Atlantic Reef Balls

A global initiative with a local impact.

Clean launched the Atlantic Reef Ball program in 2012 to create, install and monitor artificial reefs in the Halifax Harbour, one of the deepest harbours in the world. We are partnering with local, regional and international groups to help create and improve coastal habitat and biodiversity in the harbour.


To date: 472 reef balls have been deployed in the Halifax Harbour

Representing 85,000 square metres of marine habitat or almost 16 football fields!

Check out the inventor of Reef Balls


Reef Ball Foundation

Why are artificial reefs necessary?

Near the shorelines, coastal development can have a detrimental effect on coastal habitats, leading to a decline in the health of marine ecosystems.

Artificial reefs are designed to create or restore marine habitat by fostering the growth of an ecosystem that supports fish and shellfish populations. In addition to providing shelter and protection to fish species, artificial reefs support the growth of marine plants, like algae or seaweed, which are foundational species in these ecosystems. They also serve as habitat for spawning and reproduction in many types of fish and shellfish – critical to the success of a rebuilding population.


What’s a Reef Ball?

Reef balls are prefabricated, artificial reef structures used to create or restore marine habitat. They are used around the world for a variety of applications including:

  • habitat enhancement/environmental offsets
  • impact mitigation
  • coral rehabilitation
  • shoreline protection
  • creating new fishing/diving/snorkeling sites

Designed by the US-based Reef Ball Foundation, reef balls come in ten different sizes ranging from the size of a basketball to the size of a car, which allows flexibility for individual projects.  The Clean Foundation’s reef ball casts produce structures which are approximately 3 feet tall and 4 feet wide.

All reef balls are made with pH-neutral concrete that is cast with specialized surface features to enhance coral and algal settlement.  Each reef ball is expected to last approximately 500 years. They do not leach toxins into the water, and do not contain biologically active compounds.

Why Reef Balls?

Artificial reefs are not a new idea. Around the world various artificial structures are used to create reefs, but not all materials and designs are equal. Although well intended, some of these structures can actually harm the environment by leaking toxic chemicals or introducing biologically active compounds such as copper, iron, zinc, chromium, or fertilizers. This often happens when artificial reefs are built from materials of opportunity such as old cars, boats, or other large structures.

Among the artificial reef designs that are environmentally friendly, some are more effective than others. The composition of certain materials can promote the growth of some species over others, creating a thriving but unbalanced ecosystem. Other materials are short-lived or highly vulnerable to damage from the heavy currents that often come hand in hand with strong storms. Furthermore, some artificial reefs are better designed to promote and sustain marine plants and animals than others.

After evaluating a wide range of options, Clean Foundation selected reef balls as the strongest artificial reef design for the Nova Scotian marine environment. Reef balls are designed specifically for supporting life in the ocean and are currently one of the most widely used designs for an artificial reef system in the world. They do not leach toxins into the water and do not contain biologically active compounds. The stability and longevity of the structures also makes them ideal for marine habitat restoration work.

Of most importance, however, is the physical design of the reef balls, which creates habitat and space for sea life while also promoting circulation and maximizing exposure to sunlight. In combination, these features make reef balls the ideal structure for artificial reefs in Atlantic Canada.

There have been hundreds of scientific studies supporting the efficacy of the reef ball design, which are the most widely used human-designed artificial reef systems in the world. Over one and a half million reef ball modules have been deployed in over 4,000 projects. International projects include:

  • designed artificial reefs
  • ground breaking coral propagation and planting systems
  • habitat enhancement
  • estuary restoration
  • red mangrove plantings
  • oyster reef restoration
  • erosion control (primarily beach erosion)
What do Reef Balls Look Like?

The Pallet Reef Balls are hollow structures with holes throughout, which keep the ball stable on the sea floor and provide sea life access to the protective interior. The holes also create eddies in the water, which help circulate nutrients to the species living on and within the structure.

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