Aquaculture is currently the fastest growing animal food production sector and will soon supply more than half of the world's seafood for human consumption. Continued growth in aquaculture production is likely to come from intensification of fish, shellfish, and algae production. Intensification is often accompanied by a range of resource and environmental problems. We review several potential solutions to these problems, including novel culture systems, alternative feed strategies, and species choices. We examine the problems addressed; the stage of adoption; and the benefits, costs, and constraints of each solution. Policies that provide incentives for innovation and environmental improvement are also explored. We end the review by identifying easily adoptable solutions and promising technologies worth further investment.

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Searching for Solutions in Aquaculture: Charting a Sustainable Course

Over the past decade, the large-scale cultivation of seaweed Gracilaria has expanded rapidly in the Chinese coastal waters. The production of Gracilaria increased from 50,536 tons (t, dry weight) in 2003 to 114,722 t in 2010. The production of the seaweed ranks third only to kelps Saccharina (formerly referred to as Laminaria) and Undaria in China. Nan'ao located in Shantou City, Guangdong Province has been successfully developed as one of the major cultivation bases of Gracilaria lemaneiformis at an industrial scale in South China since 2000, and the farmed area increased by 11,538-fold from 0.13 ha in 2000 to 1500 ha in 2011. From lab-scale study to field industrial practice, it has been documented that Gracilaria cultivation is beneficial in environmental improvements such as mitigating eutrophication, controlling harmful algal blooms, maintaining healthy mariculture systems, and sequestrating CO2. Gracilaria may significantly remediate contaminants in mariculture ecosystems and improve the water environment, and its cultivation provides a new approach to coastal environmental improvement in China and the world.

Cultivation of seaweed Gracilaria in Chinese coastal waters and its contribution to environmental improvements

The continuous development of world aquaculture demands new strategies and alternatives aimed to achieve sustainability. The use or microorganisms in aquaculture has greatly evolved during the last two decades. From being considered as a potential threat, during the last years, they have been used as probiotics and inclusively as food source for fish and crustacean. The microbial-based systems represent one of the most viable strategies to achieve a sustainable aquaculture. In short, these systems are based on the promotion of microbial proliferation, either autotrophic or heterotrophic microorganisms; these microbes are expected to use, recycle and transform the excess of nutrients from faeces, dead organisms, unconsumed food and diverse metabolites into biomass, which would be further consumed by the cultured organisms. Successful results on using microbial-based systems have been documented around the world; however, there are key aspects to consider and yet to experiment before a system could be implemented. Some of those aspects are analysed in this manuscript, while new advances in the use of microbial-based systems and recommendations are also presented.

Microbial-based systems for aquaculture of fish and shrimp: an updated review

Aquaculture has been considered as an option to cope with the world food demand. However, criticisms have arisen around aquaculture, most of them related to the destruction of ecosystems such as mangrove forest to construct aquaculture farms, as well as the environmental impacts of the effluents on the receiving ecosystems. The inherent benefits of aquaculture such as massive food production and economical profits have led the scientific community to seek for diverse strategies to minimize the negative impacts, rather than just prohibiting the activity. Aquaculture is a possible panacea, but at present is also responsible for diverse problems related with the environmental health; however the new strategies proposed during the last decade have proven that it is possible to achieve a sustainable aquaculture, but such strategies should be supported and proclaimed by the different federal environmental agencies from all countries. Additionally there is an urgent need to improve legislation and regulation for aquaculture. Only under such scenario, aquaculture will be a sustainable practice.

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World aquaculture: environmental impacts and troubleshooting alternatives.

The growing demand for fish products and the dwindling productivity of marine fish stocks due to the overexploitation of fisheries place the aquaculture industry as a key contributor to the global fish supply. The intensive development of aquaculture has raised a range of environmental concerns such as effluent discharge, excessive use of resources and dependence on commercial feed. In this context, the development of sustainable aquaculture systems is becoming the cornerstone for long-term aquaculture expansion, and to achieve environmental sustainability. Integrated multitrophic aquaculture (IMTA) is regarded as a suitable approach to limit aquaculture nutrients and organic matter outputs through biomitigation. The cocultured species are used as biofilters, and each level has its own independent commercial value, providing both economic and environmental sustainability. Here, environmental issues of aquaculture and the current status of IMTA are reviewed and its future prospects discussed. Also, the opportunities to expand this systems’ complexity with increased added-value and trophic levels are introduced.

Is integrated multitrophic aquaculture the solution to the sectors’ major challenges? – a review

Bioremediation of aquaculture wastes.

The use of micro organisms for heavy metal remediation in water is a technique widely studied. This review describes a number of methods used for Acid Mine Drainage (AMD) remediation, containing high concentration of this type of contaminant. The AMD is a problem generated in abandoned mines and low grade stock of active mines, therefore it is an existing problem in mining countries. In this review it is described the problem in Chile, regulations and the challenge to resolved this problem for a sustainable industrial future.

Johanna Obreque-Contreras

Papers

Bioremediation of aquaculture wastes.

Acid Mine Drainage in Chile: An Opportunity to Apply Bioremediation Technology

Desalination Plants: Technology to Supply Water to Mining Processes and Local Populations, Opportunities and Environmental Impact