Anthropogenic debris pollution in peri-urban mangroves of South China: Spatial, seasonal, and environmental drivers in Hong Kong.

Excessive mismanaged debris along tropical coasts pose a threat to vulnerable mangrove ecosystems. Here, we examined the spatial, seasonal and environmental drivers of anthropogenic debris abundance and its potential ecological impact in peri-urban mangroves across Hong Kong. Seasonal surveys were conducted in both landward and seaward zones, with identification, along belt transects, of macrodebris (>5 mm) based on material type and use. Our results indicate spatial variability in debris abundance and distribution, with plastic being the predominant material type identified. Both plastic and non-plastic domestic items covered the most surface area. Debris aggregation was highest at the landward zones, consistent with the literature. In the dry season, more debris accumulated and covered greater surface area in both seaward and landward zones. These results confirm that land-derived debris from mismanaged waste, rather than debris coming from the Pearl River, is the primary source of anthropogenic debris pollution threatening Hong Kong's mangroves.