In 2013, divers started placing simple cinder-block pyramids on a Caribbean seabed; by 2025, 100 pyramids had been installed, with the Grenada project reporting over 30 fish species and 15 kinds of coral

A question that has recently been central to much scientific research across wildlife conservations is: can artificial reef structures eventually help support natural reef recovery? With the rising decline of healthy coral reef structures, entire marine ecosystems are put at risk. Therefore, off the coast of Grenada, a Caribbean island, a conservation project has been searching for an answer to the problem using concrete construction blocks.The Grenada Artificial Reef Project (GARP), founded in 2013 by Dive Grenada, began with four trial pyramids made from concrete blocks, which were installed off Grand Anse Beach. The idea was simple: to create an alternative habitat where marine organisms could eventually settle and grow. With the aim of replicating a reef design without spending a huge amount on more elaborate artificial designs, the project was set in motion, with initial growth of algae and a varied range of invertebrates, such as lobsters, crabs and urchins, being observed within three months.

The project’s development over the years

By January, according to the project’s official data, 100 pyramids had been installed with additional funding from the non-profit Clean Reefs Organization. Since the project’s beginning, it has seen immense growth and expansion. According to the project’s own records, the artificial reefs have become home to more than 30 fish species and 15 different kinds of coral, alongside algae and other invertebrates. However, the development of this project was also studied over a period of continuous inquiry.In a report titled A Report on the Artificial Reef Use in Grenada, West Indies, published in The Journal of Marine Science and Engineering in January 2024, researchers wanted to study a crucial distinction. In the face of damage to natural reefs, adding a structure to the seabed may provide a new surface for marine life to settle upon, but does the presence of organisms on an artificial surface immediately mean that the surface is healthy or can help the recovery of this natural ecosystem? This question prompted a comparative study between the artificial pyramids in Grenada and two nearby natural reefs. The research focused on the distribution of living organisms across the artificial and natural reefs.

What has research on the GARP project revealed?

The findings revealed that some coral categories present on the artificial pyramids were also present on the natural reefs, indicating that the structures were attracting organisms that were present in established reef environments as well. Furthermore, the researchers also determined a difference in the algae growing on the two types of reefs. Coralline algae, which can help bind reef structures together and provide favourable surfaces for coral larvae to settle, accounted for a larger proportion of the algae recorded on the pyramids. Meanwhile, macroalgae were considerably less abundant on the pyramids than at the natural reef sites examined.The reason why this distinction matters is that not all algae affect coral development in the same way. This research, which was carried out in 2018, offered an insight into whether artificial pyramids can actually help address the mounting pressures from warming seas, coral bleaching and pollution that threaten the ecosystem. The researchers also emphasised the need for further monitoring to establish whether the structures can function as secondary nurseries for corals and contribute to the recovery of natural reef communities.Still, the project offers an interesting example of how relatively simple interventions can create new opportunities for marine life. Coral reefs provide habitats for numerous species, support fisheries and help protect coastlines from waves and storms, yet they face mounting pressures from warming seas, coral bleaching, pollution, disease and other disturbances. Artificial structures cannot remove these threats, but carefully designed and monitored reefs may offer additional surfaces and shelter in places where natural habitats have been degraded or are limited.What began as concrete blocks on a largely sandy stretch of seabed has gradually developed into a place where different forms of marine life can find shelter, food and surfaces on which to grow. For Grenada, the growing number of pyramids attests to an ongoing attempt to provide marine organisms with somewhere to establish themselves. The scientific question now is how far this initial growth can develop, and whether the benefits observed on the artificial structures can extend to the natural reefs nearby. Concrete blocks may seem an unlikely beginning for a thriving underwater habitat, but the life gathering around them offers researchers a reason to keep watching.