In September 1992 in the Netherlands, an experiment was started with four artificial reefs in the North Sea, eight kilometers from the coast by Noordwijk, next to the REM-island. The artificial reefs are 1.60 meters high, 12 meters wide and 14 meters long. They lie 50 meters apart and 18 meters deep and are made from 112 tons of basalt blocks from Norway. It cost 41,000 euros. Rijkswaterstaat (Dept. of Public Works) began the experiment in order to study the biological effects in particular. The reef lies too deep to function as a breakwater.
Rijkswaterstaat wanted to see whether similar effects occurred the North Sea with these artificial reefs as in other parts of the world. One of the hopes was to increase the number of plants and animals close by the reef, as well as attracting new sorts. From years of researching ship wrecks in the North Sea, it was expected that the experiment will have a true chance of succeeding. A spectacular increase already occurred rapidly with the amount of plant and animal species that were present as well as the total number of organisms.
Since the construction, five dives per year have been made and the first results correspond well with the expectations. The first 'colonists' were hydroid polyps, which started growing on the reef after a week of placement. Edible crabs and starfish had also quickly found refuge by the reef. Barnacles and plumose anemones were found within a month. In 1993, the artificial reefs were practically completely overgrown in particular with sea anemones. After a period of time, every reef had an estimated thirty edible crabs. Furthermore, eggs from cuttlefish were also found. The most important discovery was the sea slug Polycera, which had never been found before in the Netherlands.
Artificial reefs was in the news again at the end of 2005 when Rijkswaterstaat signed an agreement with Royal Haskoning to research the possibilities of artificial reefs in the North Sea. The reefs could decrease the energy in the waves that hit the shore and they are also interesting for divers and surfers. Furthermore, they could be used as a foundation for wind turbines at sea.
Rijkswaterstaat decided to stop with the experiment by Noordwijk in March 1996. The departmen involved found too little support for the experiment. In addition, there were too few results after three years. A balance in the growth and inhabitance of the artificial reefs should have been attained by 1997. However based upon the last measurements, it appeared that the biomass and the number of organisms on and around the reef continued to increase, but much less extensively than by shipwrecks. The increase of the number of species was low in comparison with artificial reefs in England, where two times as many species of fauna were counted.
It is expected that constructing artificial reefs with the only goal being nature development will not occur in the Netherlands. However, Rijkswatersaat is interested in the possibilities of using them for coastal protection, artificial islands and drilling platforms, whereby nature development would be a secondary goal. The North Sea Foundation does not believe that the reefs will contribute to coastal defence.
The Council for Transportation and Waterworks advised the government at the end of 2005 to sink drilling platforms that are no longer in use so that they can serve as artificial reefs. Up till now, the oil companies are required to tow them away.
