Paddle surfing for science on microplastic pollution

摘要

Microplastics have pervaded all oceans on Earth and their impact on marine ecosystems is a matter of debate. However, there is a lack of information from a few meters from the coastline even though monitoring the near-shore is absolutely needed to fully understand the paths and magnitude of microplastic pollution, including its implications for coastal management and water quality. Traditional scientific data acquisition using conventional platforms such as research vessels or small boats is expensive and hampered by numerous limitations in the nearshore zone, ranging from too shallow (and risky) depths to the presence of swimmers. Here, we provide the scientific community with an affordable and easy to use manta trawl called paddle trawl to be attached to a paddle surf board to acquire scientific samples in the nearshore within the frame of a citizen science monitoring project with the Spanish delegation of the non-governmental organization Surfrider Foundation Europe. Our results show, as a proof of concept, that a lightweight and low-cost paddle trawl towed behind paddle surfers allows obtaining samples for microplastic characterization and quantification while raising awareness of pollution by the allochtonous particles. An average of 11.7 × 10~4 items km~(-2) was found in the nearshore, similar to those found offshore in the Mediterranean Sea. However, a comparison with offshore data obtained with a standard manta trawl shows differences in plastic size distributions. Whereas microplastics dominated in offshore waters mesoplastics and macroplastics prevailed in the nearshore. A larger variety of polymers, including high-density ones and higher average lengths nearshore shows that this area is likely to produce and export microplastics towards offshore waters.