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1.
This study quantified the accumulation of nitrogen (N) in the water column, sediments, fish and seepage water during a production cycle of Colossoma macropomum. By combining estimates of the deposition rates of uneaten feed, faeces and dead phytoplankton with measurements of N accumulation in the sediment, the rate of decomposition of organic matter in the sediment was estimated. The first‐order rate constant for organic matter decomposition was 0.237±0.019 day?1. Total N recovery during the first weeks of the experiment was about 65%. Later, the N recovery was close to 100%. The cumulative recovery at the end of the experiment was almost 100%, meaning that the N budget in the system studied can be fully explained without consideration of N volatilization, due to either denitrification or ammonia volatilization. In the beginning of the growth cycle, the major flux of N was sedimentation. Intensive microbial degradation process occurred about 3–4 weeks later, leading to a release of inorganic N and an approach towards a steady state as to the accumulation of organic N. Feed was irregularly applied during the experiment but fish growth was constant, showing that the fish utilized detrital or planktonic feed during periods of low feeding. Nitrogen accumulated in the pond during periods of excessive feeding and was utilized by the fish during periods of low feeding. This cycling should be further studied and may be an important pond management technique.  相似文献   

2.
A participatory on-farm study was conducted to explore the effects of food input patterns on water quality and sediment nutrient accumulation in ponds, and to identify different types of integrated pond systems. Ten integrated agriculture-aquaculture (IAA) farms, in which ponds associate with fruit orchards, livestock and rice fields were monitored in the Mekong delta of Vietnam. Pond mass balances for nitrogen (N), organic carbon (OC) and phosphorus (P) were determined, and pond water quality and sediment nutrient accumulation were monitored. Data were analyzed using multivariate canonical correlation analysis, cluster analysis and discriminant analysis. The main variability in pond water quality and sediment nutrients was related with food inputs and water exchange rates. Water exchange rate, agro-ecological factors, pond physical properties and human waste input were major variables used to classify ponds. Classification was into: (1) low water exchange rate ponds in the fruit-dominated area, (2) low water exchange rate ponds in the rice-dominated area receiving homemade feed, and (3) high water exchange rate ponds in the rice-dominated areas receiving wastes. Pond water exchange rate was human-controlled and a function of food input patterns, which were determined by livelihood strategies of IAA-households. In the rice-dominated area with deep ponds, higher livestock and human wastes were found together with high water exchange rates. In these ponds, large organic matter loads reduced dissolved oxygen and increased total phosphorus concentrations in the water and increased nutrient (N, OC and P) accumulation in the sediments. In the rice-dominated area with wide ponds, higher homemade feed amounts were added to the ponds with low water exchange rate. This resulted in high phytoplankton biomass and high primary productivity. The contrary occurred in the fruit-dominated area, where fish were grown in shallow and narrow ponds, receiving more plant residue which resulted in lower phytoplankton biomass and lower sediment nutrient accumulation.  相似文献   

3.
Sediment cores were collected from 7-yr-old, 20- to 25-yr-old, and 30- to 35-yr-old ponds at a bait minnow farm at Lonoke, Arkansas, USA. Average depths of soft sediment (S and M horizons) were 8 cm in young ponds, 12 em in intermediate-age ponds, and 26 cm in old ponds. Organic carbon concentrations in sediment were low to moderate (1–2%) and carbon to nitrogen ratios were wide (20–50). Phosphorus and sulfur concentrations increased as ponds aged. Most of the phosphorus (78.9%) was in organic form, but sulfur was primarily inorganic in form (presumably iron sulfide). There appears to be two major problems associated with sediment accumulation over time. Deep, soft sediment interferes with pond management and especially with harvest. High phosphorus concentration in old sediment may contribute to dense phytoplankton blooms by supplying phosphorus to the water. Sodium nitrate treatment did not increase the rate of sediment organic matter decomposition in laboratory trials and would not be expected to enhance the degradation of sediment organic matter in ponds. The best method for improving the condition of bottoms in older bait minnow ponds probably is to remove the sediment.  相似文献   

4.
Selected water quality variables were measured at monthly intervals for 1 yr in 10 commercial channel catfish ponds in northwest Mississippi. Temporal changes in most variables appeared to be related to seasonal periodicity of phytoplankton abundance. Phytoplankton standing crops and total organic matter were highest in summer months when primary production was favored by warm water temperatures, high solar irradiance, and large inputs of nutrients resulting from high summer fish feed allowances. As day length, water temperature, and feed inputs decreased in autumn and winter, phytoplankton abundance and organic matter concentrations decreased. Seasonal changes in total nitrogen and total phosphorus concentrations were similar to phytoplankton abundance because much of the total nitrogen and phosphorus was contained within phytoplankton cells. Contrasting to the seasonal trend for total nitrogen, concentrations of dissolved inorganic nitrogen were lowest in the summer and highest in the cooler months. Rapid assimilation by phytoplankton served to maintain relatively low concentrations of dissolved inorganic nitrogen during the summer despite highest nitrogen loading rates during that period. Low water temperatures and generally less favorable conditions for phytoplankton growth decreased rates of nitrogen assimilation in the winter and ammonia, nitrite, and nitrate accumulated. Soluble reactive phosphorus concentrations were low throughout the year because physico-chemical processes, such as precipitation and adsorption to bottom muds acted to continually remove inorganic phosphorus from the water column.  相似文献   

5.
An experiment was conducted in six earthen ponds with 20 shrimp/m2 ( Litopenaeus stylirostris ) during the cold season in New Caledonia to determine the effect of water exchange rate on characteristics of effluents and pond sediment. The nitrogen budget was established, taking into account the different forms of nitrogen in the water, sediment, feed, and shrimp. Mean water exchange rates ranged from 10 to 23% per day. Increasing water exchange rate did not cause any significant change in the average quality of the rearing environment (water and sediment) during the whole growout period. However, the results showed that increasing exchange rates boosted primary productivity. Compounds produced by the mineralisation and metabolism of organic matter (feces, uneaten feed) were exported as particulate, rather than soluble matter. The nitrogen budget showed that the amount of exported wastes from the pond into the coastal environment was only 40–50% of nitrogen inputs due to nitrogen accumulation in the pond sediments and/or release to the atmosphere. The highest accumulation of dry material, as well as the highest Δ N (concentration of total N at the end of rearing - concentration of total N before rearing), was observed in ponds with the highest WER.  相似文献   

6.
Sediment depth and organic carbon (OC) concentration were measured in sediment cores (n=675) collected from 45 commercial channel catfish ponds in northwest Mississippi from April to September in 1998 and 1999. Ponds had been in continuous catfish production from 14 days to 21 years. Sediment depth ranged from 1 to 95 cm and was heterogeneously distributed within ponds: least in the shallow end (26.3 cm) and greatest in deeper areas (33.7 cm). Mean sediment depth increased with pond age, although the rate of sediment accumulation was greatest in the first year (12.5 cm per year). Organic carbon concentration varied slightly within ponds ranging from 0.76 to 3.43% of dry matter (DM). Mean organic carbon concentration in the upper 2 cm of sediment (1.77%) was significantly greater than in the deeper sediment layer (1.55%). Mean dry matter content in the upper 2 cm of sediment averaged 24.2% of total wet weight. Mean dry matter for the lower sediment fraction was 37.8% of total wet weight. Despite large inputs of organic matter from feed and primary production, sediment organic carbon concentrations did not increase with pond age.  相似文献   

7.
In fish production under organic standards, only organic feeds and manures can be supplied. The cost of organic pelleted feeds is twice that of regular feeds. To support the organic production of hybrid tilapia [Oreochromis niloticus (L.) ×Oreochromis aureus (Steindachner)], a series of experiments in earthen ponds, to improve natural food production for this fish while reducing costs of added feed, are in progress. To improve natural food production for tilapia, plastic substrates equivalent to 50% of the pond surface were introduced into the water column to induce periphyton growth on them. To reduce costs, the feeding rate on pelleted feed was reduced to 60%. Tilapia growth in these periphyton ponds was then compared with ponds without underwater substrates that received the full feed rate. The polyculture consisted of 90% large (320 g stocking weight) hybrid tilapia and small amounts of other fish, at a total stocking density of 13 800 fish ha?1, during 87 summer days. The results showed improved nitrification and the development of a large autotrophic periphyton biomass that competed with the phytoplankton in the periphyton ponds, and only a 10% and 15% reduction, respectively, in the tilapia daily and specific growth rates, with 40% feed saving. These results point towards periphyton‐based aquaculture as an appropriate technology for the reduction in production costs, allowing economically viable organic tilapia production.  相似文献   

8.
Commercial intensive aquaculture systems werebuilt and are managed in a somewhat differentway in each farm. To evaluate the effects ofseveral management procedures on water qualityin intensive fish ponds, data from severallocations, times and culture conditions indifferent farms were collected and are hereinanalyzed through multivariate statistics. Water quality in the intensive ponds depends onthe water entering, the biological processeswithin, and the water leaving the ponds. Areservoir used as source and sink water supplied theintensive ponds with higher organic loadingthan clear source waters, and its phytoplanktoncontent affected nitrogen cycling within theintensive ponds. The systems with a reservoirhad better water quality in the intensive pondsthan those with only clean source water. Within the ponds (1) compared to paddle-wheelaeration, aeration by pure oxygen increasedoxygen concentration, improved nitrificationand promoted decomposition that reduced organicloading. (2) In concrete ponds accumulation oforganic matter and development of anerobicconditions on the pond bottom was higher thanin the slippery plastic-covered ponds. (3) Allintensive ponds provided good growthconditions, tilapia biomass having relativelysmall influence on water quality. Only inpaddle-wheel aerated ponds did increased tilapiabiomass increased inorganic nitrogen compoundsand soluble phosphorus through excretion, andreduce organic nitrogen through a moreefficient removal of food particles. Water leaving the ponds removes matteraffecting water quality within the pond. (1)Draining sediments accumulated on the bottomavoided development of anaerobic conditionswhere denitrification and phosphorus liberationcan occur. (2) Water exchange removed particleswith nitrifying bacteria and algae that absorbnutrients. A high water exchange rate may havea negative effect from the water quality pointof view and from the extra costs incurred inenergy and feeds washed out. The processes described occur simultaneouslythroughout the culture period and shape waterquality dynamics in the ponds. This researchcontributed to the understanding of howmanagement procedures affect the differentphases of water quality dynamics in real-scaletilapia commercial intensive systems.  相似文献   

9.
Commercial intensive aquaculture systems werebuilt and are managed in a somewhat differentway in each farm. To evaluate the effects ofseveral management procedures on water qualityin intensive fish ponds, data from severallocations, times and culture conditions indifferent farms were collected and are hereinanalyzed through multivariate statistics.Water quality in the intensive ponds depends onthe water entering, the biological processeswithin, and the water leaving the ponds. Areservoir used as source and sink water supplied theintensive ponds with higher organic loadingthan clear source waters, and its phytoplanktoncontent affected nitrogen cycling within theintensive ponds. The systems with a reservoirhad better water quality in the intensive pondsthan those with only clean source water.Within the ponds (1) compared to paddle-wheelaeration, aeration by pure oxygen increasedoxygen concentration, improved nitrificationand promoted decomposition that reduced organicloading. (2) In concrete ponds accumulation oforganic matter and development of anerobicconditions on the pond bottom was higher thanin the slippery plastic-covered ponds. (3) Allintensive ponds provided good growthconditions, tilapia biomass having relativelysmall influence on water quality. Only inpaddle-wheel aerated ponds did increased tilapiabiomass increased inorganic nitrogen compoundsand soluble phosphorus through excretion, andreduce organic nitrogen through a moreefficient removal of food particles.Water leaving the ponds removes matteraffecting water quality within the pond. (1)Draining sediments accumulated on the bottomavoided development of anaerobic conditionswhere denitrification and phosphorus liberationcan occur. (2) Water exchange removed particleswith nitrifying bacteria and algae that absorbnutrients. A high water exchange rate may havea negative effect from the water quality pointof view and from the extra costs incurred inenergy and feeds washed out.The processes described occur simultaneouslythroughout the culture period and shape waterquality dynamics in the ponds. This researchcontributed to the understanding of howmanagement procedures affect the differentphases of water quality dynamics in real-scaletilapia commercial intensive systems.  相似文献   

10.
Abstract. The application of different combinations and levels of pellet formulated feed and chicken manure to ponds stocked with Macrobrachium rosenbergii (de Man) did not result in any significant differences in water quality, sediment chemistry, or benthic macroinvertebrate populations. Water chemistry data indicated that all ponds were eutrophic. Chlorophyll was strongly correlated with total nitrogen, but not with total phosphorus, suggesting that nitrogen limited algal biomass. There was evidence that added organic matter was rapidly decomposed and mineralized. The sediments appeared to act alternately as sources and sinks of nutrients, although there was least variation in sediment nutrient levels in the treatment which received manure only. Applied pelleted feed was directly consumed by the prawns. In the absence of pelleted feeds, macrobenthos appeared to limit prawn growth after 1 month of culture. Simple nutrient mass-balance equations indicated that the losses of nitrogen, phosphorus and carbon from the treatments receiving feed were not dissimilar to previously reported values in finfish culture.  相似文献   

11.
张玉平  刘金金  张芬 《中国水产科学》2020,27(12):1448-1463
为综合评估上海地区池塘沉积物环境质量状况,2016-2019年对上海地区36个养殖场池塘采集沉积物样品360个,检测和分析沉积物中总氮（TN）、总磷（TP）、总有机碳（TOC）及重金属Cu、Zn、Pb、Cd、Cr、Hg和As含量。研究结果表明,池塘0~10 cm层和10~20 cm层沉积物中TN、TP、TOC及各重金属均值分布无显著差异（P>0.05）,0~20 cm层沉积物（干重）中TN、TP和TOC平均含量分别为（873.37±352.45）mg/kg、（685.66±199.66）mg/kg和（6.62±3.05）mg/g,三者相关性显著。综合污染指数法和有机指数法评价结果表明,池塘沉积物中氮和有机物质的累积量较低,磷累积量相对较高,均低于其他地区高产池塘。池塘沉积物中Cr、Cd、Cu和Hg样品超标率分别为6.42%、3.21%、4.13%和1.38%,Zn、Pb和As无超标现象。地质累积指数、潜在生态危害指数法和一致性沉积物质量基准评价结果表明,上海地区池塘沉积物中重金属整体上处于清洁等级、低潜在生态危害状态,预测不会引发生物毒性效应。  相似文献   

12.
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.  相似文献   

13.
Annual sedimentation, re-suspension rates and contents of particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP) in the sediment were investigated in two sea cucumber culture ponds at Rongcheng, Shandong Province, China. The results showed that the average flux of total particulate matter in the ponds was 22.1 g m2 d−1. The average re-suspension rate of the sediment in the ponds was 81.7%. The re-suspension rates in spring and autumn were higher than those in summer and winter. The mean contents of POC, PON and TP in the sediment of the ponds were 4.4, 0.5 and 0.6 (mg g−1), respectively, and the mean contents of Chlorophyll a (Chl a) and pheophytin in the sediment were 8.1 and 12.1 μg g−1 respectively. The POC, PON and TP contents in the sediment of the ponds increased during the period of sea cucumber aestivation (summer) and hibernation (winter), while they decreased during the feeding periods. The organic matter accumulation rate and the contents of POC, PON, TP, Chl a and pheophytin in the sediment were even lower than those in the pond without sea cucumber (P<0.05). The results demonstrated that sea cucumber culture can effectively stop nutrient accumulation at the bottom of the cucumber culture ponds.  相似文献   

14.
海水鱼类网箱养殖水域沉积物有机质的来源甄别   总被引：4，自引：1，他引：3  
利用稳定碳氮同位素示踪技术,对南沙港网箱养殖水域沉积物中有机质的来源进行了分析研究。结果表明,网箱养殖区(距离网箱边缘100 m范围内)及对照区(距离网箱边缘大于500 m)沉积物的δ13C值分别为(-17.72±1.2)‰和(-12.73±0.38)‰,δ15N分别为(6.44±0.2)‰和(5.61±0.2)‰。网箱养殖区沉积物的有机质来源主要为残饵和鱼类粪便,比例分别占47.70%和27.71%。随着与养殖网箱距离的增加,网箱养殖源有机质(残饵和鱼类粪便之和)的比例降低,变化趋势符合指数方程y=97.167e-0.007 4x(R2=0.848 1),在潮流驱动的沉积物再悬浮及野生鱼类的扰动影响下,网箱养殖源有机质的水平位移可达400 m。鱼类网箱养殖的养殖废物是南沙港水域沉积物有机污染的主要来源。  相似文献   

15.
The effects of introducing common carp (CC) and of adding artificial feed to fertilized rohu ponds on water quality and nutrient accumulation efficiency were studied. All ponds were stocked with 15 000 rohu ha?1. Treatments included ponds with rohu alone, rohu plus 5000 common carp ha?1 and rohu plus 10 000 CC ha?1. A comparison was also made between supplementally fed and non‐fed ponds. The overall highest nitrogen (N) and phosphorus (P) concentrations were observed in ponds with 5000 CC ha?1, followed by ponds with 10 000 and 0 CC ha?1. The largest fractions of N and P inputs accumulating in fish, phytoplankton and zooplankton were observed in ponds with 5000 CC ha?1, followed by ponds with 10 000 CC ha?1 and subsequently ponds without CC. Relatively more nutrients accumulated in benthic organisms in ponds without than in ponds with CC. A smaller fraction of the nutrient input was retained in fish, plankton and benthic organisms in ponds without CC compared with ponds with CC. Compared with 5000 CC ha?1, stocking 10 000 CC ha?1 can be considered as overstocking, because this leads to lower fish production and relatively less nutrients retained in plankton and benthic organisms.  相似文献   

16.
为了修复对虾养殖池塘的养殖环境。从昌黎、乐亭、黄骅等3地的对虾池塘中取底泥,共分离出215种细菌．通过其对对虾饵料和蛤蜊内降解能力的测定,筛选出9株虾池有机污染降解茵。这些菌株能以对虾饵料作为生长的唯一碳源和氮源。并且对对虾的配合饵料和蛤蜊肉具有较强的降解能力。通过7d的培养。有4株细菌对对虾的饵料的COD去除率约70％。对蛤蜊肉的COD去除率超过50％,其他5株细菌对对虾饵料及蛤蜊肉的COD去除率也在30％以上。结果表明。这些细菌能快速消除对虾池塘的有机污染,具有修复虾池环境的潜力。  相似文献   

17.
Sediment oxygen demand (SOD) measured in 45 commercial channel catfish ponds in northwest Mississippi using in situ respirometry ( N = 167) ranged from 63 to 1,038 mg/m2 per h. Mean SOD in this study (359 mg/m2 per h) was greater than that reported previously for catfish ponds but was similar to SOD in semi-intensive marine shrimp ponds. Nine variables were selected and measured to assess their relative importance in accounting for variation in SOD. Six variables were included in multiple regression models that explained slightly more than half of the variation in SOD. These variables were: dissolved oxygen concentration at the beginning of respirometry incubation:, particulate organic matter concentration in water above the sediment surface: organic carbon concentration at the immediate sediment-water interface (flocculent or F-layer) combined with the upper 2 cm of sediment (S-layer); organic carbon concentration in the mature (M) underlying sediment layer: water temperature: and total depth of accumulated sediment. Sediment oxygen demand was most sensitive to changes in dissolved oxygen concentration in the overlying water, particulate organic matter concentration in the water, and the concentration of organic carbon in the combined flocculent and upper sediment (F+S) layer. Models for SOD in this research predict that the mass of sediment below the upper 2-cm surface layer on average contributes only ∼20% of total SOD. Stratification and normal daily fluctuation of dissolved oxygen concentration in eutrophic culture ponds likely limit expression of sediment oxygen demand. Maintaining aerobic conditions at the sediment-water interface will minimize accumulation of organic matter in pond sediment.  相似文献   

18.
沉积环境对鱼类网箱养殖的响应   总被引：1，自引：0，他引：1  
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。  相似文献   

19.
We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow‐out ponds supplied with a high inflow of nutrient‐rich water. Prawns were subject to different stocking and harvesting strategies: upper‐graded juveniles, lower‐graded juveniles, non‐graded juveniles+selective harvesting and traditional farming (non‐grading juveniles and total harvest only). Dissolved oxygen, afternoon N‐ammonia and N‐nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1–8.0) waters indicated a non‐readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day?1 and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow‐out in ponds subjected to a high inflow of nutrient‐rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non‐readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient‐rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.  相似文献   

20.
Aquaculture ponds receive inputs of organic matter such as uneaten feed, fertilizer and faeces. Analytical methods for four parameters are described to assess the sediment quality. These parameters are redox potential, pH, the hydrogen sulphide activity potential (pH2S) and soluble ammonium nitrogen. The techniques are simple, rapid, and are practical on site. Ranges encountered are given and safe ranges suggested.  相似文献   

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