Characteristics of typical biological communities and identification of key environmental factors in the seagrass bed of Xingcheng-Juehua Island, Bohai Sea

Seagrass bed is one of the most crucial and productive coastal ecosystems, with multiple ecological functions such as water purification and biodiversity maintenance．We surveyed typical biological communities, including Zostera marina L., phytoplankton, zooplankton and zoobenthos, in seagrass beds in August and October 2020 in Juehua Island, Liaodong Bay, to analyze seasonal and spatial difference, and key environmental factors．The length, density, and biomass of Zostera marina L.．in summer were found to be significantly higher than in autumn (P < 0.05)．Shannon-Wiener index (H'), Margalef index (D'), Pielou index (J) of communities in the seagrass bed fluctuated from 1.09 to 1.77, 0.46 to 1.17, and 0.65 to 0.88, respectively．Shannon-Wiener index (H') of phytoplankton, zooplankton and zoobenthos were found to be lower, higher and significantly higher in summer than in autumn．RDA analysis found that sediment sand content, water inorganic nitrogen, and pH were significant factors for seagrass, but total phosphorus, inorganic nitrogen, and dissolved oxygen in seawater were significant for phytoplankton, zooplankton and zoobenthos in seagrass bed．