Daily Archives: September 5, 2012

Artificial Reef

Written by . Filed under Indian Ocean Gyre. Tagged . No comments.

Mauritius is surrounded by one of the largest coral reefs in the world. It is however in very poor condition due to beach erosion and human impact ranging from the use of fertilizers to the overload of sewers from the endless hotels that are build for bulk tourism. I join the Blue Safari 1100 submarine to have a look.

It only took 5 minutes on the launching boat to remember the time on the Sea Dragon in 2010. The water was rough and I had to go to the toilet. Especially when you try to stand still it becomes even more evident that you are constantly moving. I lean hard against the wall and stick on to it to create some stability and try not to pie on my pants. Oh sweet memories! We go to the diving boat pretty soon and once under water everything is calm again.

With every meter that we descend the colours are fading and our faces start to look purple. It has been experimentally established that seawater alters different colors in the same way as a blue lens. Ultraviolet rays reach farthest, whereas infrared ones are absorbed literally centimeters under the surface of the water. At a depth of 5m water lets through up to 45% of the blue sector of the spectrum, in the same time absorbing up to 60% of the red sector. That is why the surface layer looks blue-green. We go up to a depth of 35 meters and see a huge ship wreck, one of the 14 that is deliberately put on the bottom to create an artificial reef. It looks just like a pile of junk. That it takes 50 years before this metal dump becomes a real reef is apparently not an objection.

We see a lot of different fish including Moorish Idols, the dangerous Tigerfish, and a slimy Golden Eal. While trying to get as close as possible to a giant turtle the submarine cracks of a piece of coral. Hey well, it only takes another 50 years or so to grow it back….