Evaluation of the trophic structure and energy flow of a rice-crayfish integrated farming ecosystem based on the Ecopath model

Abstract

Rice field integrated farming combining aquaculture and rice cultivation effectively stabilizes food security and maintains sustainable agricultural development. To analyze the trophic structure and energy flow of rice field integrated farming ecosystem, the food web model of a rice-crayfish ecosystem was developed based on the Ecopath model approach. The functional group with the highest ecotrophic efficiency (EE) value was crayfish Procambarus clarkii (0.97), and those with the lowest EE values were chironomid larvae and benthic bacteria (0.02) in the rice-crayfish systems. The effective trophic level of P. clarkii was 2.20 with consumer consumption share of 19%. The transfer efficiency of trophic level II was 3.90% in the rice-crayfish system. The total system throughput was 19,262 g/m2/90 days, showing very high scale and activity. The rice-crayfish ecosystem showed high value of Finn's cycling index (0.266), and low value of connectance index (0.252) and system omnivory index (0.053). Therefore, the food web model structures of the rice-crayfish integrated farming ecosystem in this study was unstable, simple, and linear. The carrying capacity of P. clarkii was 138.85 g/m2. Ecosystem properties such as scale, energy consumption, and stability indicated that this farming model has room for improvement, and rice-crayfish integrated farming should be further optimized to improve energy utilization, stability, and comprehensive benefits based on the different ecosystem properties.