Mark Ruffalo tweets to save Barrier Reef

Mark Ruffalo has thrown his weight behind the movement to save Queensland's Great Barrier Reef.

The Avengers actor has tweeted his support along with a link to the Greenpeace site, takeanotherlook.gp, which states that the reef is "under threat from the coal industry".

Greenpeace's campaign states that the sea bed is being dredged to make way for four "mega ports" to be serviced by 7000 industrial ships that will cross the Reef every year.

"Coal & coral don't mix. Join the movement to save the Great Barrier Reef:" Ruffalo tweeted, alongside a photograph of himself smiling and holding up a sign that read "#savethereef".

Greenpeace was the first to respond, tweeting back "Thank you so much for sharing this!"