Dynamic emergy evaluation of a fish farm rearing process

The environmental sustainability of a fish farm rearing process was examined by means of emergy analysis. Many emergy analyses integrate data for a whole year smoothing short term variations and sometimes losing meaningful information (aliasing). For this reason we developed a model for an instantaneous emergy evaluation in an aquacultural system so that transformities, efficiency and effort spent at each moment during the fish rearing activity could be calculated. By means of the model and dynamic emergy calculations it is possible to recognize step by step the importance of the various emergy contributions and verify where and when to modify the system to move toward optimum production of a sustainable product. By the application of the model we confirmed that the emergy trends in a fish farm installation follow wide oscillations during a year due to variations in both internal and external emergy contributions. Among the fluxes considered, those due to the introduction of fingerlings represented the highest contributions to the total emergy budget. Thus, to improve the sustainability of the analyzed system the amount, frequency and timing of these fluxes must be carefully considered. For this purpose, a comparison between two different fry introduction schedules was performed to evaluate differences in the efficiency of the rearing process.     

Ecological and economic dynamics of the Shunde agricultural system under China's small city development strategy

The agricultural and industrial development of small cities is the primary environmental management strategy employed to make full use of extra labor in the rural areas of China. The ecological and economic consequences of this development strategy will affect over 100 million people and change the organization of the Chinese landscape. In this study, we examined the agricultural development of Shunde, a small city in Guangdong Province, over the period 1978 until 2000. Our analysis of the ecological and economic dynamics of the agricultural system revealed the dominant role of labor in the intensification of agricultural production, even though the use of fuels, fertilizers and machines also increased during this time. The Shunde agricultural system was examined from both biophysical or donor-based and human utility or receiver-based perspectives, using emergy and economic methods, respectively. After 22 years of urbanization, the Shunde agricultural system was still able to fill 96% of the local demand for agricultural products using only 6% of its total yield compared to using 14% of the total yield in 1978. Aquaculture developed quickly during the study period as grain production decreased. In 2000, the production of fish, pork, and vegetables accounted for 92% of the total emergy output of the system; however, the emergy buying power of the money received in exchange was lower than the emergy contained in the products exported. The excess emergy exported is the basis for a high quality diet delivered to city dwellers at a relatively low price. In the 1980s, the productivity of both land and labor increased; but after 1992 the productivity of labor decreased, causing the efficiency of the whole agricultural system to decrease. We recommend that processing plants be established for the main agricultural products of Shunde to decrease the emergy loss in trading and to increase employment. The effect of including monetized ecosystem services in the balance between the emergy delivered to the markets in agricultural products and the emergy buying power of the money received was to decrease the emergy gained by the Shunde agricultural system.     

Energy economy of salmon aquaculture in the Baltic sea

Resource utilization in Atlantic salmon aquaculture in the Baltic Sea was investigated by means of an energy analysis. A comparison was made between cage farming and sea ranching enterprises each with yearly yields of 40 t of Atlantic salmon. A variety of sea ranching options were evaluated, including (a) conventional ranching, (b) ranching employing a delayed release to the sea of young smolts, (c) harvesting salmon both by offshore fishing fleets and as they return to coastal areas, and (d) when offshore fishing is banned, harvesting salmon only as they return to coastal areas where released. Inputs both from natural ecosystems (i.e., fish consumed by ranched salmon while in the sea and raw materials used for producing dry food pellets) and from the economy (i.e., fossil fuels and energy embodied in economic goods and services) were quantified in tonnes for food energy and as direct plus indirect energy cost (embodied energy). The fixed solar energy (estimated as primary production) and the direct and indirect auxiliary energy requirements per unit of fish output were expressed in similar units. Similar quantities of living resources in tonnes per unit of salmon biomass output are required whether the salmon are feeding in the sea or are caged farmed. Cage farming is about 10 times more dependent on auxiliary energies than sea ranching. Sea ranching applying delayed release of smolts is 35–45% more efficient in the use of auxiliary energies than conventional sea ranching and cage farming. Restriction of offshore fishing would make sea ranching 3 to 6.5 times more efficient than cage farming. The fixed solar energy input to Atlantic salmon aquaculture is 4 to 63 times larger than the inputs of auxiliary energy. Thus, cage farming and sea ranching are both heavily dependent on the productivity of natural ecosystems. It is concluded that sustainable development of the aquaculture industry must be founded on ecologically integrated technologies which utilize the free production in marine ecosystems without exhausting or damaging the marine environment.     

The Environmental Impact of Shrimp Aquaculture: Causes, Effects, and Mitigating Alternatives

Attracted by the demand for shrimp in the developed countries, shrimp aquaculture has expanded rapidly, mainly in the subtropical and tropical lowlands of America and Asia. This work provides a global review and viewpoint on the environmental impacts of shrimp aquaculture, considering the causes and effects of the siting and operation of shrimp ponds and abandonment of farm facilities. Additionally, mitigating alternatives are discussed. To date, approximately 1–1.5 million ha of coastal lowlands have been converted into shrimp ponds, comprising mainly salt flats, mangrove areas, marshes, and agricultural lands. The impact of shrimp farming of most concern is the destruction of mangroves and salt marshes for pond construction. Compatibility with other users, the presence of buffer zones, maintaining an acceptable balance between mangroves and shrimp pond area, improved pond design, reduction of water exchange, and an improved residence time of water, size and capacity to assimilate effluents of the water body, are examples of ways to mitigate the adverse effects. The use of mangroves and halophytes as biofilters of shrimp pond effluents offers an attractive tool for reducing the impact in those regions where mangrove wetlands and appropriate conditions for halophyte plantations exist. Healthy seed supply, good feed with the use of prophylactic agents (including probiotics), good water quality, and lower stocking densities are examples of actions suggested to control disease in shrimp farming. Finally, in the context of integrated management, research priorities are suggested.     

Emergy Assessment of a Wheat-Maize Rotation System with Different Water Assignments in the North China Plain

Sustainable water use is seriously compromised in the North China Plain (NCP) due to the huge water requirements of agriculture, the largest use of water resources. An integrated approach which combines the ecosystem model with emergy analysis is presented to determine the optimum quantity of irrigation for sustainable development in irrigated cropping systems. Since the traditional emergy method pays little attention to the dynamic interaction among components of the ecological system and dynamic emergy accounting is in its infancy, it is hard to evaluate the cropping system in hypothetical situations or in response to specific changes. In order to solve this problem, an ecosystem model (Vegetation Interface Processes (VIP) model) is introduced for emergy analysis to describe the production processes. Some raw data, collected by investigating or observing in conventional emergy analysis, may be calculated by the VIP model in the new approach. To demonstrate the advantage of this new approach, we use it to assess the wheat-maize rotation cropping system at different irrigation levels and derive the optimum quantity of irrigation according to the index of ecosystem sustainable development in NCP. The results show, the optimum quantity of irrigation in this region should be 240–330 mm per year in the wheat system and no irrigation in the maize system, because with this quantity of irrigation the rotation crop system reveals: best efficiency in energy transformation (transformity = 6.05E + 4 sej/J); highest sustainability (renewability = 25%); lowest environmental impact (environmental loading ratio = 3.5) and the greatest sustainability index (Emergy Sustainability Index = 0.47) compared with the system in other irrigation amounts. This study demonstrates that application of the new approach is broader than the conventional emergy analysis and the new approach is helpful in optimizing resources allocation, resource-savings and maintaining agricultural sustainability.     

Emergy Evaluation of the Natural Value of Water Resources in Chinese Rivers

Emergy theory and method were used to evaluate the economy of China and the contributions of water resources in Chinese rivers to the real wealth of the Chinese economy. The water cycle and energy conversion were reviewed, and an emergy method for evaluating the natural value of water resources in a river watershed was developed. The indices for China calculated from the emergy evaluation were close to those of developing countries. Despite a small surplus in its balance of payments, China had a net emergy loss from its trade in 2002. The efficiency of Chinese natural resource use was still not high and did not match its economic growth rate. Furthermore, the Chinese economy placed a stress on its ecological environment and natural resources. Several indices of Chinese rivers from the emergy evaluation were close to those of average global river water. The main average indices of Chinese rivers were transformity (4.17 × 10⁴ sej/J), emergy per volume (2.05 × 10¹¹ sej/m³), and emdollar per volume (0.06 $/m³). The total value of all the rivers’ water made up 13.0% of the GDP of China in 2002, and that of water consumption accounted for 2.1%. The value of the water resources in the Haihe-luanhe River (11.39 × 10⁴ sej/J) was the highest, followed by the Yellow River (10.27 × 10⁴ sej/J), while the rivers in Southwest China had the lowest values (2.92 × 10⁴ sej/J).     

Ecological limitations and appropriation of ecosystem support by shrimp farming in Colombia

Shrimp farming in mangrove areas has grown dramatically in Asia and Latin America over the past decade. As a result, demand for resources required for farming, such as feed, seed, and clean water, has increased substantially. This study focuses on semiintensive shrimp culture as practiced on the Caribbean coast of Colombia. We estimated the spatial ecosystem support that is required to produce the food inputs, nursery areas, and clean water to the shrimp farms, as well as to process wastes. We also made an estimate of the natural and human-made resources necessary to run a typical semiintensive shrimp farm. The results show that a semiintensive shrimp farm needs a spatial ecosystem support—the ecological footprint—that is 35–190 times larger than the surface area of the farm. A typical such shrimp farm appropriates about 295 J of ecological work for each joule of edible shrimp protein produced. The corresponding figure for industrial energy is 40:1. More than 80% of the ecological primary production required to feed the shrimps is derived from external ecosystems. In 1990 an area of 874–2300 km² of mangrove was required to supply shrimp postlarvae to the farms in Colombia, corresponding to a total area equivalent to about 20–50% of the country’s total mangrove area. The results were compared with similar estimates for other food production systems, particularly aquacultural ones. The comparison indicates that shrimp farming ranks as one of the most resource-intensive food production systems, characterizing it as an ecologically unsustainable throughput system. Based on the results, we discuss local, national, and regional appropriation of ecological support by the semiintensive shrimp farms. Suggestions are made for how shrimp farming could be transformed into a food production system that is less environmentally degrading and less dependent on external support areas.     

Integrated emergy,energy and economic evaluation of rice and vegetable production systems in alluvial paddy fields: Implications for agricultural policy in China

China is the largest rice producing and consuming country in the world, but rice production has given way to the production of vegetables during the past twenty years. The government has been trying to stop this land-use conversion and increase the area in rice-vegetable rotation. Important questions that must be answered to determine what strategy is best for society are, “What is the reason behind this conversion?”; “Which system is more productive and which is more sustainable?”; and “How can economic policy be used to adjust the pattern of farmland use to attain sustainable development?” To answer these questions, a combined evaluation of these agricultural production systems was done using emergy, energy and economic methods. An economic analysis clearly showed that the reason for this conversion was simply that the economic output/input ratio and the benefit density of the vegetable production system were greater than that of rice. However, both energy and emergy evaluations showed that long-term rice was the best choice for sustainable development, followed by rotation systems. The current price of rice is lower than the em-value of rice produced from the long-term rice system, but higher than that of rice produced from the rotation system. Scenario analysis showed that if the government increases the price of rice to the em-value of rice produced from the long-term rice system, US$0.4/kg, and takes the value of soil organic matter into account, the economic output/input ratios of both the rice and rotation systems will be higher than that of the vegetable system. The three methods, energy, emergy and economics, are different but complementary, each revealing a different aspect of the same system. Their combined use shows not only the reasons behind a system’s current state or condition, but also the way to adjust these systems to move toward more sustainable states.     

Economic simulation modeling of reprocessing alternatives for corn masa byproducts

Increasing production of corn masa for tortillas, chips, and related snack foods is resulting in large quantities of organic residuals requiring environmentally sound management. These byproduct streams appear suitable for use as livestock feed material, thus eliminating landfilling costs. Possibilities for developing livestock feed include direct shipping to livestock feeding facilities, blending prior to shipping, extrusion processing, pellet mill processing, and dehydration. To assess the viability of these options for reprocessing masa byproducts as livestock feed materials, an economic model was developed and applied to each of these alternatives. Through a series of simulation runs with this model, it was determined that direct shipping was by far the most inexpensive means of recycling masa processing residuals (10–57 $/Mg). Other alternatives examined in increasing order of costs included blending prior to shipping, extrusion, pellet mill processing (3–15, 5–18, and 4–18 times greater than direct shipping, respectively), while dehydration was clearly cost-prohibitive (33–81 times greater). Bagged feed was slightly more expensive to produce than bulk feed (1.1 times greater), and reprocessing costs increased as delivery distance increased, due to increased labor, equipment, and fuel costs, but decreased as byproduct generation rate increased, due to the development of the economies of scale. Alternately, based on a tipping fee of 50 $/Mg, the total estimated cost to landfill ranged from 65 to 112 $/Mg. Based on this cost analysis, direct shipping and feeding to livestock is the recycling option of choice for masa processing byproducts. Although specific details of process configurations and associated costs will vary, similar results are likely for other high moisture food processing residuals destined for utilization as livestock feed or components thereof.     

Response to the environmental and welfare imperatives by U.K. Livestock production industries and research services

Production methods for food from U.K. livestock industries (milk, dairy products, meat, eggs, fibre) are undergoing substantial change as a result of the need to respond to environmental and animal welfare awareness of purchasing customers, and to espouse the principles of environmental protection. There appears to be a strong will on the part of livestock farmers to satisfy the environmental imperative, led by the need to maintain market share and by existing and impending legislation. There has been support forthcoming in the form of Government-sponsored scientific research and technological development to provide the necessary framework for new environmentally sensitive practices. The agricultural community has itself made substantial responses to market demand through the inception of Farm Assured Quality Assurance Schemes. These appear to have a more sustainable future than the extremes of organic farming and free-range practices. Pollution of agricultural land with nitrate and phosphate by intensive livestock industries is a greater problem in some parts of continental Europe than it is in the U.K. The distribution of livestock out of intensive units and into mixed farming systems, would require substantial restructuring of the industry. Many of the animal welfare requirements which have been forwarded as a part of the environmental agenda for agriculture have been voluntarily accepted by livestock producers. However, some major aspects, such as alternative housing systems for pigs and poultry, remain unresolved. Analysis of the science and technology support for the environmental imperative, especially from Government sources, would suggest that, although dramatically increased in recent years, environmentally orientated research remains a relatively small proportion of the whole. Whilst a movement away from governmental funding of volume production appears to be justifiable, there has not been an equivalent balancing of effort toward funding for product quality, sustainability, environmental protection and animal welfare. Nevertheless, the university education system is producing a generation of more environmentally aware agricultural science graduates who are opting to pursue Government-sponsored environmentally orientated postgraduate research programs.     

Landscape changes in agrarian landscapes in the 1990s: the interaction between farmers and the farmed landscape. A case study from Jutland, Denmark

Recent landscape changes in a farmed landscape are analysed and related to farm and farmer characteristics. It is assumed that farm and farmer characteristics serve as mediators of large scale or macro driving forces of change-in the present case, a changing farming context including demands for a more environmentally friendly farming practise and a reduced output. The results are based on multivariate analyses of data collected from structured interviews of 160 farmers in a case study area, in central Jutland, measuring 5000 ha. The analysis shows that farmers are highly involved in landscape changes. The investigated landscape changes include creation and removal of landscape elements as well as certain management changes. The most common activity was creation of elements: hedgerows, small woodlands and conversion of rotational arable land to permanent grassland, whereas removal of elements, mainly hedgerows and semi-natural grasslands, were seen less frequently. Management changes like abandonment of permanent grassland were widespread. The results indicate a general extensification of the land use and the authors interpret the results partly as an indication of a change from productivism to a more multifunctional agricultural regime. The observed landscape changes at the farm level show a low, but structured relationship with the current farm and farmer characteristics, meaning that landscape changes were undertaken by various farmers and on various farms. On a general level, however, the age of the farmer and the duration of farm ownership seem to have a major influence on the landscape changes.     

Nitrogen recovery in an integrated system for wastewater treatment and tilapia production

An integrated system, consisting of Up-flow Anaerobic Sludge Blanket (UASB)-duckweed-tilapia ponds was used for recovery of sewage nutrients and water recycling. A UASB reactor with 40 liter working volume was used as pre-treatment unit followed by a series of three duckweed ponds for nitrogen recovery. The treated effluent and duckweed biomass was used to feed fishponds stocked with Nile tilapia (Oreochromis niloticus). The UASB reactor was fed with raw, domestic sewage at 6 h hydraulic retention time. The three duckweed ponds were stocked with Lemna gibba and fed with UASB effluent at 15 days hydraulic retention time. Nitrogen recovery from UASB effluent via duckweed biomass represented 81% of total nitrogen removal and 46.5% from the total nitrogen input to the system. In subsequent fishponds the nitrogen recovery from duckweed as fish feed was in the range of 13.4–20%. This nitrogen in fish biomass represented 10.6–11.5 g N from the total nitrogen in the raw sewage fed to the UASB reactor. The growth performance of tilapia (Oreochromis niloticus) showed specific growth rates (SGR) in the range of 0.53–0.97. The range of feed conversion ratio (FCR) and protein efficiency ratio (PER) were 1.2–2.2 and 2.1–2.28, respectively. The results of the experiments showed total fish yield and net fish yield in the range of 17–22.8 ton/ha/y and 11.8–15.7 ton/ha/y respectively. In conclusion UASB-duckweed-tilapia ponds provide marketable by-products in the form of duckweed and fish protein, which represent a cost recovery for sewage treatment.     

Sustainable Aquaculture: Are We Getting There? Ethical Perspectives on Salmon Farming

Aquaculture is the fastest growing animal producing sector in the world and is expected to play an important role in global food supply. Along with this growth, concerns have been raised about the environmental effects of escapees and pollution, fish welfare, and consumer health as well as the use of marine resources for producing fish feed. In this paper we present some of the major challenges salmon farming is facing today. We discuss issues of relevance to how to ensure sustainability, by focusing on animal production systems, breeding approaches, sources for feed ingredients, and genetic engineering strategies. Other crucial issues such as animal welfare, environmental quality, and ethics are elaborated with regard to relevance for the sustainability of aquaculture. Additionally, we comment on socio-economic distributive implications by intellectual property rights (IPR) strategies on access to genetic material and traceability. To improve sustainability of salmon farming we suggest that there is a need for new approaches to guide research, for identification of ethical issues, and for engaging stakeholders in resolving these challenges.     

Integrating emergy evaluation and geographic information systems for monitoring resource use in the Abruzzo region (Italy)

This paper presents an application of an environmental accounting method, namely emergy evaluation, developed for the monitoring and assessment of environmental resource use by local communities in the Abruzzo Region (Italy). Once quantified and classified according to their origin (renewable or non-renewable, local or external), emergy flows were elaborated through a geographic information system (GIS) that allowed us to represent their spatial distribution throughout the region. Outcomes took the form of patterns in which different emergy intensities, namely empower (unit: seJ yr^?1), were represented through a graduated grey-scale and visualized on a cartographic basis. The concentration of emergy flows, depending on the activity of local communities, showed variable levels of environmental load in different areas. In particular, spatial zones with homogeneous values of empower density (unit: seJ yr^?1 km^?2) – high, medium and low – were detected in order to identify areas with a similar “thermodynamic” nature, emergy being a thermodynamics based function. This allowed for the representation, at a glance, of a kind of geography that mirrors the behavior of a population settled in an area as additional information for investigating the effects of the use of urban structures and functions and improving our understanding of regional systems. A combined use of emergy evaluation and GIS could thus provide a complementary view of a territorial system and inform policy makers for planning specific strategies of future development.     

基于能值分析的苏州市城市生态系统可持续发展评估

本文利用能值分析的方法,分析了苏州城市生态系统的各种生态流,并建立了苏州城市生态系统可持续发展能值评价指标体系,评估其可持续发展程度,并对其能值指标的发展进行了预测。研究结果显示,2007年苏州市系统利用总能值达到616.71×1021sej,能值自给率仅为35.5%,环境负载率达到61.67。与其他国家和地区能值指标对比得出,苏州市是一个高度外向型生态经济系统,其系统的发展高度依赖于外界资源的输入,面对现在不稳定的世界经济发展和外部环境,苏州市必须加大系统自身的供给能力,提高系统自身的稳定性;发展循环经济,降低系统环境负载率;加强高科技和人才投入,提高系统可持续发展潜力。     

Potential of Corporate Social Responsibility for Poverty Alleviation among Contract Sugarcane Farmers in the Nzoia Sugarbelt, Western Kenya

Although contract sugarcane farming is the most dominant and popular land use among farmers in Nzoia Sugarbelt, results from a 2007 study suggests that the intended goal of increasing farmers’ incomes seems to have failed. With a mean monthly income of Kenya Shillings 723 (US $ 10) from an average cane acreage of 0.38 hectares, it would be difficult for a household of eight family members to meet their basic needs and lead a decent life. Analysis of farmer statements showed that up to 86% of the changes in net income were significantly determined by six cost variables as a group (i.e., acreage, tillage costs, seedcane costs, transport costs, yield, and farmer’s education level). Area under sugarcane had the greatest influence on net income whereby an increase in one hectare under cane would result in an increase of Kenya Shillings 110,427 in net income (per crop cycle of 21 months), holding other variables constant. This translates into Kenya shillings 5,258 per month (or 175 per day per household, or for a family of eight people—KES 22 or US $ 10) from an average cane acreage of 0.38 hectares, it would be difficult for a household of eight family members to meet their basic needs and lead a decent life. Analysis of farmer statements showed that up to 86% of the changes in net income were significantly determined by six cost variables as a group (i.e., acreage, tillage costs, seedcane costs, transport costs, yield, and farmer’s education level). Area under sugarcane had the greatest influence on net income whereby an increase in one hectare under cane would result in an increase of Kenya Shillings 110,427 in net income (per crop cycle of 21 months), holding other variables constant. This translates into Kenya shillings 5,258 per month (or 175 per day per household, or for a family of eight people—KES 22 or US 0.3) per member, which is far below the international standard of absolute poverty. Key net income depressors were tillage, seedcane, and transportation costs, all of which were determined by the company with no input from farmers. To bridge income gaps between the company and farmers in favor of sustainable community livelihoods, this paper argues strongly for the need to institutionalize Corporate Social Responsibility within the daily operations of the company particularly to address net-income depressors. Ten key building blocks for such a policy for Nzoia Sugar Company are suggested, based on farmers’ responses and ethical considerations.     

Coastal Aquaculture Development in Bangladesh: Unsustainable and Sustainable Experiences

Coastal aquaculture in Bangladesh consists mainly of two shrimp species (Penaeus monodon and Macrobrachium rosenbergii). Currently, there are about 16,237 marine shrimp (P. monodon) farms covering 148,093 ha and 36,109 fresh water shrimp (M. rosenbergii) farms covering 17,638 ha coastal area. More than 0.7 million people are employed in the farmed shrimp sector and in 2005–2006 the export value of shrimp was 403.5 million USD. Thus, coastal aquaculture contributes significantly to rural employment and economy but this is overshadowed by negative social and ecological impacts. This article reviews the key issues, constraints and opportunities of sustainable shrimp farming. In addition we present the results of two case studies from southwestern coastal areas where shrimp farming originated and central coastal areas where shrimp farming, especially M. rosenbergii, began in recent years. Lessons learned from the review and case studies are considered in the context of recommendations to encompass a socially equitable and ecologically sound coastal aquaculture.     

Farmers' assessment of the social and ecological values of land uses in central highland Ethiopia

Often in land use evaluations, especially those in developing countries, only the financial aspect receives serious attention, while the social and ecological values are overlooked. This study compared the social and ecological values of four land use types (small-scale woodlot [SSW], boundary tree and shrub planting [BTP], homestead tree and shrub growing [HTG] and cereal farming [CF]) by a criteria-based scoring approach using a bao game. The impacts of local wealth status and proximity to a forest on the value the community renders to the land use types were also assessed. The value comparison, assessed by relative scoring, was accompanied by farmer’s explanations to reveal the existing local knowledge about land use values. It was found that HTG ≥ SSW > BTP > CF for both social and ecological values. Though this trend applies for the medium and rich households, the poor ones chose SSW as the most valuable. With increasing distance from a forest, the social and ecological values of land uses increased. The accompanying scoring justifications indicated the existence of in-depth ecological knowledge, which conform to contemporary scientific reports. Generally, this study showed that social and ecological values, besides financial values, strongly influence farmer’s decision in implementing various practices related to the land use types. Thus, such values are worth considering for a holistic understanding of the diverse benefits of land uses. Finally, the strong preference for tree and shrub-based land use types is a good opportunity for enhancing tree and shrub growing to minimize the major environmental problems (e.g., soil degradation, wood shortage and deforestation) in the central highlands of Ethiopia.     

Issues,impacts, and implications of shrimp aquaculture in Thailand

Water quality impacts to and from intensive shrimp aquaculture in Thailand are substantial. Besides the surface and subsurface salinization of freshwaters, loadings of solids, oxygen-consuming organic matter, and nutrients to receiving waters are considerable when the cumulative impacts from water exchange during the growout cycle, pond drainage during harvesting, and illegal pond sediment disposal are taken into account. Although just beginning to be considered in Thailand, partial recirculating and integrated intensive farming systems are producing promising, if somewhat limited, results. By providing on-site treatment of the effluent from the shrimp growout ponds, there is less reliance on using outside water supplies, believed to be the source of the contamination.The explosion in the number of intensively operated shrimp farms has not only impacted the coastal zone of Thailand, but has also resulted in an unsustainable aquaculture industry. Abandonment of shrimp ponds due to either drastic, disease-caused collapses or more grandual, year-to-year reductions in the productivity of the pond is common. To move Thailand towards a more sustainable aquaculture industry and coastal zone environment, integrated aquaculture management is needed. Components of integrated aquaculture management are technical and institutional. The technical components involve deployment of wastewater treatment and minimal water-use systems aimed at making aquaculture operations more hydraulically closed. Before this is possible, technical and economic feasibility studies on enhanced nitrification systems and organic solids removal by oxidation between production cycles and/or the utilization of plastic pond liners need to be conducted. The integration of semi-intensive aquaculture within mangrove areas also should be investigated since mangrove losses attributable to shrimp aquaculture are estimated to be between 16 and 32% of the total mangrove area destroyed betweeen 1979 and 1993.Government policy needs to devote as much attention to sustainability issues as it has on promoting intensive pond culture. Such a balanced policy would include training and education monitoring and enforcement, rehabilitating abandoned ponds, managing land use within the coastal zone, more community involvement, and government reorganization to eliminate overlapping jurisdictions among agencies.As integrated aquaculture management becomes more the practice than the exception, less risk of crop failure to the industry and reduced discharge loadings from intensively managed shrimp ponds to receiving waters can be expected. Projected limitations on growing and marketing shrimp in the future, such as scarcity of land and broodstock, continued disease outbreaks, negative publicity, regulatory enforcement, water treatment and solids disposal costs, and increased competition from growers in other Asian countries will also drive the government and the industry towards adopting integrated aquaculture management.The data for this paper was obtained while the senior author was a Visiting Fulbright Researcher at the Coastal Resources Institute (CORIN), Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.     

Balancing Conservation and Economic Sustainability: The Future of the Amazon Timber Industry

Logging has been a much maligned feature of frontier development in the Amazon. Most discussions ignore the fact that logging can be part of a renewable, environmentally benign, and broadly equitable economic activity in these remote places. We estimate there to be some 4.5 ± 1.35 billion m³ of commercial timber volume in the Brazilian Amazon today, of which 1.2 billion m³ is currently profitable to harvest, with a total potential stumpage value of $15.4 billion. A successful forest sector in the Brazilian Amazon will integrate timber harvesting on private lands and on unprotected and unsettled government lands with timber concessions on public lands. If a legal, productive, timber industry can be established outside of protected areas, it will deliver environmental benefits in synergy with those provided by the region’s network of protected areas, the latter of which we estimate to have an opportunity cost from lost timber revenues of $2.3 billion over 30 years. Indeed, on all land accessible to harvesting, the timber industry could produce an average of more than 16 million m³ per year over a 30-year harvest cycle—entirely outside of current protected areas—providing $4.8 billion in returns to landowners and generating $1.8 billion in sawnwood sales tax revenue. This level of harvest could be profitably complemented with an additional 10% from logging concessions on National Forests. This advance, however, should be realized only through widespread adoption of reduced impact logging techniques.