Changes in perceived risk and ecosystem services after herbicide use on an aquatic invader

Biodiversity conservation can entail socially controversial management interventions such as herbicide applications to eradicate aquatic invasive plants from highly productive native ecosystems. This study used a case example of the successful eradication of Alaska’s first aquatic invasive plant, Elodea spp. from two lakes surrounded by waterfront homes with the objective to measure perceived changes in the use of the lakes by local residents. A household survey was conducted with homeowners before and after the application of herbicides to measure public attitudes and human behavior changes related to the use of herbicide. We found fears and subjective expectations of survey respondents did not match the eventually collected objective scientific data on water quality. Also, we measured a significant negative change in lake-related activities over the duration of the management intervention that is smaller compared to the reduced activity level lake residents anticipated before the application of herbicide. Swimming and the consumption of fish caught in the lakes were the most negatively affected ecosystem services. The study showed the indirect and often hidden effects of management interventions on human risk perceptions that can translate to unintended human behavior changes and a reduction in related ecosystem service use. To account for complex social dimensions of controversial resource management interventions, resource managers require information on broad public value trade-offs and perceived risk beyond that which public meetings can provide. In this context, household surveys before and after resource management interventions can offer insights few other approaches can. The potential for more advanced outreach methods is discussed.