Seagrass Fairy Circles as Boundary-First Diagnostics: A Sulfide Inhibition Hypothesis for Ring Formation in Scottish Zostera Beds

Description Rare ring-shaped formations (“fairy circles”) observed in Scottish seagrass meadows are interpreted here using a boundary-first, reaction–diffusion framework. Rather than anomalous structures, the circles are treated as transient diagnostic patterns that emerge when uniform growth collapses under stress. Drawing on direct precedents from eelgrass systems, the analysis identifies sediment redox shifts and sulfide accumulation—often associated with nutrient loading, organic enrichment, or other pollution-linked pressures—as the most parsimonious inhibitory mechanism for ring interiors, with continued clonal growth at the advancing edge. The work frames these marine fairy rings as early-warning indicators of reduced meadow resilience, proposes falsifiable chemical and biological predictions across ring gradients, and outlines a minimal field protocol for monitoring, restoration prioritisation, and adaptive management of seagrass ecosystems. Keywords seagrass; Zostera; fairy circles; fairy rings; pattern formation; reaction–diffusion; boundary-first analysis; sulfide toxicity; hypoxia; sediment redox; eutrophication; pollution indicators; ecosystem resilience; early-warning signals; marine ecology; Scottish waters; Outer Hebrides