Among inland waters, ponds and lakes play a critical role in climate change, collectively accounting for up to a quarter of global greenhouse gas (GHG) emissions. Small water bodies are particular hotspots for sequestration, processing and emission of terrestrial carbon. Indeed, existing literature indicates that small ponds contribute approximately 41% of CH4 and 15% of CO2 emissions of all inland waters.The Dombes region (France) represents the largest continental fishery in France, with over 1,100 fish ponds covering nearly 12,000 hectares. These solely rain-fed ponds display unique hydrological patterns. They are characterized by alternating phases of impoundment for fish production (“évolage”), lasting four years, followed by a 1-year dry period (“assec”) when the pond is drained, cleaned, and cultivated with crops. In this context, common management practices in the ponds of the Dombes include the use of organic and inorganic fertilizers, feeds, and lime, which increase nutrient concentrations to enhance fish yields. Using a large gradient of ponds from highly to minimally managed, the main objective of this study is to explore how management practices influence carbon dynamics, GHG emissions, and biomass uptake into fishes during the “évolage”.
To represent the major management gradients, we selected 38 ponds that were sampled in June and July 2023. We analysed dissolved CO2 and CH4 in the water, along with various physico-chemical parameters such as pH, dissolved oxygen, nutrients, and sediment carbon content. Our ongoing analyses and results aim to bring significant insights into carbon fluxes, including both GHG emissions and carbon sequestration within these aquaculture ponds. Moreover, this study will strengthen our comprehension of the underlying physico-chemical parameters structuring CO2 and CH4 dynamics. Considering that CH4 has a warming potential 30x greater than that of CO2, it will be crucial to co-develop best-management practices that limit CH4 emissions, while maintaining a profitable fish yield. Given the increasing global importance of inland aquaculture, this study will be instrumental in reducing GHG emissions across many regions worldwide.