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1.
We compared production variables between channel catfish, Ictalurus punctatus, nursery ponds fed according to industry standards, that is feeding immediately at stocking, to an alternative practice of delaying feeding for 6 wk after stocking in an effort to utilize natural pond productivity and reduce feed use. Twelve 0.04 ha ponds were fertilized and stocked with swim‐up fry (4–5 d posthatch) at a rate of 10,000/pond (250,000/ha). Ponds were then randomly assigned to either the standard feeding protocol (feeding daily starting immediately at stocking) or an alternative feeding protocol (no feeding until 6 wk post‐stocking). After 18 wk of production, there were no differences in water quality or zooplankton abundance between the two treatments. Fish length was not affected by treatment throughout the study, and survival and total weight harvested were similar. Total kg of feed fed was significantly reduced in the delayed feed treatment, averaging 26 kg/pond less feed fed. If proper fertilization practices are implemented, large numbers of desirable zooplankton for catfish fry culture are attained, and these zooplankton are able to sustain catfish fry stocked up to 250,000/ha. Therefore, no commercial diets are required during the first 6 wk of culture, saving over $95.55/ha in initial feed costs.  相似文献   

2.
Fish-environment relationships in ponds with several different combinations of fish species are analysed. The study was carried out in 18 earthen fish ponds in a farm at Lohamei HaGetaot, Israel, during the 1986 fish culture season. Water was analysed for temperature, dissolved oxygen, pH, ammonium, nitrite, nitrate, and phyto- and zooplankton. Factor analysis was applied to the physico-chemical and plankton datasets to identify respectively the main ecological processes and species groups in the ponds. The general linear model was applied to analyse the effect of fish species combination and month on the ecological and plankton factors identified. The main source of water quality variability was accounted for by three factors: pond loading (CHF1), oxygenation of the water (CHF2), and pH effect on the second step of nitrification (CHF3). The main source of variability in the plankton composition was due to presence or absence of a blue-green algal bloom (PLF1). Another four plankton factors were identified. Each factor was differently affected by the fish species combination in the pond and the month. The complex nets of interactions between common carp, tilapia and mullet, and how these fish in different cominations affect pond water quality and food webs are discussed.  相似文献   

3.
Abstract

One of the most important issues concerning fish-pond fertilization is the determination of the optimal amount of fertilizer to be applied to the pond system. Another important concern is the suitability of fish species for polyculture in order to optimize production. The dynamics of nutrients, phytoplankton, and fish is a complex subject and practitioners are often compelled to formulate solutions without detailed scientific and practical consideration. The primary objective of pond fertilization is to maintain an optimal nutrient concentration for sustained biological production. Current fertilization practices in the Asia-Pacific region include: a fixed rate of fertilization and fertilization based on water color. Individual pond ecology determines how fertilization affects pond productivity, not the pond's physical location in relation to international borders. There is no universal recipe of “maximal” fertilization rates due to pond-specific variability. There is also no clear guide in the literature with regard to many aspects of fish-food; the type of organisms consumed, mechanisms of food consumption, and the digestibility and nutritive value of plankton. The usual practice is to divide fish according to their foraging in natural habitats; feeding on phytoplankton, zooplankton, zoo benthos, or detritus. The distinction between different feeding habits is not always absolute as many species of fish may change food preference depending on the abundance of different food items. This paper reviews the nutrient (nitrogen, N and phosphorus, P) management in regard to pond fertilization; use of organic and inorganic fertilizer and the impacts on fish production; use of organic fertilizer from different organisms (pig, cow and buffalo) and their interactions with primary production and water quality; optimum N:P concentration in pond water; and individual pond factors and their influence on fish production. A significant interaction was evident with time between water quality variables such as pH and alkalinity, and other factors, including manure type and fish species composition. This was reflected in the difference between pig and cow manure treatments. A significant interaction between species composition and fish production has been demonstrated. Fish survival and biomass production was influenced by the stocking ratio of the: rohu, Labeo rohita; mrigal, Cirrhinus mrigala; and Nile tilapia, Oreochromis niloticus. The recommended nutrient level for pond fertilization based on the South Australian Research and Development Institute (SARDI) and Research Institute for Aquaculture No. 1 (RIA#1) study is 1 ppm N:0.5 ppm P. The required quantity of fertilizer varies significantly with time. However, regional research is highly recommended to optimize fish production focusing on significant climate variability, which affects both primary and secondary production.  相似文献   

4.
Diets containing 28% and 32% crude protein were compared for pond‐raised channel catfish Ictalurus punctatus stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48.5 g/fish were stocked into 30 0.04‐ha ponds. Five ponds were randomly allotted for each dietary protein ± stocking density combination. Fish were fed once daily to satiation for two growing seasons. There were no interactions between dietary protein concentration and stocking density for any variables. Dietary protein concentrations (28% or 32%) did not affect net production, feed consumption and weight gain per fish, feed conversion ratio, survival, processing yields, fillet moisture, protein and ash concentrations, or pond water ammonia and nitrite concentrations. Fish fed the 32% protein diet had slightly but significantly lower levels of visceral and fillet fat than fish fed the 28% protein diet. As stocking density increased, net production increased, while weight gain of individual fish, feed efficiency, and survival decreased. Stocking densities did not affect processing yield and fillet composition of the fish. Although highly variable among different ponds and weekly measurements, ponds stocked at the highest density exhibited higher average levels of total ammonia‐nitrogen (TAN) and nitrite‐nitrogen (NO2‐N) than ponds stocked at lower densities. However, stocking density had no significant effect on un‐ionized ammonia‐nitrogen (NH3‐N) concentrations, calculated based on water temperature, pH, and TAN. By comparing to the reported critical concentration, a threshold below which is considered not harmful to the fish, these potentially toxic nitrogenous compounds in the pond water were generally in the range acceptable for channel catfish. It appears that a 28% protein diet can provide equivalent net production, feed efficiency, and processing yields as a 32% protein diet for channel catfish raised in ponds from advanced fingerlings to marketable size at densities varying from 14,820 to 44,460 fish/ha under single‐batch cropping systems. Optimum dietary protein concentration for pond‐raised channel catfish does not appear to be affected by stocking density.  相似文献   

5.
Hatchery ponds were manipulated by timing of filling to increase the efficiency of production of fingerling largemouth bass, Micropterus salmoides. The effects on pond productivity of fertilizing with chicken manure versus plant meals (consisting of equal parts by weight of cottonseed meal, alfalfa meal, and wheat shorts) were also examined. When ponds were filled in stages, more favorable water temperatures for largemouth bass were achieved, and desirable dissolved oxygen concentrations were maintained. Chlorophyll a levels and plankton community respiration rates were higher in ponds that were fertilized with the plant meals than in ponds fertilized with chicken manure (25% dry matter). Secchi disk visibility was relatively greater in chicken manure ponds than in ponds fertilized with the plant meals; however all differences were not significant. Zooplankton densities were comparable among treatments. Filling ponds in stages had no significant effects on chlorophyll a, plankton community respiration rate, Secchi disk visibility, or zooplankton abundance and population dynamics. Daily production of largemouth bass was greater in ponds filled in stages and fertilized with plant meals than in other treatment ponds. Yield was highest in stage-filled ponds fertilized with plant meals and lowest in full ponds fertilized with chicken manure. Filling ponds in stages reduced the fertilizer cost per kilogram of largemouth bass by 50% in ponds fertilized with plant meals and by 65% in manure-fertilized ponds.  相似文献   

6.
Many fish culturists are interested in applying copper sulfate pentahydrate (CSP) to channel catfish, Ictalurus punctatus, nursery ponds as a prophylactic treatment for trematode infection and proliferative gill disease by killing snails and Dero sp., respectively, before stocking fry. However, copper is an algaecide and may adversely affect phytoplankton and zooplankton populations. We evaluated the effects of prophylactic use of copper sulfate in catfish nursery ponds on water quality and phytoplankton and zooplankton populations. In 2006, treatments of 0 mg/L CSP, 3 mg/L CSP (0.77 mg/L Cu), and 6 mg/L CSP (1.54 mg/L Cu) were randomly assigned to 0.04‐ha ponds. In 2007, only treatments of 0 and 3 mg/L CSP were randomly assigned to the 16 ponds. Ponds treated with CSP had significantly higher pH and significantly lower total ammonia concentrations. Treatment of both CSP rates increased total algal concentrations but reduced desirable zooplankton groups for catfish culture. CSP has been shown to be effective in reducing snail populations at the rate used in this study. CSP treatment also appears to be beneficial to the algal bloom, shifting the algal population to green algae and increasing total algal biomass within 1 wk after CSP treatment. Although zooplankton populations were adversely affected, populations of important zooplankton to catfish fry began rebounding 6–12 d after CSP treatment. Therefore, if CSP is used to treat catfish fry ponds of similar water composition used in this study, fry should not be stocked for about 2 wk after CSP application to allow time for the desirable zooplankton densities to begin increasing.  相似文献   

7.
该文采用生态学试验方法,对鳜池塘和大棚养殖模式的水质变化规律进行了调查分析,同时采用不同微生态制剂商品(光合细菌、枯草芽孢杆菌、乳酸菌)对鳜养殖水体水质调节效果进行了研究。结果显示,整个鳜养殖周期(苗种至商品鱼),大棚养殖模式水体温度、溶氧、pH值与池塘养殖模式无明显区别;大棚养殖模式三氮(铵态氮、硝态氮、亚硝态氮)变化规律与池塘养殖模式大致相同,但大部分时间前者水体含量较高;大棚养殖模式水体总磷含量高于池塘养殖模式,且总磷最高值出现时间较池塘养殖模式推迟了近1个月。光合细菌对鳜养殖水体氨氮、亚硝态氮以及总氮整体调控效果最佳;枯草芽孢杆菌对降低硝态氮和亚硝态氮有良好的效果;乳酸菌对养殖后期降低水体pH值有一定的作用。结论:相对于鳜池塘养殖模式,大棚养殖模式氮磷物质循环转化效率较低,合理搭配使用微生物制剂调节水质养殖效果更佳,同时需注意不良天气对微生态制剂使用效果的影响。  相似文献   

8.
Four different fertilization frequencies, namely twice per week, once per week, twice a month and once a month, were used in ponds to assess their effects on nutrient release, pond productivity and fish biomass. All ponds received the same total fertilizer inputs during the experimental period of 60 days (cow dung 208.3 kg ha?1 week?1, TSP 9.8 kg ha?1 week?1, urea 6.0 kg ha?1 week?1). Studies have revealed that the highest values of fish biomass, specific growth rate (SGR), net primary productivity (NPP), plankton population and nutrients were observed in the ponds that were fertilized twice a month. A strong and significant correlation of fertilization frequency was observed with dissolved oxygen, biochemical oxygen demand (BOD), alkalinity, nutrient release, NPP, plankton density (no. L?1), fish biomass and SGR. The linear relationship between NPP and fish biomass/SGR for all the ponds was strong (r2= 0.88). Sediment chemistry revealed that O‐PO4, NO3‐N, organic carbon and electrical conductivity (EC) increased significantly (P<0.05) with a decrease in the frequency of fertilization, while alkalinity and calcium were high in ponds that were fertilized twice a month.  相似文献   

9.
To quantitatively define relationships among stocking densities, feeding rates, water quality, and production costs for channel catfish, Ictalurus punctatus, grown in multiple‐batch systems, twelve 0.1‐ha earthen ponds were stocked at 8,600, 17,300, 26,000, or 34,600 fingerlings/ha along with 2,268 kg/ha of carryover fish. Fish in all ponds were fed daily to apparent satiation using 32% protein floating feed. Temperature and dissolved oxygen in each pond were monitored twice daily; pH weekly; nitrite‐N, total ammonia nitrogen, and Secchi disk visibility every 2 wk; nitrate‐N, chlorophyll a, total nitrogen, total phosphorus, and chemical oxygen demand monthly; and chloride every other month. The costs of producing channel catfish at different stocking densities were estimated. There were no significant differences (P > 0.05) as a result of stocking density among treatment means of (1) gross or net yields, (2) mean weights at harvest, and (3) growth or survival of fingerlings (24–36%) and carryover fish (77–94%). Mean and maximum daily feeding rates ranged from 40 to 53 kg/ha/d and 123 to 188 kg/ha/d, respectively, and feed conversion ratios averaged 1.75. There were no differences in any feed‐related parameter as a result of density. Water quality variables showed few differences among densities at samplings and no differences when averaged across the production season. Yield of fingerlings increased as stocking density increased with significant differences between the two highest and the two lowest stocking densities. Breakeven prices were lower at the higher stocking densities as a result of the higher yield of understocked fish and similar mean individual fish weights produced at these higher stocking densities. Overall, varying stocking densities of fingerlings in multiple‐batch systems had little effect on production efficiency and water quality. Additional research on managing the population structure of carryover fish in commercial catfish ponds may be warranted.  相似文献   

10.
The effects of pond fertilization and feeding rate on growth, economic returns and water quality were investigated to develop a low‐cost cage‐cum‐pond integrated system for production of Oreochromis niloticus (L.). Hand‐sexed male fingerlings averaging 19±0.39 and 32±0.69 g were stocked in cages and open ponds at 150 fish cage?1 and 2 fish m?2 respectively. Fish were cultured for 114 days in five triplicate treatments. Cages were installed into ponds and caged fish were fed a 24% protein diet at 3% (T1) and 6% (T2) body weight day?1 (BWD) without pond fertilization, and 6% BWD with pond fertilization (T3). The open water in the fourth treatment (T4) was not stocked but contained caged fish, which were fed 6% BWD for the first 57 days followed by 3% BWD for the remaining period. Ponds in the control (T5) had no cages and were neither fertilized nor open‐pond fish fed. Feeding rate and pond fertilization significantly (P<0.05) affected fish growth, profitability and water quality among treatments. Fish growth, feed utilization, fish yield, water quality and profits were significantly (P<0.05) better in T3 than the other treatments. It was concluded that fish production and economic returns were optimized at 6% BWD in fertilized ponds.  相似文献   

11.
An environmental assessment was made of Alabama channel catfish Ictalurus punctatus farming which is concentrated in the west‐central region of the state. There are about 10,000 ha of production ponds with 10.7% of the area for fry and fingerlings and 89.3% for food fish. Food fish production was about 40,800 tons in 1997. Watershed ponds filled by rainfall and runoff make up 76% of total pond area. Water levels in many of these ponds are maintained in dry weather with well water. The other ponds are embankment ponds supplied by well water. Harvest is primarily by seine‐through procedures and ponds are not drained frequently. The main points related to Alabama catfish farming and environment issues are as follows: 1) catfish farming in Alabama is conservative of water, and excluding storm overflow, about two pond volumes are intentionally discharged from each pond in 15 yr; 2) overflow from ponds following rains occurs mostly in winter and early spring when pond water quality is good and stream discharge volume is high; 3) total suspended solids concentrations in pond effluents were high, and the main sources of total suspended solids were erosion of embankments, pond bottoms, and discharge ditches; 4) concentrations of nitrogen and phosphorus in effluents were not high, but annual effluent loads of these two nutrients were greater than for typical row crops in Alabama; 5) ground water use by the industry is about 86,000 m3/d, but seepage from ponds returns water to aquifers; 6) there is little use of medicated feeds; 7) copper sulfate is used to control blue‐green algae and off‐flavor in ponds, but copper is rapidly lost from pond water; 8) although sodium chloride is applied to ponds to control nitrite toxicity, stream or ground water salinization has not resulted from this practice; 9) fertilizers are applied two or three times annually to fry and fingerling ponds and occasionally to grow‐out ponds; 10) hydrated lime is applied occasionally at 50 to 100 kg/ha but this does not cause high pH in pond waters or effluents; 11) accumulated sediment removed from pond bottoms is used to repair embankments and not discarded outside ponds; 12) sampling above and below catfish pond outfalls on eight streams revealed few differences in stream water quality; 13) electricity used for pumping water and mechanical aeration is only 0.90 kW h/kg of production; 14) each metric ton of fish meal used in feeds yields about 10 tons of dressed catfish. Reduction in effluent volume through water reuse and effluent treatment in settling basins or wetlands does not appear feasible on most farms. However, some management practices are recommended for reducing the volume and improving the quality of channel catfish pond effluents.  相似文献   

12.
A grow‐out monoculture experiment for rohu, Labeo rohita was conducted for 1 year in nine earthen ponds of 0.04 ha each to study the impact of varied frequency of nitrogen fertilization on fish growth. Ponds were stocked at 8000 fingerlings ha?1 density. While ponds were applied with cattle manure and phosphate fertilizer at conventional dosages followed for grow‐out carp culture, nitrogen fertilization was carried out at 15‐, 10‐ and 7‐day intervals and were designated as treatments T‐1, T‐2 and T‐3 respectively. Although all the water parameters in the treatments were within the suitable range for grow‐out carp farming, annual average concentration of dissolved oxygen (DO), plankton as well as availability of nutrients such as total ammonia‐ and nitrate‐nitrogen in ponds were significantly higher in T‐3 compared with T‐1 and T‐2. Greater fluctuation of critical parameters like DO, plankton concentration and total ammonia nitrogen were observed in T‐1 and T‐3 while the same were more consistent in T‐2, revealing the prevalence of a better growing environment in the latter. Fish in T‐2 also showed better specific growth rate, higher body weight attainment and higher biomass yield compared with the other two treatments, revealing the desirability of nitrogen fertilization at 10‐day intervals in carp culture.  相似文献   

13.
Several significant differences in water quality, primary production, production of plankton, or yield of striped bass, "Morone saxatilis," fingerlings were found between ponds fertilized with either rice bran and inorganic fertilizer or those ferilized with cottonseed meal and inorganic fertilizer. Ponds fertilized with rice bran had the lowest ammonia concentrations and Secchi disc readings and the highest concentrations of cladocerans and crustracean zooplankton. At harvest, after 82 days of culture, striped bass fingerlings from ponds fertilized with rice bran were significantly larger than were those from ponds fertilized with cottonseed meal. Numbers of fingerlins produced per hectare did not differ by treatment but ferilizer cost were US$94.78/ha less for ponds fertilized with rice bran.  相似文献   

14.
There is increasing interest in intensive production of Ictalurid catfish in the United States and a better understanding of water quality dynamics in intensive culture is needed. Budgets for water, nitrogen, and phosphorus were estimated over a production season (March–November) for an In‐pond Raceway System for channel catfish, Ictalurus punctatus, and hybrid catfish, I. punctatus×I. furcatus, with co‐culture of paddlefish, Polyodon spathula, and Nile tilapia, Oreochromis niloticus. In addition to the rainfall and runoff, 70 cm of water was applied from a well to offset evaporation and seepage. Production of each kilogram of live catfish required 1.50 kg of feed and released 51.7 g nitrogen and 9.7 g phosphorus. Harvest of catfish accounted for 34.0% of nitrogen and 37.1% of phosphorus applied in feed. Seepage and overflow removed only small portions of nitrogen and phosphorus, while denitrification and ammonia volatilization removed large amounts of nitrogen. Some nitrogen accumulated in sediment. Phosphorus was harvested in fish and absorbed by pond sediment. Mechanical aeration aided in maintaining appropriate dissolved oxygen levels for fish production.  相似文献   

15.
In carnivorous fish species, zooplankton is one of the main food items in the early life stages and some fish species continue feeding on such food items further along the life stages even in the farming environment. In this study, the intake of natural food items was assessed in juvenile pirarucu Arapaima gigas reared in earthen ponds. Juvenile pirarucu (12.2 ± 4.32 g and 12.1 ± 1.13 cm) were stocked in fertilized earthen ponds (240 m²). For the analysis of the fish stomach content and plankton in the pond water, the fish and pond water were sampled weekly for 75 days and biweekly until the fish reached a mean weight of 750 g. Although artificial feed was used, pirarucu also ingested the natural food available in the pond water. Among the zooplankton, pirarucu demonstrated feeding preference for cladocerans despite the abundance of rotifers and copepods. Cladocerans were present in more than 80% of the stomach contents of fish up to 300 g and in 65%, 45% and 17% of fish of 301–500 g, 501–700 g and 701–900 g respectively. Copepods were present only in fish up to 500 g at low abundance. High ingestion of insects and plant material was observed in the stomach content of fish of all size classes. The results demonstrate that juvenile pirarucu ingest natural food available in the farming pond and suggests that the adoption of pond fertilization practices may have positive effects on fish growth performance.  相似文献   

16.
监测了公安县崇湖渔场3口草鱼主养池塘施用浓度为0.375 g/m3的二氧化氯后池塘水质理化指标及浮游生物群落结构短期变化,以分析二氧化氯对池塘水环境质量的影响。结果显示,用药后水体溶解氧显著下降,亚硝态氮、活性磷和总磷降低。然而p H值显著升高,硝态氮、铵态氮和总氮也有所升高。施用二氧化氯前浮游植物共检出6门44属79种,浮游动物36属43种;用药后共检出浮游植物7门52属109种,浮游动物44属69种,用药后浮游植物消失4属12种,新增加12属42种,用药前未见金藻门种类,用药后出现分歧锥囊藻(Dinobryon divergens)。用药后原生动物消失6属7种,新出现16属24种;轮虫消失3种,增加8种;枝角类种类无变化;桡足类新增4种成体,但用药前后优势种无变化。结果表明,施用二氧化氯短期内增加了水体氨氮毒性,并导致浮游动物的种类、密度和生物量显著增加,进而导致浮游植物生物量显著下降、小型化藻类增多、优势种显著变化。建议在养殖期间慎用二氧化氯。  相似文献   

17.
Two mesocosm experiments were conducted to study the interaction of a commercial oyster‐nursery system with the surrounding embayment, specifically, nutrient and plankton dynamics. The nursery was stocked with 80–200 L of oysters, sized 3–5 mm. Ambient water and the water passed through the oyster nursery were incubated in mesocosms, and nutrients and plankton were monitored over the course of 27‐h incubations. The first experiment conducted in July 2009 captured a phytoplankton community dominated by Peridinium quinquecorne, a rare dinoflagellate not previously reported in the northeastern USA. Dissolved nitrogen compounds in all mesocosms were depleted within the first 6 h. The second experiment was conducted in September 2009, when a more typical and diverse phytoplankton community was present. Unlike the first experiment, Nitrate plus nitrite in the mesocosms was not depleted. Both experiments indicated little difference between the water passed through the oyster nursery and the ambient water in terms of subsequent nutrient and plankton dynamics, indicating little ‘legacy effect’ of the oyster nursery upon nutrients and plankton in this embayment. This conclusion was reached under the specific operating conditions typical for this nursery system, as chosen by the commercial partner in the study; changes in oyster stocking or flow rate are likely to change the results.  相似文献   

18.
塘田联作对池塘水质及罗氏沼虾生长的影响   总被引：1，自引：0，他引：1  
为探索节能减排的池塘养殖新模式,开展了罗氏沼虾(Macrobrachium rosenbergii)-水稻塘田联作试验。以罗氏沼虾-水稻联作试验塘和罗氏沼虾单养对照塘各1口为研究对象,监测池塘的主要水环境因子动态及罗氏沼虾生长指标,分析塘田联作模式对池塘水质及罗氏沼虾生长的影响。试验塘被改造为养殖区与稻田两部分以模拟塘田联作,每部分面积各占50%。水稻于2018年4月22日机栽完毕,5月12日放养虾苗,6月28日起进行水质和生长监测。结果显示:1)试验期间试验塘平均水温比对照塘低0.82℃;2)试验塘水体无机氮(NH4+-N、NO2--N、NO3--N)、活性磷酸盐-磷(PO43--P)、总悬浮颗粒物(TPM)、颗粒有机物(POM)、颗粒无机物(PIM)浓度、化学需氧量(COD)和变异系数(CV)在整个养殖期间均低于对照塘,且NH4+-N、COD与对照塘差异显著(P<0.05),而对照塘对应水质指标在养殖后期均出现大幅升高;3)试验塘特定生长率和增重率分别为3.07%·d-1和459.40%,而对照塘分别为2.86%·d-1和397.44%。结果表明,塘田联作能降低夏季高温期池塘水温及水体氮(N)、磷(P)浓度与COD,并保持水质稳定,促进罗氏沼虾的生长。  相似文献   

19.
The effect of Chinese waterchestnut (Eleocharis dulcis) on production of channel catfish (Ictalurus punctatus) and resulting water quality were studied in 1975 in 0.04-ha earthen ponds at Clemson University. Ponds containing waterchestnut had significantly lower levels of nitrate nitrogen and ammonia nitrogen. These lower nitrient levels resulted in lower phytoplankton levels in ponds with waterchestnut.Data indicated that Chinese waterchestnut had no effect on channel catfish production. Poor fish survival may have prevented detection of any effect of waterchestnut on catfish production.Chinese waterchestnut removed nutrients from the pond water. Mean nutrient removal per ha for the 201-day growing season was 108.06 kg of nitrogen, 6.90 kg of calcium, and 37.46 kg of magnesium. Mean corm production was 4664 kg per ha. These data indicate that Chinese waterchestnut should remove nutrients in sufficient quantities to improve water quality and allow increases in feeding rates and greater catfish production.  相似文献   

20.
微生物群落是养殖池塘生态系统的重要组成部分,了解环境微生物群落结构和功能,可有针对性地进行养殖环境微生态调控。在不同季节采集尼罗罗非鱼（Oreochromis niloticus）和斑点叉尾鮰（Ictalurus punctatus）池塘水样,分析硝酸盐氮(NO3-N)、亚硝酸盐氮(NO2-N)、氨氮(NH4-N)、总氮(TN)和总磷(TP)等理化指标,利用Biolog-Eco微平板技术分析水体中微生物对各类碳源代谢的平均颜色变化率,利用高通量测序技术分析其菌群结构。结果表明,1月淡水养殖池塘水质和菌群结构不同于其他采样时间,养殖鱼类种类对池塘理化指标和微生物菌群结构影响不大。不同采样时间的池塘理化指标差异显著,同一采样时间不同养殖鱼类池塘的理化指标之间无显著差异。其中,1月尼罗罗非鱼池塘中的NH4-N含量高于其他月份,且显著高于4月和7月（P<0.05）;1月TP含量显著高于4月、7月和10月（P<0.05）。1月斑点叉尾鮰池塘的TP和NO3-N含量显著高于其他3个月份（P<0.05）。Biolog-Eco微平板技术检测到尼罗罗非鱼和斑点叉尾鮰池塘中的微生物群落对碳...  相似文献   

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