Blue Planet Live viewers were given a brutal and unplanned lesson about the harsh realities of nature during a broadcast from Queensland's Heron Island overnight.

Key points: A BBC camera crew were filming a live scene when a seagull swooped on a turtle hatchling

A BBC camera crew were filming a live scene when a seagull swooped on a turtle hatchling UK viewers watching the Blue Planet Live broadcast expressed their shock on social media

UK viewers watching the Blue Planet Live broadcast expressed their shock on social media Presenter Liz Bonnin said the scene was "hard to watch" but was ultimately an example of the region's ecosystem in action

Presenter Liz Bonnin was filming her sign-off for the BBC nature series as six baby turtle hatchlings were released on the sand.

Viewers from around the UK were watching as the tiny turtles inched towards the ocean from the beach.

But an opportunistic seagull was also looking on.

The bird swooped in and grabbed one of the babies, before the broadcast briefly cut to a shot from another camera.

A few seconds later, the offending gull could be seen walking away from the scene in a manner that, given what had just transpired, appeared cartoonishly suspicious.

The unscripted display horrified viewers, who voiced their shock on social media.

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Nature can be 'brutal'

Heron Island Research Station deputy manager Abbie Taylor was with the editors and producers in the control room and saw the whole thing unfold live.

"We witness turtle hatchlings being taken on a daily basis," Ms Taylor said.

"Whether that's by seagulls or crabs on land or sharks and fish in the water.

"It's common to see large flocks of seagulls waiting on the beach at dusk and dawn for nests to erupt."

This predation risk makes life difficult for young turtles, with an average of just one out of 1,000 baby turtles surviving to maturity.

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Ms Taylor told the ABC the hatchlings that appeared on the show had been retrieved from a nest that had erupted a few days prior.

She said this was common practice for the team from the Queensland Parks and Wildlife Ranger Station (QPWS).

"They dig up [the erupted] nest to get stats on hatching rates and to see if there are any remaining live hatchlings," she said.

"These particular nests had been replanted by QPWS to gain data on incubation periods and counts on successful and unsuccessful hatchings."

With limited human disturbance, Heron Island should be able to sustain 80 seagulls, but human influence has seen the population swell to some 300 gulls.

And this puts an increased pressure on the population of animals preyed on by the gulls.

Ms Taylor said before turtle season the gulls targeted white-capped noddy tern (a seabird) chicks, "killing them, only to eat their eyes and stomachs".

"It was a very brutal sight," she said.

Part of the food chain

On Twitter, Bonnin explained the scene broadcast to living rooms throughout the UK.

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"The scientists here take the hatchlings that would normally die in the nests, the ones that are left behind after the clutch have emerged days before, to give them a lifeline," she said in a series of tweets.

"These hatchlings are part of the food web here and the silver gulls need to feed their newborn chicks too.

"Hard to watch but we can't do anything about it."

Heron Island is located in the Great Barrier Reef Marine Protected Area and is an important nesting habitat for loggerhead and green sea turtles.

Nesting season typically spans from October to March, with most turtles hatching from their eggs in January.

Visitors are welcome to watch the hatchlings as they venture from their nests, but are reminded through the Heron Island website that the young are endangered species and are "very vulnerable to being disturbed".