维生素C对鱼类营养生理和免疫作用的研究进展

维生素C在机体内具有非常重要的生理功能。它不仅和鱼类的生长密切相关，而且对鱼类的免疫力、抗病力以及抗应激反应都具有非常重要的影响。然而，由于大多数鱼缺乏合成维生素C所需的L广古洛糖酸内酯氧化酶（L-gulonolactone oxidase，GLO），因此，它们必须通过食物获取维生素C。本文就鱼类对维生素C的需求量及其免疫力和抗应激性反应的影响作一综述。     

Bioremediation of organically enriched sediment deposited below fish farms with artificially mass-cultured colonies of a deposit-feeding polychaete <Emphasis Type="Italic">Capitella</Emphasis> sp. I

ABSTRACT:   For bioremediation of organically enriched sediment deposited below fish farms, the extremely high potential for population growth of a deposit-feeding polychaete, Capitella sp. I, in the organically enriched sediment, and the effect on decomposition of organic matter in the sediment, were examined. A mass-culturing technique was conducted for this species. Bioremediation experiments were conducted on the organically enriched sediment in a fish farm in Kusuura Bay, Japan in 2003–2006. Approximately 1.7 million individuals of the worms were placed on the sediment below one net pen in December 2003, 9.3 million individuals in November 2004, and 2.2 million individuals in November 2005. After the worms were spread on the sediment, they rapidly increased in number and reached the highest densities of approximately 134 000 inds/m² in February 2004, 527 000 inds/m² in March 2005 and 103 000 inds/m² in January 2006. In the process of rapid population growth, the decomposition of the organic matter of the sediment was enhanced markedly. Our results demonstrate that the promotion of population growth by spreading cultured colonies of Capitella can enhance the decomposition rate of organic matter markedly in organically enriched sediment below fish farms. This method is promising for minimization of the negative effects of fish farms.     

Survival and growth of the sea cucumber Holothuria leucospilota Brandt: a comparison between suspended and bottom cultures in a subtropical fish farm during summer

The feasibility of co‐culturing the sea cucumber Holothuria leucospilota Brandt in a subtropical fish farm was investigated in a field study. Sea cucumbers were cultured in the fish farm in cages suspended at 4 m deep (suspended culture) and directly on the seafloor (bottom culture). The survival and growth of the sea cucumbers were monitored twice during the 3‐month, summer experimental period (May 26–August 14, 2010). Results showed that the suspension‐cultured sea cucumbers exhibited excellent survival rate (100%) during the whole study period. There also occurred no mortality in the bottom‐cultured sea cucumbers during the first culture period (May 26–July 13); but all these died from anoxia caused by water column stratification during the second culture period (July 14–August 14). The specific growth rate of the bottom‐cultured sea cucumbers (1.05 ± 0.21 % day^?1) was nearly double that of the suspended culture animals (0.57 ± 0.21 % day^?1) during the first culture period, and the growth rates of the suspended culture sea cucumbers in the second culture periods (0.46 ± 0.24 % day^?1) was only a little lower than that of the first period. The sea cucumbers H. leucospilota could ingest and assimilate sediment with high organic matter content with an average assimilation efficiency of 14.9 ± 3.9%. This study indicated that fish farm detritus can be effectively used as a food source for the sea cucumber and that it can be turned into a valuable secondary crop in the form of the sea cucumber biomass.     

Influence of fish feed composition on oxygen utilization during decomposition of aquaculture effluents

The decomposition of the organic matter, in the form of excess feed and excreted faeces, introduced to the environment by aquaculture can endanger living organisms by lowering oxygen levels. To increase the accuracy of the oxygen utilization assessment, we developed linear (L‐MOD) and non‐linear models (NL‐MOD) for the dynamics of decomposition and accumulation of the organic matter, oxygen utilization and ammonium production. The models are based on mass‐balance stoichiometric reactions for conversion of organic matter into bacterial biomass under aerobic conditions. Organic matter is represented by a general chemical formula sensitive to protein, carbohydrate and lipid content. The mass of organic matter is expressed in chemical oxygen demand (COD) units, providing more convenient tracking of oxygen utilization. Degradable part of the organic matter is distinguished from a non‐degradable part. The model results are compared with the data sets from simulated aquaculture pond experiment.     

Bioremediation and reuse of shrimp aquaculture effluents to farm whiteleg shrimp,Litopenaeus vannamei : a first approach

Shrimp aquaculture effluents were bioremediated in a two‐phase system (System A) using the black clam Chione fluctifraga and the benthic microalgae Navicula sp., and then reused to farm whiteleg shrimp Litopenaeus vannamei. In the experimental design, Systems B and C had an identical structure as System A, but no clams or microalgae were added. System B received the same shrimp effluents while System C received only estuarine water. Shrimp raw effluents had a poor water quality. System A improved the water quality by decreasing the concentrations of total nitrogen, total ammonia nitrogen (TAN), nitrites, nitrates, phosphates, total suspended solids (TSS) and organic suspended solids (OSS). System B also decreased the concentration of TAN, TSS and OSS via sedimentation, but the effect was less pronounced than that observed in System A. Shrimp reared in the bioremediated effluents (System A) had better production (3166 kg ha^?1) and higher survival (89.2%) than those reared in effluents from Systems B (2610 kg ha^?1, 75.1%) and C (2874 kg ha^?1, 82.1%). It is concluded that the bioremediation system was moderately efficient and the bioremediated effluents were suitable to farm L. vannamei.     

The effects of fish farm effluents on the water quality in the Åland archipelago, Baltic Sea

The main aim of this study was to increase our knowledge on how fish farm effluents influences the surface water quality in the Åland archipelago (Baltic Sea). A second aim was to conduct critical model tests of three models that predicts the impact of farm emitted phosphorus on total phosphorus (TP), chlorophyll and Secchi depth. Extensive field studies were conducted between 1997 and 1999 in nine defined coastal areas with, and four reference areas without, fish farms. According to our results the most significant effects on TP concentrations, periphytic growth and phytoplankton standing crop was observed in two coastal bays with small to moderate fish farm production (≈70 tonnes per year). The significant effects in each bay was mainly due to the small size of the bay (0.48 and 0.73 km²) and the shallow mean water depth (3 and 3.8 m), rather than long water retention times (2 and 6 days). Due to a very large fish farm production (800 tonnes per year), we also observed significant effects in a coastal area of moderate size (8 km²), which had a theoretical water retention time of about 8 days. No significant effects of fish farm effluents on the surface water quality were observed in the other six areas. Furthermore, our data shows that, besides the fish farm effluents, the import of nutrients from the surrounding sea and the sediment resuspension may have a decisive effect on the water quality in the studied areas. Finally, we can conclude that at least two of the tested models are useful in context of environmental management.     

鱼类营养代谢性疾病相关基因数据库的调研与分析

集约化养殖条件下鱼类营养代谢性疾病频发,如何防治是目前亟待解决的问题。寻找导致营养代谢性疾病的关键基因,并研究其功能及作用机制是目前研究的热点。高通量测序技术为研究者提供了海量的基因信息,如何有效的挖掘、分析和存储数据并用于疾病的防治显得尤为重要。目前,鱼类营养代谢性疾病相关基因数据库的开发和利用仍处于研究初期。为了合理高效地利用现有的组学数据信息,本研究系统地调研了鱼类代谢性疾病相关数据库,明晰了NCBI数据库中265种鱼类的基因组大小和64种鱼类的染色体数目,获取了Ensembl数据库中17个目58种鱼类的基因组数据,收集了KEGG数据库中41种鱼类的糖类、脂类和蛋白质代谢相关基因。本文可为鱼类营养代谢性疾病基因数据库的研发提供数据支撑,并为鱼类营养代谢性疾病的治疗和预防奠定坚实的基础。     

Seasonal fluctuations in the flux of particulate organic matter discharged from net pens for fish farming

ABSTRACT:   Fish farming using net pens consumes large amounts of food for the reared fish, resulting in organic enrichment of the sediment below the fish farm from organic discharge in the forms of fish feces and food residues. Sediment traps were set at a net pen within and outside a fish farm, and organic flux on the sea floor was compared. The year-mean organic flux to the sea floor caused by fish farming from September 2003 to September 2004 was estimated at 2.11 gC/m²/day in total organic carbon (TOC) and 0.26 gN/m²/day in total nitrogen (TN), which were 2.5 times (TOC flux) and 2.2 times (TN flux) larger than that for natural organic flux outside the fish farm. The seasonal fluctuation patterns of organic flux to the sea floor below the fish farm did not necessarily coincide with those for the amount of food spent for the fish farming. The largest organic flux to the sea floor occurred in the autumn, when the vertical mixing of the water had just started. Therefore, organic enrichment of the sediment on the sea floor of a fish farm proceeded during this season.     

Environmental effects of a marine fish farm of gilthead seabream (Sparus aurata) in the NW Mediterranean Sea on water column and sediment

This study examined the effects of organic enrichment on water column, sediments and macrofauna caused by a fish farm in the Mediterranean Sea. Samples were collected on four sampling campaigns over a one‐year cycle. Significant differences were found in the water column in dissolved oxygen, dissolved inorganic nitrogen, phosphate and total phosphorus concentrations between the fish farm and the control. The increase in the dissolved inorganic nitrogen and phosphate concentrations at the fish farm modified the stoichiometric ratios between nutrients, with silicate acting as limiting nutrient at the fish farm 11% more than at the control. Nevertheless, chlorophyll a concentration in the water column was higher at the control station, probably due to the fouling of the underwater fish farm structures. Significant differences were found in sediment concentrations of organic matter, total phosphorus and redox potential between the fish farm and the control. The Canonical Correlation Analysis indicated that organic matter, total phosphorus, redox potential and% of gravels accounted for 68.9% of the total variance in the species data. Changes were observed in macrofauna, with a decrease in number of species and up to a nine‐fold increase in abundance with respect to the control.     

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.     

Heavy metal concentrations and sediment quality of a cage farm on Lake Volta,Ghana

This study involved the determination of sediment quality and heavy metals in the water column and bottom sediment of a selected cage fish farm in Lake Volta, to assess the potential impact of metals and organic matter pollution on the lake due to cage fish farming. Sediment analysis indicated that the texture of all sampling sites was sandy clay loam with sand dominating with a range of 31.5%–81.2%. The organic matter (TOM) ranged from 4.42%–8.89%, while organic carbon (TOC) was from 2.57%–5.22%. Total nitrogen (TN) fluctuated between 0.22% and 0.45%; total phosphate ranged between 0.22% and 5.30%. The TOC, TOM and TN content in the farm sediment were significantly lower than those of the reference sites (ANOVA, p < .05). Lead, copper, cadmium and selenium were not detected in the water. The results revealed that heavy metal concentrations in the water column and sediments were low and within tolerable levels, indicating no influence of metals from fish feed was observed on the lake water quality. However, the farm seemed to have moderate impact on sediment quality from organic matter. Water and sediment quality monitoring should be embarked upon periodically to ensure sustainable cage culture in the Lake Volta.     

GIS‐based ecological risk assessment for contaminated sites by fish farm effluents using a multicriteria weight of evidence approach

In this study, an integrative weight of evidence (WOE) tetrad methodology was developed and used to assess environmental quality and ecological risk at contaminated sites by fish farm effluents using spatial modelling tools [geographical information systems (GIS) and fuzzy logic and multicriteria analysis (MCA)], taking into account the results of four lines of evidence (LOE): the physico‐chemical characteristics of water and sediment, acute toxicity bioassays, biomarkers and the in situ alteration of benthic communities. The methodology was tested in the Rio San Pedro salt marsh creek in southwestern Spain. The proposed approach allowed for a quantitative spatial characterization of ecological risk and a better discrimination based on various types of physical, chemical and biological data. The methodology illustrates how GIS spatial models may be used in conjunction with other tools such as fuzzy logic and MCA to assist in decision‐making processes based on multiple environmental quality criteria and lines of evidence, with the transparency, objectivity and synoptic ability required to address environmental management problems in general and the management of contaminated marine areas affected by fish farms in particular.     

FOAM, a new simple benthic degradative module for the LAMP3D model: an application to a Mediterranean fish farm

The modelling framework already introduced by Doglioli, Magaldi, Vezzulli and Tucci to predict the potential impact of a marine fish farm is improved following different directions, namely (1) real historic current-metre data are used to force the simulations, (2) settling velocity values specifically targeting Mediterranean fish species are used, and (3) a new benthic degradative module, the Finite Organic Accumulation Module, is added to the modelling framework. The Finite Organic Accumulation Module uses the output of the other functional units of the modelling framework to calculate the organic load on the seabed. The Finite Organic Accumulation Module considers the natural capability of the seafloor in absorbing part of the organic load. Different remineralization rates reflect the sediment stress level according to the work of Findlay and Watling. Organic degradation for both uneaten feed and faeces is evaluated by changing the release modality (continuous and periodical) and by varying the settling velocities. It is found that the maximum impact on the benthic community is observed either for quickly sinking uneaten feed released twice a day, or for less intense near-bottom current conditions. If both the above-mentioned scenarios coexist, a high stress level is established in the sediment. The model also suggests that the use of self-feeders in cages can reduce farm impacts significantly. These results show how the new and more complete modelling framework presented here is able to improve the objectivity in the decision-making processes and how it may be successfully used for planning and monitoring purposes.     

Population ecology and prey consumption by fathead minnows in prairie wetlands: importance of detritus and larval fish

Abstract –  The fathead minnow Pimephales promelas occurs in high densities in wetlands of the prairie pothole region (PPR) of North America, but food resources sustaining these populations are poorly known. We assessed population dynamics and prey consumption of fathead minnow populations in three PPR wetlands for 2 years. Fish density peaked at 107 fish per m² for all age classes combined. Larval and juvenile fish dominated these populations in terms of abundance and accounted for 83% of total prey consumption. Detritus dominated fish diets, representing 53%, 40% and 79% of diet mass for larval, juvenile and adult fish respectively. Detritus consumption was positively related to minnow density and negatively related to invertebrate abundance, but only for adult fish. Seasonal production:biomass ratios were unrelated to proportions of detritus in the diet for all ages of fish, indicating that detritus is an important food resource capable of meeting metabolic demands and sustaining fish growth in high-density populations. Detritus consumption may also weaken links between abundance of invertebrate prey and minnows, promoting dense fish populations with strong, consistent influences on wetland ecosystems.     

Partial replacement of fish oil by flaxseed oil in Atlantic halibut (Hippoglossus hippoglossus L.) diets: effects on growth,nutritional and sensory quality

Three isonitrogenous (520 g protein kg^?1 DM) and isoenergetic (25 MJ kg^?1 DM) diets containing increasing levels of flaxseed oil (FxO; 0%, 40% and 70% of total added oil) at the expense of fish oil (FO) were tested for 33 weeks in groups of 61 individually PIT‐tagged halibut (initial weight, 849 ± 99 g). Effects on fish growth performance, fillet nutritional and sensory quality were determined. Specific growth rate (0.2% day^?1), feed conversion ratio (1.2–1.3) and nitrogen and energy retention were not affected by dietary treatments. Dietary fatty acid composition was reflected in fatty acid profiles of halibut muscle, liver and heart. Muscle of fish fed FxO diets contained higher 18:2n‐6 and 18:3n‐3 concentrations whereas 20:5n‐3 and 22:6n‐3 levels were significantly reduced. However, increasing FO replacement induced preferential retention of 22:6n‐3 especially in heart, and a trend for 20:5n‐3 conservation in heart and muscle was observed. FO replacement did not affect colour, texture and the characteristic fish odour and flavour of cooked fillets. By selectively retaining long‐chain polyunsaturated fatty acids halibut can adapt to a lower dietary supply without adverse effects on growth, feed conversion ratio, survival, and fillet nutritional and sensory quality.     

Feeding activity strongly affects the variability of wild fish aggregations within fish farms: a sea bream farm as a case study

Factors influencing within‐farm variability of wild fish aggregations have not been systematically studied. We tested the hypothesis that fish abundance and species composition vary between feeding and non‐feeding periods and different bottom substrates within a Sparus aurata (L.) farm. Sampling took place during feeding and non‐feeding periods on six consecutive days in July 2011. Visual censuses were carried out at three different depths and at three sampling stations over rocky–sandy and sandy substrates respectively. In all, 33 species belonging to 17 families were observed. Total fish abundance, biomass and species community significantly differed between feeding and non‐feeding periods. Each depth was represented by a distinct species community and was therefore affected differently by the feeding activity. At the surface, fish abundance was significantly higher during feeding compared with non‐feeding periods. The distance from the feeding vessel significantly influenced fish aggregations in the water column, indicating that planktivorous species learnt to associate the boat noise with food availability through classic conditioning. At the bottom, substrate type was the dominant factor explaining aggregation variability. This study provides new information about the dynamics of fish aggregations within farms, emphasizing the importance of considering the different sources of variability in future study designs.     

Assessment of efficiency and impacts of gillnets on fish conservation in a tropical freshwater fishery

相似文献   

Procedures for evaluating and prioritising the removal of fish passage barriers: a synthesis

Abstract Techniques for assessing the impact of structural barriers on fish passage and for prioritising restoration actions are reviewed. Current survey methodologies are biased towards specific structures, primarily culverts and economically significant fish. Assessment criteria are often based on swimming capabilities of upstream migrating adult salmonids, while ignoring other life‐stages, non‐salmonid species, downstream migration and behaviour. The development of comprehensive and centrally owned geospatial inventories of barriers is essential. The collection, maintenance and dissemination of pertinent structural and environmental data can be technically, logistically and financially challenging. Standardised procedures are needed to rapidly and cost‐effectively survey large numbers of barriers over wide geographic areas. The prioritisation of barrier repair and removal projects is most often based on simple cost‐benefit analysis, whereby individual barriers are scored based on a set of assessment criteria and then ranked in order of priority. The benefits of using scoring‐and‐ranking systems, however, are unacceptably low because they consider barriers independently, thereby ignoring the cumulative, non‐additive impacts produced by multiple, spatially interconnected structures. Optimisation modelling offers a more robust approach for efficiently prioritising decision making in river restoration planning, allowing decision makers to account for key uncertainties and effectively balance multiple, possibly competing, environmental and socioeconomic goals and constraints.     

Improvement of copepod nutritional quality as live food for aquaculture: a review

In hatchery, an adequate supply of live food for first‐feeding fish larvae is essential and nutritional quality of live food organisms can be improved through nutrient enrichment. The use of live food organisms, especially at first feeding, is a requisite for most marine fish larvae. In ocean, marine fish larvae primarily feed on copepods, but the production protocols of copepods as live food is underdeveloped in hatchery. As the food ingestion and the digestive system of copepods are different from other live food organisms (e.g. rotifers), the nutrition enrichment procedures with emulsion oil used in rotifers is not effective on copepods. This review focuses on alteration of nutrient composition of copepods through manipulation of copepod food before they are fed to fish larvae. Specifically, we discuss the relationship between the changes of fatty acid compositions in dietary algae and in copepods. The review links nutrient supply to copepods and the change of nutrition in copepods and suggests ways to improve copepod nutrition in hatcheries.     

鱼类自然死亡系数评估研究进展

自然死亡系数是渔业资源评估中不可或缺的重要参数,其准确度直接决定了资源评估结果的可靠性,进而影响渔业管理策略的制定。本文从生活史参数、标志回捕和年龄结构3个方面列举了国内外自然死亡系数的常用评估方法,讨论了相关方法的优缺点及影响因素,并以犬齿牙鲆(Paralichthys dentatus)和中国近海鱼类为例对比分析不同模型的计算结果。在此基础上,着重介绍了Pauly经验公式在中国近海主要经济鱼类自然死亡系数评估中的应用进展及存在问题。根据渔业资源调查和研究数据现状,认为现阶段使用Pauly经验公式评估中国近海经济鱼类自然死亡系数具有积极作用。