沉积环境对鱼类网箱养殖的响应

网箱养殖是鱼类集约化养殖的主要方式,近年来得到大力发展,但是网箱养殖也带来诸多的环境问题。本文从沉积环境改变的角度阐述了网箱养殖对环境的影响,包括底层水环境要素、底质理化环境要素和底栖生物环境要素对网箱养殖的响应,并探讨了有机负荷的消减对策。网箱养殖区水环境中溶解氧(DO)通常下降,而化学耗氧量(COD)、氨氮(NH4-N)和无机磷(D IP)增多;底泥沉积物中N、P、硫化物、有机质等大量富集,其中富集现象最明显的是P、硫化物和NH4-N,其次是总氮(TN)和有机质;一般情况下,网箱养殖区底栖生物尤其是多毛类增加,而当污染严重时,会使底栖生物缺失。有机负荷的消减对策包括收集残饵粪便等沉积物、利用生物方法去除有机碎屑和加强养殖管理提高饲料利用率等。     

海水网箱养殖的关键生物过程研究:花鲈生理代谢

2004年4～12月对爱伦湾抗风浪网箱养殖区养殖花鲈(Lateolabrax japonieus)的现存量、生长进行了实地调查和模型分析.结果表明,7～9月是研究爱伦湾鱼类养殖水域养殖容量的关键季节.夏季鱼类的摄食最活跃,鲈鱼的摄食率为1.4%～4.4%,8月最大.残饵率在11.0%～28.0%之间,7～9月最高.1个养殖周期内,约有38.6 t DO被养殖鲈鱼消耗,7～9月进入耗氧高峰期.养殖鱼类在网箱养殖区域的营养盐循环中起着重要的作用.花鲈4～12月向爱伦湾输出0.8 t氨氮,1.0～1.6 t N.在面积(2.0×105)m2的抗风浪网箱养殖区,养殖鱼类因排泄而再循环的N能满足浮游植物生产所需N的17.2%～27.5%.养殖花鲈因排粪向水体输出12.0 t颗粒物.     

新型高效设施化池塘养殖系统构建与应用(下)

正(2)成鱼、鱼种配合养殖:一般在15%~30%区培育鱼种,在70%~85%区养殖成鱼,也可调换养殖区或在70%~85%区的一侧区放养鱼种。鱼种的放养密度按池塘全部水体计算。养殖过程中仅投喂养成鱼类。与上原理一致,利用水流和气提作用,将养成鱼类产生的粪便残饵等集中并输入到鱼苗培育养殖区,利用粪便、残饵肥水养殖鱼种,同时净化成鱼养殖区水质,提高池塘混养的效果。     

三都湾网箱鱼类养殖容量的估算

以底质硫化物为指标,采样实地调查估算法,估算福建宁德三都湾网箱鱼类养殖容量。选取的5片网箱养殖区底质硫化物调查结果,每片网箱养殖区底质硫化物的含量从网箱养殖区的中心向边缘递减,网箱养殖区外侧硫化物含量均没有超标;利用SPSS软件的双变量相关性分析功能,分析底质硫化物与单位水体养殖密度之间的相关关系,得到指数增长曲线方程:y=81.858e1.214x,经相关性分析,得到R=0.989,R2=0.977,p0.01(n=6),相关性显著。根据该方程和底质硫化物评价标准,计算得出三都湾网箱适养水域的鱼类养殖容量为1.07kg/m3。     

虾夷扇贝对牙鲆的粪便、残饵及网箱养殖区沉积物的摄食

采用室内静水法,研究了虾夷扇贝Patinopecten yessoensis对牙鲆Paralichthys olivaceus残饵、鱼类粪便、鱼类养殖网箱沉积物及微藻的摄食行为,分析了基于虾夷扇贝的鱼＋贝多营养层次的综合养殖（IMTA）模式的可能性。研究结果显示,虾夷扇贝对鱼粪、残饵及鱼类养殖网箱沉积物都可摄食,但对微藻的滤水率和摄食率最高,显著高于其他实验组(ANOVA, P<0.01);微藻组、残饵组和鱼粪组之间的吸收效率没有显著性差异,但都显著高于沉积物组。吸收效率（AE）与有机物比率（f）呈正相关关系：AE(％)＝38.84lnf+72.7 (R2=0.378);对有机物的吸收率（AR）与有机物浓度（POM）呈线性正相关关系：AR＝0.118×POM-0.555 (R2=0.329)。假粪产生时颗粒物TPM浓度的阈值为24.09mg/L。     

渔业信息

开拓内湾养殖减污增效新思路近年来 ,长海县内湾浮筏养殖和网箱养鱼规模不断扩大 ,取得了喜人的经济效益 ,但由于养殖密度的增加也减弱了内湾水流交换能力 ,养殖品残饵、粪便等废弃物沉积污染海域 ,导致扇贝长势差 ,个体小型化 ,对养殖的可持续发展带来了隐患。 2 0 0 4年 ,为减轻内湾压力 ,改善海域环境 ,化解养殖风险 ,长海县一是有计划地把网箱养鱼逐步调出内湾 ,先后减少内湾网箱养鱼规模近 5 0 0个 ,降低网箱养鱼对近岸水域带来的污染 ;二是稀疏高密度、超负荷的浮筏养殖区的台筏数量 ,把相对密集的浮筏养殖和鱼类网箱养殖调转到海参网…     

象山港南沙岛不同养殖模式沉积物微生物群落结构分析

通过构建16S rDNA克隆文库对象山港南沙岛不同养殖模式(贝类养殖、藻类养殖及网箱养殖)表层沉积物微生物多样性和群落结构特征进行了比较和分析,共获取136个OUT。其中,贝类养殖区、藻类养殖区和网箱养殖区OTU分别为58、48和57个。各站位OTU分布差异明显,表现出高度的多样性。基于16S rDNA序列的生物多样性和丰富度分析表明,网箱养殖区丰富度指数ACE为739,香浓指数H?为3.8,均为最高值,丰富度指数Chao为245,略低于于贝类养殖区。贝类养殖区丰富度指数Chao为303,在各养殖区中最高。藻类养殖区丰富度指数ACE为174、Chao为89,香浓指数H?为3.6,均为最低值。系统发育分析表明,南沙岛各养殖区的优势种群均为变形菌门(Proteobacteria),但是藻类养殖区微生物群落结构与其他养殖区域相比,16S rDNA克隆文库差异显著,其中根瘤菌属(Rhizobium)及其他光合细菌在藻类养殖区分布较多。网箱养殖区沉积物表层微生物群落中出现了与环境污染密切相关的菌群,如志贺氏菌属(Shigella)、埃希氏菌属(Escherichia)和ε-变形菌纲的微生物种群,揭示网箱养殖对底质沉积物环境的影响较大。     

哑铃湾网箱养殖海区表层沉积物磷的含量特征

在哑铃湾不同养殖历史网箱下、距离网箱50m和100m以及对照海区共布设8个采样点,于2002年4月~2003年1月分四季采集表层沉积物样品,对沉积物中总磷、无机磷和有机磷进行了测定,分析了调查区磷的空间分布和季节变化特征。结果表明:哑铃湾海水养殖网箱下沉积物磷含量明显高于对照点,沉积物中总磷是对照点的3.71~9.99倍。养殖历史越长,沉积物中的磷含量越高;网箱养殖引起的沉积物磷累积仅限于网箱下及距离网箱50m范围内,对距离100m以外的海区影响较小;沉积物中的无机磷占70%以上,以无机磷为主;养殖历史较长的东升村养殖区沉积物磷的季节变化明显,有机磷的变化与养殖活动密切相关。     

象山港紫菜区和网箱区沉积物异养细菌的生态分布

为探讨紫菜和网箱两类海水养殖活动对沉积物异养细菌生态分布的影响,于2006年1月和2006年10月对象山港紫菜养殖区、网箱养殖区沉积物细菌数量和群落结构进行了研究,并与周边非养殖海域对照点进行了比较。结果显示,沉积物异养细菌数量呈现10月份>1月份,网箱养殖区>网箱对照区>紫菜养殖区和紫菜对照区的分布特点,各区异养细菌数量平均值依次为(9.6×104±2.0×105)、(1.5×104±2.4×104)、(4.3×103±1.6×103)和(4.7×103±3.0×103)cfu/g。紫菜养殖区分离细菌109株,归属于17个属,其中芽孢杆菌属(Bacillus)、棒状杆菌属(Coryneforms)为优势菌属;紫菜对照区分离细菌95株,归属于18个属,其中芽孢杆菌属、棒状杆菌属为优势菌群;网箱养殖区分离细菌136株,归属于11个属,其中假单胞菌属(Pseudomonas)、弧菌属(Vibrio)、芽孢杆菌属、不动杆菌属(Acinetobacter)为优势菌群;网箱对照区分离细菌110株,归属于11个属,芽孢杆菌属、棒状杆菌属、假单胞菌属、不动杆菌属、弧菌属为优势菌属。紫菜区和紫菜对照区沉积物检出菌属大多为海洋沉积物中的常见菌属,细菌群落多样性较网箱区和网箱对照区高,而网箱区沉积物长期受到高有机质等外界条件的选择作用,系统中细菌群落多样性下降,菌属组成与污浊海域相似,并且这种影响可能已波及至周边海域。可见,两类养殖区沉积物细菌分布特征存在明显差异,细菌数量和菌属组成与养殖自身污染密切相关。     

2013年渔业主推技术 （四）大黄鱼标准化网箱养殖技术

技术概述：海水鱼网箱养殖过程中,大量残饵和排泄物排入养殖区,不同程度地污染了海洋环境;网箱过密布局,造成水流不畅、水质富营养化、底部有机质的沉积,严重污染水质,引发鱼病而频繁施药后,反过来又引起鱼产品和加重了水环境的污染;同时,还存在着浪费资源和增加养殖成本等问题。为此,推广大黄鱼标准化网箱养殖     

Quantification of waste feed and fish faeces in sediments beneath yellowtail pens and possibility to reduce waste loading by co‐culturing with sea cucumbers: an isotopic study

To evaluate environmental impacts of yellowtail culture and to examine the efficiency of the sea cucumber Apostichopus japonicus in reduction of waste loading, surface sediments were sampled and A. japonicus were cultured at a yellowtail farm in Owase Bay, Japan. Waste feed‐ and faeces‐derived organic matter (WOM, FOM) in sedimentary organic matter (SOM) was estimated based on the δ¹³C and δ¹⁵N of the fish feed (?21.7‰, 9.2‰), yellowtail faeces (?20.6‰, 6.2‰) and SOM reference (?24.4‰, 4.4‰). Small WOM (0–22% in SOM) but substantial FOM (28–61%) loadings in the fish farm area and high sulphide concentrations in the sediments (1.0 mg g^?1) suggest that reduction in the fish stocks or mitigation of the faeces should be considered. A. japonicus juveniles were cultured in three cages deployed below a pen and growth was assessed after three different periods (62, 107, 181 days). A. japonicus grew well during the first 107 days (daily specific growth rate, 3.7%) and their survivorship was high (80–90%). Growth ceased after 107 days, probably due to fouling on the cages. The δ¹³C and δ¹⁵N of their hypothetical diet (–19.7‰, 5.5‰) were close to the FOM values, suggesting assimilation of FOM.     

崇明东滩南部大弹涂鱼食源的稳定同位素分析

利用稳定同位素技术,对崇明东滩南部湿地4、5月份采集到的大弹涂鱼(Boleophthalmus pectinirostris)的食源进行初步研究。结果显示,大弹涂鱼δ13C和δ15N值分别为-19.28‰~-14.59‰,7.96‰~10.13‰。利用同位素混合模型(Iso Source)计算包括白茅(Imperata cylindrical)、芦苇(Phragmites australis)、互花米草(Spartina alterniflora)、糙叶苔草(Carex scabrifolia)、底栖微藻、颗粒有机物和沉积质在内的7种初级生产者对大弹涂鱼碳源食源贡献的可能范围及分布频率,结果表明白茅、芦苇、互花米草、糙叶苔草、底栖微藻、颗粒有机物和沉积质对大弹涂鱼食源的可能贡献范围分别为0%~69%、0%~30%、0%~72%、0%~30%、0%~76%、0%~44%和0%~47%。利用后整合方法计算得到C_3植物(芦苇和糙叶苔草)、藻类及有机质(底栖微藻、颗粒有机物和沉积质)和C4植物(白茅和互花米草)三大类生产者对大弹涂鱼食源的贡献情况,结果表明C_3植物、藻类及有机质和C_4植物对大弹涂鱼春季食物贡献范围分别为0%~30%、0%~76%和24%~72%,中值分别为15%、38%和48%,表明C_4植物是大弹涂鱼不可缺少的食源。同时,根据大弹涂鱼的δ15N值,得出大弹涂鱼属于2.07~2.65级营养级,为次级消费者。     

Effects of organic effluents from a salmon farm on a fjord system. I. Vertical export and dispersal processes

Vertical flux of organic waste from a Norwegian salmon farm (which produced 2910 tonnes of fish in 19 months) located in 230-m-deep water was measured nine times in the course of 2 years by sediment traps along a transect stretching from the farm and 3 km out towards the sea. The chemical composition of the trapped material and the sediment below the traps were analyzed. The results showed that when the fish farm was empty, sedimentation rates of organic matter were similar all along the transect. Throughout the production cycle high and very variable sedimentation rates of particulate organic matter, particulate organic carbon and particulate organic nitrogen were measured within 250 m from the farm, while between 550 and 3000 m away from the farm sedimentation rates were lower and constant throughout the cycle. During the second year of production, the annual vertical flux of particulate organic carbon to the bottom adjacent to the farm was 365 g m^− 2, nine times as high as what was found 3 km away from the farm. While the sedimentation rates showed that most of the waste matter settled within 250 m of the farm, the fatty acid composition and δ¹³C isotope ratio of the material in the bottom traps indicate that some components of the organic waste were transported as far as 550 to 900 m, probably due to resuspension of surface sediment. Despite the high sedimentation rates the content of sedimentary organic matter, total organic carbon and total organic nitrogen was not elevated in the sediment around the farm. However, phosphorus was found in higher concentrations in the sediments close to the farm, indicating that organic matter had settled on the sediment and been decomposed. The unchanged content of organic matter in the sediment during the production cycle showed that at this site the local resuspension and dispersal conditions and the decomposition capacity of the benthos were sufficient to prevent overloading of the locality.     

Bacterial community structure and activity in fish farm sediments of the Ligurian sea (Western Mediterranean)

The environmental impact of a well-established fish farm has beeninvestigated in surface sediments of the Ligurian Sea in order to assess thebiodeposition, bacterial community structure and dynamics at a mature stage oforganic enrichment.The Biopolymeric carbon (BPC) fraction of organic matter and phytopigmentconcentrations displayed very high values beneath the fish cages. In particularlipid, carbohydrate and chlorophyll-a concentrations werehigher in farm sediment while protein concentrations did not show significantchange between farm sediment and control.Benthic bacteria were closely related to organic enrichment and their densitywas three times higher (up to 3 × 10¹⁰ cellsg^–1) in stations beneath the cages being positivelycorrelated with BPC (n = 10, p < 0.05) and lipid (n = 10, p < 0.05)concentrations. Colony forming units (CFU) counts of heterotrophic bacteriaindicate a shift in the relative importance of the gram negative bacterialfraction, displaying the predominance of theCytophaga/Flexibacter-like bacteria (CBF), as well as theoccurrence of pathogenic bacteria (such as Vibrio) insediments beneath the farm. In contrast, Gram positive bacteria were moreprevalent in control site where they represented up to 90% of total isolates.Aminopeptidase activity displayed higher values in sediment beneath the cages,whereas the enzymatic activity per bacterial cell was lower. These data suggesta functional stress of bacterial degradation rates and represent a potentialvaluable environmental index of imbalance between supply and removal of organicmatter in eutrophicated environments.Data presented in this study also suggest that either the biochemicalcomposition of sedimentary organic matter as well as the selected microbialvariables may represent useful tools for evaluating the effects of organicenrichment due to fish farming and could be proposed as new environmentalindices of aquaculture impact on marine sediment.     

Effects of sea cage salmon farming on sediment nitrification and dissimilatory nitrate reductions

Within a few months of the establishment of a sea cage salmon farm in the Marlborough Sounds, New Zealand, sediment physical and chemical characteristics reflected the extremely high sedimentation rate immediately underneath the fish cages. In the surface sediment, dry weight was reduced to about one-third, density was halved and the volatile solids content increased about seven-fold compared with nearby sediments. Similarly, the sediment pools of ammonium, organic N and total phosphorus were much higher underneath the cages than at farther removed sites. The total N/P ratios were the same (1.5) in the surface sediment underneath the cages and in the feed but markedly higher in the less affected areas. In situ nitrification and denitrification were not measurable in the immediate vicinity of the salmon farm. The potentials for nitrification and denitrification gradually increased from virtually nil underneath the fish cages to commonly observed rates about 30 m from the cages. The complete absence of denitrifying enzymes in the salmon farm sediment to a depth of 6 cm explained why nitrate diffusing from the water column into the sediment was not denitrified. Within 10 m of the fish cages the bulk of added ¹⁵N-nitrate was reduced to ¹⁵N-ammonium. The results demonstrate that nitrification/denitrification in the immediate vicinity of a sea cage fish farm is not a significant mechanism of N removal.     

应用同位素分析黑龙江中游主要鱼类营养层次

2010年5月—2011年10月对黑龙江中游采集的32种鱼类和6种底栖无脊椎动物,运用稳定碳、氮同位素方法进行水生态营养层次的分析。结果显示,鱼类δ13C值为-32.00‰～-17.32‰,相差14.68‰;δ15N值为7.58‰～14.78‰,差值达6.80‰,跨度都很大。底栖无脊椎动物δ13C值和δ15N值的跨度不大,δ13C值为-29.64‰～-26.10‰,相差3.54‰;δ15N值为7.09‰～9.91‰,相差2.82‰。通过δ15N值计算出黑龙江中游32种主要鱼类和6种底栖无脊椎动物食物网营养层次,其中肉食性鱼类鳇(Huso dauricus)占据了黑龙江中游鱼类中最高的营养位置。通过分析初步建立了水体食物网连续营养谱,并结合底栖无脊椎动物同位素数据勾勒出黑龙江中游食物网营养结构图。     

Polychaetes as indicators of marine fish farm organic enrichment

Marine fish farms cause environmental disturbance of sediment due to uneaten food and fish faeces that accumulate on the sea bottom. These products give rise to organic enrichment followed by degradation processes; reduction of level of dissolved oxygen in the bottom water; generation of high levels of sulfides; changes of benthic assemblages and even azoic conditions. The soft bottom benthic communities and, above all, the polychaetes are considered good indicators of environmental perturbations considering their relatively fast changes in diversity and abundance and because their trophic flexibility and life-history traits are considered a pre-adaptation to the condition of disturbed habitats. The aim of the present study is to evaluate the polychaete population changes as a result of organic enrichment produced by a marine fish farm. The study was carried out on a fish farm located in the coastal water of Porto Ercole (Tyrrhenian Sea) with two submersible sea cages and a year production of 180 tonnes. The macrobenthos samples were collected during four campaigns (July and December 2001, May and October 2002). The results showed: 1) a rapid change of the assemblage located beneath the cages related to the fish biomass reared and a high dominance of the opportunistic Capitella spp.; 2) limited sediment disturbance close to cages (20–50 m); 3) no effect in the area 50 m beyond the cages. Two months after the fish harvest and thus reduction of organic enrichment, perturbated assemblages showed signals of recovery like species richness increase and reduction of opportunistic species.     

Effect of feed and feeding in the culture of salmonids on the marine aquatic environment: a synthesis for European aquaculture

While marine aquaculture has grown rapidly, so have concerns regarding the environmental impacts caused by the industry. In particular, increasing discharges of solid and dissolved fish excretions, nutrients and therapeutic chemicals have coincided with greater public awareness of the possibility of environmental damage. This has stimulated a number of criticisms, drawn from a wide spectrum of interests, ranging from the use of natural fish stocks to produce fish meal for aqua feeds to the effects of enhanced nutrient input on the coastal marine environment. The present study reviews available information on the environmental effects of feeding practices in salmonid aquaculture in Europe. Accumulation of waste food and fish faecal material results in changes in the sediment under fish cages, characterized by a low redox potential, high content of organic material and accumulation of nitrogenous and phosphorous compounds. Although significant environmental impacts have been reported in the literature at distances of up to 100 m from the cages, in general such impacts are reported to be localized to within 20–50 m around the cages. For farmed salmon and trout, mass balance models have been developed for nitrogen and phosphorus, indicating that 50% of the nitrogen and 28% of the phosphorus supplied with the food is wasted in dissolved form. The maximum nutrient release can be estimated from the hydrographic conditions in the immediate vicinity of the farm, such as water volume, tidal water exchange and currents. At present production levels, improvements in the feeding efficiency and feed quality of aquafeeds could reduce waste and consequent environmental impacts.     

Effects of restricted feeding on growth of red sea bream and sedimentation of aquaculture wastes

For improving the economic and environmental sustainability of fish farming, it is necessary to optimize feeding regimes. From this viewpoint, we monitored the growth and mortality of red sea bream (Pagrus major), C and N fluxes and sediment chemistry at 2 commercial fish cages; cage 1 (conventional satiation feeding) and cage 2 (restricted feeding: same feeding frequency but 18% reduction in the feed amount) for 276 days. The similar specific growth rates (0.43% in cage 1 and 0.39% in cage 2) but different feed conversion efficiencies (0.54 in cage 1 and 0.62 in cage 2) and mortality (> 2-times higher in cage 1) between the 2 cages, indicate overfeeding in cage 1 culture. Elemental and stable isotopic analyses of sediment trap materials enabled the quantification of waste feed- and fecal matter-derived organic matter (OM) separately. The results shows that (1) aquaculture-derived OM comprised most of the fish-farm settling OM, excluding the period from January to April, when natural OM often accounted for a half of the bulk OM, (2) there was a difference in the seasonal trend between the fluxes of waste feed and fecal matter, and (3) there were no differences in the percentage compositions and fluxes of waste feed and fecal matter between the 2 cages. The isotopic analysis showed that the waste feed-derived OM in the sediment below cage 2 was 24% less than that below cage 1, suggesting effect of restricted feeding. Determining the relative amount of waste feed and fecal matter in settling and sedimentary OM is an effective method to evaluate the optimum feeding regime.     

Sedimentation of organic matter from fish farms in oligotrophic Mediterranean assessed through bulk and stable isotope (δ13C and δ15N) analyses

Bulk sedimentation and carbon and nitrogen stable isotopes were used to investigate the dispersion of particle waste products from 3 fish farms distributed along the Mediterranean Sea and characterized by the seagrass Posidonia oceanica growing in immediate vicinity of the fish cages. The farms were located at sites with rapid water exchange (average current speeds > 5.5 cm s^− 1) and water depths ranging from 16 to 28 m. Sedimentation traps were deployed along transects from each farm on bare and vegetated sites for 48 h during summer, where the production in the farms is at maximum. The sedimentation under the net cages was 8 to 25 times higher than at control sites located 1 km away. The farm with the largest production showed the highest sedimentation rates. Phosphorus (P) deposition rates were particularly high at all farms, and the underlying sediments were enriched in P. These results indicate that P can be used as a sensitive indicator of farm loadings. The isotopic signals (δ¹³C and δ¹⁵N) of the sediment trap materials at the control sites varied among the 3 study sites (δ¹³C − 14.9‰ to − 23.4‰ and δ¹⁵N 2.2‰ to 6.2‰), but some general trends were observed with less negative δ¹³C and more positive δ¹⁵N signals under the net cages. These signals were reflected in the underlying sediments, in particular for δ¹⁵N, suggesting that N isotopes can be used as indicators of farm waste products in traps and sediments.