Fish assemblage structure in urban streams of Puerto Rico: the importance of reach- and catchment-scale abiotic factors
Fish assemblage structure in urban streams of Puerto Rico: the importance of reach- and catchment-scale abiotic factors
复制标题
波多黎各城市河流中的鱼类组合结构：河段和流域规模非生物因素的重要性
作者：
A. Engman;A. Ramírez
荒漠化和城市化是人为的改变，分别作用于河段和流域尺度，使溪流生境退化。随着城市地区在热带地区的不断扩大，渠化河流的数量也可能会增加。我们研究了在流栖息地和鱼类组合结构流达到一系列的通道改建和子集水区城市土地利用在里奥Piedras流域，波多黎各。九个河段进行了调查，并分为三类：未改变的渠道（自然），渠道已被拉直，并可能有加强银行（中间），或渠道的银行和底部被替换为混凝土（混凝土渠道化）。鱼类采样使用三重通过电捕鱼和相关的达到和集水区规模的非生物环境变量进行了测量，为每个网站。鱼类组合结构在里奥彼德拉斯似乎都达到和集水区规模的非生物环境因素的影响。自然和中游具有中等水平的子流域城市化有相对较高的生物量，物种丰富，本地为主的鱼类组合，而混凝土渠化达到非常高度城市化的子流域的鱼类组合很少或没有本地物种和高度丰富，宽容，外来物种。
Channelization and urbanization are anthropogenic alterations that act on the reach- and catchment-scale, respectively, to degrade stream habitats. As urban areas continue to expand in the tropics the number of channelized streams will likely increase as well. We examined in-stream habitat and fish assemblage structure in stream reaches with a range of channel alterations and sub-catchment urban land use in the Río Piedras watershed, Puerto Rico. Nine reaches were surveyed and classified into three categories: unaltered channels (natural), channels that had been straightened and may have reinforced banks (intermediate), or channels where the bank and bottom was replaced with concrete (concrete-channelized). Fishes were sampled using triple-pass electrofishing and relevant reach- and catchment-scale abiotic environmental variables were measured for each site. Fish assemblage structure in the Río Piedras appears to be influenced by both reach- and catchment-scale abiotic environmental factors. Natural and intermediate reaches with moderately high levels of sub-catchment urbanization had relatively high biomass, species-rich, and native-dominated fish assemblages whereas concrete-channelized reaches with very highly urbanized sub-catchments had fish assemblages with few to no native species and highly abundant, tolerant, and exotic species.