Anglers’ Riverfly Monitoring Initiative (ARMI): A UK-wide citizen science project for water quality assessment

The Anglers' Riverfly Monitoring Initiative (ARMI) is a UK-wide citizen science project focused on river water quality assessment. There are currently >2000 ARMI volunteers monitoring >1600 sites that are organized into 35 regional hubs across the UK. ARMI is effective in the early detection of water pollution and complements the routine monitoring undertaken by the UK statutory environment agencies. ARMI volunteers are trained to take standardized 3-min kick-samples of freshwater invertebrates from a river site, and use these samples to produce an ARMI score based on the abundance of key pollution-sensitive taxa. ARMI scores and standard invertebrate monitoring metrics are closely correlated. Each sampling site has a 'trigger level' score set by the national regulatory authority-e.g., the Environment Agency (EA) in England. If the ARMI score falls below this trigger level, the regulatory authority is notified and agency officers investigate the cause of the low score. This process has resulted in many reports of pollution incidents that otherwise may have gone undiscovered but were instead rapidly detected and neutralized. In some cases, investigations resulted in fines being levied against those responsible. ARMI data have also proved useful in assessing the effectiveness of river restoration schemes. Here, we demonstrate the effectiveness of the ARMI as a structured citizen science program in enhancing the environmental protection of rivers. We also show that the ARMI program complements the work of statutory authorities and describe how it promotes community engagement with river environments.