Can Selective Farming of “Super Kelp” Save Our Cold Water Reefs from Warmer Seas?

Australia’s vital kelp forests are disappearing in many areas as our waters warm and our climate changes.

Until swift action to reduce carbon emissions – including the UN climate talks now underway in Glasgow – we urgently need to buy time for these vital ecosystems.

How? ‘Or’ What? By “protecting for the future” our kelp forests to be more resilient and adaptable to changing ocean conditions. Our recent trials have shown that selectively selected kelp with higher heat tolerance can be successfully replanted and used in catering.

This is important because these large species of algae are the basis of South Australia’s Great Reef, a vast but little-known temperate reef system and a global biodiversity hotspot.

The reef kelp forests extend along 8,000 km of the southern coast of Australia from Geraldton in Western Australia to the Queensland border with New South Wales. These submarine forests support coastal food webs and fisheries. Think of the famous Australian giant cuttlefish mass spawning off Whyalla, lobster and abalone fishing, or our iconic grassy and leafy sea dragons.

Unfortunately, these seas are hot spots in the literal sense, with the waters southeast and southwest of the country heats up several times faster than the global average and suffering from some of the worst marine heat waves on record.

These rising temperatures and other impacts of climate change are devastating our kelp, including shrinking forests and permanent losses of golden kelp (Ecklonia radiata) on the is and the west coasts, and dizzying drops giant kelp now threatened (Macrocystis pyrifera) forests of Tasmania.

The forests of golden kelp are home to a wealth of life.
André Vert, Author provided

Read more: Australia’s ‘other’ reef is worth over $ 10 billion a year, but have you heard of it?

We need new measures to buy time for climate action

Australian researchers are leading the way in trying to find ways to sustain our critical ocean ecosystems, such as kelp forests and coral reefs. Part of the reason is that climate change is hitting our ecosystems early and abruptly.

Climate change is changing much faster than kelp species can adapt. In turn, this threatens all the species that depend on these forests, including us.

If climate change did not happen, we could try to stop or reverse the loss of kelp forests using traditional restoration methods. But in an increasingly hot world, this is futile in many cases. Even if we soon reduce carbon emissions, more decades of warming are coming. already locked up.

If we are to keep these marine forests alive, we must now consider advanced methods to help kelp survive current and future ocean conditions while governments pursue the urgent goal of reducing emissions.

How to sustain an underwater forest

Together and separately, we explored techniques to accelerate the rate of natural evolution in order to strengthen the resilience of kelp. Together with other researchers, we have tested several techniques in the real world, with promising results. Others remain hypothetical.

At present, there are several general approaches long-term restoration work. These include:

  • Genetic rescue focuses on improving the genetic diversity of genetically compromised populations to increase their potential to adapt to future conditions. This involves planting and restoring a mixture of seaweed from disconnected populations of the same species. Improved genetic diversity can strengthen the capacity of these forests to respond to change. We expect this approach to be particularly useful in areas where climate change poses a limited threat at present.

  • Assisted gene flow the strategies introduce naturally adapted or tolerant kelp individuals into threatened populations to increase their ability to survive specific threats, such as warmer seas. This could help kelp forests in areas affected by climate change now or in the near future. In these situations, the genetic rescue technique could be counterproductive if the new genetic diversity introduced is not able to cope with the heat.

  • Selective breeding is a well-known agricultural technique and can be used to identify the best kelp to use in these cases. In short, we try to identify kelp with naturally higher tolerance and then use them as the basis for restoration efforts. These can be transplanted into diseased kelp forests. Tests are currently underway in Tasmania using giant kelp. The first results are exciting, with the largest “super kelp” reaching over 12 meters high per year after being planted.

In the future, we may need to explore more forward-thinking strategies to deal with changing conditions. These include:

  • Genetic manipulation. This technique extends what is possible with selective breeding by directly manipulating genes to improve traits or characteristics that could further enhance the ability of kelp to thrive in warmer waters.

  • Assisted expansion It is when species with little chance of survival are moved to better but new locations, assuming they exist. This technique could also allow new species of kelp to be planted to replace existing ones, guided by the need to protect the forest ecosystem as a whole, rather than saving specific species.

Read more: Underwater health check shows kelp forests in decline around the world

Scientist experimenting on kelp
Co-author Melinda Coleman, Adjunct Professor, is working on kelp genomics as part of her selective breeding research.
Photo by Alejandro Tagliafico, Author provided

Are these approaches ethical?

Each of these techniques – tested or untested – poses difficult ethical questions. This is because we are not undertaking traditional conservation, where we are working to restore a historic kelp ecosystem. Instead, we modify these ecosystems in the hope that they can better cope with the extreme conditions of their current limits of survival.

This means that we must act with caution, weighing potential drawbacks such as genetic pollution and maladaptation (accidental misadaptation to other stressors) against the likelihood of further destruction of the kelp forest. if we don’t do anything.

Such sustainable interventions could be well suited to areas already hard hit by severe loss of kelp forests, those that will be threatened in the near future, or where kelp losses would be particularly damaging from an environmental, social or economic perspective.

What is certain is that the communities that live and depend on our southern coasts must now talk about what they value about kelp forests and how they want them to look and function in the future.

Our view is that traditional approaches focused on recreating past ecosystems are likely to be increasingly difficult, given the rate and magnitude of disturbance underway in our oceans.

It is crucial that we do not nostalgically restore rapidly changing ocean conditions, but rather work to ensure the long-term survival of these spectacular underwater forests while waiting for swift action to reduce carbon emissions.

Jeanetta J. Stewart

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