Abstract Macroalgae in Mar Chiquita coastal lagoon (37° 40′ S, 57° 23′ W, Argentina) settle on small-hard substrates on sediments and complex reef-like structures with tubes and crevices of the invader polychaete Ficopomatus enigmaticus (Fauvel, 1923) acting as ecosystem engineers with multiple community structuring effects. In this study, we compared the structural effects of macroalgae generating new habitat for other organisms in two systems with originally different structural complexity. Therefore, we hypothesized that macroalgae relative importance as an ecosystem engineer providing new habitat and refuge for other organisms would be higher in flat soft-sediments than on reefs. Through sampling and experimental studies, results showed that macrofaunal assemblages were different between areas with and without macroalgae in both reefs and sediment. Experimental results on macroalgae and macroalgae-mimics to separate structural effects in both reefs and sediment showed that macroalgae affect macrofauna on both systems but, structural mechanisms did not prevail in the reefs or sediment. The effect varied on species responses and physical gradients (i.e., depth) of each type of area. Therefore, our results did not support our hypothesis and suggest that macroalgae effects are the result of a summary of their multiple effects in interaction with species and habitat type.

中文翻译：

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大西洋西南部沿海泻湖中侵入性造礁多毛类动物介导的大型藻类生态系统工程效应

摘要 Mar Chiquita 沿海泻湖（南纬 37° 40'，西经 57° 23'，阿根廷）中的大型藻类定居在沉积物和复杂的礁状结构上的硬质小基质上，具有入侵多毛类 Ficopomatus enigmaticus 的管和裂缝（Fauvel，1923 ) 作为具有多重社区结构效应的生态系统工程师。在这项研究中，我们比较了大型藻类在原本具有不同结构复杂性的两个系统中为其他生物产生新栖息地的结构效应。因此，我们假设大型藻类作为生态系统工程师为其他生物提供新的栖息地和避难所的相对重要性在平坦的软沉积物中比在珊瑚礁上更高。通过抽样和实验研究，结果表明，珊瑚礁和沉积物中有和没有大型藻类的区域的大型动物群落是不同的。大型藻类和大型藻类模拟物在珊瑚礁和沉积物中分离结构效应的实验结果表明，大型藻类影响两个系统的大型动物，但结构机制在珊瑚礁或沉积物中不占优势。影响因物种反应和每种类型区域的物理梯度（即深度）而异。因此，我们的结果不支持我们的假设，并表明大型藻类效应是它们与物种和栖息地类型相互作用的多重效应总结的结果。结构机制在珊瑚礁或沉积物中不占优势。影响因物种反应和每种类型区域的物理梯度（即深度）而异。因此，我们的结果不支持我们的假设，并表明大型藻类效应是它们与物种和栖息地类型相互作用的多重效应总结的结果。结构机制在珊瑚礁或沉积物中不占优势。影响因物种反应和每种类型区域的物理梯度（即深度）而异。因此，我们的结果不支持我们的假设，并表明大型藻类效应是它们与物种和栖息地类型相互作用的多重效应总结的结果。