Environmental DNA effectively reveals spatial patterns of benthos in a nursery habitat of the highly endangered Tachypleus tridentatus

Mudflat are heavily relied upon by the highly endangered Tachypleus tridentatus, nature reserves have been established to protect such habitats. However, inadequate habitat status monitoring hinders evaluation of conservation achievements and the promotion of future management. We used benthic community as sensitive indicator to reflect the habitat status of T. tridentatus in a mudflat disturbed by different degrees of anthropogenic activity, using the environmental DNA (eDNA) method. Results indicated that anthropogenic disturbances may alter benthic composition via changing resource competition pattern or sediment property. Sediment benthos displayed much obvious spatial heterogeneity than water. In sediment covered with mangroves, benthos tended to form more stable networks, potentially contributed by high proportion of negative correlations and ecological services provided by mangroves. In contrast, sediment benthos in anthropogenically disturbed zones might reshape species-interacting patterns and then decrease network stability; they displayed less dispersal ability, which might be related to their narrow niche width and spatial segregation caused by intense mudflat farming. Benthos have migration potential between different zones, and frequent human’ movements will increase this migration. In conclusion, the eDNA method effectively revealed that sediment benthos are sensitive to anthropogenic disturbance by decreasing their network stability and dispersal capability, which may weaken their resilience to environmental changes and increase their spatial heterogeneity even on a small scale. Future attentions should focus on ensuring habitat connectivity during management. The efficient and non-destructive eDNA method should be included in the habitat monitoring and protection framework for T. tridentatus.