Spatiotemporal dynamics of macrobenthos in Zhanjiang mangroves

To reveal the spatiotemporal dynamics of macrobenthic communities in the intertidal zone of Zhanjiang mangrove forests and to assess their disturbance status, we carried out two fixed-site surveys at eight mangrove intertidal stations across eastern and northwestern Zhanjiang in September 2022 and November 2024, covering Leizhou Bay, Techeng Island, Xinliao Bay, Gaoqiao and Anpu Port. We employed the percentage similarity (PS), abundance-biomass comparison (ABC) curves, W statistic, index of relative importance (IRI), as well as abundance- and biomass-based dominance indices (Y_abun, Y_bio). We applied multivariate analyses including nMDS, ANOSIM, SIMPER and two-way ANOVA to identify species dominance patterns and analyze community structure, diversity and disturbance status of macrobenthos. PS, nMDS and SIMPER revealed obvious compositional differences and remarkable spatial differentiation between the two surveys. Two-way ANOVA showed that diversity indices were significantly affected by station and survey period; biomass exhibited highly significant inter-period effect, while abundance only showed marginal significance. Seasonal factors may confound the observed community differences, as the two surveys were sampled in different months. ABC curves and W statistics indicated high-intensity disturbance at partial stations. Combined IRI-Y analysis showed that Sesarma plicata dominated in the first survey, whereas species such as Paracleistostoma depressum became dominant in the second survey; only Geloina coaxans maintained dominance in both surveys. This study reveals divergent features of macrobenthic communities along Zhanjiang mangrove coasts and provides baseline data for mangrove biodiversity conservation and ecological health management.