Research by four organisations has estimated that there are 752 million plastic particles in the Minorca Channel, the equivalent of 3.7 tonnes. The research involved taking quarterly samples and was carried out in 2014 and 2015.
The results of the research have been published in the academic journal Environmental Pollution. They include the finding that there are 220,000 particles for every square kilometre - 1.1 kilos of plastic. The particles are smaller than five millimetres and have been fragmented by currents and waves. Given this size, they represent a significant threat to marine ecosystems and enter the food chain.
The study shows that the highest concentrations of particles occur in spring and summer and are therefore directly linked to tourism.
The Minorca Channel between Majorca and Minorca is approximately 36 kilometres wide. There are reckoned to be around 16,000 species, 58 of them protected, such as the loggerhead turtle.