Assessing factors driving the distribution and characteristics of shoreline macroplastics in a subtropical reservoir

Very little is known about the extent of macroplastics in African freshwater ecosystems, whilst the distribution of different types of macroplastic in other systems is rapidly increasing. This study explored the distribution and concentration of different macroplastic debris types in Nandoni reservoir, South Africa over four sites (2 high household- and 2 low household-density) and two seasons (cool-dry, hot-dry). Similarities were observed for macroplastic debris numbers and weights across sites and seasons. Although slight insignificant differences in macroplastics abundances were observed, no significant relationships were recorded between household density (i.e. as proxy for human population density) and macroplastic debris abundances. The amount of plastic debris and ‘species’ (i.e. γ-diversity value) decreased with distance from the shoreline, with the highest amount of plastic debris and ‘species’ being observed at the shoreline in all sites and seasons. Polypropylene was the most dominant (>45%) in terms of abundance for both seasons and sites. The information derived serves as a baseline for future studies on macroplastic distributions along freshwater reservoir shorelines.