Oyster Recruitment And Growth On An Electrified Artificial Reef Structure In Grand Isle, Louisiana

摘要

Coastal protection remains a global priority as rising sea levels, development, and tropical storms threaten coastal habitat. A common tool used to combat shoreline erosion involves armoring the land/water interface (Yohe and Neumann, 1997; Mimura and Nunn, 1998; Klein et al., 2001). While typical armoring is done with heavy, often non-native materials, recent shoreline protection projects are moving towards promoting the use of native, living materials. One promising method that has been used to restore degraded reef systems and protect shorelines in southeast Asia, is mineral accretion technology which involves the electrochemical deposition of minerals from seawater (Hilbertz, 1979; Hilbertz and Goreau, 1996; Sabater and Yap, 2002, 2004). Essentially, the method involves creating reef units consisting of a rebar structure and passing a weak electrical current through the structure. These artificial reef units use low-voltage direct current that, in the right conditions, results in the precipitation of dissolved minerals in seawater to create a reef structure ten times stronger than concrete (Hilbertz, 1979). In addition to rapidly building mineral substrate, electrified reef structures may also confer survival and growth benefits to coral and mollusks that become attached to the structure (Hilbertz and Goreau, 1996; Sabater and Yap, 2002, 2004). Enhanced growth is suggested to result from the effects of electrolysis of seawater which raises the pH on the mineral precipitate, thus reducing the metabolic energy requirements needed for growth (Goreau and Hilbertz, 2005). It is hypothesized that the electrolysis of seawater creates the high pH conditions for the organisms, hence providing an energy subsidy to the organisms, allowing them to put more energy in growth, reproduction, and disease resistance.