Coral Spawning, photo credit: Paul Selvaggio

Coral reefs need our help – how can we save them?

By Carin Jantzen and Heinz Krimmer.

Corals have existed for millions of years, but now their future is in jeopardy. Better protection alone is no longer enough to ensure their survival on a large scale. Combating climate change is a top priority and lies in our own interest as well. Local stress factors such as overfishing and pollution must be eliminated. At the same time, reefs should be actively supported by applying restoration.

“Rebuilding coral reefs – a decadal challenge”
The title of the strategy paper published by the International Coral Reef Society (ICRS) clearly expresses the current state of the world’s coral reefs. The ICRS is the mouthpiece of coral researchers worldwide and its appeal is directed at international policymakers to take action in the “three critical and interlinked areas of international policy—Climate Change, Biodiversity, and Sustainable Development” so that these diverse and economically valuable ecosystems survive.

There are three areas of action that are both interlinked and need to be tackled simultaneously:

  • Reducing global climate threats by reducing greenhouse gas emissions and increasing carbon sequestration.
  • Improving local conditions through increased protection and better management to enhance the resilience of coral reefs.
  • Invest in a) research to develop innovative methods and technologies for reef restoration and b) active restoration of coral reefs to improve recovery and adaptation, as well as maintain or restore biodiversity.

Mitigating the impact of climate change

Time is pressing: This “decade likely offers the last chance for international, regional, national, and local entities to change the trajectory of coral reefs from heading towards world-wide collapse to heading towards slow but steady recovery.” (Rebuilding coral reefs – a decadal challenge).

Investing in the restoration of coral reefs will also pay off economically, for example through self-sustaining coastal protection and income from fisheries. Ultimately, losing our reefs would be much more expensive than financing their future (UN Environment Program: The Coral Reef Economy).

We must give the corals time so that they can eventually spread again! Because the overriding threat to the reefs is climate change, as we explain in part 2: ocean acidification and, above all, global warming. It is therefore essential to meet the agreed climate targets and reduce emissions of climate-damaging greenhouse gases. Life on our planet, the preservation of important ecosystems and biodiversity – as well as our very own future – should be close to our hearts. (Report on Climate Change 2023 by the International Panel of Climate Change).

Turn the tide for coral reefs, photo credit: Zach Ransom.

Aerial view of a reef, photo credit: Ishan-Unsplash.

Catching invasive lionfish in the Caribbean, photo-credit: Paul Selvaggio.

Protecting the remaining reefs – reducing stress on site

Our coral reefs need all the strength they can get. It is therefore important to reduce local stress factors as much as possible – ideally to eliminate them altogether.

Corals need clean water! Therefore, any marine pollution should be avoided, Measures are needed to reduce waste, chemicals and sediments entering the sea. This includes improving wastewater treatment, promoting recycling and avoiding disposable products. Especially on the coasts, construction projects of all kinds, as well as raw material extraction, can damage the reefs. Tropical downpours wash the resulting sediments into the sea and the algae symbionts of the corals receive too little light to photosynthesize. These interventions must therefore be planned a way that sediment input into the sea is avoided. In some places, the corals themselves, the limestone of their skeletons, have also been used as building material – as in the construction of the airport in the Maldives.

Overfishing is a common fact for the reefs and is a dangerous interference with the ecosystem. As we explained in blog 1, a coral reef is a team effort. The team also includes algae-eating fish and sea urchins. If these grazers are removed from the reef, stony corals cannot withstand the competition with algae.

Protecting the remaining reefs – reducing stress on site

Our coral reefs need all the strength they can get. It is therefore important to reduce local stress factors as much as possible – ideally to eliminate them altogether.

Corals need clean water! Therefore, any marine pollution should be avoided, Measures are needed to reduce waste, chemicals and sediments entering the sea. This includes improving wastewater treatment, promoting recycling and avoiding disposable products. Especially on the coasts, construction projects of all kinds, as well as raw material extraction, can damage the reefs. Tropical downpours wash the resulting sediments into the sea and the algae symbionts of the corals receive too little light to photosynthesize. These interventions must therefore be planned a way that sediment input into the sea is avoided. In some places, the corals themselves, the limestone of their skeletons, have also been used as building material – as in the construction of the airport in the Maldives.

Overfishing is a common fact for the reefs and is a dangerous interference with the ecosystem. As we explained in blog 1, a coral reef is a team effort. The team also includes algae-eating fish and sea urchins. If these grazers are removed from the reef, stony corals cannot withstand the competition with algae.

Aerial view of a reef, photo credit: Ishan-Unsplash.

Catching invasive lionfish in the Caribbean, photo-credit: Paul Selvaggio.

Protection of the remaining reefs – refugees

In order to avoid overfishing, fishing quotas, closed seasons and protection zones must be introduced (Marine Protection Areas). The acceptance of the population, which is dependent on fishing, is key. Networks of many small and protected areas interspersed with usable zones have therefore proved successful. This allows local residents to catch fish and the fishing zones can be repopulated from the protected zones. A good compromise if complete protection is not possible.

And they still exist, the intact reefs! Remote and protected, the Kingman Reef in the central Pacific, for example, shows impressive resistance to climate change. The coral colonies are large and healthy, and the water is teeming with fish. Although storms and increased water temperatures also left their mark here, the corals recovered quickly. This shows that there are still reefs far away from human influence that have the potential to survive and can certainly withstand climate change. We should therefore protect these reefs in particular, which are still largely intact and have a good chance of surviving the effects of climate change better due to their location.

Coral planet, photo credit: Jamie Craggs.

Local fishing practices, photo credit: Arseny Togulev, Unsplash.

Locally and sustainably caught fish in the Caribbean, photo credit: Paul Selvaggio.

Parrot fish in a caribean reef, photo credit: Paul Selvaggio.

Protect coral reefs, photo-credit: Paul Selvaggio.

Protect my reef, photo credit: Paul Selvaggio.

Coral Fragments growing on a tree nursery, photo credit: SECORE.

Reef restoration

However, better protection alone is no longer enough to ensure the survival of the reefs – “Marine Protected Areas do not buffer corals from bleaching under global warming” a study shows.

Therefore, reef restoration measures are often necessary. So far, fragmentation has been the main method used. Fragments of coral, e.g. caused by storms or cut off by hand, are used for restoration. These fragments are, so to speak, “cuttings” (analogous to plant breeding; even if corals are animals; The importance of the coral reef ecosystem), i.e. clones of the parent colonies and not created by natural reproduction. Local projects can be successful under good conditions and offer opportunities to involve the local population. This is important to achieve better acceptance of reef protection measures among the people.

 

One such successful project is “MARS Symbioscience”. In 2013, a project to restore a coral reef on the island of Badi was launched, not far from the Indonesian city of Makassar. The coral reef, which covers around 7,000 m², had been destroyed by dynamite fishing 30 years previously and has not recovered since. Within three years, a densely overgrown reef was created; fishermen became reef protectors and the local fish populations recovered – also thanks to an inner protection zone.

Reef restoration

However, better protection alone is no longer enough to ensure the survival of the reefs – “Marine Protected Areas do not buffer corals from bleaching under global warming” a study shows.

Therefore, reef restoration measures are often necessary. So far, fragmentation has been the main method used. Fragments of coral, e.g. caused by storms or cut off by hand, are used for restoration. These fragments are, so to speak, “cuttings” (analogous to plant breeding; even if corals are animals; The importance of the coral reef ecosystem), i.e. clones of the parent colonies and not created by natural reproduction. Local projects can be successful under good conditions and offer opportunities to involve the local population. This is important to achieve better acceptance of reef protection measures among the people.

 

One such successful project is “MARS Symbioscience”. In 2013, a project to restore a coral reef on the island of Badi was launched, not far from the Indonesian city of Makassar. The coral reef, which covers around 7,000 m², had been destroyed by dynamite fishing 30 years previously and has not recovered since. Within three years, a densely overgrown reef was created; fishermen became reef protectors and the local fish populations recovered – also thanks to an inner protection zone.

Coral Fragments growing on a tree nursery, photo credit: SECORE.

Breeding corals for reef restoration

Utilizing bred corals for the reforestation of reefs has only been implemented on a large scale in recent years. The Coral Seeding approach used here was developed by the non-profit organization SECORE International (www.secore.org). Coral larvae are reared in floating nurseries from coral spawn collected in the reef. The resulting corals are then released into damaged reef areas.

The use of natural coral reproduction not only promotes genetic diversity and thus preserves the coral’s potential to adapt to changing environmental conditions  (coral resilience). It also enables the mass production of coral babies.
SECORE pursues a two-pronged strategy in the application of coral seeding: on the one hand, local partners are trained to use coral seeding sustainably, and on the other hand, methods and technologies are further developed and innovations are implemented as soon as they become available.

And there is indeed reason for hope: many young, bred corals that were put on reefs throughout the Caribbean survived the devastating heat wave of 2023 unscathed. So far, SECORE has implemented its Coral Seeding approach with partners in nine Caribbean countries and is in the process of advancing its application in the Indian Ocean and Pacific. As a non-profit organization, SECORE relies on donations to continue its work.

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A floating coral kindergarten, photo credit: Paul Selvaggio.

Baby coral, photo credit: SECORE.

Collecting coral spawn, photo credit: Reef-Patrol.

Seeding Corals, photo credit: Paul Selvaggio.

Coral breeding lab at Frost Museum, photo credit: SECORE.

X-reef project, Reefense, credit: DARPA.

X-reef project corals as wave breaker, photo credit: Paul Selvaggio.

Bred corals on the reef, photo credit: Paul Selvaggio.

Research: Searching for the super coral

Some coral species can adapt to the worsened conditions and thrive besides high temperatures, acidic water and poor light conditions. There are more heat-tolerant strains of symbiotic algae too. Research laboratories are already trying to breed so-called “super corals” from resistant species. The researchers are applying “assisted evolution”, which in principle corresponds to classical breeding: Individuals with preferred characteristics are intentionally bred – such as certain coat colors in dogs, or plants that are more resistant to disease. At some point, such super corals could become the anchor to sustain the function of coral communities and thus supporting the survival of coral reefs as a whole.

One innovative idea is the construction of a hybrid reef off the coast of Florida. This project would actually represent a major intervention into the reef ecosystem, however, unfortunately there is not much left of Florida’s reefs. The X-Reefs project is a joint project within the framework of the Reefense Program of DARPA, a research branch of the US Department of Defense, and the focus lays on coastal protection. This reef is to be colonized with temperature-tolerant corals, which will later maintain the reef through their growth. A team of well-known scientists from various institutions is working at full speed on this. It is possibly the last resort to save reefs there.

Research: Searching for the super coral

Some coral species can adapt to the worsened conditions and thrive besides high temperatures, acidic water and poor light conditions. There are more heat-tolerant strains of symbiotic algae too. Research laboratories are already trying to breed so-called “super corals” from resistant species. The researchers are applying “assisted evolution”, which in principle corresponds to classical breeding: Individuals with preferred characteristics are intentionally bred – such as certain coat colors in dogs, or plants that are more resistant to disease (). At some point, such super corals could become the anchor to sustain the function of coral communities and thus supporting the survival of coral reefs as a whole.

One innovative idea is the construction of a hybrid reef off the coast of Florida. This project would actually represent a major intervention into the reef ecosystem, however, unfortunately there is not much left of Florida’s reefs. The X-Reefs project is a joint project within the framework of the Reefense Program of DARPA, a research branch of the US Department of Defense, and the focus lays on coastal protection. This reef is to be colonized with temperature-tolerant corals, which will later maintain the reef through their growth. A team of well-known scientists from various institutions is working at full speed on this. It is possibly the last resort to save reefs there.

Coral breeding lab at Frost Museum, photo credit: SECORE.

X-reef project, Reefense, credit: DARPA.

X-reef project corals as wave breaker, photo credit: Paul Selvaggio.

Bred corals on the reef, photo credit: Paul Selvaggio.

Migration of coral reefs

Animal and plant species react to climate change by migrating to climatically more suitable distribution areas. The migration almost always takes place poleward. This also applies to corals. As it can be witnessed in southern Japan, approximately 600 km north of the most species-rich marine area on earth: the Coral Triangle of which the northern tip is the Philippines. From here, the Kuroshio Current drifts warm water as well as coral and fish larvae all the way to Tokyo. No wonder there are extensive coral reefs around the southern Japanese Ryūkyū Islands of the Okinawa Prefecture. These are among the northernmost reefs in the world and have already successfully migrated to the cooler subtropics. But even here, the reefs almost completely bleached in 2016. Corals in cooler regions must therefore also develop strategies to combat climate change, and they are.

A long-term study revealed that corals have been migrating northwards at a rate of 14 km/year since the 1930s, displacing algae and seaweed growth from southern Japan to Tokyo. Among the migrants you’ll find climate refugees from the tropics, still most are corals that were already indigenous and are now becoming established in new reefs. Two important tropical reef-building coral species have been detected in larger populations. We view corals as the big losers of climate change. This is justifiable as far as the tropics are concerned, but in Japan it is becoming apparent that some coral species can also adjust, making the leap from the tropics to the subtropics.

 

Fukui reef, Japan, photo credit: XL Catlin Seaview Survey.

Follow me, photo credit: Paul Selvaggio.

Look up, photo credit: Zach Ranson.

What can I do?

The IPCC climate report from September 2019 urgently warns that even a warming of 1.5 °C (3.3°F) poses a major risk to coral reefs. Any mitigation and removal of CO2 from the atmosphere is therefore the top priority. We can all reduce our own ecological footprint. Urgent action is also needed in politics and business. In a democracy, everyone has the opportunity to influence decision making, i.e. to elect politicians who are committed to taking effective measures to deal with climate change.

Spread the word!
And it is also important to raise awareness of the dire situation of coral reefs: Talk to your family, friends, and colleagues why we cannot afford to lose these wonderful, diverse and valuable ecosystems!

What can I do?

The IPCC climate report from September 2019 urgently warns that even a warming of 1.5 °C (3.3°F) poses a major risk to coral reefs. Any mitigation and removal of CO2 from the atmosphere is therefore the top priority. We can all reduce our own ecological footprint. Urgent action is also needed in politics and business. In a democracy, everyone has the opportunity to influence decision making, i.e. to elect politicians who are committed to taking effective measures to deal with climate change.

Spread the word!
And it is also important to raise awareness of the dire situation of coral reefs: Talk to your family, friends, and colleagues why we cannot afford to lose these wonderful, diverse and valuable ecosystems!

Follow me, photo credit: Paul Selvaggio.

Look up, photo credit: Zach Ranson.

What do coral reefs look like – a cinematic introduction!

 

1. Support policies for healthy reefs

  • Vote for policies that promote conservation and reduce greenhouse gas emissions.
  • Advocate for science-based decisions and reef protection.
  • Communicate your priorities with politicians and policy makers

2. Reduce your environmental footprint

  • Avoid single-use items (especially single-use plastic).
  • Buy sustainable food from local producers.
  • Reduce your consumption and avoid environmentally harmful products.
  • Move with less greenhouse gases: Cycle, walk, take public transport, drive electric.
  • Reduce your energy consumption: use energy-saving appliances, heat with climate-friendly technology, avoid energy-intensive products.
  • Offset your greenhouse gas emissions: If emissions are difficult to avoid, offset them by donating to reputable organizations that promote CO2 reduction projects

3. Promote environmental education and awareness for reef protection

  • Participate in local actions such as beach clean-ups and fundraising activities.
  • Educate yourself and share your knowledge.
  • Donate to reef research and conservation. Websites such as GlobalGiving (Explore Projects), GuideStar and Charity Navigator (US-based NGOs only), help you to find NGOs that are active in the thematic or geographical area you want to support via selectable search criteria and at the same time evaluate their work based on various criteria, whereby you can usually also set priorities here.
  • Share this call with others.

Carribean coral reef, photo credit: Reef Patrol.

Intactact elkhorn coral stand, Mexico, photo credit: Paul Selvaggio.

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