The influence of coastal geomorphology and human activity on plastic debris distribution on a micro-tidal recreational beach on the north coast of Trinidad

Coastal plastic debris is a major problem affecting both sandy beaches and nearshore environments. Over several decades, plastic debris has become a global threat to the natural environment due in part to single-use culture, pervasiveness and accumulation following years of improper disposal. Despite the global research effort, in the Caribbean region, only a few studies attempt to quantify the amount and sources of debris. This paper combines coastal geomorphology and plastic debris collection with GIS spatial analysis at Maracas Beach, Trinidad between 2015 and 2016. Overall, 567 separate plastic items were captured and classified from within two 30 m wide zones at the central and eastern portions of the microtidal sandy beach. Macro- and meso-plastic debris associated with beach activity (n=233) and single use waste (n=215) were the most abundant debris. Microplastic debris (n=94) consists mainly of polystyrene granules and unidentifiable fragments from larger recreational debris that are readily lost to the environment. Using manufacturer’s information, polystyrene (n=206) was the most dominant debris. Regression models were also conducted using the average beach size and average beach angles where a weak positive linear relationship was found. Kernel density estimation was used to geovisualize the distribution of plastic items per square metre to develop a plastic debris signature. Despite current beach management activities, a large proportion of macro- and meso-sized debris can enter the environment. Studies such as these are invaluable for the Caribbean region where attempts to manage the pollution caused by plastic are limited by data.