Structure and diversity of sessile zoobenthic assemblages seem to be driven not only by chemical-physical constraints and biological interactions but also by substrate lithology and its surface features. Nevertheless, broadly distributed crustose epilithic corallines could mask the role of substrate on animal settling. To evaluate the direct influence of different rocky substrates, occurrence and coverage of several sessile species, growing on the dark (i.e. coralline-free) face of sublittoral limestone and granite boulders were compared in the Tavolara MPA (Mediterranean Sea). The analysis of photographic samples demonstrated significant differences in terms of species composition and coverage, according to lithology. Moreover, limestone boulders were widely bare, while the cover per cent was almost total on granite. The leading cause of observed patterns could be the different level of dissolution of the two types of rocks, due to their different mineral composition and textural characteristics. Limestone has previously been shown to have higher dissolution compared with granite, and consequently, a more unstable surface. Our results suggest that, in dark habitats, the absence of the crustose coralline layer allows more rock dissolution and consequent lower stability of the limestone compared with granite, which, in turn, reduces the zoobenthos colonization.

中文翻译：

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岩性可能会影响生活在巨石下的底栖​​生物群落

固着的底栖动物组合的结构和多样性似乎不仅受化学-物理约束和生物相互作用的驱动，还受基质岩性及其表面特征的驱动。然而，广泛分布的壳状附石珊瑚可以掩盖基质在动物定居中的作用。为了评估不同岩石基质的直接影响，几种固着物种的出现和覆盖，在 Tavolara MPA（地中海）比较了生长在暗色（即无珊瑚）面上的沿海石灰岩和花岗岩巨石。根据岩性，对照片样品的分析表明，在物种组成和覆盖范围方面存在显着差异。此外，石灰岩巨石广泛裸露，而覆盖率几乎全部在花岗岩上。观察到的模式的主要原因可能是由于两种岩石的不同矿物成分和结构特征，它们的溶解程度不同。与花岗岩相比，石灰石先前已被证明具有更高的溶解度，因此表面更不稳定。我们的研究结果表明，在黑暗的栖息地中，与花岗岩相比，没有甲壳珊瑚层会导致更多的岩石溶解，从而降低石灰岩的稳定性，进而减少底栖动物的定殖。