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Nemo is actually a 'false clownfish'. Motoya Kawasaki/Flickr, CC BY-NC-ND

Anemonefish, or clownfish, were made famous by the 2003 Disney-Pixar film Finding Nemo, and are about to play a starring role in the sequel, Finding Dory. They are well known for their special relationship with anemones, which provide a safe place to call home.

But anemonefish face a number of threats. Some researchers have warned of an increase in the wild-caught anemonefish trade, as happened following Finding Nemo.

Anemones, on which anemonefish depend, are threatened by warming seas in a similar way to corals. In fact anemones were affected by the recent coral bleaching on the Great Barrier Reef, which recent updates show has left a third of coral colonies dead or dying in the north and central parts of the reef.

So will Nemo be left homeless?

A healthy (left) and bleached (right) bubble-tip anemone (Entacmaea quadricolor) on the Great Barrier Reef. Ashley Frisch Nemo and his 27 cousins

There are 28 species of anemonefish. Although some people call this group “clownfish”, technically this name is only used for one species, Amphiprion percula. “Nemo” (A. ocellaris) looks similar, but is actually known as the “false clownfish”.

Anemonefish are famous for their special relationship with anemones. Although they can survive in aquariums without anemones, in nature they rely on anemones for protection from predators.

The pink anemonefish (Amphiprion perideraion) in a bleached anemone (Heteractis magnifica) at Christmas Island. JP Hobbs.

In return for providing a safe home, the resident anemonefish will provide nutrients and defend the anemone from predators such as butterflyfish. Both the number and size of anemonefish is linked to the size and number of anemones – and vice versa. Therefore, any decrease in one partner affects the other.

The collection of anemones and anemonefish for the aquarium trade has to be managed properly to ensure the future of anemonefishes. Anemonefish can be easily bred in captivity and this provides a reliable source for aquarium enthusiasts without impacting wild populations.

Cinnamon anemonefish (Amphiprion melanopus) in a bleached anemone (Entacmaea quadricolor) on the Great Barrier Reef. Ashley Frisch

Ten species of anemones are inhabited by anemonefish. The highest diversity of anemonefish occurs in Indonesia, where anemonefish species outnumber anemones. As a result, different species of anemonefish have learnt to share the same anemone.

In most other locations, anemonefish aggressively prevent other species from entering their anemone. Anemonefish species differ in the number of anemone species they associate with.

Clark’s anemonefish (Amphiprion clarkii) in a bleached anemone (Cryptodendrum adhaesivum) at Christmas Island. JP Hobbs.

Clark’s anemonefish (A. clarkii) can live in all ten anemone species and is widely distributed throughout the Indian and Pacific Oceans. In contrast, McCulloch’s anemonefish (A. mccullochi) inhabits only one species of anemone and occurs only on reefs around Lord Howe Island.

After hatching, anemonefish larvae use their keen sense of smell to find their preferred anemone species and avoid unhealthy (bleached) anemones.

Anemones in hot water

Anemones are closely related to corals and get their colour from microscopic algae (zooxanthellae) that live symbiotically within the tissue of the anemone. Like corals, anemones expel their algae and turn white when they become stressed.

This process – termed “bleaching” – is usually in response to periods of elevated seawater temperatures. All ten species of anemones are susceptible to bleaching, which can result in a decrease in the size and number of anemonefishes and reduced reproduction.

McCulloch’s anemonefish (Amphiprion mccullochi) in a bleached anemone (Entacmaea quadricolor) at Lord Howe Island. Justin Gilligan.

If seawater temperatures remain high for too long, then bleached anemones will die. In 1998, a prolonged period of elevated water temperatures in Japan resulted in mass mortality of bleached anemones and local extinction of anemonefish.

In March 2016, the Great Barrier Reef experienced a severe bleaching event due to elevated water temperatures associated with a strong El Niño event. There was mass bleaching of both corals and anemones.

Marine biologist Jean-Paul Hobbs studying anemonefish (Amphiprion mccullochi) and their host anemones (Entacmaea quadricolor) at Lord Howe Island. Justin Gilligan.

In April 2016, elevated water temperatures also caused mass bleaching of corals and anemones off north-west Australia, including Christmas Island. Bleached anemones have also recently been reported elsewhere in the Pacific Ocean, Indian Ocean and in the Red Sea.

The future of the bleached anemones and their resident anemonefish will depend on how quickly the water temperature returns to normal. If the temperature decreases swiftly, bleached anemones can regain their colour (reabsorb zooxanthellae) and survive.

However, the frequency and intensity of bleaching events are predicted to increase as the climate changes. Consequently, there are serious concerns about the ability of anemones and anemonefish to cope with rising water temperatures.

Reducing global greenhouse gas emissions will limit subsequent bleaching events and help ensure the future of Nemo and its relatives.

Jean-Paul Hobbs currently receives funding from Curtin University and Christmas Island Divers Association. His past research on anemones and anemonefishes has been funded by James Cook University, ARC Centre of Excellence for Coral Reef Studies, Great Barrier Reef Marine Park Authority, Lord Howe Island Marine Park, Parks Australia, WA Department of Fisheries, Wet n Dry Adventures Christmas Island and the Australian Government Department of the Environment.

Ashley J Frisch has received funding from the ARC Centre of Excellence for Coral Reef Studies, James Cook University, and the Great Barrier Reef Marine Park Authority.

Tara national park, Serbia The extraordinary thing is not how comfortable local people are around bears but how they live in almost parallel worlds

Sitting in a forest hut for three hours watching a glade fill with shadows tests to the limits all that modern life has made of us, especially our capacities for patience, stillness, silence.

Not that I expected the objects of our vigil to reciprocate. On the contrary, brown bears in this park can be 250kg, so I was assuming that they might give warning of their approach: inadvertent rustling perhaps, or anxious alarm calls from nearby birds. Not a bit of it: what was so affecting was how the bears brought the stillness with them. On one occasion an animal walked right by us and while just 4 metres away we heard nothing.

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Wildlife authorities in Thailand are removing tigers from a controversial Buddhist temple after accusations of wildlife trafficking and animal abuse.

Greens leader Richard Di Natale criticises Labor and the Coalition for their commitments to new coalmines, accusing them of taking huge donations from the fossil fuel lobby and harming the future of renewables on ABC’s Q&A program on Monday. When asked about his plans for central Queensland, Di Natale says: ‘I tell you what we won’t be doing is opening up a new coalmine and killing the Great Barrier Reef.”

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After a nation-wide search by the Australian Institute of Landscape Architects, Australia's best playground has been announced, and the winner is Nature Play in inner-city Melbourne's Royal Park.

GREAT MOMENTS IN SCIENCE: Today's technology looks so slick and clean as it brings magic to your screen. But behind the scenes, our data comes at a cost, says Dr Karl.

Australia’s WWI sunken fleet poster was released to promote Australia’s WWI underwater cultural heritage.

In April - May 2015 Curtin University concluded a successful remote survey of the shipwrecks HMAS Sydney II and HSK Kormoran.

ANCIENT JOURNEY: Ancient charred grains of rice and mung beans excavated from Madagascar provide the first archaeological evidence that ancestors of people living on the East African island known as Malagasy came from South-East Asia, scientists say.

Ever since visiting a remote Indonesian village as a teenager, Justine Flynn nurtured the dream of improving the lives of millions of people. Today, she has raised more than $4 million for life-changing food, water, health and sanitation programs by selling innovative local products

It was a week after the terror attacks of 9/11, and 14-year-old Justine Flynn was about to get on a plane to a remote village in Indonesia to help out at a local children’s foundation.

The fact her mum and dad let her go, despite the climate of fear, became a life-changing moment which set her on her path as a social entrepreneur and for which she is forever grateful.

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Comedy comes in all shapes and sizes. From the clever to the quirky, there is something for everyone in this selection of 25 of our funniest films. Warm up your winter with a little humour from some of the masters of modern comedy

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Polling indicates 71% would be more likely to vote for a party that supported distributed small-scale solar and storage

Battery storage technology has the potential to reshape not just the energy and transport sectors but also the upcoming Australian federal election, according to a new report.

The Australia Institute report Securing Renewables: How Batteries Solve the Problem of Clean Electricity includes polling indicating that 71% of Australians would be more likely to vote for a party that supported distributed small-scale solar and storage.

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The director of Cincinnati zoo says he would do the same again after a gorilla, into whose enclosure a child fell, was shot dead.

The problems caused by mass bleaching on the Great Barrier Reef have continued to deepen, with the latest estimates based on results from our surveys showing that 35% of corals are now dead or dying along the northern and central sections of the reef north of Townsville.

We have been tracking this severe bleaching event for months, documenting the damage as abnormally high water temperatures caused the coral to bleach, losing the algae that live within their tissues and supply most of the corals' energy.

Although corals can recover from bleaching when water temperatures drop, they can also die if they are without their algae for too long. From our surveys, we estimate this has now happened to one-third of the corals on reefs north of Townsville and to half of the corals on reefs that were hit hardest by the bleaching event.

The scale of the damage

For this latest survey, my colleagues and I carried out in-water surveys of corals on 84 reefs, spanning 1,300 km from Townsville to the Torres Strait, between mid-March and mid-April this year. We counted the number of coral colonies that were either recently dead, bleached completely white, partially bleached or healthy, as well as quantifying the percentage cover of hard corals and other organisms at each reef.

When you’re underwater, it’s easy to spot corals that have recently died due to bleaching because their white skeletons are coated in a thin film of greenish-brown algae. Over time, the algae grows to form a thick mat that obscures the skeleton – a hallmark of long-dead corals that are not victims of the recent bleaching. Our surveys did not include these colonies.

Corals that are bleached totally white, having lost nearly all of their symbiotic algae, have an extremely low chance of recovering because it takes several months for the algae to come back. In contrast, most corals that are only partially bleached will survive and recover quickly.

In the reef’s central section, between Cairns and Townsville, colonies tended to be partially bleached instead of completely white or dead. We estimate that fewer than 5% of colonies will die on many of these reefs.

But on the reef’s northernmost section, north of Cooktown, we estimate that more than half of the coral colonies on many reefs have died.

What do these figures really mean?

Corals are made up of tiny modules, called polyps, that are joined together to form colonies. Most of the polyps in each colony can reproduce, and this obviously means that larger colonies can produce more larvae.

Similarly, reefs with more different colonies living on them can produce more larvae overall, providing a supply of new corals that can disperse to nearby damaged reefs and kick-start their recovery.

In places where corals have died on just a few reefs among many other healthy reefs, the supply of larvae from the neighbouring healthy reefs can facilitate more rapid recovery.

But in places where coral deaths are spread across most of the reefs, such as the stretch north of Cooktown, the coral larvae needed to recolonise the reefs have to travel much longer distances and this slows down the recovery.

Recovery prospects

This shows why coral bleaching is particularly damaging to reefs: its effects can be apparent over a scale of thousands of kilometres. Other disturbances, like cyclones, can also kill lots of coral, but their effects are usually more localised, meaning that recovery is easier.

Based on previous bleaching events, it can take several decades before these reefs recover, and much longer before the oldest and largest colonies are able to re-establish themselves. Some areas of the reef that were severely bleached in 1998 still haven’t recovered. The fear is that the time between bleaching events is now shorter than the time needed for reefs to recover.

Ocean currents are crucial to reef recovery, because of the importance of dispersing coral larvae for repopulating damaged reefs. On the Great Barrier Reef, the East Australian Current helps to transport larvae from north to south. However, this current begins its southward path at around 18º South (just north of Townsville), meaning that this current will be little help (and will in fact be an active hindrance) to the recovery of the most severely bleached reefs beyond that.

Another factor that impedes recovery is that bleached corals have lower reproductive output after a bleaching event. This means that even colonies that don’t die this year will contribute fewer larvae in the coming years.

Fixing the damage?

Coral bleaching events happen mainly when ocean temperatures are abnormally warm. Consequently, reducing greenhouse gas emissions is the main way we can help to prevent more global bleaching events from striking in the future.

Improving water quality and controlling outbreaks of crown-of-thorns starfish are also very important, because reducing coral loss due to these other factors can increase the resilience of the reef to bleaching.

Technological approaches, like shading reefs or artificially restocking reefs, might be considered for specific small reef sites, but they are not feasible for the conservation of the 2,300 km Great Barrier Reef, or for coral reefs on a global scale.

Mia Hoogenboom receives funding from Australian Research Council.

Officials in Thailand take three tigers away from a Buddhist temple during a raid over wildlife trafficking claims. The tigers are tranquilised and taken away on stretchers to be transferred to a state-owned sanctuary. Dozens of tigers remain at the temple in Kanchanaburi province, and tourists are seen taking selfies with the big cats. The temple claims it is a wildlife sanctuary, but authorities are investigating it for animal trafficking and abuse

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Data released to Greenpeace in response to FoI requests show number of prosecutions has dropped significantly in recent years

Far fewer pirate fishermen are being caught in English and Welsh waters, with prosecutions, warnings and inspections all plummeting in recent years following cuts at the enforcement agency.

The reduction in action against illegal fishing, a multi-million pound activity, is putting marine life at risk and allowing “blackfish” to become a normal catch for some rogue operators, according to experts. Those convicted of major fishing crimes are also free to continue fishing afterwards.

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A worried mother elephant looks on as her calf is rescued by wildlife officials in Sri Lanka, after it fell into an open drain. Rescuers in the town of Hambantota fire smoke bullets to keep her from coming too close while they dismantle the drain and pull the calf to safety

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Officials remove three animals following raid at temple, which has been investigated for animal abuse in recent years

Wildlife authorities in Thailand have raided a Buddhist temple where tigers are kept, taking away three of the animals and vowing to confiscate scores more in response to global pressure over wildlife trafficking.

The Buddhist temple in Kanchanaburi province, west of Bangkok, has more than 100 tigers and has become a tourist destination where visitors take selfies with tigers and bottle-feed their cubs.

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The new Tun Mustapha marine park & shark sanctuary in Borneo is the biggest marine protected area in Malaysia

Malaysia has just established the biggest marine protected area (MPA) in the country. The Tun Mustapha park (TMP) occupies 1m hectares (2.47m acres) of seascape off the northern tip of Sabah province in Borneo, a region containing the second largest concentration of coral reefs in Malaysia as well as other important habitats like mangroves, sea grass beds and productive fishing grounds.

It is also home to scores of thousands of people who depend on its resources – from artisanal fishing communities to the commercial fisheries sector – making it in many ways a microcosm of the entire Coral Triangle bioregion, where environmental protection must be balanced with the needs of growing coastal populations.

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Farming minister George Eustice says leave vote would free up £2bn now spent on insurance schemes and incentives for farmers

The UK could develop a more flexible approach to environmental protection free of “spirit-crushing” Brussels directives if it votes to leave the EU, the farming minister, George Eustice, has said.

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