A systematic review to assess current surface water and sediment microplastic sampling practices in seagrass and mangrove ecosystems.

Global plastic production is estimated to be 400 million tonnes per annum, with ~ 5.25 trillion fragments floating in our oceans. Microplastics (< 5 mm) have the potential to disproportionately accumulate and become trapped in mangroves and seagrass meadows, creating plastic 'sinks'. This is concerning as these ecosystems are of great ecological and economic importance, with microplastics causing harm to inhabiting flora and fauna. However, accurately measuring microplastic abundance, comparing findings, and determining potential impacts are difficult due to a lack of standardised sampling protocols. Therefore, a systematic literature review was completed to review currently adopted microplastic sampling methods in surface water and sediment in seagrass and mangrove ecosystems. These were compared with recommendations from existing governmental and institutional groups as a first step to standardising methods for future sampling procedures in seagrasses and mangroves.