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5. The Reef-Olution: The Future of Human-Made Reefs

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The Future of Coastal Protection Methods In the past, artificial reefs have been made with old car frames, tyres, train carriages, and concrete rubble, but due to issues, like leaching toxins and physical instability, their use has declined. In 1970s Florida, USA, there were approximately two million tyres used to create an artificial reef - called the Osborne Reef (pictured below). This was created to attract fish and to repurpose old tyres to free up space in landfill sites. The reef was extremely unsuccessful as hurricanes and storms would move the tyres causing them to cover and damage existing corals. The leaching of toxic chemicals from the tyres killed and further hindered growth of coral, overall reducing the biodiversity in the area and creating a worse environment. While improving the environment is a good thing, and at most times necessary, it can be exploited. This can lead to greenwashing, in this instance, a practice in which companies dispose of waste materials u...
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4. Fin-Tastic New Homes: Artificial Reefs as Biodiversity Boosters

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Habitat Creation at Varbjerg The Storå river is home to various fish species including the brown trout ( Salmo trutta ) and European eel ( Anguilla anguilla ) .  This river's mouth at Varbjerg Strand is the site of a unique conservation project. It was here that the world's first smolt reef was implemented, which was specifically designed to increase the survivability of brown trout smolt. Smolt refers to juvenile trout and salmon undergoing smoltification, a crucial process that allows these fish to transition from freshwater rivers to the saline environment of the sea. During smoltification, their bodies become more streamlined and silver, losing the camouflage parr marks beneficial only in rivers. Internally, their osmoregulatory system (an internal system that regulates the balance of water and solutes in an organism's body fluids) transforms to cope with the sea's salinity. Additionally, they begin to display more schooling behaviour rather than territorial, and e...
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Location: Varbjerg Strand, Denmark
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3. Pier Pressure: Man-Made Reefs as Scour Protection

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Infrastructure Protection at  Lillebælt Lillebæt , Danish for Little Belt, is a strait between the island of Funen and the Jutland Peninsula.  The area has two large bridges, the first being a truss bridge (pictured on the left) which opened in May 1935, and the much newer, larger bridge (pictured on the right) that opened in June 1998.  To help stabilise and mitigate erosion of the bridge’s pillars/piers, scour protection is implemented on the riverbed. In this case, it is in the form of rock armour. These are large, heavy, angular rocks that can withstand the rivers force and dissipate the energy of the flow, which helps protect the underlying soil from being eroded further and swept away.  The diagram above presents a pier foundation and its associated scour protection, illustrating the internal arrangement and relative densities of the materials beneath the seabed.  Lack of secure foundations for bridge pillars can lead to collapses, which may result in...
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Location: Little Belt, Denmark
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2. Breaking Waves: How Artificial Reefs are Protecting Coasts

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Coastal Protection for Samsø Island The BARREEF Project seen the implementation of an artificial reef east of Samsø Island. The purpose of this reef is to mitigate hydrodynamic energy, thus reducing erosion and sand wash-back along the coastline, of which there are many homes (see image below for location and erosion sites). The reef itself likely creates new habitats, different to the majority of sandy or muddy seabeds, promoting growth of seaweed and providing shelter for diverse marine life, including commercially important species like Atlantic cod ( Gadus morhua ).  The reduced wave movement can also encourage the colonisation of eelgrass ( Zostera marina ). This aquatic plant can stabilise seafloor sediment through its horizontally growing root known as a rhizome. This rhizome creates new roots and shoots which further expands the eelgrass. Eelgrass beds can also store limited amounts of carbon from the atmosphere, and absorb some of nitrogen which can reduce eutrophicat...
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Location: Samsø, 8305 Samsø Municipality, Denmark
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1. Somewhere... Below the Sea: Artificial Reefs Explained

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What Are They and Why Use Them? Artificial reefs are human-made underwater structures, deliberately placed to mimic natural reefs and enhance marine habitats that can  provide shelter, promote vegetation growth, and create breeding and nursing grounds for various marine organisms. These reefs are also created to aid in coastal defence as they  can dissipate hydrodynamic energy (fluid energy associated with flow, velocity and pressure) which in turn reduces the amount of erosion and wash-back caused by waves. These calmer conditions allow aquatic plants, like eelgrass, to colonise, which further helps to mitigate erosion as the plants further mitigate hydrodynamic energy and stabilise sediment to the sea floor.   The picture above is an artificial reef that was implemented off Hinatuan Island, the Philippines. This project was created to help boost marine diversity, as fish numbers had dwindled due to the destruction of coral reefs by commercial fishing methods like trawli...
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