Kelp Forest Restoration

Kelp forests are vital underwater ecosystems that support marine biodiversity, sequester carbon, and protect coastlines.

Kelp forests are vast underwater ecosystems formed by large, brown seaweeds known as kelp. These marine forests thrive in nutrient-rich, cold waters along coastlines. They are biodiversity hotspots, providing food and shelter for a diverse array of marine life, including fish, marine mammals and invertebrates.

What Are the Kelp Genera in New Zealand’s Kelp Forests?

In New Zealand kelp forests are our coral reefs. Large kelp forests can be found along much of New Zealand’s coastline and are provide significant value from a biodiversity, cultural and economic perspective.These forests host three genera of native true kelps including Ecklonia, Lessonia, and Macrocystis.

The Role of Kelp Forests in Ocean Health

Kelp forests act as underwater carbon sinks, absorbing carbon dioxide from seawater through photosynthesis. The carbon absorbed by kelp forests and other marine and coastal ecosystems is referred to as blue carbon, distinguishing it from the carbon absorbed by terrestrial plants.

Along with other seaweeds, kelp forests can sequester between 61 and 268 million tonnes of carbon per year globally, averaging 173 million tonnes. This plays an important role in limiting ocean acidification and helping regulate the climate. Live Ocean is supporting Dr Caitlin Blain’s world-leading research into the long-term fate of the carbon kelp forests sequester. This work will deepen our understanding around the role of kelp forests in climate change mitigation and provides an exciting opportunity to quantify and value blue carbon.

Additionally, kelp forests serve as coastal buffers, reducing wave energy and preventing shoreline erosion, protecting littoral ecosystems.

The Decline of Kelp Forests

Over the past few decades, kelp forests throughout the world have suffered dramatic losses, with some regions experiencing up to a 95% decline. The primary causes of this decline include:

Climate Change: Some kelp species thrive in colder waters so are negatively impacted by rising sea temperatures. Rising temperatures also reduce nutrient availability, slowing or completely stopping kelp growth.
Overgrazing by Kina (Sea Urchins): Left unchecked due to a lack of predators kina populations can boom, devastating kelp forests through overconsumption. This leaves the area in ecological collapse, often reffered to as a kina barren.
Pollution and Coastal Development: Runoff containing pollutants or large levels of sedimentation can degrade water quality and reduce light filtration. Kelp, like plants, relies on photosynthesis, requiring sunlight to thrive, and the amount and type of light reaching kelp forests significantly impacts their growth and health.
Destructive Fishing Practices: Destructive fishing practices like bottom trawling and seabed mining can devastate kelp forests and the ecosystems that live in them.

What Is Kelp Forest Restoration?

Kelp forest restoration refers to the active efforts to regenerate lost or degraded kelp ecosystems. This involves a variety of methods to rebuild kelp forests, restore biodiversity, and strengthen their ability to sequester carbon.

Key restoration techniques include:

Active Kina Management : This involves the controlled harvesting of kina (sea urchin) populations within kina barrens to give kelp the opportunity to naturally re-establish itself. Research by Dr Nick Shears has shown kelp forests can return within as little as two years and active management can accellerate restoration efforts by 20-30 years. For this method to be successful it needs to be done in tandem with the reintroduction of natural predators and marine protection to restore balance to the ecosystem which helps prevent kina barrens from re-forming.
Kelp Seeding and Transplanting: Cultivating young kelp in nurseries and transplanting them into the wild to stimulate forest regrowth. Projects like Māra Moana are exploring transplanting climate-resilient kelp which is can naturally survive in warming waters.
Artificial Reef Structures: Artificial underwater structures are placed in deforested areas to provide a stable surface for kelp attachment and growth.
Water Quality Improvement: This calls for reducing pollution and improving nutrient cycling in affected coastal areas.

Why Kelp Forest Restoration Matters for Humans

The restoration of kelp forests offers direct and indirect benefits to human populations:

Carbon Sequestration and Climate Change Mitigation: Healthy kelp forests absorb vast amounts of carbon, helping to slow down climate change. If kelp forests were restored to their historical levels, they could remove as much carbon as millions of mature trees.

Live Ocean Foundation is currently supporting Dr Caitlin Blain’s research into blue carbon. This research will help us know exactly how much carbon is sequestered by kelp forests and the rate at which it is being released back into the environment.
Coastal Protection: Kelp forests absorb wave energy, protecting coastal ecosystems and protecting communities.
Economic Value: Kelp forests have an estimated total value of USD $500 billion (NZD $875 billion) per year. Many commercially valuable fish species depend on kelp forests for breeding and shelter. Restoring them may also help mitigate the economic damage of storm surges.
Sustainable Industry Growth: Kelp restoration initiatives can create economic opportunities in industries like biotechnology, sustainable food production, and carbon credit markets. For instance, the reforestation of kelp forests in Hauraki Gulf Marine Park is estimated to be worth nearly NZD $8 million in carbon storage.

Future Challenges and Opportunities

Despite the promise of kelp forest restoration, the increasing frequency of marine heatwaves and continued ocean acidification threaten newly restored forests. However, new advancements in marine science, meaningful policy support, and community initiatives offer hope for large-scale restoration success, both in New Zealand and globally. Emerging technologies, such as Seascape 3D underwater mapping for monitoring and AI-driven ecosystem modelling are also bringing visibility to the issues and progress of current restoration efforts, helping drive engagement, decision making and efficiency in this space, giving optimism for future restoration of these remarkable ecosystems.