Preservation and recovery of mangrove ecosystem carbon stocks in abandoned shrimp ponds

Mangrove forests capture and store exceptionally large amounts of carbon and are increasingly recognised as an important ecosystem for carbon sequestration. Yet land-use change in the tropics threatens this ecosystem and its critical ‘blue carbon’ (carbon stored in marine and coastal habitats) stores. The expansion of shrimp aquaculture is among the major causes of mangrove loss globally. Here, we assess the impact of mangrove to shrimp pond conversion on ecosystem carbon stocks, and carbon losses and gains over time after ponds are abandoned. Our assessment is based on an intensive field inventory of carbon stocks at a coastal setting in Thailand. We show that although up to 70% of ecosystem carbon is lost when mangroves are converted to shrimp ponds, some abandoned ponds contain deep mangrove soils (>2.5 m) and large carbon reservoirs exceeding 865 t carbon per hectare. We also found a positive recovery trajectory for carbon stocks in the upper soil layer (0-15 cm) of a chronosequence of abandoned ponds, associated with natural mangrove regeneration. Our data suggest that mangrove carbon pools can rebuild in abandoned ponds over time in areas exposed to tidal flushing

How is mangrove ecosystem health defined? A local community perspective from coastal Thailand

Mangroves, intertidal forests, are increasingly considered a high-priority ecosystem for international conservation efforts. Setting targets for future mangrove conservation and restoration requires understanding of the health of the ecosystem. However, the way ‘ecosystem health’ is defined varies across locations, users, and indices due to differences in knowledge of the ecosystem, scales of the ecosystem being assessed, perceptions of what is ‘healthy’, or because of differences in the way people use or benefit from ecosystems. This can result in misunderstandings which can undermine effective actions to protect and restore functioning ecosystems. Here, we use a case study of a mangrove fishing community in coastal Thailand to examine how local people assess and define mangrove ecosystem health. Through participatory workshops, we show that local people use at least 27 indicators to define mangrove ecosystem health, including biological, physical, and human indices. Mangrove ecosystem health is defined by both direct material benefits derived from the ecosystem, non-material aspects, and the relational value experienced through ‘bundles’ of benefits linked to people's livelihood activities. Our findings suggest that ecosystem health frameworks would be more useful if they incorporated social components and metrics, recognising both the interdependencies between ecosystems and human societies, and that ecosystems possess intrinsic value. Local communities that interact most closely with ecosystems can contribute to improving and operationalising frameworks for ecosystem health

Characterizing shrimp-farm production intensity in Thailand: beyond technical indices

This study examines shrimp farmer behaviour in relation to production intensity along the eastern coast of the Gulf of Thailand, and its embeddedness in the wider socio-economic context of shrimp farming households. The integrative agent-centred (IAC) framework was used as a basis for designing a structured survey to collect semi-quantitative data for a range of explanatory variables that potentially drive shrimp farmer behaviour. The results show that shrimp farming intensity is associated with a combination of technical (e.g. farm area, pond size, stocking density and production), economic (shrimp selling price, production costs and farm revenue), social (e.g. farm operating years, the use of family labour, engagement in shrimp farming and with other shrimp farmers), and ecological factors (e.g. farmer reliance on natural pond productivity, and constraints brought about by environmental change and fluctuations in productive areas). In addition, the results indicate that a number of external and internal socio-economic factors are related to the decision to adopt a certain level of production intensity, including training received on farming practices, access to technical equipment, proportion of total income from shrimp farming, season-specific changes in production, risk perception, and subjective culture (social norms and roles). This study therefore illustrates that levels of shrimp farming intensity are in fact an indicator of a diversity of socio-economic conditions and behavioural choices, which need to be targeted by sustainability policies differentially and beyond the technical sphere. In showing this, we conclude that national standards aimed at achieving aquaculture sustainability should be designed to reflect the diversity needed to support such a diverse sector, and should be adjustable to better represent different socio-economic contexts

How is mangrove ecosystem health defined? A local community perspective from coastal Thailand

Mangroves, intertidal forests, are increasingly considered a high-priority ecosystem for international conservation efforts. Setting targets for future mangrove conservation and restoration requires understanding of the health of the ecosystem. However, the way ‘ecosystem health’ is defined varies across locations, users, and indices due to differences in knowledge of the ecosystem, scales of the ecosystem being assessed, perceptions of what is ‘healthy’, or because of differences in the way people use or benefit from ecosystems. This can result in misunderstandings which can undermine effective actions to protect and restore functioning ecosystems. Here, we use a case study of a mangrove fishing community in coastal Thailand to examine how local people assess and define mangrove ecosystem health. Through participatory workshops, we show that local people use at least 27 indicators to define mangrove ecosystem health, including biological, physical, and human indices. Mangrove ecosystem health is defined by both direct material benefits derived from the ecosystem, non-material aspects, and the relational value experienced through ‘bundles’ of benefits linked to people's livelihood activities. Our findings suggest that ecosystem health frameworks would be more useful if they incorporated social components and metrics, recognising both the interdependencies between ecosystems and human societies, and that ecosystems possess intrinsic value. Local communities that interact most closely with ecosystems can contribute to improving and operationalising frameworks for ecosystem health

Preservation and recovery of mangrove ecosystem carbon stocks in abandoned shrimp ponds

Mangrove forests capture and store exceptionally large amounts of carbon and are increasingly recognised as an important ecosystem for carbon sequestration. Yet land-use change in the tropics threatens this ecosystem and its critical ‘blue carbon’ (carbon stored in marine and coastal habitats) stores. The expansion of shrimp aquaculture is among the major causes of mangrove loss globally. Here, we assess the impact of mangrove to shrimp pond conversion on ecosystem carbon stocks, and carbon losses and gains over time after ponds are abandoned

Characterizing shrimp-farm production intensity in Thailand: Beyond technical indices

This study examines shrimp farmer behaviour in relation to production intensity along the eastern coast of the Gulf of Thailand, and its embeddedness in the wider socio-economic context of shrimp farming households. The integrative agent-centred (IAC) framework was used as a basis for designing a structured survey to collect semi-quantitative data for a range of explanatory variables that potentially drive shrimp farmer behaviour. The results show that shrimp farming intensity is associated with a combination of technical (e.g. farm area, pond size, stocking density and production), economic (shrimp selling price, production costs and farm revenue), social (e.g. farm operating years, the use of family labour, engagement in shrimp farming and with other shrimp farmers), and ecological factors (e.g. farmer reliance on natural pond productivity, and constraints brought about by environmental change and fluctuations in productive areas). In addition, the results indicate that a number of external and internal socio-economic factors are related to the decision to adopt a certain level of production intensity, including training received on farming practices, access to technical equipment, proportion of total income from shrimp farming, season-specific changes in production, risk perception, and subjective culture (social norms and roles). This study therefore illustrates that levels of shrimp farming intensity are in fact an indicator of a diversity of socio-economic conditions and behavioural choices, which need to be targeted by sustainability policies differentially and beyond the technical sphere. In showing this, we conclude that national standards aimed at achieving aquaculture sustainability should be designed to reflect the diversity needed to support such a diverse sector, and should be adjustable to better represent different socio-economic contexts