Nebra Alfonso, Alcaraz Carles, Caiola Nuno, Muñoz-Camarillo Gloria, Ibáñez Carles
IRTA-Aquatic Ecosystems, Ctra. Poble Nou, km 5.5, E-43540, Sant Carles de la Ràpita, Spain.
IRTA-Aquatic Ecosystems, Ctra. Poble Nou, km 5.5, E-43540, Sant Carles de la Ràpita, Spain.
Mar Environ Res. 2016 Jun;117:21-31. doi: 10.1016/j.marenvres.2016.03.009. Epub 2016 Mar 31.
The spatial distribution of benthic macroinvertebrate community in relation to environmental factors was studied along the Ebro Estuary (NE Iberian Peninsula), a salt wedge Mediterranean estuary. Both ordination methods and generalized additive models were performed to identify the different benthic assemblages and their relationship to abiotic factors. Our results showed a strong relationship between macrofaunal assemblages and the predominant environmental gradients (e.g. salinity); thus revealing spatial differences in their structure and composition. Two different stretches were identified, namely the upper (UE) and the lower Ebro Estuary (LE). UE showed riverine characteristics and hence was colonized by a freshwater community; whereas LE was influenced by marine intrusion and sustained a complex marine-origin community. However, within each stretch, water and sediment characteristics played an important role in explaining species composition differences among sampling stations. Moreover, outcomes suggested a total species replacement pattern, instead of the nestedness pattern usually associated with well-mixed temperate estuaries. The sharp species turnover together with the estuarine stratification point out that the Ebro Estuary is working, in terms of ecological boundaries, under an ecotone model. Finally, despite obvious differences with well mixed estuaries (i.e. lack of tidal influence, stratification and species turnover), the Ebro Estuary shares important ecological attributes with well-mixed temperate estuaries.
在伊比利亚半岛东北部的埃布罗河口（一个地中海咸水楔河口），研究了底栖大型无脊椎动物群落的空间分布与环境因素的关系。运用排序方法和广义相加模型来识别不同的底栖动物组合及其与非生物因素的关系。我们的结果表明，大型动物组合与主要环境梯度（如盐度）之间存在很强的关系；从而揭示了它们在结构和组成上的空间差异。确定了两个不同的河段，即埃布罗河上游（UE）和下游（LE）。UE呈现出河流特征，因此被淡水群落占据；而LE受海水入侵影响，维持着一个复杂的海洋源群落。然而，在每个河段内，水和沉积物特征在解释采样站之间的物种组成差异方面发挥了重要作用。此外，结果表明存在完全的物种替代模式，而不是通常与充分混合的温带河口相关的嵌套模式。物种的急剧更替以及河口分层表明，就生态边界而言，埃布罗河口在生态交错带模型下运行。最后，尽管与充分混合的河口存在明显差异（即缺乏潮汐影响、分层和物种更替），但埃布罗河口与充分混合的温带河口具有重要的生态属性。
