We used to expect crystal blue waters on our coastlines. Now we often encounter green, red, or brown unhealthy waters, yet many coastal communities aren’t succumbing to the change. Instead, they’re installing artificial reefs of all sizes, which can improve fisheries’ production, provide ecosystem restoration, and enhance water quality.
By extracting particles from the water, communities of filter-feeding invertebrates have a beneficial effect on coastal water quality. Some of these animals filter and sequester other pollutants such as heavy metals, as well as organic matter. Thus, artificial reefs supporting filter-feeder communities may be able to mitigate water quality degradation from organic enrichment.
What Are Artificial Reefs?
An artificial reef is a human-made structure that may mimic some of the characteristics of a natural reef, according to NOAA. When a structure is intentionally placed on the seafloor or at the end of a dock as an artificial reef, it can create habitat for a variety of marine life. Marine life take up residence in and around a platform’s frame supports, or “jackets,” so that, as the platforms age, the populations of fish and other marine organisms that live near the structure increase.
The creation of artificial reefs in the sea favors biological productivity, therefore enhancing the population of fish and invertebrates. They not only constitute a shelter but are also a valuable reproduction reservoir, which can recreate a whole ecosystem in biologically depleted zones.
A single platform can provide habitat for thousands of fish. Mostly, artificial reefs are reef balls made of microsilica concrete and are sunk offshore.
Materials used to construct artificial reefs have included rocks, cinder blocks, and even wood and old tires. Today, several companies specialize in the design, manufacture, and deployment of long-lasting artificial reefs that are typically constructed of limestone, steel, or concrete.
Ocean Habitats, Inc. — An Example Of Affordable Artificial Reefs
What can be done to encourage the growth of barnacles, tunicates, and other filter-feeding organisms that clean seawater and create an environment to mimic the safety of mangroves for juvenile fish?
Ocean Habitats, Inc. creates, sells, and maintains artificial reef structures that can be attached to docks in canals and waterways. More than 4,000 units are installed in Florida and close to 5,000 elsewhere in the US and other countries. Almost 3 decades of research produced the company’s Mini Reef, which starts at $297.
“What our unit does is replicate nursery habitat, something more like mangrove trees,” David Wolff, founder and CEO of Ocean Habitats, Inc. said, as reported by the Sarasota Herald-Tribune. “We’re trying to grow baby shrimp, crabs, and fish. Technically, they leave our units, and someday may end up on the reef balls,” he added with a laugh.
Ocean Habitats’ artificial reefs are made of polypropylene sheet layers that are connected by cord and PVC tubes and vary by size from 24 inches wide by 36 inches long to 36-inch wide x 48-inch long x 24-inch deep. Each Mini Reef can support hundreds of fish, crabs, and shrimp each year and will start to develop a complete ecosystem starting as soon as it enters the water. Dozens of different fish have been found utilizing these underwater reefs.
Each Mini Reef filters 30,000 gallons of water per day once barnacles, tunicates, or other filter feeders attach. The filter feeders improve water quality in about a 10-foot radius; as macroalgae flourish, it creates the nursery environment. The Mini Reef floats, so the filter feeders attached to the unit will always be where 90% of marine food source is found, within 24″ of the water surface.
Wolff notes that Ocean Habitats looked at several materials for sustainability and durability before going forward with polypropylene. Dating back to his work with Marine Habitat Foundation, he tested hundreds of materials, including wood, fiberglass, and shapes that would resist wave action, before establishing the current model. Wolff described the decision to use polypropylene.
“One of the reasons we use polypropylene is because animals are able to attach to it, they’re able to get their hold fast on it and last their whole lives. It holds up decently to the sun, it holds up to saltwater and it holds up to thermal ranges without starting to disintegrate and release microplastics. All plastics eventually do that. Sometime in the future, our units should be recycled – they can actually be recycled.”
Because more than 300 fish and 200 crabs each year can be nurtured at each mini reef, the increased presence of fish is what most people who have the mini reefs notice first, said Jim McDaniel, the development director of the Center of Anna Maria Island. The Center, which has 145 units installed or on order, is promoting use of the Ocean Habitats-made mini reefs as part of a community science initiative, and 28 mini reefs will be paid for by an impact grant from the Community Foundation of Sarasota County.
Water quality will also improve as the animals on the Mini Reefs begin to remove the overabundance of plankton in the water. The 4,000 Mini Reefs in the water today represent almost 200 million hours of combined time in the water. This amounts to about 145,635 billion gallons of water filtered and over 6.6 million fish, crabs, and shrimp grown.
New Ocean Habitats designs are being tested and becoming available. More residential as well as commercial units will be delivered in the coming months and years.
In an exclusive quote for CleanTechnica, Wolff said, “The mini reef is a product that helps harness the power of mother nature to correct some of the human-made environmental issues that we have in our coastal water systems.”
For environmentalists of all kinds, from conservation to wildlife advocates, artificial reefs are an encouraging indication of a potential technique to help species at a small-scale, local level. Of course, creating artificial reefs is not as simple as throwing some wooden structures in the water: care needs to be taken in terms of the materials, construction, and placement of artificial reefs. Artificial reefs create new homes and habitats for the sea life and welcome new life, creating systems giving biodiversity a necessary helping hand.