It's impossible not to notice the two excellent murals in the Argentine city of San Nicolas de los Arroyos, which sits on the banks of the Parana River. They are emblematic of the local worries about a growing environmental issue for the area, namely the declining levels of the waterway.

The two forty meter high paintings on the sides of buildings in the city centre were inspired by the artist, Martin Ron's wish to remind the world of the river's decline. Affected by a lack of rainfall upriver in Brazil, lately the Parana reached its worst level in almost 90 years.

One mural shows a boy pulling a native flower from the river, while the other shows a girl whose image is reflected in the declining water. Argentine muralist Martin Ron, who has painted hundreds of murals around the world, said he particularly noticed the decline in the river Parana. He felt there was an ecological message which needed to get out.

The river, which begins in city of Brazil before flowing through Paraguay and then Argentina to the ocean, carries almost all of Argentina's farm exports such as soy, corn and wheat, transported in giant Panamax ships from inland farm regions to the rest of the world.

This commercial activity is vital to the country's economic wellbeing, as well as establishing an important ecosystem near the river delta.

The low levels have seen ships forced to take on smaller loads to sit higher in the water, hindering trade and hurting what is usually a competitive advantage for the country - the deep waterways that allow access for big container vessels.

Ron said his art was meant to encourage people to look at what needs to change.

The forty year old artist paints between about twelve 12 murals every year and has evolved his style from urban surrealism to what he describes as 'magical hyper-realism'. Other murals he has done include a girl building with Lego blocks and a portrayal of soccer player Carlos Tevez.

Although Ron spends much of his life on cranes and scaffolding, the artist confesses he suffers from a fear of heights.

He wryly says that in each project he has to acclimatise himself to the altitude.

Marvellous pieces, Mr Ron! Keep up the good work!