Characteristics and influencing factors of benthic macroinvertebrate community in Shenzhen Futian Mangrove Wetland

Benthic macroinvertebrate communities are key bioindicator taxa for the health of mangrove ecosystems, as their community structure and function can directly reflect habitat quality and ecological integrity. To understand the characteristics of large benthic invertebrate communities in the Guangdong Neilingding Island-Futian Mangrove Nature Reserve, a survey of benthic macroinvertebrates was conducted in September 2023. Samples of benthic macroinvertebrates and water quality were collected from Fengtang Estuary, Shazui Wharf, Bird Watching Pavilion, No. 1-10 saltwater fish ponds, and freshwater ponds for analysis. The results showed that a total of 42 species belonging to 6 classes were identified, predominantly from the phyla Mollusca and Arthropoda. In the mangrove area, the abundance and biomass of benthic macroinvertebrates ranged from 111.93 to 469.04 ind./m² and 57.33 to 1150.05 g/m², respectively, with the highest values recorded at the middle and high tidal zones of the Bird Watching Pavilion. In the gei wai fish ponds, the abundance and biomass varied from 37.31 to 389.09 ind./m² and 0.30 to 605.65 g/m², respectively, with the peak values observed in Pond 9 and Pond 7. The dominant species in the mangrove area included Nephtys oligobranchia, Neanthes glandicincta, and Potamocorbula laevis, while those in the gei wai fish ponds were Tarebia granifera, Sermyla riqueti, and Angulyagra polyzonata. The Abundance-Biomass Comparison (ABC) curve indicated that the benthic macroinvertebrate community in the reserve was structurally stable and less disturbed by external factors. Based on biodiversity indices, the Shannon-Wiener diversity index, Margalef richness index, and Pielou evenness index in the mangrove forest area were 2.42-4.18, 1.36-3.81, and 0.86-0.95, respectively, whereas those in the gei wai fish ponds were 1.15-3.32, 0.71-2.87, and 0.72-0.93, respectively. Significant differences were detected in community composition between the mangrove forest area and gei wai fish ponds (p<0.01), the mangrove forest area exhibited higher species number, abundance, biomass, and biodiversity. Environmental factors exerted varying degrees of influence on the benthic macroinvertebrate community, with petroleum pollutants, salinity, and electrical conductivity being the main driving factors. Specifically, salinity showed a significant negative correlation with the Shannon-Wiener diversity index, richness index, and evenness index (p<0.05). Combined with historical data and previous research findings, this study demonstrated that the biodiversity and biomass of benthic macroinvertebrates in Futian Mangrove Wetland have been significantly improved after more than two decades of protection and management.