928 resultados para aquatic mesocosms
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There is a persistent need to assess the effects of TiO2 nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO2 nanoparticle-induced acute toxicity at sub-ppm level (<= 1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. (C) 2014 Elsevier Inc. All rights reserved.
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Compost, vermicompost and biochar amendments are thought to improve soil quality and plant yield. However, little is known about their long-term impact on crop yield and the environment in tropical agro-ecosystems. In this study we investigated the effect of organic amendments (buffalo manure, compost and verrnicompost) and biochar (applied alone or with vermicompost) on plant yield, soil fertility, soil erosion and water dynamics in a degraded Acrisol in Vietnam. Maize growth and yield, as well as weed growth, were examined for three years in terrestrial mesocosms under natural rainfall. Maize yield and growth showed high inter-annual variability depending on the organic amendment. Vermicompost improved maize growth and yield but its effect was rather small and was only significant when water availability was limited (year 2). This suggests that vermicompost could be a promising substrate for improving the resistance of agrosystems to water stress. When the vermicompost biochar mixture was applied, further growth and yield improvements were recorded in some cases. When applied alone, biochar had a positive influence on maize yield and growth, thus confirming its interest for improving long-term soil productivity. All organic amendments reduced water runoff, soil detachment and NH4+ and NO3- transfer to water. These effects were more significant with vermicompost than with buffalo manure and compost, highlighting that the beneficial influence of vermicompost is not limited to its influence on plant yield. In addition, this study showed for the first time that the combination of vermicompost and biochar may not only improve plant productivity but also reduce the negative impact of agriculture on water quality. (C) 2015 Elsevier B.V. All rights reserved.
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In view of the increasing usage of anatase and rutile crystalline phases of titania NPs in the consumer products, their entry into the aquatic environment may pose a serious risk to the ecosystem. In the present study, the possible toxic impact of anatase and rutile nanoparticles (individually and in binary mixture) was investigated using freshwater microalgae, Chlorella sp. at low exposure concentrations (0.25, 0.5 and 1 mg/L) in freshwater medium under UV irradiation. Reduction of cell viability as well as a reduction in chlorophyll content were observed due to the presence of NPs. An antagonistic effect was noted at certain concentrations of binary mixture such as (0.25, 0.25), (0.25, 0.5), and (0.5, 0.5) mg/L, and an additive effect for the other combinations, (0.25, 1), (0.5, 0.25), (0.5, 1), (1, 0.25), (1, 0.5), and (1, 1) mg/L. The hydrodynamic size analyses in the test medium revealed that rutile NPs were more stable in lake water than the anatase and binary mixtures at 6 h, the sizes of anatase (1 mg/L), rutile NPs (1 mg/L), and binary mixture (1, 1 mg/L) were 948.83 +/- 35.01 nm, 555.74 +/- 19.93 nm, and 1620.24 +/- 237.87 nm, respectively]. The generation of oxidative stress was found to be strongly dependent on the crystallinity of the nanoparticles. The transmission electron microscopic images revealed damages in the nucleus and cell membrane of algal cells due to the interaction of anatase NPs, whereas rutile NPs were found to cause chloroplast and internal organelle damages. Mis-shaped chloroplasts, lack of nucleus, and starch-pyrenoid complex were noted in binary-treated cells. The findings from the current study may facilitate the environmental risk assessment of titania NPs in an aquatic ecosystem. (C) 2015 Elsevier B.V. All rights reserved.
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Extensive and indiscriminate use of synthetic compounds and natural compounds obtained from plant sources have resulted in serious threats to the aquatic ecosystem and human health. Aqueous extract of the root of the plant, Milletia pachycarpa Benth, is currently used for killing fish in the state of Manipur, India. Moreover, this plant is also used as traditional medicine in this region. Although it is widely used in traditional medicine, there is limited information available regarding the adverse effects and mechanism underlying its toxicity. This study examined the effects of exposure to aqueous extract of M. pachycarpa (AEMP) on early embryonic development of zebrafish embryos and mechanisms underlying toxicity. Zebrafish embryos treated with different concentrations of the AEMP produced embryonic lethality and developmental defects. The 96-hr-LC50 of AEMP was found to be 4.276 mu g/mL. Further, multiple developmental abnormalities such as pericardial edema, yolk sac edema, spinal curvature, swim bladder deflation, decreased heart rate, and delayed hatching were also observed in a dose-dependent manner. Zebrafish embryo showing moderate-to-severe developmental defects following AEMP exposure cannot swim properly. Further, this study examined oxidative stress and apoptosis in embryos exposed to AEMP. Enhanced production of ROS and apoptosis was found in brain, trunk, and tail of zebrafish embryos treated with AEMP. Data suggest that oxidative stress and apoptosis are associated with AEMP-induced embryonic lethality and developmental toxicity in zebrafish embryos.
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The otoliths (N = 12) of freshwater invasive species tilapia (Tilapia mossambicus) collected from two water bodies located at Kolkata and Bangalore, India, were analyzed for stable isotopes (delta 18O, delta 14C) and major and trace elements in order to assess the suitability of using otoliths as a tracer of aquatic environmental changes. The stable isotope analysis was done using the dual inlet system of a Finnigan-MAT 253 isotope ratio mass spectrometer (Thermo-Fisher, Bremen, Germany). Concentrations of major and trace elements were determined using a Thermo X-Series II quadrupole mass spectrometer. The stable isotope composition in tilapia otolith samples from Bangalore and Kolkata water bodies are quite good agreeing with that of the respective lake/pond and rain water. Elemental composition revealed in a pattern of Ca > Fe > Na > Sr > K > Ba > Cr > Mg > As > Mn > Zn > Co > Cu > Cd > Pb. The otoliths from Kolkata pond water are more enriched in Ba, Zn, Pb, Mn, Se, Cu, Zn, Cd, and Ni whereas Cr and As were found to be higher in otolith samples from Bangalore lake. The enrichment factor (EF) values of Cr were higher for both the sampling location in comparison with other metals, although all the studied metals exhibited EF values >1. The PCA shows clustering of metals in the otolith which are related either with the metabolic and physiological attributes or waterborne source. The study demonstrated the potential of stable isotope techniques to distinguish otolith specimens from varied climatic zone, while elemental composition recorded the quality of water at both the locations. The role of climate driving the quality of water can be understood by detailed and continuous monitoring of otolith specimens in the future. Future method allows reconstruction of climate and water quality from old specimens from field exposures or museum collection.
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The use of sustainability indicators for evaluating sanitation systems is applied to the Erdos Eco- Town Project (EETP) in China for illustration. The EETP is the largest urban settlement in the world employing ecological sanitation, which incorporates separation of waste streams, dry toilets, and resource recovery. The EETP’s dry sanitation system is compared against the Dongsheng District’s conventional sewer and centralised STP. The two systems are compared based on technological, environmental, economic, and societal indicators. Overall, the two systems perform reasonably well from a technological perspective. The conventional system performs significantly better than the dry system with regards to land and energy requirements, and global warming potential; it also performs better based on freshwater aquatic and terrestrial ecotoxicity potentials, but by a smaller margin. The dry system has superior environmental performance based on water consumption, eutrophication potential, and nutrient and organic matter recovery. The dry system is a more costly system as it requires greater infrastructure and higher operational costs, and does not benefit from economies of scale. The waterborne system performs better based on the societal indicators largely because it is a well-established system.
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*Table of Contents* Research & farming techniques Nursery rearing of Puntius goniotus: A preliminary trial K.N. Mohnta, J.K. Jena & S.N. Mohanty Artemia enrichment and biomass production for larval finfish and shellfish culture A.S. Ninawe Vembanad Lake: A potential spawner bank of the giant freshwater prawn Macrobrachium rosenbergii on the southwest coast of India Paramaraj Balamurugan, Pitchaimuthu Mariappan & Chellam Balasundaram Seed production of mud crab Scylla serrata at the Rajiv Gandhi Center for Aquaculture, Tamil Nadu, India Mohamed Shaji, Emilia T. Quinitio, Thampi Samraj, S. Kandan, K. Ganesh, Dinesh Kumar, S. Arulraj, S. Pandiarajan, Shajina Ismail and K. Dhandapan. Sustainable aquaculture Fish wastes in urban and suburban markets of Kolkata: Problems and potentials Kausik Mondal, Anilava Kaviraj & P.K. Mukhopadhyay People in aquaculture Peter Edwards writes on rural aquaculture: Farming carps in leased ponds by groups of poor women in Chandpur, Bangladesh Aquatic animal health Lymphocystis disease and diagnostic methods in China Jing Xing, Xiuzhen Sheng & Wenbin Zhan Asia-Pacific Marine Finfish Aquaculture Network Mesocosm technology advances grouper culture in northern Australia Elizabeth Cox, Peter Fry & Anjanette Johnston
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*Table of Contents* Sustainable aquaculture Peter Edwards writes on rural aquaculture: Small-scale pond culture in Bangladesh. People in aquaculture Community based aquaculture - issues and challenges H.K. De and G.S. Saha. Aquaculture as an action programme: An exercise in building confidence and self worth. B. Shanthi, V.S. Chandrasekaran, M. Kailasam, M. Muralidar, T. Ravisankar,.C. Saradad and M. Krishnan The STREAM Column: Transforming policy recommendations into pro-poor service provision Graham Haylor. Research & farming techniques. Grow out of juvenile spotted Babylon to marketable size in earthen ponds II: Polyculture with seabass. S. Kritsanapuntu, N. Chaitanawisuti, W. Santhaweesuk and Y. Natsukari Asia-Pacific Marine Finfish Aquaculture Network. Influence of economic conditions of importing nations and unforeseen global events on grouper markets. Sih Yang Sim. Present status of hatchery technology for cobia in Vietnam. Nhu Van Can. Report on grouper hatchery training course in Indonesia. Nguyen Quoc Thai. Aquatic animal health. Biosecured and improved penaeid shrimp production through organic nursery raceway system in India. Felix. S. and M. Samaya Kannan. Management of monogenean parasites in brackishwater finfish. K.P. Jithendran, M. Natarajan and I.S. Azad. Vembanad Lake: A potential spawner bank of the giant freshwater prawn Macrobrachium rosenbergii on the southwest coast of India. Paramaraj Balamurugan, Pitchaimuthu Mariappan & Chellam Balasundaram.
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(121 p.)
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*Table of Contents* Sustainable Aquaculture Fertilization, soil and water quality management in small-scale ponds part II:Soil and water quality management S. Adhikari Fisheries and aquaculture activities in Nepal Tek Gurung Peter Edwards writes on rural aquaculture: A knowledge-base for rural aquaculture Farmers as Scientists: Commercialization of giant freshwater prawn culture in India M.C. Nandeesha Aquaculture in reservoir fed canal based irrigation systems of India – a boon for fish production K.M. Rajesh, Mridula R. Mendon, K. N. Prabhudeva and P. Arun Padiyar Research and Farming Techniques Production and grow-out of the Black-lip pearl oyster Pinctada margaritifera Idris Lane Breeding of carps using a low-cost, small-scale hatchery in Assam, India: A farmer proven technology S.K. Das Genes and Fish: Hybridisation – more trouble than its worth? Graham Mair Breeding and culture of the sea cucumber Holothuria scabra in Vietnam R. Pitt and N. D. Q. Duy The potential use of palm kernel meal in aquaculture feeds Wing-Keong Ng Using a Simple GIS model to assess development patterns of small-scale rural aquaculture in the wider environment Simon R. Bush Aquaculture fundamentals: Getting the most out of your feed Simon Wilkinson Marine finfish section Status of marine finfish aquaculture in Myanmar U Khin Kolay Regional training course on grouper hatchery production Aquatic Animal Health Advice on aquatic animal health care: Problems in Penaeus monodon culture in low salinity areas Pornlerd Chanratchakool
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*Table of Contents* Sustainable Aquaculture Peter Edwards writes on rural aquaculture: Peri-urban aquaculture in Kolkata A case of informal shrimp farmers association and its role in sustainable shrimp farming in Tamil Nadu, India M. Kumaran, N. Kalaimani, K. Ponnusamy, V.S. Chandrasekaran, D. Deboral Vimala Diffusion and adoption of shrimp farming technologies M. Kumaran, K. Ponnusamy and N. Kalaimani Farmers as Scientists: Aquaculture education in India - opportunities for global partnership M.C. Nandeesha Information system of fish germplasm resources in China Yang Ningsheng, Ge Chanshui, Ouyang Haiying, Yuan Yongming Status and development needs of freshwater crustacean aquaculture in China Xu Pao Research and Farming Techniques Aquaculture fundamentals: Getting the most out of your feed Part II: The role of macronutrients Simon Wilkinson Fish breeding in captivity - some innovative adaptations of technology by Bengal farmers N.R. Chattopadhyay Scientific guidelines for farmers engaged in freshwater prawn farming in India Vishal Saxena Marine Finfish Section News and publications Status and development of mariculture in Indonesia Ketut Sugama Aquatic Animal Health Use of probiotics in larval rearing of new candidate species Rehana Abidi Advice on aquatic animal health care: Problems in shrimp culture during the wet season (Thai/English languages) Pornlerd Chanratchakool
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Infestations of the marine macrophytic alga Caulerpa taxifolia were discovered in Agua Hedionda Lagoon, California in 2000. Rapid response actions included containment under pvc tarps coupled with injection of liquid sodium hypochlorite. To assess the efficacy of these treatments, replicated sediment cores were removed from representative treated sites and transferred to grow-out facilities. Similar cores from uninfested (control) sediments were removed, inoculated with viable explants of C. taxifolia and placed in grow-out facilities. Results from two sampling periods (1 year, 2 years post-treatment) showed that no viable C. taxifolia emerged in cores, and that inoculated “control” sediments supported normal growth. Eelgrass ( Zostera marina L.) seedlings emerged from native seed-banks in “treated” cores, which also supported growth of some invertebrates (annelid worms and hydroids). This study provided essential verification of C. taxifolia eradication efforts, and demonstrates the feasibility of incorporating quality control/quality assurance components in rapid response actions. Results of this study also suggest that seeds of eelgrass are viable for at least two years. (PDF has 9 pages.)
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Recommendations for changes to service provision and fisheries policy in support of poverty alleviation emerged recently in India from a process know as facilitated advocacy (see Case Study SI 2) that helped to negotiate and support a role for poor people and their service providers, to contribute to changes in services and policies. Two of the key recommendations to emerge from farmers and fishers, which were prioritized by Fisheries Departments, were to change the way that information is made available and to simplify procedures for accessing government schemes and bank loans. This case which identifies the origin of these recommendations to change the way that information is made available, shows how different models of the concept have emerged, and follows the development of the One-stop Aqua Shops (OAS) in the eastern Indian states of Jharkhand, Orissa and West Bengal, that represent a new and vital tier in communications in aquaculture. (12 p.)
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Listening to people, especially those who are poor, and involving them in policy making and decisions about service delivery processes are logical steps in building better services and improving policies aimed at poverty alleviation. This case describes a facilitated advocacy that helped to negotiate and support a role for poor people who farm and fish, to contribute recommendations for changes in services and policies that impact on their lives. The national Government of India’s Department of Animal Husbandry and Dairying and the Indian Council for Agricultural Research, both in the capital Delhi, have been linking with farmers and fishers and state government officials in the eastern states of Jharkhand, Orissa and West Bengal, in partnership with the STREAM Initiative of the intergovernmental Network of Aquaculture Centers in Asia Pacific and with the support of the UK Government Department for International Development, Natural resources Systems Program supporting farmers to have a voice(13 p.)