Artificial reefs

What is an artificial reef?

Most people are familiar with the idea of a reef: it’s an underwater feature, often comprising rocks, sand or coral, that is distinct from and rises out of the sea floor around it. Most reefs are naturally occuring – such as the fossilised sand dune that is Aliwal Shoal, or the coral atolls of the South Pacific.

There is another kind of reef, however. Artificial reefs are man-made reefs. They are most often created by scuttling a ship, whether deliberately or through an act of war, or a sinking in a storm. They can also be created by dumping tyres, rubble, or other materials on the sandy ocean bottom.

Isn’t it just pollution?

The idea seems crazy: isn’t one just dumping garbage into the ocean, and creating a problem where there wasn’t one before? The problem with this thinking is that it neglects to consider the power of the sea to claim and colonise whatever is given to it. On a small scale, think of the bits of glass and other rubbish that sometimes end up on the beach after a storm. The glass is worn smooth by the action of the waves against it and the sand. The bits of garbage often have seaweed growing on them. Ships that traverse the world’s oceans have to be cleaned constantly in order to prevent barnacles, mussels and other sea creatures from making their homes on their hulls and causing structural damage. Marine animals are powerful – even the tiny ones.

If the materials from which artificial reefs are built are carefully chosen, the sea will accept the new reef, and within months change it into something beautiful and much better than it was before. Ships that are deliberately scuttled are specially cleaned to avoid oil spills and polluting the marine ecosystem.

Why make an artificial reef?

Artificial reefs are created for many reasons. Some are pure accidents – think of a ship that sinks in a storm or is holed by enemy fire during a battle. Some are created to enhance the experience of surfers, in order to force a wave to break at a particular spot. Some are created as part of harbour alterations, and others are created to relieve the strain on natural reefs. Reefs are an important breeding ground for fish, as the juveniles have places to hide and shelter from predators. The addition of an artificial reef to a region that is heavily fished can do much to restore fish stocks in the area.

Cape Town artificial reefs

Many of the wrecks around Cape Town are located where they are as a result of the incompetence of the crew (think of the Kakapo on Noordhoek Beach), foul weather (the SS Clan Stuart springs to mind), and hidden rocks and blinders such as Albatross Rock. There are also several deliberately scuttled ships that are much beloved by Cape divers:

All of these wrecks are now heavily overgrown with diverse marine life, much of it found almost nowhere else. They have done much to boost fish stocks – think of how full of fishing boats the area just south of the Smits wrecks is on a busy weekend. And they are a source of immense enjoyment to divers living in and visiting Cape Town.

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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