The present study attempts to evaluate an allegedly promising instrument of environmental policy: public information campaigns for raising awareness, as reflected by enhanced environmental preferences. We evaluate an intensive campaign addressing plastic pollution in a coastal and marine environment, an issue of high environmental importance which is increasingly attracting public interest. Using stated preference surveys, we evaluate the effects of the campaign on preferences for ecosystem services and environmental goods. Our focus lies in the temporal effects across seasons, inducing different ecosystem services, approximating the effects of information on use and non-use values. Our findings indicate that systematic provision of information can enhance preferences and, although a time-decay effect exists, awareness remains significantly enhanced after the end of the campaign albeit not uniformly across different (use and non-use) values. As the impacts on preferences are subject to variation of seasonal experience with ecosystems - implying variation in the intensity of use – additional to a time-decay effect, it emerges that although information is a necessary instrument of environmental policy, it cannot be a sufficient one. An effective policy, addressing the needs of future generations, also requires instruments that give economic signals (taxes) and constrain preferences (standards) with information provision enhancing their impacts.