Abundance of microplastic pollution and the impact of land-use and ocean current on plastic pollution in the Maldives

Abstract

Approximately 4.8 to 12.7 million tonnes of plastics enter the marine environment annually contributing to 5 trillion pieces of plastic in the global oceans and surface waters. Plastics in the marine environment can exist as macro, meso, and microplastics and due to its durability and longevity, once they are introduced into the environment, it can persist and be distributed globally by ocean currents and winds. Regardless of the high abundance of plastic pollution in the environment and its various negative impacts on marine ecosystems, human health, and the economy of countries such as the Maldives that depend on biodiversity-based economic sectors such as tourism and fisheries, research regarding causes of plastic pollution and sources of microplastics and its abundance is scarce. This study aims to quantify microplastic pollution in the Maldives and to identify sources of plastic pollution by investigating the effects of land-use and ocean currents on plastic pollution in the Maldives. A combination of field and laboratory methods was used to collect beach sediment samples, log macro and mesoplastics and to isolate, identify and quantify microplastic pollution on three different islands of varying land-use intensity (Industrial, Urban and Rural) in the Maldives. Additionally, Geographic Information System (GIS) was used to map ocean currents and identify the influence of ocean currents on microplastic distribution on the Maldivian islands. The results of this study shows that there is a significant level of microplastic pollution at the studied islands: K. Thulusdhoo, K. Villingli and B. Dhonfanu. Additionally, it also showed that the pollution levels at these three islands were higher compared to other coastal areas in the Indian Ocean, as well as other regions of the world. Furthermore, the results showed that the microplastic abundance at Thulusdhoo, an industrial island, was statistically different to both Dhonfanu which is a rural island and the urban island, Villingili proving that land-use influences plastic pollution. However, the difference between the Urban and Rural islands, despite the Urban island having a higher microplastic abundance was not significant, indicating that other factors such as ocean currents also influence microplastic abundance. The ocean current direction and speed along with the difference in the shape and size of microplastic found on the islands proves that ocean currents were also an influencing factor in microplastic abundance on the Maldivian islands.