Felicity Wishart from the Australian Marine Conservation Society. Rae Wilson

THE Australian Marine Conservation Society and the Australian environmental community is in mourning over the sudden and unexpected loss of Felicity 'Flic' Wishart who passed away in her sleep on Sunday night aged 49.

She was one of Australia's leading conservationists and was a great and inspiring champion for the planet, the cause she dedicated her life to.

Vale Felicity Wishart. We've lost a true hero for the environment. Her legacy will endure. Her fight is our fight. pic.twitter.com/S3rM9F644E — Fight for the Reef (@fightforthereef) July 21, 2015

For 30 years Flic played a fundamental role in many of the key environmental campaigns in Australia, the Australian Marine Conservation Society said in a statement.

They said Flic was a leader of seminal campaigns to protect the rainforests, to stop land clearing in Queensland, to confront the threat of climate change and national campaigns to protect the marine environment through the creation of a national network of marine protected areas and in her last, greatest and yet unfinished campaign, to protect the Great Barrier Reef.

Oh too sad. I worked with Flic at ACF. Vale Felicity Wishart – Aust loses a true hero for the environment who passed away on Sun aged 49 — Deborah Nesbitt (@DeborahNesbitt) July 21, 2015

Ms Wishart is survived by her partner and two young sons.

Details for her memorial service will be announced shortly.