As Italy battles to control the COVID-19 pandemic, residents of Venice have noticed a significant change in the quality of the city’s famous canals.

While the shutdown has left the streets empty of tourists and businesses on the edge, the dramatic reduction in water traffic has reduced the amount of sediment in the waterways.

The canals are now running clear for the first time in years, and marine life is now visible in the usually murky waters.

"There is a limited reduction in the solids coming from the lagoon and settling in the canals, as a consequence of the reduction of the water traffic," said Davide Tagliapietra, an ecologist at the Institute of Marine Sciences in Venice.

"As soon as humans stop disturbing other species, they gain space".

Several videos have been shared online, claiming to show not only fish and swans, but also dolphins appearing in Venice’s canals.

Screenshot - Twitter

The footage appears shows a dolphin swimming alongside a pier in a port, as several onlookers kneel close to the water and record the encounter.

The video was shared by several international news outlets, such as CGTN, who posted a clip from the footage on their official YouTube channel with the headline "Coronavirus upside? Fish and dolphins seen in Venice canals during lockdown".

Similar headlines appeared on Evening Standard and MSN News.

But the footage does not show dolphins in Venice. The video was actually taken in the port of Cagliari in Sardinia, around 750 km away from Venice.

A simple reverse search for key frames in the video found many links referring to Cagliari as the location, including several uploads by Italian news agency, ANSA.

ANSA reported that the video was taken by members of Luna Rossa sailing team, on Ichnusa pier in Cagliari, in their training for the America's Cup of 2021.

In the video, at least one of the individuals kneeling next to the dolphins is seen wearing a grey uniform, with the visible logo of Pirelli, the sponsors of Luna Rossa. This matches the uniforms pictured on the team’s official website.

In the background of the video, you can also match the skyline of Cagliari port to images on Google Earth, taken from the Luna Rossa Prada Pirelli Team location, as seen in the image above.

According to ANSA, this is not the first time that the sailors have encountered dolphins around Sardinia, but it is unusual for the marine mammals to swim so close to the port of Cagliari.

ANSA reports that this may possibly be linked to Italy’s deserted waterways due to the coronavirus emergency.

Dolphins in Italian port waters are "increasingly frequent", but the last sighting in the San Marco Basin was "three years ago".

This according to a joint statement from Tagliapietra, physicist Roberto Zonta, and ecotoxicologist Annamaria Volpi Ghirardini, from University Ca’ Foscari in Venice.

"It is clear that a decrease in the disturbance facilitates the entry of animals into the city."

An increase in oxygen levels in the water and recent favourable weather have also had an impact on the lagoon around Venice.

"The images from the canals these days prompt us to think about the model of city we want".

A number of people have also posted images of the improved condition of Venice's canals on the Facebook page 'Venezia Pulita' ('Clean Venice') following the countrywide lockdown.

But while the coronavirus pandemic has had an unexpected positive effect on marine life around the city, a viral video does not show dolphins swimming through the Venice’s canals.