In this guide we provide some key information about artificial reefs.
We explain what they are, types of artificial reefs, what materials they are made of, how they work, how they might help, examples of artificial reefs already in use & where they are located, & more.
What Are Artificial Reefs?
An artificial reef is a human made underwater structure built or deployed to mimic some of the traits and functions of natural reefs
They may also have some of their own beneficial traits and functions
Types Of Artificial Reefs
Some of the main types of artificial reefs might include, but aren’t limited to:
– Non electrified artificial reefs made from natural materials
These reefs don’t use an electrical supply, and are made from natural materials like bamboo, wood, and other plant based matter
There’s evidence of this in countries like the Phillipines where ‘fish nests’ are built, harvested and re-built
Indigenous cultures in Indo-Pacific regions have also done something similar to attract fish
Some classify these types of structures more as ‘Fish Attraction Devices’ rather than artificial reefs though
– Non electrified artificial reefs made from man made materials
These reefs don’t use an electrical supply, and are made from man made materials like concrete, steel, and so on
They may also involve the deployment of large objects like ships and cars into the sea
– Electrified artificial reefs
A specific type of artificial reef that uses an electrical supply and a metal structure, to form the basis of the reef
– Proprietary and licensed reef systems
There’s also different proprietary or licensed reef systems and products, offered by different companies or groups
Beyond the above general types of artificial reefs, different reefs:
– Have different designs for different ocean zones and to carry out different functions
– Are made from different materials
– Are different sizes, shapes and structures
– And might have a range of other differentiating features
What Are Electrified Reefs? (Biorock)
Electrified reefs are artificial reefs made from biorock that rely on a small low voltage electric charge
Limestone forms on a metal frame from the electric charge and the minerals in the surrounding seawater
Coral can then attach to and grow onto the mineral surface.
Divers sometimes manually transplant coral fragments onto the mineral surface too
What Do Artificial Reefs Do?
It depends on what the purpose of the reef is i.e. what it’s designed for
For example, some reefs might be designed to be a general purpose reef that acts as a habitat for marine life.
Other reefs might be designed for other purposes such as reducing beach and coastal erosion, by breaking up waves and dissipating their energy before they get to the shoreline, so they limit how much sand can be carried back out to sea.
There’s other designs and purposes for reefs too.
How Do Artificial Reefs Work?
Again, how artificial reefs work depends on their design and what they are intended to do.
As one example, a general purpose artificial reef might act as a surface that micro organisms and coral (and sponges) can attach themselves to, and small fish and small marine life can hide in.
newheavenreefconservation.org (paraphrased) lists the things that make general purpose artificial reefs successful in fulfilling their functions as being stable, being made from durable and non toxic materials, having a surface suitable for corals and sponges, having adequate structural complexity for fish, and having either the right design to blend in or stand out
What Are Artificial Reefs Made Of? (Materials)
It depends on the type of reef.
General purpose reefs might be made of a range of materials and items, including but not limited to:
– Sunken and submerged ships that become intentional shipwrecks and reefs (these are some of the most common artificial reefs structures)
– Natural materials like bamboo, wood, logs, and organic matter
– Construction materials and other materials like rocks, rubble and debris, concrete blocks and cinder blocks, steel and metal, geotextile bags and other materials etc.
– Oil and gas platforms and rigs, and other offshore structures
– Rubber tires
– Discarded or significantly damaged cars and vehicles
– Decommissioned subway carriages
– Some companies specialize in designing, manufacturing and installing artificial reefs that are made from materials like limestone, steel and concrete
– According to wikipedia.org: ‘3D printing technology has also been employed both to create moulds for cast ceramic and concrete artificial reefs, and to directly create artificial reefs, also through the use of environmentally friendly materials’
Specific systems or products offered or licensed by certain groups include:
– Reef Balls (explained further down in this guide)
– MOREEF modules (explained further down in this guide)
How Do Artificial Reefs Help? (Marine Life, The Environment & Ecosystems, Humans, & More)
There’s a range of ways artificial reefs might help, including but not limited to:
– Provide a surface for coral and sponges to attach to
– Providing a habitat for other marine life to live in (for example, algae, plankton, oysters and other sea life may live around artificial reefs)
– Providing a food source for small fish, and also larger fish and predators. Larger artificial reefs like large sunken ships may attract larger fish
– Encouraging rehabilitation or growth of populations of micro-organisms and invertebrates, along with sea life further up the food chain
– Providing protection and hiding spots for some marine life
– Providing recreation (especially for divers and snorklers as dive sites, but also sometimes for surfers), tourism and fishing opportunities for local populations near the reef
– Providing income and economic opportunities for those who benefit from the reef in their business or employment
– Help reduce erosion on beaches and coastlines by dissipating wave energy before it gets to shore, or helping trap sand and sediments on the coastline
Other Pros & Cons Of Artificial Reefs
We go further into the above points, and list other potential benefits as well as potential drawbacks to artificial reefs in this guide.
Examples Of Artificial Reefs, & Where Some Are Located
There’s a range of artificial reefs located in different parts of the world
The wikipedia.org resource listed provides an extensive list of these reefs, a description of them, and also their locations.
In particular, they provide the details and/or locations of sunken ship artificial reefs
Florida Keys National Marine Sanctuary is an example of a region with various sunken ships
Artificial Reefs In Different Countries
There’s a range of online resources that provide lists of different types of artificial reefs in different countries
Other Artificial Reef Systems & Products & Technology
Some other artificial reef technologies and products include but aren’t limited to:
– Reef Balls
These are hollow semicircle objects (made from PVC or concrete) made by the Reef Ball Foundation, and are used to create artificial reef structures
– MOREEF modules
These are stackable modules that can house small forms of marine life, and have other features such as being resistant to natural events
Other Coral Technology & Methods That May Be Used With Artificial Reefs
Other technology and methods that may be used in conjunction with artificial reefs might include, but aren’t limited to:
– Coral propagation
– Coral transplantation
– Lab grown or lab bred coral
– Gene edited coral
We discuss these technologies and methods in more detail in this guide.