海南昌江近岸海域大型底栖动物群落结构季节变化及其影响因子OACHSSCD

To investigate the species composition,biodiversity,dominant species,community structure,and their sea-sonal dynamics of macrobenthos in the nearshore waters of Changjiang,Hainan,quantitative and qualitative sampling was conducted at 12 stations during two seasonal cruises in spring(April)and autumn(October)2024.Species composition,abundance/biomass,the Shannon-Wiener diversity index(H′),Pielou's evenness index(J),Margalef richness index(d),and dominant species were analyzed.Ecological quality and environmental influencing factors were assessed using ABC curves,the Marine Biotic Index(IMB)and Multivariate Marine Biotic Index(IMMB),as well as principal component analysis(PCA).A total of 39 macrobenthic species were identified,revealing a clear seasonal succession:polychaetes dominated in April(42.11%),while arthropods dominated in autumn(46.15%).Mean inhabitant density and biomass were 14.51 ind·m‒2 and 22.45 g·m‒2 in spring,and 13.68 ind·m‒2 and 26.26 g·m‒2 in autumn.The diversity index(H′)declined from 1.44±0.38 in spring to 0.84±0.44 in autumn,indicating community simplification in autumn.IMB and IMMB as-sessments revealed that most stations were classified as"undisturbed/lightly disturbed"and"good/moderate",though some stations showed ecological deterioration in autumn.ABC curves and their corresponding W values indicated no extreme de-structive disturbance to the overall community.PCA indicated that biomass and inhabitant density were positively corre-lated with chemical oxygen demand(COD)and inorganic nitrogen concentrations,but significantly negatively correlated with suspended solids concentration,identifying suspended solids as a key stressor impairing ecological quality.It is there-fore recommended to establish long-term seasonal monitoring based on indicator indices and management measures to con-trol suspended solids input,so as to protect macrobenthic resources and ecological functions in the nearshore waters of Changjiang.