Effects of different intertidal hard substrates on the recruitment of Crassostrea gigas

Abstract

Physical properties, distribution, and abundance of natural hard substrates are important variables modulating the potential distribution of sessile aquatic species. In this study, we analyze the effects of the geological origin of different rock types common in intertidal environments of Argentina on the recruitment success of the nonindigenous Pacific oyster Crassostrea gigas, accounting for spatial and interannual variation. A series of experiments showed that although recruitment occurs on all of the five most widespread hard substrates in the region (i.e., pelitic mudstone, limestone, conglomeradic sabulitic sandstone, gray sandstone, and volcanic rock) it is significantly higher on pelitic mudstone. Accounting for the geographic distribution of these substrate types along the coast of Argentina, it is concluded that the Valdes Peninsula and central San Jorge Gulf areas, where pelitic mudstone outcrops are the dominant intertidal hard substrate, are the regions with highest potential for C. gigas intertidal reef formation. Pelitic mudstone displayed the highest mean values of specific heat and porosity as well as high values of luminosity.