Assessing the Effectiveness of Nature-Based Solutions in Reducing Greenhouse Gas Emissions from Shrimp Aquaculture

Shrimp aquaculture in South Asian countries has long played a critical role in improving socio-economic conditions and nutritional security, but its contribution to greenhouse gas (GHG) emissions raises concerns about the sustainability of these systems. Nature-based solutions (NbS), such as Najas-based aquaculture and Integrated Multi-Trophic Aquaculture (IMTA), present potential strategies for reducing the carbon footprint of shrimp farming. However, their effectiveness in mitigating GHG emissions has not been well studied. This research investigates the impact of Najas-based NbS and the IMTA system on GHG emissions from shrimp farms in southwestern Bangladesh over a three-month period. Gas samples were collected both day and night using the floating chamber method, and GHG concentrations (CO₂, CH₄, N₂O) were analyzed via gas chromatography-mass spectrometry (GC-MS). Our results show that shrimp farms emit significant amounts of CO₂ (1572.7 ± 273.4 g/day/hectare), CH₄ (19.8 ± 4.9 g/day/hectare), and N₂O (1.09 ± 0.35 g/day/hectare). Notably, CO₂ emissions were higher at night (1834.7 ± 154.3 g/day/hectare) than during the day (1374.2 ± 341.5 g/day/hectare). Both the Najas-based culture and IMTA systems significantly reduced CO2 emissions during daylight hours (p>0.05). Najas enhanced oxygenation at the sediment-water interface, which helped reduce methane production significantly (p>0.05) during the day, while IMTA reduced organic matter and methane emissions throughout the day and night. No significant reduction in N₂O emissions was observed. When combined, these systems resulted in substantial reductions in both CO₂ and CH₄ emissions. This study demonstrates the potential of integrating Najas-based NbS with IMTA to significantly reduce the carbon footprint of shrimp farming and contribute to more sustainable aquaculture practices.