Is conscientious beachcombing the key to 'unlock' marine plastic pollution trends through citizen science? A case study from Cockburn Sound, Western Australia

Despite the global implementation of plastic waste reduction policies and bans on single use plastics (SuPs), their effectiveness for protecting marine ecosystems remains unclear. Frequent monitoring could confirm policy effectiveness, but this is difficult due to resourcing and logistic constraints. This study tested a 'beach litter' beachcombing citizen science approach that could overcome some constraints. Between November 2018 and January 2021, 168 beach visits led to the collection of 12,659 pieces of litter from a beach in Western Australia. Litter was predominantly plastic (87%) and mostly associated with fishing/boating (34%). Significant reductions in six types of litter, including fishing/boating items, balloons, and straws were detected and four coincided with local government waste mitigation measures. We show potential to harness conscientious beachcombers as citizen scientists to help evaluate plastic policy impact. Furthermore, we propose how to harness this effort and increase spatial and temporal coverage of marine plastic pollution monitoring.