Flow Regime and the Structure and Productivity of Macroinvertebrate Communities in Tropical Streams

本研究的重点是生态和进化 流态对大型底栖动物群落重要性 哥斯达黎加的热带干燥森林溪流。 原始热带 流域是测试水流对 溪流群落因为季节性的混杂效应 在温度和光周期以及高泥沙和泥沙负荷下 与大多数温带河流相关的是缺席的，许多 有常年水流的原始小溪 为了学习 这项研究将量化大型无脊椎动物群落 结构和生活史特征及生产 浅滩中所有广泛分布的常见大型无脊椎动物 六条常年溪流的栖息地。 该项研究将集中 这些参数的时间变化响应于长时间（6 月）期间的恒定（旱季）和升高（湿 季节）流量以及在潮湿的短期洪水缺陷 赛季 该研究的中心假设是： 大型无脊椎动物群落中的物种并没有过饱和 (in没有干扰），并可能能够 承受长期的非生物稳定性而不损失 多样性，即不存在“河流底栖生物悖论”。 该研究项目的主要目标是： (1)量化相对丰度的季节性变化， 大型无脊椎动物的物种组成和测试的效用， 流量作为解释这种变异性的协变量;（2）文件 大型无脊椎动物生活史的季节性程度， 评价季节性对流态的适应性;（3）评价 风暴在解释季节性气候方面的相对重要性 大型无脊椎动物群落结构的变化（4）评估 空间尺度（即斑块大小）在底栖生物研究中的作用 群落演替;（5）评价干扰在 维持溪流群落的多样性。

This research focuses on the ecological and evolutionary significance of flow regime to macroinvertebrate communities in tropical dry forest streams of Costa Rica. Pristine tropical watersheds are ideal sites for testing the effects of flow on stream communities because the confounding effects of seasonality in temperature and photoperiod and high silt and sediment load associated with most temperate streams are absent, and many pristine small streams with perennial flow regimes are available for study. The research will quantify macroinvertebrate community structure and the life history characteristics and production of all widespread and common species of macroinvertebrates in riffle habitat of six perennial streams. The study will focus on temporal changes in these parameters in response to prolonged (6 month) periods of both constant (dry season) and elevated (wet season) flow as well as to short-term flood flaws during the wet season. The central hypothesis of the study is that: stream macroinvertebrate communities are not oversaturated with species (in the absence of disturbance) and may be capable of withstanding long periods of abiotic stability without loss of diversity, i.e. there is no "paradox of the stream benthos". The principal objectives of this research project are to: (1) quantify seasonal variation in the relative abundance and species composition of macroinvertebrates and test the utility of flow as a covariate for explaining this variability; (2) document the extent of seasonality in macroinvertebrate life histories and evaluate sesonality as an adaptation to flow regime; (3) evaluate the relative importance of storms in explaining seasonal variability in macroinvertebrate community structure (4) assess the role of spatial scale (i.e. patch size) in studies of benthic community succession; and (5) evaluate the role of disturbance in maintaining the diversity of stream communities.