Venice battles seaweed invasion

The weed has the potential to clog Venice's famous canals

Venice is bracing itself for its summer tourist invasion, but an unwelcome newcomer has joined the thousands of visitors filling the Italian city.

This unwanted guest is a huge seaweed, originally from China, that grows up to three metres long.

The advent of summer means it is thriving in the warm shallow waters of the lagoon, near the city.

Scientists are warning that if left to its own devices it could clog up the city's famous canals.

Locals ousted

Researchers say the voracious weed, undaria pinnatifidaea, it was probably brought to the Adriatic accidentally by a ship that dumped bilge water into the sea.

From the Adriatic it spread into the nearby lagoon and has now reached as far as the city itself.

The tagliatelle-like weed is so big and invasive that it leaves little space for local species.

Biologists at Venice's Natural History Museum say that while the seaweed is unlikely to damage the city's historic buildings because it does not have roots, it is almost impossible to destroy and the only answer may be to find another foreign predator to eat it.

The seaweed is the second invader to make Venice its home in recent years. Filipino clams have already virtually wiped out local species in the lagoon.