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Our iconic giant clams face new threats from warmer waters and acidic oceans – let’s buy them time

Our iconic giant clams face new threats from warmer waters and acidic oceans – let’s buy them time

Man looking at giant clams for sale

Think of the inhabitants of a coral reef, and chances are you’ll think of a giant clam, the largest aquatic mollusc on Earth at up to 250 kilograms and a metre long.

The giant clam is not famous for its size or fame.Tridacna gigas) is in trouble. Climate change is making the Indo-Pacific tropical waters hotter. Their shells and flesh are in high demand. Some species are already extinct.

Our new researchToday’s research has shown that these iconic megafauna are facing new threats, such as the rising sea levels and acidifying oceans associated with climate change.

Is it over? It’s not yet. We believe there are better ways to manage clams on coral reefs. We also believe we can create new breeding programs to increase resilience to these threats, and buy time as we transition to net zero greenhouse gas emissions.

What’s been tried to save our iconic clams?

Despite their reputation as man-eaters – which came from exaggerated 19th century seafaring tales and Pacific Island legends – giant clams are gentle giants.

These charismatic animals are also the only invertebrate in the area Great 8This species is listed alongside clownfish and manta rays as a must-see by visitors to the Great Barrier Reef. Here, giant clams have been well protected from harvesting and snorkelers and divers can see eight of the world’s twelve giant clam species.

Although giant clams are still quite common in Australian waters they have been over-exploited in other areas.

Man looking at giant clams for sale

Giant clams are long sought after for their meat and shells. This photo is from Madagascar. They now face new threats.
Getty Images

In the late 1980s, breeding programmes have helped to rebuild over-exploited wild populations in Japan, Southeast Asia, the Pacific Islands and Japan. While the success of breeding programmes is not well known, it is known that they are labour-intensive, have high running costs, and are limited in the amount of coral reefs that they can restock.

We need to find other ways to protect our giants clams from these new threats. We can save them and use their fame to protect coral reef habitat. This will help corals, fish, and other invertebrates.

Continue reading:
Coral reefs are dying as climate change decimates ocean ecosystems vital to fish and humans

Why is giant clams under threat again?

Over-exploitation has led to nine giant clam species being added to the Red List of Threatened Species maintained by the International Union for Conservation of Nature. All giant clams are covered by the Convention on International Trade in Endangered Species of Wild Fauna and Flora Appendices.

Global climate change and pollution are major threats to giant clams. Meanwhile, the slowly acidifying oceans have an impact on the diversity of giant clam species, from the Red Sea to Pacific Ocean. Ocean acidification makes it more difficult for animals to build and keep strong shells, especially in their early years.

Like corals, giantclams also host symbiotic microalgae. They use their photosynthesised energies to grow to enormous sizes. When stressed, these clams can release their symbiotic microalgae to become white. They bleach just like corals.

Degree heating weeks combine the intensity of heat stress and its duration into one number. This map shows how heat stress has already affected the range of 12 giant clam species (scientific name on right). Figure credit to Blake Spady. Benjamin Leow. Sue-Ann Watson.

How can we make giant clams while decarbonising?

Global change and pollution are key stressors that reduce the number of habitats available for giant clams. Figure by Sue Ann Watson, Benjamin Leow

It is far and away the best strategy to conserve biodiversity. stable climate below 1.5℃ warming. Keeping well below 1.5℃ warming will help save giant clams and coral reefs.

While we wait, we can help clams adapt to climate change and survive. We gathered recent research from lab groups all over the globe to examine giant clam responses and how they cope with pollution and climate change.

We now know high temperatures from global warming and marine heatwaves cause the most stress to giant clams in shallow waters, while ocean acidification is causing most impact – whether lethal or just damaging – = on giant clams in deeper waters.

Low water quality and low light levels due to sediment-heavy runoff from cities or farms are making it harder. Climate change and pollution are making life harder for giant clams.

Continue reading:
5 major heatwaves in 30 years have turned the Great Barrier Reef into a bleached checkerboard

This information is important because it can be used to assist reef managers in planning the best conservation strategies to ensure giant clams are able to withstand rapid climate change. breeding more resilient individuals.

Aquaculture programs can help by getting babyclams used a slightly warmer, more acidic, and darker environment during breeding and rearing. After that, they are released to the wild. They could also offer the clams symbiotic microalgae, which is more tolerant to higher temperatures and light levels in the early years.

We need to raise the profile of giants clams. We will have a greater chance of helping them if more people recognize them as a key coral reef species. We can help these amazing creatures by protecting their habitat, valuing the potential of their tourism, and deploying citizen science programs to make their plight more widely known.

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