An integrated quantitative valuation model of HABs impacts on coastal marine ecosystems: In the case of hypoxia

Harmful algal blooms (HABs) are a typical ecological and environmental issue in coastal waters worldwide. One of their most significant impacts is the alteration of ecosystem structure and function through the induction of hypoxia. However, due to the public goods nature of ecosystem services and the absence of markets, damages caused by HABs, particularly non-market values, are difficult to quantify accurately. This hinders the valuation of HAB-induced damages severely, and affects government decision-making and policy framework built regarding the prevention and mitigation of HABs. This study uses HAB-induced hypoxia as a case study to develop a quantitative valuation model for hypoxia-induced losses in marine ecosystems. The model decomposes the total loss (V_T) into directly marketable losses of aquaculture species (V_Q) and non-marketable losses of ecological functions (V_S). For V_Q, population dynamics model is coupled with residual value approach to capture changes in biomass under hypoxic stress and estimate losses. For V_S, replacement cost method is applied, estimating the cost of supplementing dissolved oxygen artificially to maintain basic ecosystem functions as a proxy for the losses of ecological functions. The results demonstrate that this model provides a more quantitative and scientific valuation of losses due to hypoxia, mitigating limitations of overestimating losses in traditional market-based approach, and reducing biases and subjective judgments often present in non-market valuation. Sensitivity analysis further identifies that the weight growth index (η) and mortality power exponent (ρ) as key ecological parameters influence the outcomes of valuation. This study offers a decision-making basis for valuation of marine ecological damages, payments for ecosystem services (PES), policy framing for disaster prevention and mitigation. It also serves as a reference for establishing valuation methods for the impacts of HABs on marine ecosystems.