Grass-dominated stream sites exhibit low fish species diversity and dominance by guppies: an assessment of two tropical pasture river basins
Grass-dominated stream sites exhibit low fish species diversity and dominance by guppies: an assessment of two tropical pasture river basins
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DOI：
10.1007/s10750-009-9849-y
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发表时间：
2009-10-01
期刊：
影响因子：
2.6
通讯作者：
Carvalho, Fernando Rogerio
中科院分区：
文献类型：
--
作者：
Casatti, Lilian;Ferreira, Cristiane de Paula;Carvalho, Fernando Rogerio
本研究调查(1)溪流的结构形态(考虑底物组成、木屑、边缘和河岸植被)是否意味着流域尺度上的栖息地简化，以及(2)鱼类群落结构是否遵循溪流生境形态。随机选择了巴西东南部两个牧场盆地的95个地点。在每个地点75米的范围内进行了两次电子捕鱼。在每条溪流河段评估了10个与溪流中和河岸物理结构有关的生境描述符。通过主成分分析识别出两组溪流：有草组和非有草组。与非草地相比，草为主的溪流由于物种多样性较低和优势度较高而表现出更多的同质性鱼类区系，特别是孔雀鱼，这是一种高度通才的外来物种。草群不仅拥有最简单的栖息地，也拥有最简单的鱼类动物群，以草为主、完全砍伐森林、严重淤泥的条件与最近的土地利用转换相结合，可能导致未来的生境同质化，随后是区域尺度上的鱼类动物群同质化。
This study investigates whether (1) structural configuration (considering substrate composition, wood debris, marginal and riparian vegetation) of streams suggests habitat simplification on a basin scale and (2) fish assemblage structure follows stream habitat configurations. Ninety-five sites in two pasture basins in southeastern Brazil were randomly selected. Two passes of electro-fishing were done in a 75-m reach at each site. Ten habitat descriptors related to in-stream and riparian physical structures were evaluated at each stream reach. Two groups of streams were identified by principal component analysis: a grassy and a non-grassy group. In comparison to non-grassy sites, grass-dominated streams exhibited a more homogenous fish fauna due to lower species diversity and higher dominance, especially by the guppy Poecilia reticulata, a highly generalist exotic species. The grassy group had not only the most simplified habitat but also the most simplified fish fauna, and the combination of grass-dominated, completely deforested, heavily silted conditions with recent land use conversion may cause a future habitat homogenization followed by a fish fauna homogenization on a regional scale.