Modeling the Biomass of Benthic Invertebrates and Fishes in Poyang Lake by Bivariate Coupled Method

Benthic invertebrates and fishes are the most important aquatic organisms in rivers and lakes, as belong to prey-predator relation, their spatial distribution are closely relevant. The hydrodynamic environment constitutes the ecological habitat of aquatic animals, thereby impacting the abundance and distribution. In this study, a bivariate coupled method is newly established to calculate the biomass of benthic invertebrates and fishes, simultaneously considering their biological behaviors and environmental preferences. The benthic invertebrate sub-model is dominated by growth dynamic equation, characterizing the growing process affected by flow condition and predation. The fish sub-model adopts the modified Boltzmann kinetic equation, synthetically describing the growing and moving behaviors driven by flow velocity and food uptake availability. The two sub-models are coupled by the trophic interactions, and biomass are simulated as variables. All the models are solved in the two dimensional Eulerian framework with hydrodynamic results as input, which is suitable for large scale regions. The proposed model was applied to simulate he biomass distribution of benthic invertebrates and Chinese carps in Poyang Lake, which is the largest freshwater lake in China. Results show good agreement with the field investigation data, and reflect the spatial association between the benthic invertebrates and fishes. Moreover, the results indicate the hydrodynamic preference of aquatic animals. Thus, the newly developed method can be employed to predict the distribution of aquatic animal biomass in freshwaters, and provide references for evaluating and protecting the habitat in water ecosystems.