Accumulation rate and sources of plastic marine litter at nesting grounds of green turtles on the North Island of Qilianyu, Xisha Islands, South China Sea.

In this study, the accumulation rate of plastic litter was investigated by sampling quadrats placed on the North Island of Qilianyu, and the composition was analyzed and identified to determine its source. The results showed that the annual average accumulation rate of plastic litter on North Island was 0.64 ± 0.32 pieces·m-2·month-1, with a mass accumulation rate of 11.30 ± 7.73 g·m-2·month-1. The accumulation rate of plastic litter was mainly influenced by wind speed and direction, with higher accumulation rates occurring during the southwest monsoon season and tropical cyclones. ATR-FTIR analysis indicated that polyethylene (44 %) and polypropylene (41 %) were the most abundant types of polymers. This study reveals the current status of plastic litter pollution in green turtle nesting grounds on North Island in Qilianyu, which can be used as a reference for management strategies that mitigate plastic litter pollution.

Microplastic pollution at Qilianyu, the largest green sea turtle nesting grounds in the northern South China Sea.

Microplastics, new persistent pollutants, have recently attracted considerable attention. When present in beach sediments, microplastics may adversely affect the nesting and hatching of sea turtles on beaches. In this study, we investigate microplastic pollution at Qilianyu (northeastern Xisha Islands), the largest known nesting ground for green sea turtles (Chelonia mydas) in China. We found that the average abundance of microplastics in the beach surface sediments was 338.44 ± 315.69 thousand pieces·m-3 or 1,353.78 ± 853.68 pieces·m-2, with foam and fragments as the main microplastic type identified. The microplastic particles were categorised as small and were predominantly within the 0.05-1 mm size category. Most microplastic particles were white (71.31%). Polystyrene and polyethylene were found to be the most common forms of plastic present. Microplastic pollution was not only observed on the beach surface but also at the bottom of nests approximately 60 cm may be harmful to the incubation of sea turtle eggs. We suggest removing plastic litter, especially small pieces of plastic, on beaches to reduce the threat of microplastic pollution to marine life, including sea turtles. Furthermore, the foam used in aquaculture should be recovered and replaced before it becomes fragmented due to age. In addition, regional cooperation between stakeholders in the South China Sea should be strengthened to collectively promote the reduction and cleanup of marine litter.