Citizen science study on maritime traffic and plastic debris in Asturias estuaries

Worldwide shipping currently moves some 11 billion tons per year and is expected to grow by at least 240 % by 2050. However, the increase in maritime traffic can also create challenges in terms of pollution, safety, and conservation of the marine environment. Maritime traffic on the Asturian Coast is an important part of the region's economic activity, with the estuary of Avilés being a key point for the entry and departure of merchant traffic as well as fishing and recreational traffic. There are also smaller fishing ports and marinas such as San Juan de la Arena (Nalón River estuary) or Ribadesella (Sella River estuary) with a long tradition of both fishing and recreational boating. In this citizen science study, maritime traffic was analyzed in the three estuaries. Water samples were taken from these ports to determine the concentration and types of microplastics through filtration and examination under the stereomicroscope. Marine litter was surveyed from adjacent beaches, also with the help of citizen volunteers. The results obtained from the analysis showed highly significant differences between ports for both the type of plastic litter and microplastics pollution, according to the type of maritime traffic and the port size. The microplastics were directly associated with the number of vessels in each estuary and did not differ in the types of polymers, suggesting a common marine origin. This research shows the importance of implementing sustainable management measures to ensure that maritime traffic on the Asturian Coast develops in an environmentally friendly way. • Citizen science as a novel approach for monitoring maritime traffic. • Between December 2023 and February 2024, volunteers collected 33,887 ship data points. • Beach cleanups provided 2699 plastic items across estuaries. • Statistical analysis supports a connection between ship traffic and plastic pollution. • The study calls for better control of marine and land-based pollution sources.