Oil platforms, and other man-made offshore structures such as breakwaters and shipwrecks, create circalittoral hard substratum in areas where it did not exist before. The amount of substratum is probably fairly insignificant, but its position may play a role as a staging post in promoting spread of species. Certainly artificial structures quickly accumulate a diverse animal community (Forteath et al., 1983). This is not so much a question of man posing a problem for CFT communities, as the other way round.

In terms of their effect on the structures CFT species increase drag, and accelerate corrosion (Pipe, 1981). Detail would not be appropriate here, but a better understanding of the biology of the important species involved (Tubularia spp., Akcyonium digitatum, Metridium senile, Pomatoceros triqueter, Balanus spp.) could perhaps help to mitigate the problem.

Whilst CFT communities are not desired on most artificial structures, there are some which are deliberately constructed to promote natural communities. These are the ‘artificial reefs’, developed primarily to provide increased habitat for fish and shellfish. An integral aspect of this is the establishment of a complex community to provide habitat and food for the target species. An example of such a development is the Poole Bay Project where the reef was constructed of stabilised coal-fired power station waste (Collins et al., 1990; Jensen et al., 1994).

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