Competing Circular-Economy Uses of Oyster Shell Waste: Uncertainty-Aware Life-Cycle Allocation Between Reef Restoration and Low-Carbon Construction

Manuscript prepared for the Journal of Cleaner Production (Elsevier). A per-tonne, multi-objective Monte Carlo allocation model compares three uses of recovered oyster shell: (a) reef restoration, (b) cement-replacement or filler use in concrete, and (c) landfill/disposal, with transport, cleaning and curing energy, habitat opportunity cost and life-cycle carbon, evidence-graded priors, Pareto and exchange-rate analysis (oysters per tonne CO2e), Sobol sensitivity and falsification maps. Reef survival is calibrated to publicly reported Billion Oyster Project site-level survival; the project is used as an external reference only (no collaboration or validation by the project is claimed). In-silico study; conclusions are conditional on the stated assumptions. Code, tests and results: https://github.com/sandlerleon/oyster-shell-allocation-mc.