HUMAN VERSUS ENVIRONMENTAL INFLUENCE ON BARRIER ISLAND EVOLUTION

Modern barrier island evolution varies globally due to differences in the physical environment (e.g., climate) and cultures of barrier island inhabitants (e.g., economics, politics). The Anthropic Force (the collective actions of humans) is often the principal evolutionary force on barrier islands, yet its form and its impact in varying environments is relatively unexplored. The Anthropic Force affects the innate dynamic properties of barrier islands along a range of spatial and temporal scales. Each island is an individual entity with unique physical and ecological gradients, is linked to adjacent islands via tidal inlets and longshore transport, and responds dynamically to environmental change via the shoreface. Local human activities (e.g., buildings) affect the character of an individual island. Regional activities (e.g., jetties) disrupt the linkage between adjacent islands. Stabilization (e.g., seawalls) halts dynamic change, whether natural or human-induced. Island “termination” occurs when the island surface is entirely altered, is no longer linked to adjacent islands, and cannot respond to environmental change. Geomorphic carrying capacity is the resiliency of barrier islands to activities of the Anthropic Force. Geomorphic risk factors may serve as a basis for predicting resiliency, indicating both rates of dynamic change and available buffer space (which may or may not be utilized). As risk factors increase, island termination becomes more likely, but not inevitable. Ultimately the response of the Anthropic Force to risk factors (retreat, abandonment, or stabilization), which is strongly influenced by cultural factors, will determine the overall influence of the Anthropic Force on island evolution.