Speak to just about anyone at all and they will know what a coral reef is in general. What about an artificial coral reef though?
Most when asked the question could make a rough guess, saying it’s one built by people or something along those lines. They may even say it’s one in an aquarium, which is correct of course, and perhaps this is the answer that many marine aquarists would give.
However the artificial reefs in mind here are those that are out in the wild. They’re man-made and, as far as able, mimic the wild reef.
The wild reef is anything from a quite small affair to the huge 1000 mile + length of the Australian barrier reef. Why should anyone wish to create an artificial reef at all, what’s the point? Nature has done a wonderful job over a very long period of time.
Creating a reef may be to enhance the wild fish etc populations in an area, and at the same time help boost tourism by giving scuba and snorkel enthusiasts something to look at. Some scuba people are qualified wreck divers and no doubt really appreciate an extra wreck or two. So there’s a ship available which is no longer economical to run or repair and is ready to be broken up. On several instances these ships, military or mercantile, have been obtained by conservation/tourism interests. They are very carefully prepared, having all oil removed plus any electrical cable or other items that could be detrimental to sea life. Once prepared they are towed to the required area and sunk.
It takes a while for life to appear on the wreck, though the period of time varies. Encrusting algae often takes a hold, and soft corals. Later, hard corals appear. It can be years before the coral population is widespread. Eventually the whole ship is covered in sea life of one type or another. This can be seen on World War 2 ships that were sunk in action in suitable areas – they’re totally covered and in many cases not recognizable as ships. Many ship parts have rotted away but the corals cover the rest and maybe even keep some together. One of the high priorities of fish is a safe sanctuary and a ship offers many hiding places from the word go – once corals are present its even better. So there are myriads of fish present of different varieties approaching the diversity of the natural reef and perhaps in time equaling it.
Another type of artificial reef is one created again for tourism/conservation but this time it is created out of rock. Some land based rock was once part of a coral reef and this rock can be transported for building the new reef. Other land based rock is suitable if it does not disintegrate in seawater and is porous so that the creatures of the reef, including bacteria, can find a home. This rock is taken out to sea and dumped until there is enough for the required reef design. Though I don’t have any figures, I would guess that this is a more expensive option than the sunken ship. Again the same process occurs, with algae and corals of various types finding a home and multiplying. The fish find sanctuary and food and make it their home.
The rock built artificial reef could be a commercial project. The new reef will produce collectable corals and fish given time, and as there wasn’t a reef there in the first place it permits a supply of livestock and at the same time reduces the pressure on nature’s own products. In addition, live rock, which is much favoured by aquarists for filtration and aquascaping, can be collected and exported. When the rock is removed it is replaced by rock which then goes through the cycle of becoming live rock.
There is an artificial reef that has been constructed out of worn out vehicle tyres. It has not been in existence for very long and it will be interesting to see how this progresses and how the reef life reacts to the unusual material. If all is well what a good way of disposing of some of man’s discarded products.
I find it difficult to fault the creation of artificial reefs whether they are ship or rock structures. With proper supervision and given the time to populate, they can only enhance livestock numbers. If used with common sense, they are also of benefit to local people who should find extra revenue from employment that has been created in the export of livestock or in the service of the local tourism industry.