Don't tread on me: human trampling on a sandy beach alters behavior of the ghost crab, Ocypode stimpsoni

Human activities in coastal areas, such as trampling, are increasing hazards to benthic ecosystems. We hypothesized that trampling stressor disrupts the behavioral patterns of intertidal benthos and conducted an experiment on ghost crab Ocypode stimpsoni at a sandy beach on Jawol Island, South Korea. Individual ghost crabs were subjected to either a single trampling event or a simple visual stimulus, and the types and duration of their behaviors were recorded. The reemergence time in the trampled group was three times longer than that of the non-trampled group, and total surface activity was significantly reduced. Trampling also increased the time allocated to vigilance behavior, decreasing it in larger individuals while increasing it in smaller individuals compared to the non-trampled group. These behavioral shifts may disrupt energy budgets, by interfering with other vital activities. Our results suggest behavioral responses can serve as an effective indicator to assess the impact of human trampling on benthic ecosystems.