Are artificial reefs comparable to neighbouring natural rocky areas? A mollusc case study in the Gulf of Castellammare (NW Sicily)

Abstract

Mollusc assemblages of three concrete artificial reefs (ARs) in the Gulf of Castellammare were compared with those of two nearby natural reefs (NRs). The reefs were located in areas characterized by different degrees of water transparency, with average annual Secchi disk visibility ranging from clear (>20 m) to turbid waters (<6 m). In spring 1995, 28 samples of 400 cm 2 were scraped off the reefs at depths of 16-22 m (20 from ARs; 8 from NRs), which yielded a total of 116 species and 1084 specimens of molluscs. The assemblage derived from a NR in clear water showed the highest diversity, species richness, and evenness, while the highest number of specimens and dominance values were observed at an AR in turbid water. The lowest values of diversity and species richness were found at ARs in turbid water and the lowest number of specimens at a NR in turbid water. Comparison of the five reefs showed significant differences in average number of species and in diversity values, while differences in the number of specimens were not significant. Factorial correspondence analysis showed a pattern that was strongly polarized along the first axis by the NR in clear water and by the AR in turbid water. The most distinctive feature was the dominance of Bittium latreillii at AR sites. Three years after deployment, mollusc assemblages of ARs in the Gulf remain entities that are distinct from those of nearby natural reefs. However, the potential of the assemblages in terms of density of individuals is comparable to that of natural reefs.

Can artificial reefs mimic natural reef communities? The roles of structural features and age

“…Artificial reefs (ARs) have been suggested as a potential tool for reef restoration and rehabilitation (Clark & Edwards, 1999;Spieler, Gilliam, & Sherman, 2001). Consequently, there is increasing awareness of the importance of understanding the interactions between artificial and natural reef (NR) communities, and thus of the need for a comparison between these communities (Badalamenti, Chemello, DÕAnna, Henriquez Ramoz, & Riggio, 2002;Carr & Hixon, 1997;Perkol-Finkel & Benayahu, 2004). Although early development of benthic communities on ARs has been intensively investigated over the past few decades (e.g., Ardizzone, Gravina, & Belluscio, 1989;AseltineNeilson, Bernstein, Palmer-Zwahlen, Riege, & Smith, 1999;Cummings, 1994;Qiu, Thiyagarajan, Leung, & Qian, 2003), knowledge of the late developmental stages of AR communities is still lacking.…”

Epibenthic colonization of concrete and steel pilings in a cold-temperate embayment: a field experiment

“…Knowledge is needed about their ecological eVect in order for environmental managers to make ecologically correct decisions about managing urbanized coastal areas. In addition, large infrastructural structures should not be regarded as surrogates for natural substrates since the epibenthic assemblages on these surfaces are shown to diVer compared to assemblages on natural hard substrates (Connell 2001;Badalamenti et al 2002;Bulleri et al 2005;Perkol-Finkel et al 2006). However, there are few experimental that use standardized units of diVerent materials to evaluate the eVect of diVerent substrates on the development of the epibenthic assemblage (but see Chapman and Clynick 2006).…”

Expected Effects of Offshore Wind Farms on Mediterranean Marine Life

“…In several studies, initial colonization was followed with the establishment and dominance of the commercially farmed Mytilus galloprovincialis [112,115,119,120]. However, the establishment of mussel beds on artificial structures in the Mediterranean may be highly localized, as several artificial structures showed no such dominance [117,[121][122][123] or highly variable results [124]. The only long-term data set on a concrete artificial reef (20 years) reported five distinct phases of species assemblage: dominance of pioneer species, mussel dominance, mussel regression, mussels absence, and finally dominance of bryozoan bio-constructions [125].…”

“…The susceptibility of the Mediterranean Sea to non-indigenous species [126] and the colonization of artificial substrata in the Mediterranean by alien species [122,127] mean that wind farms may also act as benthic "stepping stones" that facilitate range extension of alien species within the Mediterranean marine environment, which in turn may potentially reduce the biodiversity of the basin [111,128]. Due to the apparent locality factor of benthic colonization communites, small-scale pilot studies are essential for understanding whether windfarms will proliferate alien species at potential wind farm locations.…”