Redefining Aquatic Waste within a Blue Circular Economy: The HALOS Project

The HALOS project is all about creating artificial reefs from waste materials. We’re using spent oyster shells, coffee grounds, glass, and even sargassum seaweed to build these reefs.

July 3, 2024

Imagine transforming everyday waste – oyster shells, coffee grounds, even carnival cast-offs – into underwater havens for marine life. That's the inspiring vision behind the "Habitats for Aquatic Life and Ocean Systems (HALOS) Project" in Trinidad and Tobago. 

The Vital Role of Coral Reefs 

Did you know that coral reefs are often called the rainforests of the ocean? It’s a fitting name considering they’re home to around 4000 fish species, 840 coral species, and over a million other marine creatures. Although they cover less than 0.1% of the Earth’s surface, their intricate patterns and formations take thousands of years to develop, making them truly spectacular. 

These underwater structures are built by tiny animals called polyps that secrete layers of calcium carbonate. The colours we see come from microscopic plant cells called zooxanthellae, which live on the polyps’ skin. They have a mutualistic relationship – the zooxanthellae provide food through photosynthesis, and in return, the polyps offer shelter and nutrients. 

Coral reefs do so much for us and marine life. They support 25% of all marine species, reduce coastal erosion by buffering shorelines, and help sustain the livelihoods of about a billion people through fisheries and tourism. Even in medicine, materials from coral exoskeletons are used for bone grafting, and compounds from reef organisms are used in treatments for diseases like leukemia and skin cancer. Altogether, coral reefs provide resources and services worth $375 billion annually! 

The Threats to Coral Reefs 

Human activities have put coral reefs under immense stress, leading to issues like global warming, ocean acidification, and pollution. These factors have drastically reduced reef health, making them susceptible to bleaching and diseases. Predictions suggest that by 2050, we could see a 70-90% decrease in live coral cover. 

A Glimmer of Hope from Trinidad and Tobago 

Trinidad and Tobago, particularly Tobago, is famous for its stunning coral reefs, but sadly, they’re not immune to degradation. That’s why the Trinidad and Tobago Accelerator Lab embarked on an innovative project to help turn the tide: the “Habitats for Aquatic Life and Ocean Systems (HALOS) Project,” a collaborative effort with the UNDP Accelerator Lab and the Institute of Marine Affairs (IMA). 

Turning Waste into Reef Wonders 

The HALOS project is all about creating artificial reefs from waste materials. We’re using spent oyster shells, coffee grounds, glass, and even sargassum seaweed to build these reefs. It’s a fresh take on artificial reefs, aiming to shelter marine life and provide a substrate for regeneration while also addressing waste management. 

Unlike other coral rehabilitation projects that are expensive and rely heavily on foreign expertise, the HALOS project offers a low-cost, low-maintenance alternative. The project turns waste into high-value products like activated carbon for water filtration, coral frag plugs, and even insulation paint. The best part? It supports local economies by utilizing abundant local waste streams. 

A Splash of Local Culture 

One of the best aspects of HALOS is how it taps into Trinidad and Tobago’s carnival culture. The intricate coral patterns are crafted by skilled wire-benders, artists who traditionally create elaborate wire sculptures for Carnival. Their artistry adds a unique cultural touch to the project, transforming waste into intricate coral structures and building awareness of coral conservation among creatives. 

Early Success and Future Plans 

On May 28th, a pilot reef was launched at Nelson Island, and within just ten days, it attracted multiple sea sponge species. This unexpected success led the team to explore sea sponge farming opportunities. Additionally, the project tested sargassum seaweed, black carbon, and oyster shell coral plugs in saltwater reef tanks, showing promising results. 

The project also involves pyrolysis, a process of deoxygenated combustion, to convert sargassum seaweed into activated carbon. While sargassum can contain heavy metals like arsenic, pyrolysis at high temperatures can render it safe for marine use. Testing at the University of Trinidad and Tobago and the Institute of Marine Affairs ensures the processed carbon is safe for our ocean friends. 

What’s Next? 

The next steps include submerging the reef composite at the Nelson Island site, followed by compressive strength testing and biological monitoring. The reef systems will be observed remotely via the Aqualink online platform with live video feeds managed by the Institute of Marine Affairs. This allows us to share the wonders of our marine life with the world and promote conservation efforts. 

The HALOS project represents a significant development for marine habitat restoration in Trinidad and Tobago. By leveraging local resources and culture, it provides a model for sustainable, scalable, and cost-effective coral reef rehabilitation. It’s a shining example of how we can turn waste into something beautiful and valuable for our planet. 

Let’s continue to innovate and protect our oceans, one reef at a time, to ensure these vital ecosystems thrive for generations to come. 

Authors: 1. Alan Cooper, Head of Solutions Mapping, Accelerator Lab, UNDPTT 2. Denyse Montrose, HALOS Project Coordinator 3. Darion Fraser, UNDP Project Associate