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1.
鳜鱼—虾—蟹池塘高密度生态混养河蟹喜食底栖动物,特别喜欢螺蚬,也喜食水生植物;鳜鱼喜食活鱼、活虾;青虾食性为杂食性偏动物性。河蟹、青虾都摄食配合饲料,河蟹主要摄食颗粒饲料,两者从食性角度互为补充,鳜鱼白天有卧穴习性,这也减少了鳜鱼对虾蟹的攻击。因鳜鱼和河蟹都喜食青虾,青虾既可被它们捕食,另一方面也获得一部分产量。在水质要求上,河蟹、鳜鱼、青虾都喜栖息在水质清新的水域,混养时对水质要求一致。  相似文献   

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为了探讨人工生态浮床栽培对养殖池塘水环境的净化作用,进行了人工生态浮床栽种生菜试验。结果表明:人工生态浮床能够提高池塘水体的透明度,降低水体中(TN,NH4+-N,NO2-N,NO3-N,TP,COD等)污染物的含量,达到净化养殖水质效果、改善池塘水体环境的作用。  相似文献   

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依据青虾、黄颡鱼、塘鳢等品种与河蟹共生互利、优势互补的生物学特性,适当降低蟹种放养量,提高青虾、黄颡鱼、塘鳢等优质鱼类放养量,发展蟹虾、蟹虾鱼高产高效生态混养,可较大幅度提高河蟹养殖池塘的综合产出率和综合效益。一、蟹虾高产高效生态混养1.池塘清整冬季抽干池水,清除过多淤泥,留淤15cm,用于种植水草和培育底栖生物。修护池埂池坡,使坡比达到1∶2.5以上。池塘冻晒1个月后,  相似文献   

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利用河蟹养殖池塘混放套养青虾,可以在不影响河蟹规格、产量的情况下.增加效益。蟹池中套放青虾,是近年来成功推广应用的一种特种水产养殖模式.不仅可以改善水质、培育栖息生物.而且也能获得较高的综合经济效益。养蟹池塘套养青虾生态养殖要把握好这样几个方面的关键:  相似文献   

5.
组合生态浮床净化养殖水体效果研究   总被引:2,自引:0,他引:2  
为了研究由水生植物与人工介质构建的组合生态浮床对养殖水体的净化效果,通过在大薸(Pistia stratiotes)底部放置生物陶粒基质构建了组合生态浮床,研究了该组合浮床对养殖水体的净化效果。数据表明,组合生态浮床对总氮、氨氮(NH+4-N)、亚硝氮(NO-2-N)、总磷、化学需氧量(COD)去除率分别达到52.38%、77.78%、81.97%、67.57%和43.98%,均显著高于植物对照组和基质对照组(P0.05)。经组合浮床净化后的养殖水体中,TN、TP水平分别达到淡水池塘养殖排放水一级标准,NH+4-N水平降至0.15 mg/L以下,NO-2-N水平降至0.02 mg/L以下。结果表明,组合生态浮床中植物吸收、基质吸附及微生物的协同作用提高了其对污染物的去除效果,合理的生物组合对提高生态浮床净化养殖废水效果具有积极的促进作用。研究结果为构建适宜养殖水体净化的组合型生态浮床提供了技术支撑。  相似文献   

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池塘单一养殖青虾或河蟹,普遍存在不能充分利用水体资源和饵料生物、经济效益不高的弊端;单一养殖鱼类,大多养殖周期长、产品价格低。采用蟹、虾、鱼生态混养技术,便可化弊为利,大大提高池塘的养殖效益。本文介绍的新型养殖模式系通过太量试验和生产实践总结出来的,值得水产养殖场(户)借鉴。  相似文献   

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依据青虾、黄颡鱼、塘鳢等品种与河蟹共生互利、优势互补的生物学特性,适当降低蟹种放养量,提高青虾、黄颡鱼、塘鳢等优质鱼类放养量,发展蟹虾、蟹虾鱼高产高效生态混养,可提高河蟹养殖池塘综合产出率和经济效益。一、蟹虾高产高效生态混养1.池塘清整冬季抽干池水,清除过多淤泥,留淤15厘米,用于种植水草和培育底栖生物。修护池埂池坡,使坡比达到1∶2.5以上。池塘冻晒1个月后,上水40厘米,每亩用生石灰250公斤化水全池泼浇,消毒杀菌。  相似文献   

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对传统河蟹池塘主养模式和藕-蟹-鱼生态养殖模式的养殖结果及水体营养状况进行了评价.结果表明,河蟹主养模式河蟹平均规格为102 g/只,经济效益为33 750元/hm2,投入产出比为1∶2.12,藕-蟹-鱼套养模式河蟹平均规格为133g/只,经济效益为56 350元/hm2,投入产出比为1∶3.94,藕-蟹-鱼套养模式比河蟹主养模式经济效益增加22 600 元/hm2,经济效益提高66.96%;河蟹主养模式池塘6、7、8月份水体为中度富营养类型,藕-蟹-鱼生态养殖模式池塘水体6月份为中营养类型,7、8月份为轻度富营养类型,总体而言,藕-蟹-鱼生态养殖模式池塘水体营养状况均好于传统的河蟹主养池塘2~3个数号级.  相似文献   

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为能够确定虾蟹混养池中青虾的实际养殖效益,进一步完善虾蟹混养技术模式,提高养殖效益,本文通过河蟹与春秋二茬青虾混养的方式进行虾蟹混养池中青虾的养殖效益分析,通过试验确定虾蟹混养池中青虾的产出量为86.5kg/667m2,实际经济效益为6967元/667m2。此外,在研究中还对虾蟹混养中所需要注意的诸多事项进行分析阐述,以期能够进一步提高青虾的养殖效益。  相似文献   

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河蟹与青虾、小龙虾混养能有效提高对水体空间利用率,增加养殖效益。本文阐述了河蟹与青虾、小龙虾混养模式与疾病防治的一线技术,以期对虾蟹养殖相关的生产及研究有所裨益。  相似文献   

11.
Hotspots, basalts, and the evolution of the mantle   总被引:2,自引:0,他引:2  
The trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. The relative sizes of the source regions for these fundamentally different basalt types can be estimated from the trace element enrichment-depletion patterns. Their combined volume occupies most of the mantle above the 670 kilometer discontinuity. The source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that lost its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, whereas the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are consistent with the evolution of a terrestrial magma ocean.  相似文献   

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Climate change, deforestation, and the fate of the Amazon   总被引:4,自引:0,他引:4  
The forest biome of Amazonia is one of Earth's greatest biological treasures and a major component of the Earth system. This century, it faces the dual threats of deforestation and stress from climate change. Here, we summarize some of the latest findings and thinking on these threats, explore the consequences for the forest ecosystem and its human residents, and outline options for the future of Amazonia. We also discuss the implications of new proposals to finance preservation of Amazonian forests.  相似文献   

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The reaction dolomite + 2 coesite --><-- diopside + 2 diamond + 2O(2) defines the coexistence of diamond and carbonate in mantle eclogites. The oxygen fugacity of this reaction is approximately 1 log unit higher at a given temperature and pressure than the oxygen fugacities of the analogous reactions that govern the stability of diamond in peridotite. This difference allows diamond-bearing eclogite to coexist with peridotite containing carbonate or carbonate + diamond. This potential coexistence of diamond-bearing eclogite and carbonate-bearing peridotite can explain the presence of carbon-free peridotite interlayered with garnet pyroxenites that contain graphitized diamond in the Moroccan Beni Bousera massif at the Earth's surface and the preferential preservation of diamond-bearing eclogitic relative to peridotitic xenoliths in the Roberts Victor kimberlite.  相似文献   

17.
The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a "galactic" form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity.  相似文献   

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