We evaluated the structural responses of marine sponge assemblages to different substrates as well as their positioning around Ilha Grande, a local hotspot of marine biodiversity sheltered in a bay area off Southeast Brazil. Sampling sites were distributed between sides of the island facing the continent (North) and ocean (South) across two depth-dependent substrates. As proved by ordination and permutation analyses, these two factors accounted for nearly half the variation observed among assemblages, either with species abundance or coverage area data. Out of 46 OTUs surveyed (~ 3000 individuals), Tedania ( Tedania ) ignis , Scopalina ruetzleri, and Iotrochota arenosa dominated the community, even though most of the dissimilarity detected among assemblages relied on 20% of the OTUs. The northern side was proved as more diverse, and the south-facing side held more unspecific, putatively new OTUs. Assemblages dwelling on rocky-to-sandy interface bottoms were meager in species number, although they mainly included Dragmacidon reticulatum and the endemic Brazilian sponge Polymastia janeirensis. By highlighting structuring factors operating on Ilha Grande’s sponge assemblage, we hope to support future monitoring surveys on an environment increasingly impacted by human activities over the years.

中文翻译：

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亚热带岛屿周围海海绵组合的生物多样性和结构

我们评估了海洋海绵组合对不同基质的结构响应以及它们在 Ilha Grande 周围的定位，Ilha Grande 是巴西东南部海湾地区的海洋生物多样性当地热点。采样点分布在岛的两侧，面向大陆（北）和海洋（南），跨越两个依赖于深度的基质。正如排序和排列分析所证明的那样，这两个因素占了在组合中观察到的变异的近一半，无论是物种丰度还是覆盖面积数据。在接受调查的 46 个 OTU（约 3000 个人）中，Tedania (Tedania) ignis、Scopalina ruetzleri 和 Iotrochota Arenasa 在社区中占主导地位，尽管在组合中检测到的大部分差异依赖于 20% 的 OTU。北侧被证明更加多样化，朝南的一侧持有更多非特异性的、推定的新 OTU。栖息在岩石到沙质界面底部的组合物种数量很少，尽管它们主要包括 Dragmacidon reticulatum 和地方性巴西海绵 Polymastia janeirensis。通过突出 Ilha Grande 海绵组合的结构因素，我们希望支持未来对多年来受人类活动影响越来越大的环境进行的监测调查。