Impact of single-use waste reduction initiatives using citizen science data: Western Australia as a case study

Single-use plastic (SuP) waste reduction initiatives have emerged globally to curb the increasing issue of plastic pollution. However, evaluation of their impact on the marine environment is difficult due to spatial and temporal variation of debris and the need for regular monitoring. This study aimed to determine whether a frequent community-driven beach debris collection approach could provide quality data to evaluate the impact of recent (2019-2024) waste reduction initiatives in Western Australia (WA). The citizen science (CS) program commenced in January 2023 at Bathers Beach, Fremantle, WA, with a purpose built 'bin' installed to provide beach users with a place to donate debris. From February 2023 to November 2024, 19,998 items were analysed with 17,263 (86 %) classified as marine debris, and 6615 (38 %) of these items classed as single-use. Of the 26 single-use items targeted by WA's waste reduction initiatives, 21 were found on the beach. Under the 'best-case' scenario, a 17 % reduction in marine debris is possible from these initiatives, with significant reductions in takeaway beverage plastic lids and cigarette butts already detected (p < 0.05). Moreover, findings were comparable with data collected via the national standardised CS beach litter monitoring program (i.e., Australian Marine Debris Initiative (AMDI) over a similar period (2023-2024)). This suggests the trends detected at Bathers Beach are indicative of the broader region. Incorporation of this data into the AMDI Database could provide additional information for policy and decision makers to evaluate single-use waste reduction initiative impact, with significant trends detectable within two years.