Macrobenthos communities and ecological quality assessment in the subtropical estuary: Insights for management of marine protected area

Abstract

The marine protected area in the Jianjiang River Estuary was established in 2011; however, subsequent research on the ecological health of the estuarine biological community has been lacking, making it difficult to scientifically evaluate or inform the management of the reserve. In this study, we assessed the composition and diversity of macrobenthic communities at ten different sites in the Jianjiang River estuary reserve in both Spring and Autumn and used three biotic indices to evaluate the ecological quality status (EcoQs) across the reserve. We identified 58 macrobenthic taxa, of which the largest proportion were Mollusca (48.28 %), followed by Annelida (27.59 %) and Arthropoda (18.97 %). Macrobenthic abundance and biomass varied among sites and seasons, and community composition was driven by different environmental variables in Spring and Autumn. With respect to our three indices of ecological quality, abundance-biomass comparison (ABC) curve analysis and the associated W-statistics indicated that macrobenthic communities in the reserve were undisturbed in the Spring but disturbed in Autumn. The AZTI marine biotic index (AMBI) indicated that most sites have high or good EcoQs, with higher EcoQs in the Spring, and the multivariate AMBI (M-AMBI) index similarly suggested that the average EcoQs were good in Spring but only moderate in Autumn. We suspect that the consistently lower EcoQs in Autumn across all sites were largely due to a 1-in-10-year flood discharge that occurred during our sampling year and disturbed sites near the river outflow. Overall, our results point towards specific, scientifically informed suggestions for future management of the Jianjiang River estuary reserve.