Analysing ecological carrying capacity of bivalve aquaculture within the Yellow River Estuary ecoregion through mass-balance modelling

As the largest aquaculture producer in the world, China is facing the challenge of maintaining sustainability while continuing to develop the aquaculture industry to meet socio-economic needs. Models of trophic structure and energy flow can be used to analyse ecological carrying capacity in order to determine whether a large and rapidly increasing aquaculture industry potentially puts sustainable development at risk. The Yellow River Estuary ecoregion in Shandong Province, China, is an ecologically important region, with extensive bivalve aquaculture that is increasing rapidly at an overall growth rate of 4 % annually during recent decades. A trophic mass-balance model was used to analyse the ecological carrying capacity of bivalve aquaculture in this ecoregion. The biomass of cultured bivalves is currently 13.3 t km(-2) and could be increased to 62.0 t km(-2) without exceeding the ecological carrying capacity. Zooplankton are a key factor limiting the ecological carrying capacity and represent a sensitive functional group within the food web system in this ecoregion. At the ecological carrying capacity of cultured bivalves in the Yellow River Estuary ecoregion, harvests would amount to 353.2 t km(-2) yr(-1) or a total of 4.2 million t yr(-1) in this region. If the current average rate of growth in aquaculture in China is maintained, under cautious development, the biomass of cultured bivalves would reach half of the estimated ecological carrying capacity (31.0 t km(-2)) after 20 yr. This implies that there is capacity for sustainable development of bivalve aquaculture under current environmental conditions.