Effect of the conversion of mangroves into shrimp farms on carbon stock in the sediment along the southern Red Sea coast, Saudi Arabia

The conservation of coastal ecosystems and specially mangroves ''blue carbon'' is receiving more attention as consequence of their recognition as high ecosystem carbon stocks and for the fact that these areas are undergoing land conversion. The aim of the present study is to evaluate the impact of land use changes due to conversion of mangroves to shrimp farms on the bulk density (SBD), organic carbon (SOC) concentration, and SOC stock in the sediments along the southern Saudi Arabian Red Sea coast. Shrimp farms and mangrove locations showed significant (P < 0.001) differences in SBD with high mean values in the sediments of shrimp farms. Shrimp farms and mangrove locations showed significant (P < 0.001) SOC concentration differences with high mean values in the sediments of mangroves. Considering the whole depth of sediment interval (0-100 cm), the highest value of SOC stock was recorded at mangroves (29.2 kg C m⁻²) and the lowest was identified at the locations of shrimp farms (19.9 kg C m⁻²). The results show that SOC stock of mangroves is 147% higher than that of shrimp farms confirming the fact that anthropogenic factors contributed significantly to SOC stock decrease. The mean cumulative potential carbon dioxide (CO₂) emission due to loss soil carbon stock from mangrove conversion to the shrimp ponds was 34.9 kg CO₂ m⁻². In conclusion, the conversion of mangroves into shrimp farms contributed to the loss of SOC stock, therefore, the preservation of mangrove areas has an important value especially in arid areas such as Saudi Arabia.