Chapter 21. Fauna of jetties and artificial reefs CHAPTER 21. FAUNA OF JETTY PILES, ARTIFICIAL REEFS AND BIOGENIC SURFACES ALAN BUTLER C.S.I.R.O. Marine Research, Hobart, Tasmania 7001. Email:
[email protected] Figure 1. Piling of Edithburgh jetty showing sponges, ascidians and bryozoans. (CAS) Introduction This chapter is not a comprehensive description or natural history of the fauna of all jetties, artificial reefs and biogenic surfaces in Gulf St Vincent (GSV) and its approaches. It is about studies done on certain jetties, etc., in the Gulf, using them as experimental systems to increase our understanding of the larger ecosystem of which they are a part. I think of the fauna attached to pilings, artificial reefs and biogenic surfaces as a window on that larger system. Pilings have been convenient places to do experiments and make repeated observations. It has to be remembered, however, that the organisms we are studying on such surfaces are part of larger populations. They have dispersive larvae which may travel short to long distances with the currents; they have predators that move about; the assemblage on one jetty is thus connected to assemblages on other jetties and reefs. We can learn a great deal by observations and experiments at the small scale, but ultimately it only makes sense if we can successfully ‘scale up’—understand these habitats in the context of the system in which they are embedded. I say more, at the end, about this ‘scaling up’. Also, the jetties etc. are artificial—a type of substratum that was not present during the millions of years of evolution of these organisms—and are, in various respects, different from their ‘natural’ habitats.