Assessment for seawall modifications to mitigate land crabs roadkills from field experiments and agent-based modeling

Area of Science:

• Ecology
• Conservation Biology
• Wildlife Management

Background:

• Coastal development, including seawalls and roads, obstructs land crab migration and increases roadkill in Gaomei Wetland.
• Previous mitigation efforts involved modifying seawalls from vertical to sloped, but effectiveness requires further assessment.

Purpose of the Study:

• To assess land crab climbing behavior and roadkill events before and after seawall modification using field experiments and agent-based modeling (ABM).
• To evaluate the effectiveness of sloped seawalls in mitigating land crab roadkill.

Main Methods:

• Field experiments measured land crab climbing willingness on vertical and sloped seawalls.
• Three years of roadkill data were collected during breeding seasons before and after seawall modification.
• Agent-based modeling (ABM) simulated various seawall configurations to estimate roadkill mitigation effectiveness.

Main Results:

• Land crabs exhibited significantly higher climbing willingness on sloped seawalls compared to vertical ones.
• ABM simulations showed a 28% reduction in individuals remaining on the ground post-modification, aligning with field observations.
• ABM highlighted the critical need to identify and address roadkill hotspots.

Conclusions:

• Seawall modification to a sloped design effectively increases land crab climbing willingness and mitigates roadkill risk.
• The combined approach of field experiments and ABM provides a robust framework for evaluating wildlife mitigation strategies.
• Findings support the implementation of habitat-friendly infrastructure to enhance coastal ecosystem connectivity and reduce wildlife mortality.