Anthropogenic Litter Abundance and Accumulation Rates Point to Seasonal Litter Sources on a Great Lakes Beach

Abstract

AbstractThe ecology of anthropogenic litter (AL) (i.e., trash) in marine ecosystems is a growing field of research. Freshwater and marine ecosystems have similar AL densities, but research on the assemblage and accumulation rates of AL in freshwater environments is less common. We studied AL accumulation at Pratt beach, located on Lake Michigan in Chicago, IL, USA. The beach has a concrete pier at the south end, with two areas of grass bisected by a walking path. Pratt beach receives many daily visitors, but unlike other urban beaches, it has no daily municipal beach grooming. We established five 60 m transects parallel to the shoreline, with increasing distance to the shoreline. Each transect was divided into four habitat zones (i.e., pier, south vegetation, path, and north vegetation). All AL within 1 m of each transect was collected biweekly from March‐November 2015. AL density (No. m−2) and input rate (No. m−2 day−1) were highest at the pier, regardless of distance from the shoreline. Fall had the highest AL density relative to spring or summer. We concluded AL inputs at the pier were dominated by direct littering and the retention of wind‐ and wave‐blown AL at the pier's wall. The study beach had much higher AL than adjacent beaches which received municipal AL cleaning, suggesting cleaning is effective at reducing AL density. This study suggests that, given the mobile nature of AL by natural processes, infrequent sampling may underestimate total AL abundance. Management efforts for AL should be directed towards the greatest AL accumulation sites within a beach, and at prevention of direct littering from visitors.