Ocean Acidification and Coral Reefs | Effects & Solutions

Ocean acidification damages coral reefs. It reduces carbonate ions in seawater that corals need to build their skeletons. Studies show acidification decreases coral calcification rates by 10-50%. Corals grow thinner, weaker skeletons that erode easily. As CO2 levels rise, seawater absorbs more CO2 which increases acidity and hydrogen ions. Corals pump out hydrogen ions to get carbonate ions for calcification. But in acidic conditions, there are fewer carbonate ions available.

Weaker calcification by corals and other reef-builders like coralline algae reduces reef growth and complexity. This threatens reef biodiversity and coastal protection benefits. Acidification compounds stresses like warming which also disrupt reefs. Globally, ocean acidification directly impairs the ability of reef ecosystems to construct and maintain their calcium carbonate structures. Healthy coral reefs are at risk as acidification worsens.

ocean acidification and coral reefs

Interesting Facts About Ocean Acidification and Coral Reefs

  • 🌊 Ocean Chemistry Shift. Ocean acidification occurs when CO2 absorbed by seawater reduces pH levels, making the water more acidic and less hospitable for marine life.
  • 🪸 Impact on Coral Skeletons. Acidic waters decrease the availability of calcium carbonate, essential for coral skeletons, making it harder for corals to grow and maintain their structure.
  • 🐠 Disrupted Marine Ecosystems. Coral reefs support about 25% of all marine species; acidification threatens this biodiversity, leading to potential collapse of these ecosystems.
  • 🌐 Global Climate Change Link. Ocean acidification is a direct result of increased atmospheric CO2 from human activities like burning fossil fuels, making it a significant aspect of global climate change.
  • 💡 Economic Consequences. Coral reefs contribute to the economy through tourism, fishing, and coastal protection, and their decline due to acidification could result in significant economic losses.
  • 🔬 Research and Monitoring Efforts. Scientists use advanced monitoring systems and modeling to study acidification impacts on coral reefs, aiming to develop strategies to mitigate these effects and protect marine biodiversity.
How is climate change impacting coral reefs? Ocean Acidification | Biscayne National Park

What is Ocean Acidification?

Ocean acidification happens when there’s more carbon dioxide in the air. This comes from burning fossil fuels. The seawater absorbs this carbon dioxide, leading to chemical changes. It becomes harder for marine life, like corals, to form their structures.

This is because the process results in a decrease of carbonate ions and an increase of bicarbonate ions in the water. With less carbonate, building shells and skeletons becomes tricky.

Rising Carbon Dioxide Levels

Carbon dioxide levels in the air are going up from burning fossil fuels. Over time, Earth’s climate changes have made seas warmer and more acidic. But today, we’re seeing acid levels that are very high, something we haven’t seen in 300 million years.

Seawater Chemistry Changes

More CO2 in seawater means more HCO3– ions but less CO32- ions. This change makes it tough for corals to grow.

Corals and other sea life that rely on calcium carbonate for their shells face challenges. Additionally, this change affects the pH, which slows the growth of corals. This is bad news for coral reefs.

Coral Reef Vulnerability to Ocean Acidification

Coral skeletons are tough, made from special calcium carbonate called aragonite. Corals build their skeletons up by adding aragonite crystals on top of each other. When ocean water becomes more acidic, thanks to pollution, the coral’s ability to make these crystals shrinks. This makes their skeletons weaker and easier to break.

Chris Cornwall - Vulnerability of coralline algae to ocean acidification at the organism-level

Reduced Aragonite Saturation

Before the Industrial Revolution hit, almost all coral reefs were in good water. This water had plenty of aragonite, which corals use to build their skeletons. Now, only around 60% of reefs enjoy such good conditions. With more pollution, it’s predicted that over 90% of reefs will struggle to find enough aragonite in the water. If we don’t stop pollution soon, no coral will live in water that helps them grow strong.

Coral Skeletal Growth Impairment

Studies have already shown that higher carbon dioxide levels in the ocean hurt corals. They slow down or even stop growing. This can lead them to wear away over time. Recently, in the Great Barrier Reef, coral growth has dropped significantly. This lower growth is the worst seen in the last 400 years. It shows how much corals are struggling today.

Ocean Acidification and Coral Reefs

coral reefs

Coral Skeletal Density Decline

A team from the Woods Hole Oceanographic Institution (WHOI) discovered how ocean acidification harms coral skeletons. This helps us know where corals are most at risk. Ocean acidification slows down the thickening of coral skeletons. As a result, their density decreases, making them more prone to break.

Regional Impacts on Reefs

Research shows that coral skeleton density will decrease in many reefs. This is a big issue in the Indo-Pacific. Specifically, in the Coral Triangle, it’s predicted that coral skeleton density may decrease by up to 20 percent by 2100. Corals in the Caribbean, Hawaii, and the northern Red Sea might see smaller drops, under 10 percent.

Bioerosion and Reef Resilience

SoMAS - Waves of Change: How Ocean Acidification is Reshaping Coral Reefs

Corals are vital for reefs because they grow upward, trying to find sunlight. They also must make their skeletons stronger. They do this to fight against damage from currents, waves, and animals like worms and parrotfish.

When the ocean’s acidic, corals find it hard to make their skeletons tougher. This makes them more at risk from being worn down by bioerosion. This problem upsets the important balance between how corals grow and how much they are worn away.

Keeping this balance is key to making sure coral reef structures stay strong and bounce back when hit. If this balance is broken, the home, food, and safety of many creatures living in coral reefs are threatened.

Coral Growth vs Erosion Balance

Over the past 30 years, more than a quarter of the world’s live coral has died due to coral bleaching. Between 2014 and 2017, a worldwide event affected 75% of corals, showing how serious the issue is.

In a study, it was found that dead corals without any live cover dissolve faster because of ocean acidification and bioerosion. However, live coral tissue can slow down this process. It does this by protecting the skeleton and by growing, thus helping reefs fight against the dangers of ocean acid.

Threat to Reef-Dependent Species

Coral reefs support a third of marine life in less than 1% of the ocean, proving their huge importance. Yet, around two-thirds of reef fish have disappeared since people started counting. Less fish are found near important markets.

Losing the balance between coral growth and erosion is a danger to the many species that depend on the reef. These creatures need the reef’s complex structure for their home, food, and protection.

Helping coral reefs in the future might mean we need to repair and replant them. This is to fight the bad effects of the changing climate and ocean acid. As the ocean gets warmer and more acidic, corals and other reef life find it hard to live and reproduce. This threatens their ability to withstand hard times.

Future Projections and Tipping Points

ocean acidification projections

Ocean acidification is a big problem for coral reefs. The research team says we’re in trouble. They studied how the ocean might change. This is based on different pollution levels.

They found that coral reefs in places like the Indo-Pacific are in real danger. By the year 2100, the stuff that makes up coral could be 20% less dense in some areas. These changes could be really bad if we keep polluting like we are now.

Corals in other places, like the Caribbean, might not be as hard hit. But in general, things look tough for corals around the world.

Emissions Scenarios and Reef Survival

Ocean acidification is just one problem for coral. The team thinks other issues, like warmer seas, will also hurt. They are worried that most of the world’s reefs could be at risk.

Even if we somehow limit the warming to 1.5°C, things might not be okay. Warm-water reefs are facing tough times within the Paris Agreement’s rules.

The study also talks about looking at both global and local risks. While many studies look at what might happen close by, others look at the big picture.

This mix of studies is important. It helps us plan to save the reefs from climate problems. This includes threats like ocean acidification and warmer seas.

Cold-Water Coral Vulnerability

Many talk about ocean acidification’s effect on shallow tropical reefs. Yet, deep-sea cold-water corals face similar threats. These corals are vital for marine life variety. They hold key chemical components with great value for medicine. Still, ocean acid and warmth, along with other challenges, endanger these corals. To keep our oceans rich with life and resources, we must protect these deep-sea ecosystems.

cold-water corals

Deep-Sea Habitat Importance

Cold-water coral reefs can be as deep as 3,000 meters or as shallow as 50 meters. They are found everywhere, creating homes for many creatures, some of which are vital for seafood. Over 1,300 animal species live in these reefs, making them very diverse.

Medical Potential of Cold-Water Corals

Cold-water corals not only support ocean life, but they offer chemicals with huge medical promise. These corals help fish that we eat and grow sponges we can use for medicine. We’re just starting to tap into the health benefits these organisms might offer.

But their challenges are real. Ocean acidification may weaken coral skeletons. This could harm many marine life forms. To protect these corals, we need to reduce our use of fossil fuels.

Crustose Coralline Algae: Unsung Heroes

Research on how ocean acidification affects corals is well-known. But, the story of crustose coralline algae is just as important for tropical reefs’ future.

crustose coralline algae

These algae are key in reef systems. They help corals grow by providing a surface. In addition, they send chemical signals for coral larvae to settle. This starts the growth of the reef structure. Yet, with ocean acidity rising fast, these algae struggle to build their calcium carbonate structures.

Role in Reef-Building

Crustose coralline algae (CCA) are essential in building reefs. They offer a stable base for corals to thrive on. By secreting calcium carbonate, they glue the reef parts together. This creates a habitat for many marine species. The survival of these “unsung heroes” is crucial for coral reefs to endure.

Adaptation Challenges

Studying how corallines can evolve under changing ocean conditions is vital. As ocean acidification limits the carbonate ions, CCAs need to build, they face a big hurdle. Ensuring the survival of crustose coralline algae is key for reefs to withstand climate change and stressors.

MarineGEO: Monitoring Reef Changes

Maggie Johnson is a postdoctoral fellow with the Smithsonian MarineGEO network. She focuses on ocean acidification’s impacts on coral reefs. Her approach includes both lab and field work. She uses innovative techniques, like waterproof enclosures for measuring coral growth. And she places PVC plates in the water to record different reef life on them.

Meet Smithsonian MarineGEO Scientist Maggie Johnson

Johnson aims to set a foundation for the MarineGEO network with her research. This base will allow other researchers to study reef changes over many years. It helps monitor how reefs cope with problems like acidification and warming.

Field Research Techniques

In Panama’s Bocas Del Toro, research includes lab work and many hours in the field. They use advanced tools for water samples and simple PVC pipes to measure coral growth. Small corals turning white, known as bleaching, have spurred more research. Scientists also compare photos of the same spots to see how reefs change.

Baseline Data for Long-Term Studies

Johnson is working to set up essential data for the MarineGEO network. This information will help track how reeds change over time. It’s important for understanding the effects of acidification and warming on reefs.

MarineGEO reef monitoring

Coral Reef Conservation Efforts

The story of how ocean acidification affects coral reefs in the Pacific Basin shows why we must protect them. Adopting a plan that covers adapting, lessening harm, and strengthening is crucial. This approach stands as the key to saving coral reefs.

  • Helping coral reefs adapt includes setting protective rules, planting more coral, and increasing safe zones for them.
  • To cut down on harmful carbon output, we need to apply solutions on local and worldwide levels. These may include methods like carbon tax, emissions trading, or setting limits on emissions.
  • It’s also vital to build up local abilities in research, teaching, raising funds, and working together. These help support rules that tackle ocean acidification locally and worldwide.

When we use all these tactics together, countries across the globe can ensure their coral reefs thrive for a long time. The dedication shown by the USCRTF to aid in the study of how coral reefs cope with change, and the ongoing resilience work in different areas, underlines this strategy’s vital role. It’s crucial for keeping coral reefs healthy against ocean acidification and other threats from climate change.

FAQs on Ocean Acidification and Coral Reefs

What is ocean acidification?

Ocean acidification refers to the decrease in the pH levels of the Earth's oceans caused by the uptake of carbon dioxide (CO2) from the atmosphere.

How does ocean acidification affect coral reefs?

Ocean acidification reduces the availability of carbonate ions, which are essential for corals to build their calcium carbonate skeletons, leading to weaker and more fragile coral structures.

Why are coral reefs important?

Coral reefs support a diverse range of marine life, protect coastlines from erosion, provide food and income for millions of people, and have potential medical benefits.

What causes ocean acidification?

The primary cause of ocean acidification is the increased concentration of CO2 in the atmosphere, largely due to human activities such as burning fossil fuels, deforestation, and cement production.

How quickly is ocean acidification happening?

Ocean acidification is occurring at an unprecedented rate, with current pH levels dropping faster than any time in the past 300 million years.

Can coral reefs recover from ocean acidification?

While some corals may adapt or acclimate to changing conditions, the rapid pace of acidification and other stressors like warming temperatures make recovery challenging.

What other factors threaten coral reefs besides ocean acidification?

Coral reefs are also threatened by rising sea temperatures, pollution, overfishing, destructive fishing practices, and coastal development.

What are the long-term impacts of ocean acidification on marine ecosystems?

Long-term impacts include reduced biodiversity, altered food webs, and compromised ecosystem services such as fisheries and coastal protection.

Are there any solutions to mitigate ocean acidification?

Solutions include reducing CO2 emissions, protecting and restoring marine ecosystems, and researching adaptive measures to help marine life cope with changing conditions.

How can individuals help protect coral reefs?

Individuals can help by reducing their carbon footprint, supporting sustainable seafood choices, participating in reef conservation efforts, and raising awareness about the importance of protecting coral reefs.

References and Sources

Woods Hole Oceanography Institute – How Ocean Acidification Weakens Coral

Oceana – Effects of Ocean Acidification on Corals

NIH NCBI – Ecosystem based management of coral reefs under climate change

Smithsonian TRI – Ocean Acidification and Reefs