A baseline study of macro, meso and micro litter in the Belize River basin, from catchment to coast

The mismanagement of waste and subsequent presence of litter in the environment is an increasingly significant problem. Globally, rivers have been shown to be a major pathway for mismanaged waste. We investigated the distribution of macro, meso and micro litter along the Belize river basin. The North-East Atlantic OSPAR beach litter monitoring protocol was adapted for Belize, taking into account local issues such as mangroves and Sargassum sp. accumulations. On average, 77.3% of litter items consisted of plastic, and the most common items categories were unidentifiable plastic pieces (0-2.5 and 2.5-50 cm), broken glass, and metal bottle caps. The study indicated that there is an increase in the litter load as you move from catchment to coast, with both Plastic Pieces (PP) and Fishing Related (FR) items also increasing in numbers down the system. Additionally, microplastics abundance was determined in riverine sediments and in the riverine fish Cichlasoma synspilum (n = 22). All sediment samples contained microplastics, with a concentration of 200-6500 particles per kg dry sediment. Microplastics were found to be present in 36% of the riverine fish. The data from this study will provide evidence for the formation of Belizean legislation to reduce marine litter.