Abstract
Several comments received in regard to the proposed Cape Wind Project have hypothesized that the addition of 130 monopile foundations to Nantucket Sound would result in a so-called “reef” effect due to the increased availability of hard substrate for sessile organisms that may colonize these structures and ultimately, that this would alter predator-prey relationships in Nantucket Sound. The diversity of the benthic community that might colonize the monopiles will depend on the substrate characteristics and a number of environmental factors including exposure to waves, current, scour, etc., similar to the variables that affect colonization of most marine habitats. Once established, the attached community is expected to include sessile animal and plant species and small mobile invertebrates. Over time, the presence of these fouling communities is expected to attract small fish species, which could in turn lead to the attraction of larger benthic or pelagic fish, and eventually, the attraction of sea birds (Elsam Engineering A/S and ENERGI E2 A/S 2005). Some commentors have also questioned the degree to which marine mammals would be attracted to the proposed wind farm. The extent to which attraction occurs, however, will be dependent upon how hospitable the surface of the monopile is for colonization. In general, substrate that has an irregular or rough surface or that offers organisms structural complexity to avoid predation and to escape from high current velocities and scour is typically more suitable for colonization and ultimately the formation of reef-like communities. The monopile foundations were selected to be smooth and devoid of complexity, unlike the scaffolding typically used for oil platforms (MMS, 2000). The monopiles will provide vertical habitat that will be colonized by organisms, however, the degree of colonization is likely to be minimal due to their smooth cylindrical form. Research conducted during the summer of 2005 on the pilings of the Cape Wind meteorological tower in Nantucket Sound showed that organisms do colonize pilings placed in Nantucket Sound, as anticipated, however, the degree of colonization is not extensive, despite the fact that these structures had been available for colonization for more than two years. Table 1 lists the species and number of individuals per square meter that colonized the meteorological tower and were recorded during the summer of 2005. Although additional time for colonization is likely to result in greater densities and species diversity than was observed during this initial investigation, it is also likely that these communities would be scoured away on a regular basis during periods of intense currents or wave activity associated with storm events.