Suspected suspicious fire burning on Great Barrier Reef 'sensitive' marine site, home to threatened species

National Parks and Wildlife officers say the blaze is impacting the fire sensitive marine plain. (Supplied: Queensland Department of Environment and Science)

Rangers are continuing to battle what they believe is a suspicious fire in a sensitive marine area on a southern Great Barrier Reef island. 

The Queensland Parks and Wildlife Service (QPWS) said on Sunday its team had finished two planned burns in the north part of Curtis Island, near Gladstone.

While doing "final mopping up" for the planned burns, rangers noticed a bushfire spreading on the marine plain about two kilometres away.

David Orgill, principal ranger for the southern Great Barrier Reef with QPWS, said due to the distance between the fires, the second one was thought to be a result of arson.

"It was against the wind, so sparks or embers couldn't have got to that location [and] it was too far for, say, a tree falling," he said.

"This one was quite obviously unrelated.

"Unfortunately, through some other observations they made at the site, they believe it was deliberately lit."

Rangers say the bushfire is about 2 kilometres from the planned burns. (Supplied: Queensland Department of Environment and Science)

Crews worked through the night and this morning to try and get the blaze under control.

They created fire breaks and called in aerial water bombers. 

It comes after rangers conducted hazard reduction burns across more than 10,000 hectares of the island in recent weeks.

The agency conducts planned burns throughout the state each year in a bid to reduce fuel loads and future bushfire risk, as well as protect important native flora and fauna.

These are usually done in the cooler months and are underway now in many parts of Queensland, ahead of the bushfire season. 

There are fears the blaze could damage the habitat of threatened species. (Supplied: Queensland Department of Environment and Science)

Yellow chat concerns

Mr Orgill said the unplanned fire was burning on a "fairly sensitive" part of the marine plain, where the threatened Capricorn yellow chat bird breeds.

Though there were no yellow chats in residence at the time of the fire, Mr Orgill said he was still very concerned about the damage the fire could do to the species' "habitat".

"It's an area that's not fire adaptive," he said.

The Capricorn yellow chat is a critically endangered flycatcher unique to the region. (Supplied: Bob Black)

"It means that through the dry period coming, a lot of waterfowl, like jabiru, brolgas, may not come here and will have to find somewhere else to spend their winter because they won't have the cover and the food source they normally get."

Police and the Queensland Fire and Emergency Service are not yet involved in the investigation.

Mr Orgill said QPWS would work with both agencies on investigating the possible cause of the fire once it was extinguished.

He urged anyone who might have more information to contact authorities.