Comparing marine ecosystems of Laizhou and Haizhou Bays, China, using ecological indicators estimated from food web models

Two Ecopath mass-balance models are built to describe the structural and functional ecosystems of Laizhou Bay (LZB) for 2014-2015 and Haizhou Bay (HZB) for 2011-2012. This is the first comparative study to analyze the similarities and differences between these two bays using ecological indicators estimated from a food web model. A comparison between the two models highlights similar characteristics in trophic functioning: zooplankton and shrimps as the structuring groups are important organisms enabling the pelagic-benthic coupling in the two ecosystems; and top-down effects are the main mechanism of control within the two ecosystems. Analysis of differences between the two ecosystems indicates that: (1) the ecological size (total system throughput, TST), total exports/TST and ecosystem efficiencies are bigger in LZB; (2) the bottom-up controls from the benthos, shrimps and zooplankton are enhanced in LZB; and (3) the ecosystem state is less mature but more stable in LZB. These differences can be attributed, at least in part, to the effects of sea ranching of low trophic-level species, such as shellfish and the holothurian Stichopus japonicus, in LZB. Analysis of similarities and differences may benefit the ecosystem-based approach to fisheries management in different ecosystems.