How much protection is enough? Public preferences for aquatic life protection in water quality standards

Understanding what people value and wish to protect is crucial for effective environmental management, including ecological risk management for chemicals. However, it remains unclear which levels of biological organization the public believes should be protected. We conducted an online survey across Japan (n = 1211), in which participants were asked to choose their preferred level of biological protection-ranging from the sub-individual (e.g.,, DNA or cellular damage) to the community level-when water quality standards are set for the conservation of aquatic life. Rather surprisingly, over half of the respondents selected the sub-individual level of protection, suggesting a preference for a stricter protection level than those commonly accepted in actual management (i.e., the population level or higher). Individuals with stronger conservation attitudes, a greater perceived risk of chemicals, a stronger connection to nature, a stronger ability to identify species, and older age were more likely to prefer stricter protection standards. Our findings suggest that regulators and environmental managers should recognize and address the gap between public preferences for biological protection levels and the protection goals commonly adopted in environmental management, particularly in stakeholder engagement settings.