度的石油污染,海水中石油类质量浓度分别达0.069 mg·L^–1和0.143 mg·L^–1,均超过国家二类海水标准限量值,综合评价结果为轻度污染;冬季海水中COD值(3.67 mg·L^–1)和Chl-a质量浓度(13.07 mg·m^–3)均显著高于其他季节,11个调查站位(90%以上) NQI值大于3,水质呈现明显的富营养化状态。     

太湖流域主要水系水环境特征分析与富营养化评价

对太湖流域苕溪、南溪、太湖、沿江和黄浦江5大水系水体环境特征进行2次全范围调查监测,在此基础上分析主要水系的水环境特征现状,并用模糊综合评价方法对主要水系的富营养化程度进行评价.结果表明,除苕溪和南溪水系外,太湖流域各水系水体透明度都较低,可能与部分水体泥沙含量较大有直接关系,但水体中藻类、有机物和水动力条件等可能也是影响透明度的因素;耗氧性有机污染物指标处于地表水Ⅳ类～Ⅴ类,且B/C(可生化性指标)比较高,分解利用引起水中溶解氧(DO)的快速下降.氮磷营养元素污染相对严重,基本处于地表Ⅴ类～劣Ⅴ类水平,且各水体中都以总磷(TP)污染最为突出.总氮(TN)和TP中分别主要以溶解无机氧( DIN)和PO43-的形式存在,其较高的浓度为藻类快速生长甚至爆发水华提供了必要条件.对污染指标主成分分析的结果表明,氮磷和有机物是流域水体污染的主要贡献指标.富营养化模糊综合评价结果表明,苕溪水系、南溪水系和太湖基本处于中度富营养化水平,而沿江水系和黄浦江水系基本处于重度富营养化水平.     

A three-dimensional numerical model for a mariculture nitrogen cycle: case study in Shizugawa Bay, Japan

A numerical model is developed for mariculture management, which consists of: (1) calculation of spatial distribution of PON (particulate organic nitrogen) using simulated current, (2) calculation of spatial distribution of DO (dissolved oxygen), (3) calculation of DON (dissolved organic nitrogen), (4) calculation of spatial distribution of DIN (dissolved inorganic nitrogen), and (5) calculation of the horizontal distribution of accumulated matter which is supplied by deposits from the mariculture of fish. This model is capable of calculating the detailed spatial distribution of PON, DON, DIN and DO by dividing the bay into many grid points. It also takes into consideration the effects of feed and fish in each raft, and the loading of DIN from rivers. The model is applied to Shizugawa Bay, in Miyagi Prefecture, Japan. The model elucidated the oxygen cycle among ecological compartments. The amount of dissolved oxygen supplied by photosynthesis is much greater than the consumption through respiration by fish and all other conditions for mariculture of fish are favourable in this bay.     

凡纳滨对虾养殖塘叶绿素a与水质因子的多元回归分析

2009年4-9月期间,对上海市奉贤区某凡纳滨对虾养殖场22个养殖池塘水体叶绿素a、水温、pH、溶解氧、透明度、悬浮物(SS)、总有机碳(TOC)、五日生化需氧量(BOD₅)、高锰酸盐指数(COD_Mn)等15项水质因子进行测定。取164组测定数据,进行描述性统计,分析叶绿素a与各项因子的相关性系数。分析结果显示,与叶绿素a呈极显著线性正相关的水质因子为SS、TOC、BOD₅、COD_Mn、TN、TP;呈显著正相关的为DO;而叶绿素a与透明度呈极显著线性负相关,与PO^3-₄-P呈显著线性负相关;与水温、pH、NO^-₂-N、 NO^-₃-N、NH₃-N则未呈现显著相关性。根据多元线性回归选择自变量的原则,选择了TOC、TN、PO^3-₄-P和TP₄项水质因子,建立了叶绿素a与4项水质因子的逐步回归模型:Chl.a =-0.054 5+0.0034 9 TOC+0.015 3 TN-0.418 PO^3-₄-P+0.276 TP(r=0.715 5)。利用偏回归系数检验各水质因子对叶绿素a的影响,结果表明,对叶绿素a影响从大到小依次是TP、TOC、PO^3-₄-P和TN。研究结果对进一步探讨养殖池塘生态系统的变化规律及水环境质量保护提供了依据。     

湛江东海岛鲍鱼养殖场水质分析

为了监测湛江东海岛鲍鱼养殖场的水质状况,2011年春季对湛江东海岛九孔鲍养殖场的水质进行采样分析,并应用单项指标评价和富营养化评价等方法,对水质状况进行了评价。结果表明,该养殖场水体采样点的水温为16.0～17.5℃,盐度是22,pH值在7.83～7.90之间,均符合我国第二类海水水质标准。各采样点的溶解氧(DO)和生化需氧量(BOD5)也符合第二类海水水质标准,但化学需氧量(COD)值在14.88～15.36 mg/L之间,与第二类海水水质标准相比严重超标;各采样点的无机氮(DIN)均以NO 3--N为主,DIN值在1.053～1.569 mg/L之间,DIN含量严重超过我国第二类海水水质标准。该养殖场水体属于氮富营养化。     

Ammonia reduction in seawater by Yucca schidigera extract: efficacy analysis and empirical modelling

Yucca schidigera is a plant native to southwestern USA and Mexico. Its extract has been used in the livestock industry to control ammonia accumulation in animal holding facilities, and to reduce ammonia concentration in animal excreta. This study investigated the potential and effectiveness of Y. schidigera extract (YUPE) for ammonia reduction in seawater. A dose–response experiment was conducted to determine the effect of different concentrations of YUPE at 0, 18, 36, 72 and 108 mg L⁻¹ on total ammonia nitrogen (TAN) at 1, 3 and 9 mg L⁻¹. At a higher YUPE dosage rate, higher TAN reduction was observed, and TAN reduction was highest during the first 12 h, and decreased thereafter. A stepwise multiple linear regression that included the initial TAN, YUPE concentration and time was developed, which accurately predicted empirical TAN concentrations. Applications of this model for ammonia management strategies were formulated for hypothetical tiger prawn (Penaeus monodon) rearing conditions. YUPE's efficacy for ammonia reduction, natural origin and safety make YUPE a potentially suitable compound for water quality management in mariculture.     

辽宁省葠窝水库水质现状与渔业性能评价

近年来,葠窝水库流域综合管理提高了水库水质状况,为了给下一步的渔业生产提供科学依据,在2008-2009年对葠窝水库6个代表性断面进行了4次采样调查和实验室分析,并采用水质综合评价方法对葠窝水库水质进行评价。检测结果表明水质状况总体有所好转,主要污染物为非离子氨和重金属铜,其他指标正常。采用流域综合水质指数法对水库总体水质状况进行评价,水库水质指数为4.33,为Ⅳ类水质;综合考虑水库理化特征、库龄和形态等,评价葠窝水库属中营养类型。通过对葠窝水库进行渔业水质分析发现,库区大部分地区符合水产养殖基本要求,建议在局部科学发展渔业生产。     

辽宁省葠窝水库水质现状与渔业性能评价

近年来,葠窝水库流域综合管理提高了水库水质状况,为了给下一步的渔业生产提供科学依据,在2008-2009年对葠窝水库6个代表性断面进行了4次采样调查和实验室分析,并采用水质综合评价方法对葠窝水库水质进行评价。检测结果表明水质状况总体有所好转,主要污染物为非离子氨和重金属铜,其他指标正常。采用流域综合水质指数法对水库总体...     

Water quality and rainbow trout performance in a Danish Model Farm recirculating system: Comparison with a flow through system

The objective was to compare water quality and fish growth and mortality in a pilot scale recirculating system (RS) and a control tank in flow through system (FTS). The RS was designed after the Danish Model Trout Farm and operated with a make up water renewal rate of 9 m³ kg^-1 of fish produced. RS water quality did not decrease significantly with water flow rate decrease in the RS. During the experiment, the RS water treatment system presented solids removal efficiency of 59.6 ± 27.7% d⁻¹, ammonia oxidation of 45 ± 32 g m⁻³ d⁻¹, oxygenation yield of 392 ± 132 g of O₂ kWh⁻¹ and CO₂ degassing of 23.3 ± 11.9% pass⁻¹. In the RS, nitrite concentration was 0.15 ± 0.07 mg l⁻¹, close to the toxicity threshold; a N₂ supersaturation phenomenon was measured, probably due to the air injection depth. The biofilter and sedimentation area management has to be improved to avoid organic matter decomposition and release of dissolved elements. Even if no N₂ over-saturation apparent effect on fish performance and aspect were detected, the airlift depth has to be modified in the case of industrial development of the RS. Some improvements of the water treatment system, especially on the airlift and sedimentation area, are suggested.Concerning fish growth, no significant differences were observed between the RS and the FTS. No pathologies were detected and cumulative mortality rates (0.1%) were similar to the farm's usual data. There were no significant effects of water flow rate decrease in the RS on fish performance and energy savings were recorded to be 0.7 kWh kg⁻¹ of fish produced between RS₁ and RS₂. The global energy cost of the RS was 3.56 kWh kg⁻¹ of fish produced (0.107 € kg⁻¹ of fish produced). Even if the energy consumption of the water treatment system can be improved, the results confirm that recirculating system can be used for industrial trout on growing, without fish performance deterioration.     

Characterization of water quality in shrimp ponds of different sizes and with different management regimes using multivariate statistical analysis

Coastal shrimp aquaculture in Bangladesh is mostly practiced in an agricultural unit called a Gher, which is a special type of agricultural field with elevated surrounding embankments/borders situated by the side of a river that is used to grow rice in winter and shrimp in summer. Ghers of different sizes are managed in different ways. An on-farm project was carried out to study the effects of Gher size and their related management practices on water quality, shrimp production and the economic returns of shrimp farming in the Southwest coastal region of Bangladesh. We present here the results of this project with respect to water quality as explored through factor analysis, which was applied as a way to understand the nature and extent of the effects of different variables. For the majority of the variables and factors, one-half to two-thirds of their variability was explained by changes over time (months), and a further one-quarter to one-third was explained by Gher size and associated management practices. The alternating dry/monsoon season and water management practices determined long-term and large-scale (annual) water exchange in the Ghers that mainly affected processes related to live and dead particles suspended in the water column. Processes related to decomposition and nitrification were more dependent on short-term (days) water circulation in the Ghers, which is turn was reliant on the time span between the exchanges of water in the Ghers and river. Our results show that improved management leads to higher natural and shrimp productivity in the smaller Ghers and strongly support the argument put forward by the policy makers and scientific community in Bangladesh that the smaller the Gher, the better they can be managed and the better the possibility of increased shrimp survival and production.     

A proposal to define vulnerability of cetacean areas to human development: variables and analysis procedures applied to the Gulf of California

相似文献   

Water quality and nitrogen budget in turbot Scophthalmus maximus culture system supplemented with lactic acid bacteria

To understand the nutrient utilization efficiency and distribution in indoor fish culture system under treatment of probiotics, this study examined water quality and nitrogen budget in turbot Scophthalmus maximus culture system supplemented with four strains of lactic acid bacteria (LAB) isolated from fishery products. The results showed that the concentration of ammonia nitrogen (NH?‐N) and nitrite nitrogen (NO?‐N) in LAB treatments were all significantly lower (p < 0.05) than in the control group. The nitrate nitrogen (NO?‐N) in LAB treatments showed no significant differences (p > 0.05) compared with control group. The fish feed and water exchange accounted for 79.07% and 17.02% of total N input respectively. For N output, the drainage and residual diets in LAB treatment accounted for 24.50%–25.80% and 1.33%–1.60% respectively, and they were significantly lower than in the control group (27.60% and 2.20% respectively). Fish growth and lost N in LAB treatments accounted for 27.10%–30.50% and 11.00%–18.50% respectively, and they were both significantly higher (p < 0.05) than in the control group (22.30% and 5.30% respectively). The results indicated that the indigenous LAB strains were capable of improving fish growth, and reducing NH?‐N and NO?‐N level (at concentration of 10⁵ cfu/ml) by directly adding in S. maximus culture water. Moreover, specific strains of LAB may increase nitrogen loss by promoting denitrification process in culture system.     

Water Quality and Growth of Rohu,Labeo rohita,in a Biofloc System

We evaluated the technical feasibility of reducing water dependency of rohu, Labeo rohita, culture with biofloc under light-limited indoor culture. Biofloc and control treatments were conducted in 700-L indoor tanks at three different stocking densities (STD): 1.3, 2.6, and 3.9 Nos. fish m^?2 of surface area of tank for a period of 90 days. In biofloc treatment, fish were fed 20% crude protein feed and extra organic carbon in the form of wheat flour, whereas in case of control treatment they were fed 30% crude protein feed only. Fish survival was 100% in both the treatments. Lower stocking density produced larger fish, but growth was similar within stocking densities among control and biofloc treatments. The nutritional quality of biofloc was found to be quite suitable for rohu. Frequency of water exchange was significantly less in biofloc treatments as compared to the control ones.     

潇河支流白马河水质污染的时空变化特征

根据调查资料和河流断面取样点的月度监测数据,研究了潇河支流白马河段水质的时空变化特征,并对水质富营养化程度进行了评价。结果表明,白马河水质较差,属于GB3838-2002《地表水环境质量标准》劣Ⅴ类水质,河流附近乡镇未经处理的生活污水以及造纸废水的排放是造成白马河水质污染的主要原因。从空间尺度上看,化学耗氧量(COD)、氨氮(NH3-N)、总磷(TP)浓度分别沿河流从上游的171.926 mg/L、3.248 mg/L、0.616 mg/L降低到下游的34.920 mg/L、0.560 mg/L、0.208 mg/L,表明白马河水体具有一定的自净能力,但自净能力较差;在时间变化特征上,COD、NH3-N、总氮(TN)浓度10-12月逐渐降低至171.926 mg/L、3.248 mg/L、4.233 mg/L,但COD在1月突然升高至308.772 mg/L,之后又逐渐降低,NH3-N从1月开始快速回升,至2月达到最高值16.576 mg/L,TN在4月达到最高值18.342 mg/L,之后急速降低;总磷浓度在0.397~0.858 mg/L之间波动,无明显变化规律。     

Effects of Diet and Organic Fertilization on Water Quality and Benthic Macroinvertebrate Populations in Ponds Used to Culture Freshwater Prawn,Macrobrachium rosenbergii

ABSTRACT

Effects of three diets: (1) complete diet; (2) supplemental diet (vitamin and mineral supplements not added); and (3) the supplemental diet with an adjunct organic fertilization regimen (using distiller's dried grains with solubles [DDGS]) on benthic macroinvertebrate populations and water quality in experimental ponds used to culture freshwater prawns, Macrobrachium rosenbergii were investigated. Benthic samples were taken from deep (1.5 m) and shallow (1.0 m) areas of each of nine 0.02-ha ponds every three weeks, using a 0.09-m² Ekman dredge. The abundance of gastro-pods, oligochaetes, total non-insects, chironomids, total dipterans, total insects, and total macroinvertebrates was significantly higher (P <0.05) in ponds receiving the complete diet, possibly due to lower predatory pressure by prawns or direct benefits of micronutri-ents. Total macroinvertebrate abundance was significantly decreased (P <0.05) in ponds receiving supplemental diet (with and without organic fertilization), possibly due to increased predation by prawns to supplement the nutrition not provided by the lower quality diet. Organic fertilization significantly increased (P <0.05) the abundance of oligochaetes and total macroinvertebrates. These data suggest that M. rosenbergii can adjust to reduced feed quality by increasing consumption of benthic fauna.     

Effects of microbial products and extra carbon on water quality and bacterial community in a fish polyculture system

A 55‐day mesocosm experiment was conducted to evaluate the effects of commercial microbial products (Novozymes Pond Protect and Novozymes Pond Plus) and extra carbon (glucose) on water quality and bacterial community in a fish polyculture system. A 2 × 2 layout, including four treatments (non‐supplementation of the microbial products or glucose, adding glucose, adding the microbial products and adding the microbial products and glucose in combination), was established. The microbial products and glucose were added on the 40th day, 46th day and 52th day. Ammonia, nitrite and nitrate reduced in the tanks after glucose addition, while adding the microbial products did not significantly affect ammonia, nitrite, nitrate, reactive phosphate, total nitrogen, total phosphorus, chemical oxygen demand and total organic carbon. Adding the microbial products and glucose affected relative abundance of some bacterial taxa, but did not reshape bacterial community. Non‐positive interactive effect on water quality and bacterial community was detected between the microbial products and glucose. This study reveals that supplementation of the microbial products did not benefit water quality in the fish polyculture system, and glucose addition could reduce ammonia, nitrite and nitrate.     

Constructed shallow zones along navigation canals: vegetation establishment and change in relation to environmental characteristics

An Erratum has been published for this article in Aquatic Conservation: Marine and Freshwater Ecosystems 12(2), 2002, 251

• 1. In recent decades shallow zones have been constructed along navigation canals in the Netherlands which form a potential new habitat for aquatic macrophytes and helophytes absent from traditional canals.
• 2. The aim of this study was to examine the relationships between the aquatic plant vegetation that becomes established and the physical and chemical characteristics of water and sediment, in order to find the determinants of species composition and the changes therein. Data were collected in 1998 and 1999 from 80 plots in bank zones at varying stages of development since construction along two navigation canals.
• 3. Plots 3–5 years old were partly dominated by rooting submerged macrophytes such as Potamogeton pectinatus, Elodea nuttallii and Potamogeton pusillus; locally non‐rooting species occurred such as Ceratophyllum demersum, Lemna minor and Spirodela polyrhiza. Older plots contained Phragmites australis, locally mixed with free‐floating species. Hydrological isolation from the eutrophic canals was indicated by the presence of Chara vulgaris.
• 4. Characteristics of both water layer and sediment could explain the variation in vegetation composition. Rooting submerged macrophytes predominantly occurred in sites with a thin (<2 cm) layer of sediment with relatively low concentrations of organic matter; moreover, ammonium concentrations in the water layer and sediment pore water were relatively low. Stands of non‐rooting macrophytes and of Phragmites australis were characterized by a relatively thick sediment layer and high ammonium levels in the pore water. Light limitation in turbid water, associated with navigation and eutrophication, may also play a role.
• 5. Although submerged aquatic macrophytes persist for a relatively short time, shallow zones nevertheless function as a habitat for helophyte communities and contribute to a higher aquatic biodiversity than is associated with traditional banks along navigation canals.

Copyright © 2001 John Wiley & Sons, Ltd.     

Comparative water quality and channel catfish production in earthen ponds and a biofloc technology production system

This 210-day study compared variation in water quality and fish growth for channel catfish (Ictalurus punctatus; 47 g/fish) stocked in earthen ponds (1.5 fish/m², 14,820/ha) and in a biofloc technology (BFT) production system with high-density polyethylene-lined rectangular tanks (12.6 fish/m², 126,000/ha). Feed input and culture environment affected water-quality dynamics. In ponds, phytoplankton uptake predominated and little nitrification occurred, whereas in the BFT system phytoplankton uptake and nitrification maintained low ammonia-nitrogen concentrations. Size classes of fish were skewed toward the larger market sizes in ponds and toward smaller market sizes in the BFT system. Mean final fish weight was 630 g/fish in ponds and 542 g/fish in the BFT system. Despite these differences, fish yield was higher in the BFT system (7.7 kg/m³ v. 1.5 kg/m³) because of the greater initial stocking rate.     

A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index

• 1. An index of riparian quality useful for the management of streams and rivers is presented. The purpose of the index is to provide managers with a simple method to evaluate riparian habitat quality. The index is easy to calculate and can be used together with any other index of water quality to assess the ecological status of streams and rivers. It may also be a useful tool for defining ‘high ecological status’ under the EC Water Framework Directive.
• 2. The index, named QBR, is based on four components of riparian habitat: total riparian vegetation cover, cover structure, cover quality and channel alterations. It also takes into account differences in the geomorphology of the river from its headwaters to the lower reaches. These differences are measured in a simple, quantitative way. The index score varies between 0 and 100 points.
• 3. The QBR index is calculated in the field through a two‐sided A4 page form that may be completed in 10 min.
• 4. The development of the QBR index included trials in four Mediterranean stream catchments in Catalonia (NE Spain). Seventy‐two sampling sites were assessed and results were used to test the index.
• 5. No taxonomic expertise is needed to apply the index, although some knowledge of local flora is required to differentiate between native and non‐native tree species.
• 6. These results show that the QBR index may be used despite regional differences in plant communities. The quality ranges obtained when the index is applied are not heavily influenced by observers at the same site.
• 7. At present, the index is being used by different research teams and tested in a comparative study of 12 watersheds along the Mediterranean Spanish coast.
• 8. It is expected that the QBR index may be adapted for use in other geographical areas in temperate and semi‐arid zones without changes in the index rationale.

Copyright © 2002 John Wiley & Sons, Ltd.