Spatial patterns of macro-debris and microplastic pollution in Sri Lankan mangrove ecosystems: Insights from Rekawa and Negombo

Macro-debris and microplastic abundance in the surface soil of mangroves were investigated at the Negombo and Rekawa sites in Sri Lanka. Macro-debris abundance was significantly higher at the Negombo site (664.8 +/- 87.47 debris/100 m(2)) than at the Rekawa site (1.53 +/- 1.32 debris/100 m(2)). At Negombo, plastic was the dominant macro-debris type (56.25%), whereas metal predominated at Rekawa (43.48%). A significant positive relationship between macro-debris abundance and the percentage cover of mangrove aerial roots was observed at Negombo, highlighting the role of these roots as traps for debris. Microplastic abundance in surface soil was also higher at Negombo than at Rekawa (Dunn's test, p < 0.05), with blue microfibres being the dominant type at both sites. Overall, both macro-debris and microplastic pollution were significantly greater at Negombo compared to Rekawa. Consequently, our study highlights the need to implement a robust plan for managing macro-debris pollution, promote environmental education on reducing, reusing, and recycling plastics, and enforcing stricter waste management and plastic production regulations to conserve the mangrove ecosystems at both sites.