This paper presents a fully distributed coordination architecture for heterogeneous UAV–USV teams operating in dynamic maritime environments. The framework integrates capability-aware online task allocation with adaptive task planning and a chemotaxis-inspired persistent coverage strategy. Persistent surveillance is achieved through a discrete artificial potential field in which revisit urgency accumulates as virtual chemoattractant, while obstacles and inter-agent interactions act as repellents. Heterogeneity is incorporated through platform-dependent responses to the shared potential landscape, enabling differentiated behaviors across aerial and surface vehicles. The architecture is validated in high-fidelity simulations of coastal surveillance and intrusion prevention missions. Results demonstrate adaptive task reassignment, continuous replanning, and robust cooperation under dynamic intruder motion and agent loss. Compared to deterministic coverage baselines, the proposed approach exhibits superior resilience to vehicle failures while maintaining effective persistent monitoring. The framework provides a scalable and biologically grounded solution for heterogeneous multi-robot coordination in maritime domains.