AEI prepress abstract  -  DOI:

Model-based analysis of the energy fluxes and trophic structure of a Portunus trituberculatus polyculture ecosystem

Jie Feng, Xiang-Li Tian*, Shuang-Lin Dong, Rui-Peng He, Kai Zhang, Dong-Xu Zhang, Qing-Qi Zhang


ABSTRACT: We constructed a quantitative Ecopath model of a trophic network to evaluate the energy flow and properties in a polyculture ecosystem containing 4 species (termed 4-species ecosystem). The four species were the swimming crab Portunus trituberculatus, white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila over a 90-day experimental period. The model contained 10 consumers, 4 detritus groups and 4 primary producers. Ecotrophic efficiency (EE) values indicated that the system had high energy utilization efficiency. However, benthic bacteria converted the largest amount of energy back to the detritus groups, which had the lowest EE value (0.01). When aggregating the network to discrete trophic levels (TLs) sensu Lindeman, most of the throughput and biomass of the system were distributed on the first 2 TLs; consequently, there was high energy transfer efficiency between TL I and II (81.98%). The trophic flow of this ecosystem was dominated by energy that originated from the detritus groups (73.77%). Imported artificial food was particularly important for the trophic flow of the total ecosystem, contributing 31.02% to total system consumption. The trophic network of the polyculture ecosystem had a moderate Finn’s cycling index (FCI: 17.44%), a relatively low connectance index (CI: 26.70%) and a low system omnivory index (SOI: 0.08). Relative ascendancy was estimated as 44.90% in this model. Overall, ecosystem properties (i.e. CI, SOI, and relative ascendancy) showed that the artificial 4-species polyculture system represents a simple and fragile, but also “balanced,” ecosystem.