Levels of microplastics are rising across the Mediterranean Sea, according to marine biologists who have spent six years studying the scale of the problem.

Alarming results from plankton samples were revealed at a conference about the sea on the island of Ponza, near Naples, Italy.

The data comes from Project Mediterranean — a floating laboratory that has been touring the waters to build a picture of the extent of pollution.

It found large amounts of garbage on the seabed, mainly in areas where the currents form vortices.

A lot of plastic waste that ends up in the sea is eroded down into microplastics and eaten by smaller fish, which in turn enter the human food chain.

"The production of plastic in the world increases of nine percent every year,” said Professor Adriano Madonna, a leading marine biologist at the University of Naples.

“When it is possible, let's go back to glass, let's go back to glass, which can be recycled.”

The Ponza Prima-Med event also heard new evidence on the extent of climate change, with the discovery of a tropical algae in the Egadi Islands, west of Sicily.

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