Notes on fauna associated with an opportunistic artificial reef near cold-water corals

Artificial reefs (AR) of many different designs and materials have been widely used for various purposes, from habitat protection and enhancement to recreational diving (Polovina 1991; Bortone et al. 2011). With more than 250 ARs covered by scientific literature world-wide (Baine 2001), very few studies concern areas deeper than 60 metres, reflecting the majority of deployment and vertical depth limits for SCUBA operations. Concurrently, with the deepening of fisheries (Morato et al. 2006) and the advent of optical and submersible technology, the ecological importance of cold water coral (CWC) habitats has become the focus of many recent large research programs. These deep-water “habitat-building species” alter sediment deposition and provide complex structural habitat (Roberts et al. 2006), considered essential for diverse fish and invertebrate communities (e.g. Reed 2002). Opportunistic fish behaviour towards habitat is a relatively well known response from habitat complexity studies on shallow natural (Harding & Mann 2001), and artificial reefs (Gratwicke & Speight 2005). Observations of deep-water AR have demonstrated that local fish populations tend to utilise artificial structures similarly to other biological or geological reefs available (e.g. Koening et al. 2004; Husebø et al. 2002), even though differences may be found in comparison with natural reef fish communities (Clark & Edwards 1994). Thus, ARs can contribute to a better understanding on the use and importance of available habitats (Hixon & Beets 1989), while simplified structures can facilitate the observation of juvenile fish (Gorham & Alevizon 1989), usually hampered by the presence of larger fish (Ross & Quattrini 2007). This short communication provides a sporadic insight on the importance of a hard three-dimensional structure for deepwater fish near CWC. Fish size and behaviour inside the structure and in the surrounding area are described. Additionally, a list of biofouling macroorganisms found on the structure after one year of deployment is presented.