Bridging the weathering-toxicity translation gap in integrated oil spill modeling

Oil spill impact assessment has progressed unevenly across its component disciplines. Operational fate and transport models predict the physical and chemical state of spilled petroleum; ecosystem-scale food-web models propagate biological forcings through multiple trophic levels; socioeconomic tools quantify the economic consequences of ecological change. The chain is incomplete at the interface between physical state and biological forcing: no operational model resolves the weathering-dependent change in petroleum toxicity across endpoints (acute narcotic, fish embryo cardiotoxicity, UV-driven phototoxicity, OPAH-mediated developmental effects) and passes the resulting endpoint-specific dose metrics to the ecosystem model. This review synthesizes the experimental evidence on weathering-driven shifts in petroleum toxicity across the endpoints most relevant for ecosystem-level assessment, evaluates the operational modeling landscape for its capacity to translate evolving chemistry into endpoint-specific effect, and develops a modular four-component coupling architecture in which a weathering-aware, endpoint-specific translation layer (Component 2) connects fate and transport to a food-web ecosystem model and a socioeconomic tool. Evaluated retrospectively against the 2010 Deepwater Horizon spill, the architecture identifies systematic underestimation of large pelagic spawner impacts arising from the absence of cardiotoxicity and phototoxicity pathways from the toxicity forcing. Evaluated prospectively against the December 2024 Kerch Strait Volgoneft heavy fuel oil incident, where quantitative monitoring data are absent, its mechanistic reasoning from oil type, timing, latitude, and species-resolved phenology yields defensible diagnostic conclusions (including high-priority sprat ELS cardiotoxicity given the cold-season spawning overlap) and structures monitoring prioritization. The architecture is a synthesis of existing evidence, not a full implementation; a worked example instantiates the Component 2 narcotic pathway on published Deepwater Horizon exposure chemistry, where a 29% decline in dissolved PAH coincides with narcotic toxic units increasing modestly (7%) and rising mechanism-specific dose metrics. The principal research gaps are endpoint-specific dose-response data for dominant species outside the Gulf of Mexico, validated dose-response functions for OPAH mixtures, integration of photo-oxidation kinetics into fate models, regional ecosystem coupling for the Black Sea, Mediterranean, and Caspian, and standardized phototoxicity protocols. Closure of the weathering-toxicity translation gap is best understood as a coordination problem across modeling traditions, and the architecture proposed here is intended as a coordination interface.