Coral Reefs Need Reforestation to Stop Sediment Run-Off

Coral reefs offer some of the most beautiful and diverse ecosystems on Earth. Find out how a new study explains the connection between land forests and preserving this vital undersea habitat.

I was never much of a surface swimmer. I found those massive indoor swimming pools where we had swimming lessons nasty and dull. The smell and the sting of the bromine didn’t help. On the other hand, when I learned how to snorkel and scuba dive, I started discovering the graceful world that lay below the surface. That’s when I began to see the point of aquatic skills.

In this part of the world, shipwrecks and rock formations are divers’ main attractions. Unlike most of my neighbours, I don’t go south in the winter, so I’ve never experienced diving on a coral reef. From all I’ve heard, it’s something I want to explore someday.

It looks like I may have to hurry because ocean acidification is threatening the world’s coral reef systems. The main culprit is climate change.

Ocean Acidification from Rising C02 in the Sea

Ocean acidification results from rising C02 concentrations in the sea. Higher acidity means lower pH levels, which impair the growth and structural strength of coral.

As ocean temperatures rise, the thermal stress causes coral to lose those vibrant colours we all admire. Unfortunately, warmer temperatures also enable infectious diseases to spread more quickly. 

On top of all these global warming threats, sediment run-offs in coastal regions pose the second-greatest threat to coral formations. This is because sediment run-off from human activity can block the sunlight that coral and seagrass need to grow and reproduce.

Climate Change and Sediment Run-Off Create Vicious Cycle

Dr. Andres Suarez-Castro from the University of Queensland explains that the combination of climate change and sediment run-off creates a vicious cycle. “Increased sedimentation can cause aquatic ecosystems to be more sensitive to heat stress, which decreases the resilience of corals to pressures caused by climate change,” he said.

Dr. Suarez-Castro led a study published this week in the journal Global Change Biology. His team assessed a possible solution to coastal sediment run-off. The researchers found that boosting reforestation along shorelines could significantly reduce the volume of sediment finding its way into marine shore habitats.

The team reviewed data representing 5,500 coastal ecosystems from around the world. They discovered that 85% of these shorelines leached sediment into nearby coral reefs. 

Solutions to the Impact of Sediment Run-Off

The team found that, if we’re serious about preserving our coral reefs, we need to find solutions to the impact of sediment run-off. “If the link between the land and sea is not recognized and managed separately,” Dr. Suarez-Castro warns, “any future efforts to conserve marine habitats and species are likely to be ineffective.”

The study recommends that coastal countries commit to land and forest restoration along their coastlines. Planting trees is a tried and true method to stop erosion.

“Reforestation is hugely important as it maintains the stability of soils that are vital in limiting erosion risk – it also helps to trap more sediments and prevent them from reaching aquatic systems,” explains Dr. Suarez-Castro. “If land management to reduce sediment run-off does not become a global priority, it will become increasingly challenging, if not impossible, to protect marine ecosystems in the face of climate change.”

“Reforestation is Hugely Important”

Some nations are already working to restore forest ecosystems along their shores. It’s encouraging to note that many such countries happen to have high coral diversity that benefits from these projects.

The challenge will be that not every country can afford to take on reforestation activities on the scale needed. It won’t be easy to build the commitment required for meaningful reforestation activities.

“The cost of reforestation, as well as political and social barriers, may make it difficult to achieve these ambitious goals,” Dr. Suarez-Castro explained. The team published their findings to encourage local authorities to identify areas where reforestation could do the most good for coral reefs.

Identify Areas Where Reforestation Could Do the Most Good

The ecologist explains, “Our approach can be adapted with local data to identify optimal actions for preserving ‘win-wins’ for multiple ecosystems spanning the land and sea. If an average of 1,000 hectares of forest was restored per coastal basin, land-based sediments reaching coral reefs could be cut by an average of 8.5 percent among 63,000 square kilometres of reefs.”

The more we learn about nature and living things, the more interrelatedness we discover. Our world isn’t a patchwork of separate habitats.

Not a Patchwork of Separate Habitats

Instead, it’s a vibrant and thriving ecosphere that environmentalists now envision as a single, holistic organism. Restoring our planet’s health calls for discovering connections like the one Dr. Suarez-Castro’s team found between lan-based forests and undersea coral reefs.

Dr. Suarez-Castro wrapped up by saying, “Our hope is that our study can facilitate more informed and educated conversations around the importance of a more integrated land-sea approach.”

We always have more to learn if we dare to know.

Learn more:

Reforestation could help save coral reefs from catastrophe
Global forest restoration opportunities to foster coral reef conservation
Climate Crisis Becomes Undeniable
Air Pollution and Greenhouse Gas Reductions Go Together
Trees and Plants Losing Capacity to Stop Climate Change


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