A framework for sustainable aquaculture within peri-urban green infrastructures protecting the Gulf of Thailand from eutrophication

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Global demand for aquaculture produce began to grow exponentially from the 1980s onwards, and in response, Thailand developed more intensive farming methods that transformed its coastal landscape. The vast tract of land between Bangkok and the Gulf of Thailand nowadays consists mainly of low biodiversity aquaculture ponds that a vulnerable to pollution and novel shrimp and fish diseases. Rapid growth of the Bangkok Metropolitan Region is responsible for very poor microbial and chemical water quality in urban drainage canals which provide water for coastal aquaculture. Our BBSRC sponsored research has shown how this urban pollution is causing algae blooms in aquaculture ponds, with and without nutrient addition to the ponds, and how small scale producers are suffering economic losses as a consequence. Overall costs to the Thai economy from algae blooms and novel shrimp and fish diseases amount to billions of pounds. In 2018, there were 35,422 hectares of seawater shrimp aquacultures in Thailand, down from 48,590 hectares in 2008. While the current decline of the aquaculture sector in Thailand is of great concern, it also provides opportunity for a re-think and movement towards more resilient production systems. The project will engage Thai government officials from the Department of Fisheries, the Water Quality Office of the Bangkok Metropolitan Administration, and small-scale aquaculture producers in a critical analysis of water policies and innovative aquaculture practices. The policy analysis will review current standards for the quality of water to be used in coastal aquaculture, and will critically consider impacts of various policies on coastal land use, food production, flood risk mitigation, water cleansing and biodiversity. Modelling will predict how different wastewater treatment fee structures could enable an expansion of Bangkok's wastewater treatment infrastructure that currently covers only 50% of residents. The model will also predict how such an enhanced wastewater treatment provision would benefit surface water quality and the coastal aquacultures which depend on it. Engagement with small-scale producers will disseminate BBSRC sponsored research outcomes on innovative methods for water quality management in aquaculture. This includes biochar amended biofilters which could be implemented as high biodiversity buffer zones between aquaculture ponds and their associated canals. It also includes novel methods for microbial pollution source tracking and the characterisation of aquaculture microbiomes and their vulnerability to pathogen invasion. The project will investigate the willingness of farmers to adapt such practices and management methods, and what support and/or incentives would be needed to facilitate the uptake of best practice. A community engagement event will show-case water treatment methods, and new molecular microbiology capabilities at the King Mongkut's University of Technology Thonburi, which were established through an institutional links grant with Newcastle University. At the event, Thai aquaculture innovators will also present their experiences with certified and organic aquaculture methods, and how recreational offerings such as accommodation for tourists on farms can provide an additional income stream. Lessons learned through the engagement with the various stakeholders will be integrated in a GIS framework to visualize water policy implications on water quality in canals and associated coastal aquacultures, with and without treatments, and implications for food production and biodiversity in the coastal belt, and pollution discharges into the Gulf of Thailand. This framework will be used for scenario analysis. The illustration of various scenarios at a public symposium will facilitate communication with decision makers and other stakeholders, and will enhance their understanding of the inter-linkages between urban and agricultural activities and the natural environment.