Abstract:Pond culture and rice-crab co-culture are currently the two main culture modes for the Chinese mitten crab (Eriocheir sinensis) in China. Due to the large differences in the aquaculture environments of paddy fields and ponds, there may be significant differences in greenhouse gas (GHG) emissions and their influencing factors. Therefore, research on the differences in GHG emissions under different culture modes is urgently needed. In this experiment, the pond culture and rice-crab co-culture modes were used as the research objects, and CH4 and N2O emission fluxes were collected and measured using a static box-gas chromatography method, along with the related environmental factors, at 10-day intervals between 9:00 a.m. and 11:00 a.m. on sunny days from June 7 to September 27, 2023, with a view to exploring the characteristics of the GHG emissions and their influencing factors under the two modes of aquaculture. Based on the results, the integrated warming potential of the two modes of river crab culture was calculated. The results showed that N2O emission in the rice-crab co-culture mode was 2.8 times higher than that in the pond culture, with a fluctuation range of 34.94−126.90 μg/(m2 ·h) and a mean value of (85.41±5.78) μg/(m2 ·h), whereas CH4 emission was 1.19 times higher than that in the pond culture, with a fluctuation range of 1.32−39.50 μg/(m2 ·h) and a mean value of (13.69±1.42) μg/(m2 ·h). The Global Warming Potentials (GWPs) of pond culture and rice-crab cultivation were (10.73±1.16) t/hm2 and (13.07±1.62) t/hm2 , respectively, and the emission peaks of both modes occurred during the high temperature period of August. Multiple stepwise regression showed that the CH4 emission in the pond culture mode was mainly affected by water temperature and total nitrogen (TN), while the N2O emission was mainly affected by nitrate nitrogen (NO3 − -N); the CH4 emission in rice-crab culture mode was mainly affected by total phosphorus (TP) content, while the N2O emission was mainly affected by dissolved oxygen (DO) and water temperature. In summary, the rice-crab cropping mode significantly increased the GHG emissions and GWP of CH4 and N2O during the cultivation of the Chinese mitten crab, probably due to the fact that the GHG emissions under the rice-crab cropping mode were mainly caused by the rice emissions, and that there was a huge space for GHG emission reduction in the rice-crab cropping mode. This study provides data support for greenhouse gas emission of Chinese mitten crab under different culture modes as well as a theoretical basis for the promotion and demonstration of rice-crab co-culture mode.
