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Researchers used discarded tires to create artificial reefs in the concrete channels of California and Arizona, restoring shade and shelter to aquatic life. In the modified areas, they recorded about three times more invertebrates and 20 times more fish compared to the smooth sections.
Researchers installed artificial reefs made from discarded tires on the bottoms of concrete channels in California and Arizona and found substantial increases in the number of aquatic organisms. In these areas, there were approximately three times more invertebrates and around 20 times more fish than in the unmodified sections.
According to a report from Diário do Litoral, published on September 1, 2026, by Luna Almeida, the experiment was conducted in 1994 by researchers Gordon Mueller and Charles R. Liston in the Coachella Canal in California and the Hayden-Rhodes Aqueduct in Arizona. The aim was to restore physical complexity to waterways that lost natural elements due to cement coating.
Concrete Was Used to Prevent Water Loss Through Infiltration
The large irrigation channels in the southwestern United States were coated with concrete to tackle infrastructure issues in an arid region.
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The impermeable surface reduced water infiltration, conserving a vital resource under significant supply pressure.
Ancient Earth Channels Had Vegetation, Sediments, and Re-Entrants
However, the engineering change altered the environment available for animals.
The earthen channels contained sediments, aquatic vegetation, irregular banks, and re-entrants, providing feeding, breeding, and protection spaces for wildlife.
The concrete removed much of this physical variety.
Smooth Walls Removed Shade and Protection Areas
After the coating, the channels became much more uniform in appearance.
Native vegetation and shaded spots disappeared, while the current sped up.
Even as fish gradually returned, species diversity and density remained lower than the former ecosystem.
Mueller and Liston Tested a Solution with Tires in 1994
Gordon Mueller and Charles R. Liston tested an intervention that could be installed without altering the main structure of the operational channels.
In 1994, they placed low-profile artificial reefs made from discarded tires directly on the channel bottoms.
The test took place in the Coachella Canal and the Hayden-Rhodes Aqueduct.
Tires Introduced Relief in an Entirely Uniform Bottom
The main change brought by the structures was physical.
The tires created relief, shadows, and obstacles, providing points absent after the concrete was poured.
This modification also created resting areas for aquatic organisms.
Structures Helped Reduce Water Speed in Specific Areas
The reefs locally impacted flow conditions.
The obstacles formed by the tires helped to reduce water speed, creating protected zones for aquatic life.
These spaces acted as small habitats within an otherwise uniform infrastructure.
Rubber Became a Surface for Algae and Small Organisms
The tires served as a physical base.
They provided a firm surface for algae, small insects, and crustaceans, enhancing available resources compared to the unmodified sections.
These organisms were part of the food chain in the modified areas.
Invertebrates Became About Three Times More Numerous
Significant differences were observed among smaller organisms.
In areas with artificial reefs, the invertebrate density was about three times greater than in the smooth sections.
The increase enhanced food availability.
The Number of Fish Increased by About 20 Times
Major differences were noted among fish.
Areas containing tire reefs recorded about 20 times more fish than the sections without structures.
This was linked to the recovery of habitat and food resources.
Experiment Reused Material That Would Have Been Discarded
The tires repurposed waste into a new role within the channels.
This transformed rubber into support for structures aimed at increasing habitat complexity.
Tires pose a disposal issue due to their durability and volume.
Technique Was Applied Without Altering Operational Channels
The scientists maintained the original infrastructure purpose.
Structures were added to the flow, allowing the creation of shelter points without altering channel configuration.
Researchers Did Not Present Tires as a Solution for Any Environment
The success was not deemed a universal solution for environmental impacts.
Tires were not proposed as a universally applicable solution.
The study was effective in the specific channels studied, where physical complexity was reduced due to concrete.
Experiment Showed Quick Response After Creation of New Shelters
Small structural changes led to significant differences in organism numbers.
With relief, shade, and protective points, the areas supported approximately three times more invertebrates and 20 times more fish than compared sections.
