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Urban dolphins: Challenges of city life revealed

1 September 2013 Last updated at 00:03 BST

Scientists from Murdoch University in Perth, Western Australia, are studying the resident pod of "urban dolphins" in the city's Swan Canning Riverpark.

The research team's ongoing survey aims to find out which areas of the river the dolphins are using the most, and therefore which areas might need greater protection.

As researcher Delphine Chabanne explains here to the BBC, the work has also shown that the population has now recovered from a sudden decline in 2009, when six dolphins died of a suspected virus.

Video journalists: Victoria Gill and Damian Fasolo