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  • 1.
    Berg, Håkan
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Berg, Charlotte
    Nguyen, Thanh Tam
    Integrated Rice-Fish Farming: Safeguarding Biodiversity and Ecosystem Services for Sustainable Food Production in the Mekong Delta2012In: Journal of Sustainable Agriculture, ISSN 1044-0046, E-ISSN 1540-7578, Vol. 36, no 8, p. 859-872Article in journal (Refereed)
    Abstract [en]

    A comparison of agricultural practices, with a specific focus on pesticide use, between rice and rice-fish farmers in the Can Tho' and Tien Giang provinces of the Mekong Delta in 2007, shows that integrated rice-fish farming can provide a competitive alternative to intensive rice mono-cropping, if the farmer restricts the use of pesticides and takes full advantage of the ecosystem services provided by the rice-field ecosystem. In Can Tho', rice-fish farmers had significantly higher income (43.6 million dong ha(-1) year(-1)) than other farmer groups, while this was not seen among rice-fish famers in Tien Giang (32.4 million dong ha(-1) year(-1)), which partly could be due to a high use of insecticides (0.9 kg active ingredient ha(-1) crop(-1)) and comparatively low fish yield among these farmers. The study emphasizes the need to rethink current agricultural systems and to provide opportunities for more diverse systems that maintain and enhance a range of ecosystem services and protect human health. Future production systems should not be optimized to only provide a single ecosystem service, such as rice, but designed to deliver a variety of interlinked ecosystem service such as rice, fish, pest control, and nutrient recycling.

  • 2.
    Berg, Håkan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Maneas, Giorgos
    Stockholm University, Faculty of Science, Department of Physical Geography. Navarino Environmental Observatory, Greece.
    Salguero Engström, Amanda
    Stockholm University, Faculty of Science, Department of Physical Geography.
    A Comparison between Organic and Conventional Olive Farming in Messenia, Greece2018In: Horticulturae, E-ISSN 2311-7524, Vol. 4, no 3, article id 15Article in journal (Refereed)
    Abstract [en]

    Olive farming is one of the most important occupations in Messenia, Greece. The region is considered the largest olive producer in the country and it is recognized as a Protected Designation of Origin (PDO) for Kalamata olive oil, which is considered extra fine. In response to the declining trend of organic olive farming in Greece, this study assesses to what extent organic olive farming in Messenia provides a financially and environmentally competitive alternative to conventional olive farming. In this study, 39 olive farmers (23 conventional and 16 organic) participated in interviews based on questionnaires. The results showed that organic olive farming is significantly more profitable than conventional farming, primarily because of a higher price for organic olive oil. Despite this, the majority of the conventional farmers perceived a low profit from organic farming as the main constraint to organic olive farming. All farmers agreed that organic olive farming contributed to a better environment, health and quality of olive oil. Organic farmers used fewer synthetic pesticides and fertilizers and applied more environmentally-friendly ground vegetation management techniques than conventional farmers. Overall, organic farming was found to provide a competitive and sustainable alternative to conventional olive farming in Messenia.

  • 3.
    Berg, Håkan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Nguyen, Thanh Tam
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Use of pesticides and attitude to pest management strategies among rice and rice-fish farmers in the Mekong Delta, Vietnam2012In: International Journal of Pest Management, ISSN 0967-0874, E-ISSN 1366-5863, Vol. 58, no 2, p. 153-164Article in journal (Refereed)
    Abstract [en]

    This study assesses the use of pesticides and attitude to pest management strategies among rice and rice-fish farmersin Can Tho’ and Tien Giang provinces of the Mekong Delta, Vietnam, in 2007. A comparison is made to a similarstudy in 1999, in order to identify changes in patterns of pesticide use and possible influences of integrated pestmanagement (IPM) programmes and brown planthopper (a major pest) outbreaks. One hundred and twenty farmersused 66 different pesticides, similar to the 64 pesticides recorded as being used in the 1999 survey. Nine of the 10 mostpopular pesticides in 2007 were the same as those found to be popular in 1999. Insecticides are used by 73–95% ofthe farmers, which is the most commonly employed type of pesticide. The number of applications of both herbicidesand fungicides has more than halved since 1999 for all farmers, while insecticide applications has doubled for IPMfarmers (those with prior training in IPM methodology). Similarly, the average dose of active ingredient (a.i.) ofinsecticides per crop has decreased slightly for non-IPM rice farmers, while it has more than doubled among IPMfarmers, resulting in almost the same amount of a.i. per crop for all groups of farmers (insecticides 0.6, fungicides 0.5,and herbicides 0.3 kg a.i. ha71 crop71). Overall, the results indicate a temporal trend for more selective use ofpesticides and an increased awareness among non-IPM farmers of the negative side effects of pesticide use.

  • 4.
    Berg, Håkan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Söderholm, Agnes Ekman
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Söderström, Anna-Sara
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Tam, Nguyen Thanh
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Recognizing wetland ecosystem services for sustainable rice farming in the Mekong Delta, Vietnam2017In: Sustainability Science, ISSN 1862-4065, E-ISSN 1862-4057, Vol. 12, no 1, p. 137-154Article in journal (Refereed)
    Abstract [en]

    The increased rice production in the Mekong Delta during the last two decades has improved agricultural income and reduced poverty, but it has also had negative impacts on the environment and human health. This study shows that integrated rice-fish farming and integrated pest management strategies provide sustainable options to intensive rice farming, because of a more balanced use of multiple ecosystem services that benefit the farmers' health, economy and the environment. The study investigates and compares farming strategies among 40 rice and 20 rice-fish farmers in two locations in the Mekong Delta. Production costs and income are used to compare the systems' financial sustainability. The farmers' perception on how their farming practices influence on ecosystem services and their livelihoods are used as an indication of the systems' ecological and social sustainability. Although rice-fish farmers used lower amount of pesticides and fertilisers than rice farmers, there were no statistical differences in their rice yields or net income. Rice was seen as the most important ecosystem service from rice fields and related wetlands, but also several other ecosystem services, such as water quality, aquatic animals, plants, habitats, and natural enemies to pests, were seen as important to the farmers' livelihoods and wellbeing. All farmers perceived that there had been a general reduction in all these other ecosystem services, due to intensive rice farming during the last 15 years, and that they will continue to decline. The majority of the farmers were willing to reduce their rice yields slightly for an improved quality of the other ecosystem services.

  • 5.
    Berg, Håkan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Tam, Nguyen Thanh
    Decreased use of pesticides for increased yields of rice and fish-options for sustainable food production in the Mekong Delta2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 619-620, p. 319-327Article in journal (Refereed)
    Abstract [en]

    This study assesses the use of pesticides and the attitude to pest management strategies among rice and rice-fish farmers in the Can Tho and Tien Giang provinces in Vietnam. Interviews were made with 80 farmers. The farmers were divided in to farmers cultivating only rice with a high use (RHP) and low use (RLP) of pesticides, and farmers cultivating rice and fish with a high use (RFHP) and low use (RFLP) of pesticides. 80% of the HP farmers relied mainly on pesticides to control pests, while >80% of the LP farmers also applied IPM strategies. Insecticides were the most commonly used pesticides. 85% of all farmers experienced health effects from using pesticides. 80% of the farmers felt that the yield of fish had decreased over the last three years, and that this mainly was caused by pesticides. The RFHP farmers had lower fish survival and fish yields as compared to the RFLP farmers. The RFHP farmers also had significant lower rice yields than the RFLP farmers, and there were significant correlations between both decreased fish yields and rice yields with increased use of pesticides among rice-fish farmers. Increased rice yields were positively correlated with increased fish survival, indicating the synergistic effects between rice and fish production. Overall, the RFLP farmers had the highest income of the four farmers´ groups, while RFHP farmers had the lowest income. This shows that rice-fish farming provides a competitive and sustainable alternative to intensive rice-farming, but only if the farmer restricts the use of pesticides. This would not only help to reduce the production costs, but also to decrease environmental and health effects, and it is proposed that rice-fish farming with a low use of pesticides provides an attractive alternative to rice-monocropping for a sustainable and diversified food production in the Mekong Delta.

  • 6. Da, Chau Thi
    et al.
    Phuoc, Le Huu
    Duc, Huynh Ngoc
    Troell, Max
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. The Royal Swedish Academy of Sciences, Sweden.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Use of Wastewater from Striped Catfish (Pangasianodon hypophthalmus) Pond Culture for Integrated Rice-Fish-Vegetable Farming Systems in the Mekong Delta, Vietnam2015In: Agroecology and Sustainable Food Systems, ISSN 2168-3565, E-ISSN 2168-3573, Vol. 39, no 5, p. 580-597Article in journal (Refereed)
    Abstract [en]

    This article investigates the feasibility of reusing wastewater from striped catfish (Pangasianodon hypophthalmus) pond culture as nutrient input for integrated rice-Nile tilapia-green bean farming systems, and to what extent this could contribute to decreasing the environmental impacts on water quality from the striped catfish industry in the Mekong Delta. Four treatments in triplicates were used to investigate the growth of rice and green bean varieties under different combinations of inorganic fertilizer and water from the river and a striped catfish pond culture. The Nile tilapia (Oreochromis niloticus) was cultured at low density without feeding in a canal adjacent to the rice field. Rice yields ranged from 3,514 to 4,023 kg ha(-1) with no significant differences between treatments (p > 0.05). The yield of green bean ranged from 2,671 to 3,282 kg ha(-1) (p < 0.05), with the highest yields for beans only receiving water from the striped catfish pond. The water quality concentrations decreased significantly when passing through the rice plots for almost all treatments (p < 0.05). Total phosphorus and nitrogen levels in the outflowing water were reduced by almost 50% compared to the inflowing water from the striped catfish pond. Overall, the results indicated that an integrated system generates both economic and environmental benefits as compared to monocultures.

  • 7.
    Maneas, Giorgos
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Navarino Environmental Observatory, Greece.
    Makopoulou, Eirini
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Bousbouras, Dimitris
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Anthropogenic Changes in a Mediterranean Coastal Wetland during the Last CenturyThe Case of Gialova Lagoon, Messinia, Greece2019In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, no 2, article id 350Article, review/survey (Refereed)
    Abstract [en]

    Human interventions during the last 70 years have altered the characteristics of the Gialova Lagoon, a coastal wetland that is part of a wider Natura 2000 site. In this study, we explore how human interventions and climate altered the wetland's hydrological conditions and habitats, leading to changing wetland functions over time. Our interpretations are based on a mixed methodological approach combining conceptual hydrologic models, analysis of aerial photographs, local knowledge, field observations, and GIS (Geographic Information System) analyses. The results show that the combined effects of human interventions and climate have led to increased salinity in the wetland over time. As a result, the fresh and brackish water marshes have gradually been turned into open water or replaced by halophytic vegetation with profound ecological implications. Furthermore, current human activities inside the Natura 2000 area and in the surrounding areas could further impact on the water quantity and quality in the wetland, and on its sensitive ecosystems. We suggest that a more holistic understanding of the broader socio-ecological system is needed to understand the dynamics of the wetland and to achieve sustainable long-term management and conservation strategies.

  • 8. McDonough, S.
    et al.
    Gallardo, W.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Trai, N. V.
    Yen, N. Q.
    Wetland ecosystem service values and shrimp aquaculture relationships in Can Gio, Vietnam2014In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 46, p. 201-213Article in journal (Refereed)
    Abstract [en]

    Wetland valuation methods often apply monetary driven approaches that may undermine intrinsic ecosystem values. Utilizing a stated preference method, the study identified and mapped local stakeholder ecosystem service values between subsistence wetland and shrimp farmer groups in Can Gio, Vietnam. Through focus group choice experiments, ecosystem services correlating to unique price increments and cost/benefit tradeoffs between hypothetical intensive aquaculture developments and mangrove conservation scenarios were investigated. Selection outcomes exhibited strong values for ecosystem services maintained at the hypothetical natural state (core area pre-intervention 45%, post-intervention 55%; buffer zone pre-intervention 65%, post-intervention 73%). Few respondents selected the hypothetical intensive aquaculture development scenario (core area pre-intervention 18%, post-intervention 9%; buffer zone pre-intervention 12%, post-intervention 5%), and instead, most respondents avoided the costs and benefits of intensive aquaculture development in preference for maintaining natural ecosystem services. Group deliberations drew out a higher sense of altruism and responsiveness to intrinsic wetland values that superseded the potential economic gains of aquaculture developments, whereby certain ecosystem services were deemed economically unassociable and irreplaceable for both study groups. The qualitative results expose the difficulties in monetarily measuring ecosystem services, highlighting the need to incorporate approaches that integrate the intrinsic values attached to ecosystem services.

  • 9.
    Myers, David
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Maneas, Giorgos
    Stockholm University, Faculty of Science, Department of Physical Geography. Navarino Environmental Observatory, Greece.
    Comparing the soundscapes of organic and conventional olive groves: A potential method for bird diversity monitoring2019In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 103, p. 642-649Article in journal (Refereed)
    Abstract [en]

    Modern intensive agricultural practices are causing stress on ecosystems worldwide, with the loss of biodiversity due to decreased landscape heterogeneity as well as high use of synthetic agro-chemicals. Organic farming is seen as an effective way of counteracting this trend. Despite this, relatively little research has been carried out on the effects of olive farming on biodiversity in Greece. This study uses bioacoustic monitoring for a first order assessment of the bird diversity in olive groves. It uses acoustic indices to compare the soundscape of eleven organic and eleven conventional olive groves in Messinia in southern Greece. Three bioacoustics indices: the Acoustic Complexity Index (ACI), the Acoustic Diversity Index (ADI) and the Bioacoustic Index (BIO) were used. Olive groves under organic farming had significantly higher values for the ACI and BIO indices, and a higher but not significant different value for the ADI index. Organic groves showed a much more heterogeneous and complex structure with a mixture of tree species and varying canopy height than conventional groves. Landscape variables were similar between management practices and did not influence the index results. Site level variables, especially underlying vegetation height, had a significant influence on the ACI and BIO indices. Our results suggest that bioacoustic indices could provide a cost effective and non-intrusive way for bird diversity monitoring.

  • 10. Nguyen, Thanh
    et al.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Nguyen, Van
    The combined effect of Bassa 50EC and Vitashield 40EC on the brain acetylcholinesterase activity in climbing perch (Anabas testudineus)2018In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, no 17, p. 17207-17215Article in journal (Refereed)
    Abstract [en]

    The combined effect of Vitashield 40EC (chlorpyrifos ethyl-CPF) and Bassa 50EC (fenobucarb-F) was compared with the effects from exposure to the two pesticides separately, by measuring the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings (Anabas testudineus). The experiment was conducted under controlled laboratory conditions and included three treatments containing 0.173 mg/L of CPF, 1.137 mg/L of F, 0.173 mg/L of CPF + 1.137 mg/L of F (M), and a control. The inhibition of the brain AChE activity in fish exposed to F was weaker and shorter than in fish exposed to CPF. The inhibition by the mixture of CPF and F was significantly lower and less prolonged than the inhibition by only CPF but significantly higher than the inhibition by only F.

  • 11.
    Nguyen, Thanh Tam
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Laureus, Jenny
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Van Nguyen, Cong
    Tedengren, Michael
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Effects of Sequential Applications of Bassa 50EC (Fenobucarb) and Vitashield 40EC (Chlorpyrifos ethyl) on Acetylcholinesterase Activity in Climbing Perch (Anabas testudineus) Cultured in Rice Fields in the Mekong Delta, Vietnam2016In: Bulletin of Environmental Contamination and Toxicology, ISSN 0007-4861, E-ISSN 1432-0800, Vol. 97, no 1, p. 98-104Article in journal (Refereed)
    Abstract [en]

    This study assesses the effects of sequential applications of the insecticides Bassa 50EC (fenobucarb-F) and Vitashield 40EC (chlorpyrifos ethyl-CPF), sprayed at concentrations used by rice farmers in the Mekong Delta, on the brain acetylcholinesterase (AChE) in climbing perch fingerlings. After spraying the pesticides on the rice fields, the water concentrations of both insecticides decreased below the detection levels within three days. The sequential applications caused significant inhibition on the brain AChE activity in the exposed fish. The inhibition by F was quicker, but less prolonged, than for CPF. The inhibition levels caused by the sequential applications were lower than those caused by only CPF and by a mixture of CPF and F. The results indicate that sequential applications of pesticides could have a negative impact on aquatic organisms and fish yields, with implication for the aquatic biodiversity, local people’s livelihood and the aquaculture industry in the Mekong Delta.

  • 12.
    Nguyen, Thanh Tam
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Nguyen, Hang Thi Thuy
    Van Nguyen, Cong
    Effects of chlorpyrifos ethyl on acetylcholinesterase activity in climbing perch cultured in rice fields in the Mekong Delta, Vietnam2015In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 117, p. 34-40Article in journal (Refereed)
    Abstract [en]

    Climbing perch is commonly harvested in rice fields and associated wetlands in the Mekong Delta. Despite its importance in providing food and income to local households, there is little information how this fish species is affected by the high use of pesticides in rice farming. Organophosphate insecticides, such as chlorpyrifos ethyl, which are highly toxic to aquatic organisms, are commonly used in the Mekong Delta. This study shows that the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings cultured in rice fields, was significantly inhibited by a single application of chlorpyrifos ethyl, at doses commonly applied by rice farmers (032-0.64 kg/ha). The water concentration of chlorpyrifos ethyl decreased below the detection level within 3 days, but the inhibition of brain AChE activity remained for more than 12 days. In addition, the chlorpyrifos ethyl treatments had a significant impact on the survival and growth rates of climbing perch fingerlings, which were proportional to the exposure levels. The results indicate that the high use of pesticides among rice farmers in the Mekong Delta could have a negative impact on aquatic organisms and fish yields, with implications for the aquatic biodiversity, local people's livelihoods and the aquaculture industry in the Mekong Delta.

  • 13.
    Nguyen, Thanh Tam
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Nguyen, Van Cong
    The joint effect of chlorpyrifos ethyl and fenobucarb on brain acetylcholinesterase activity in climbing perch (Anabas testudineus) fingerlingsManuscript (preprint) (Other academic)
  • 14.
    Nguyen, Thanh Tam
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Tuyen, Phan Thi Bich
    Van Cong, Nguyen
    Effect of Chlorpyrifos Ethyl on Acetylcholinesterase Activityin Climbing Perch (Anabas testudineus, Bloch, 1972)2015In: Archives of Environmental Contamination and Toxicology, ISSN 0090-4341, E-ISSN 1432-0703, Vol. 69, no 4, p. 515-524Article in journal (Refereed)
    Abstract [en]

    The high use of pesticides in intensive rice farming in the Mekong Delta constitutes a potential hazard to the environment and to people's health. Chlorpyrifos ethyl (CPF) is a commonly used organophosphate (OP) insecticide, but information about its potential negative impacts on the aquatic environment in the Mekong Delta is scarce. Both acute and subacute toxicity tests were performed in a static nonrenewable system to investigate the effects of CPF on brain acetylcholinesterase (AChE) activity in native climbing perch fingerlings (Anabas testudineus, Bloch, 1972). Environmental parameters, such as dissolved oxygen, water temperature, and pH, were similar to field conditions in the Mekong Delta. In a 96-h lethal concentration (LC50) test, fingerlings of climbing perch were randomly exposed to five levels of CPF ranging from 0.8 to 4.5 ppm. Five sublethal levels of CPF (1, 5, 10, 15, and 20 % of the 96-h LC50 value) were tested to assess the sensitivity and recovery of the brain AChE activity in climbing perch fingerlings exposed to CPF. The results showed that CPF were moderately toxic to climbing perch with a 96-h median LC50 of 1.73 ppm. CPF also caused long-term AChE inhibition with 70 % inhibition remaining after 96 h for the four highest test concentrations. The recovery of brain AChE activity in fish placed in CPF-free water was very slow, and after 7 days the brain AChE activity was still significant lower in fish from the four highest concentrations compared with the control. The results from this study indicate that OP insecticides, such as CPF, can have long-lasting sublethal effects on aquatic species in the Mekong Delta.

  • 15.
    Nguyen, Thanh Tam
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Van Nguyen, Cong
    The joint toxicity effects of Chlorpyrifos ethyl and Fenobucarb to Climbing perch (Anabas testudineus) from rice fields in the Mekong Delta, Vietnam2018In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, no 4, p. 13226-13234Article in journal (Refereed)
    Abstract [en]

    Organophosphates (e.g. chlorpyrifos ethyl) and carbamates (e.g. fenobucarb), are commonly used to control a wide range of pests in rice fields of the Mekong Delta in Vietnam. This study assesses the combined effect of chlorpyrifos ethyl (CPF) and fenobucarb (F) on the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings from rice fields in the Mekong Delta. It also investigates if Pyridine-2-aldoxime methiodide (2-PAM) can be used to re-activate cholinesterase that has been blocked by CPF and F. Three days after spraying, the water concentrations of both insecticides decreased quickly below the detection levels. However the brain AChE activity in fish was inhibited for more than seven days. The results indicate a quicker but less prolonged inhibition of the brain AChE activity by the mixture than by only CPF. The inhibition levels were above 70% only during the first 48 hours, which could explain why all fish survived. 2-PAM resulted in a significant re-activation of the cholinesterase blocked by a combination of CPF and F, and it is proposed that the re-activation by 2-PAM could provide a way to assess the AChE inhibition level in organisms, when no unexposed individuals are available as controls. The results indicate that current use of CPF and F in rice farming in the Mekong Delta is likely to cause negative effects on non-target organisms. Many of these effects may be sub-lethal, and there is a need to develop relevant bio-markers, that are relevant, cheap and easy to apply under tropical conditions in developing countries.

  • 16. Nguyen, Thi
    et al.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gallardo, Wenresti
    Chau, Thi
    Stakeholders' perceptions of ecosystem services and Pangasius catfish farming development along the Hau River in the Mekong Delta, Vietnam2017In: Ecosystem Services, ISSN 2212-0416, E-ISSN 2212-0416, Vol. 25, p. 2-14Article in journal (Refereed)
    Abstract [en]

    This study identifies stakeholders' perceptions of ecosystem services (ESS) along the Mekong River in Vietnam. It evaluates trade-offs made between ESS under different Pangasius catfish development scenarios, and stakeholders' preferences to these scenarios. The study was conducted through interviews, focus group discussions and a questionnaire survey with 150 households. Rice cultivation and Pangasius catfish farming were identified as the most important economic activities. Provisioning services were scored as the most important ESS, followed by supporting, regulating and cultural services. Most stakeholders perceived that an intensification of Pangasius catfish farming would increase the production of catfish, but decrease nine other ESS, while integrated Pangasius catfish farming would decrease the Pangasius catfish production but increase nine other ESS. An integrated system was preferred by the majority of the respondents, mainly because it was perceived to enhance several ESS and provide benefits to local communities. In conclusion, a sustainable development of Pangasius catfish farming in the Mekong Delta must include local stakeholders' participation and apply farming strategies that make use of the natural environment without severely or irreversibly degrading it.

  • 17.
    Stadlinger, Nadja
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Stockholm University, Faculty of Science, Department of Physical Geography.
    Berg, Håkan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Van den Brink, Paul J.
    Tam, Nguyen T.
    Stockholm University, Faculty of Science, Department of Physical Geography. Nong Lam University, Vietnam.
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Comparison of predicted aquatic risks of pesticides used under different rice-farming strategies in the Mekong Delta, Vietnam2018In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, no 14, p. 13322-13334Article in journal (Refereed)
    Abstract [en]

    This study evaluates the risks of pesticides applied in rice-fish and rice farming, with and without integrated pest management (IPM) strategies, to non-target aquatic organisms in two provinces of the Mekong Delta, Vietnam. Pesticide inventories and application patterns were collected from 120 Vietnamese farmers through interviews. Risks were assessed using (1) Pesticide RIsks in the Tropics to Man, Environment, and Trade (PRIMET), a first-tier model, which calculates predicted environmental concentrations (PECs) of pesticides in the rice field, based on the compound's physico-chemical properties and the application pattern, and then compares the PECs to safe concentrations based on literature data, and (2) species sensitivity distribution (SSD), a second-tier assessment model using species sensitivity distributions to calculate potentially affected fraction (PAF) of species based on the PECs from PRIMET. Our results show that several of the used insecticides pose a high risk to fish and arthropods and that the risks are higher among rice farmers than among rice-fish farmers. This study indicates that the PRIMET model in combination with SSDs offer suitable approaches to help farmers and plant protection staff to identify pesticides that may cause high risk to the environment and therefore should be substituted with safer alternatives.

  • 18. Thanh, Bui Xuan
    et al.
    Berg, Håkan
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Nguyen, Le Nguyen Tuyet
    Da, Chau Thi
    Effects of Hydraulic Retention Time on Organic and Nitrogen Removal in a Sponge-Membrane Bioreactor2013In: Environmental Engineering Science, ISSN 1092-8758, E-ISSN 1557-9018, Vol. 30, no 4, p. 194-199Article in journal (Refereed)
    Abstract [en]

    This is the first study on application of a sponge-membrane bioreactor (sponge MBR) for recirculation of aquaculture wastewater in the Mekong delta, Vietnam. Performance of a sponge MBR with a moving-cube sponge medium (20% v/v) was evaluated at different hydraulic retention times (HRTs) for the specific example of catfish pond wastewater. The sponge MBR was operated at HRT values of 8, 4, and 2 h, which correspond to membrane fluxes of 5, 10, and 20 L/m(2) per hour, respectively. The average chemical oxygen demand (COD) removal efficiencies were maintained at 93%, 94%, and 87% at an HRT of 8, 4, and 2 h, respectively, while the average total nitrogen (TN) removal efficiencies were 84%, 70%, and 57%. The COD and TN removal efficiencies decreased with a decrease in HRT (increase in membrane flux). Permeate concentrations of COD and TN were as low as 6.3 and 2.7 mg/L at the operated HRTs, respectively. Compared to the conventional MBR, the sponge MBR had twice the TN removal capacity at the same HRT due to simultaneous nitrification-denitrification. In addition, results implicated that the fouling rate (dTMP/dt) increased in an inverse proportion with HRT (h) according to the power equation (fouling rate = 4.2474 HRT-2.225). Free movement of sponges in the reactor improved fouling due to sweeping of the cake layer on the membrane surface. Results reveal that the sponge MBR was effective in terms of simultaneous organic and nitrogen removal, fouling control, and water recirculation.

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