ABSTRACT. During a pilot survey, sponges and mollusks were sampled from the bottom of the middle Xingu River (rapids) and lower Xingu River (ria) via hand-picking in shallows and trawling and surface-supplied dives in deeper waters. The survey revealed a benthic community composed of eight sponge species in four genera and three families, and added six species to the Xingu Basin fauna. Sponges exhibited distinct variation in body shape corresponding to local environmental conditions such as water depth, current velocity and available substrates. Sponges inhabiting rocky bottoms in swift currents (rapids) typically formed crusts. Those in the deeper, calmer waters of the ria attained massive and elaborate forms while attached to infaunal bivalves. Oncosclera navicella and Drulia cristata exhibited crusts and massive forms as adaptations to rapids and ria, respectively. In the middle to lower Xingu, sponges encrusted the shells of eleven species of bivalves (seven infaunal, three epifaunal, and one infaunal/epifaunal) and one infaunal/epifaunal gastropod. Bivalves provide key substrates for supporting sponges above the sand, mud and detritus of the Xingu ria. Potential impacts of the Belo Monte Dam complex on the sponge fauna of the middle Xingu rapids are discussed.

中文翻译：

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巴西新谷河中下游一个底栖滤食性组合中的海绵和软体动物协会

摘要。在试点调查期间，通过在浅水区手工采摘和在较深水域进行拖网和地表供应的潜水，从兴谷河中游（急流）和兴谷河下游 (ria) 底部采集海绵和软体动物。调查揭示了一个由4属3科8种海绵种组成的底栖群落，新谷盆地动物群新增6种。海绵表现出与当地环境条件（例如水深、流速和可用基质）相对应的体形的明显变化。在急流（急流）中栖息在岩石底部的海绵通常形成地壳。那些在 ria 更深、更平静的水域中，当附着在双壳类动物身上时，它们获得了巨大而精致的形态。Oncosclera navicella 和 Drulia cristata 分别表现出结壳和块状形态作为对急流和 ria 的适应。在新古中部到下部，海绵覆盖了 11 种双壳类动物（7 种小动物、3 种表层动物和 1 种小动物/表皮动物）和一种小动物/表皮腹足动物的贝壳。双壳类动物为在欣古河口的沙、泥和碎屑上方支撑海绵提供了关键基质。讨论了贝洛蒙特大坝复合体对兴古急流中部海绵动物群的潜在影响。