Flow intermittency alters longitudinal patterns of invertebrate diversity and assemblage composition in an arid-land stream network
Flow intermittency alters longitudinal patterns of invertebrate diversity and assemblage composition in an arid-land stream network
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DOI：
10.1111/fwb.12105
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发表时间：
2013-05-01
影响因子：
2.7
通讯作者：
Lytle, David A.
中科院分区：
文献类型：
--
作者：
Bogan, Michael T.;Boersma, Kate S.;Lytle, David A.
1.临时河流占大多数河流网络总长度的很大比例，占干旱-陆地河流网络的绝大多数，因此必须在地方和景观尺度上了解它们对生物多样性的贡献。2.2010年冬末，我们在美国亚利桑那州东南部的一个大型干旱-陆地河流网络(包括多年生和间歇性源头、间歇性中游和多年生河流)的12个河段采集了无脊椎动物群落。在经历了超过450天的枯水期后，间歇性河段持续了大约60天。我们对这项常年研究的子集进行了抽样，在2009至2011年间又进行了三次抽样。由于间歇性河段在这些额外的采样期间是干燥的，我们使用了研究网络中另外两个间歇性河流的集合体数据(200405和2010年抽样)，以探索间歇性溪流集合体组成的年际变化。3.无脊椎动物丰富度在间歇性河段最低，尽管它们往往与物种丰富的多年生河段有关。这些间歇河段的群落不只是多年生溪流中物种的一个子集，而是由一组适应间歇(例如卵和/或幼虫滞育)的石蝇、黑蝇和蚊子主导。平均而言，在这些样本中，86%的人是专家或对断断续续的溪流独有。多年生捕食者的数量是间歇性捕食者的714倍。4.尽管相隔很远(1225公里)，物理特征也截然不同，但多年生水源和河流的组合更类似于彼此之间的断续河段，强调了当地水文在这一系统中的首要重要性。5.枯水期的持续时间和复发间隔，以及从常年避难所扩散的相对重要性，可能会影响相邻的常年溪流和临时溪流之间的生物差异的大小。尽管多年生水源支持了无脊椎动物的最高多样性，但间歇性河段支持了一些独特的或当地稀有物种，因此有助于区域物种多样性，应纳入保护规划。
1. Temporary streams comprise a large proportion of the total length of most stream networks, and the great majority of arid-land stream networks, so it is important to understand their contribution to biotic diversity at both local and landscape scales. 2. In late winter 2010, we sampled invertebrate assemblages in 12 reaches of a large arid-land stream network (including perennial and intermittent headwaters, intermittent middle reaches and perennial rivers) in south-east Arizona, U.S.A. Intermittent reaches had then been flowing for c.60days, following a dry period of more than 450days. We sampled a subset of the perennial study reaches three more times between 2009 and 2011. Since intermittent reaches were dry during these additional sampling periods, we used assemblage data from two other intermittent streams in the study network (sampled in 200405 and 2010) to explore interannual variability in intermittent stream assemblage composition. 3. Invertebrate richness was lowest in intermittent reaches, despite their often being connected to species-rich perennial reaches. The assemblages of these intermittent reaches were not simply a subset of the species in perennial streams, but rather were dominated by a suite of stoneflies, blackflies and midges with adaptations to intermittency (e.g. egg and/or larval diapause). On average, 86% of individuals in these samples were specialists or exclusive to intermittent streams. Predators were 714 times more abundant in perennial than in intermittent reaches. 4. Despite being separated by long distances (1225km) and having very different physical characteristics, the assemblages of perennial headwaters and rivers were more similar to one another than to intervening intermittent reaches, emphasising the prime importance of local hydrology in this system. 5. The duration and recurrence intervals of dry periods, and the relative importance of dispersal from perennial refuges, probably influence the magnitude of biological differences between neighbouring perennial and temporary streams. Although perennial headwaters supported the highest diversity of invertebrates, intermittent reaches supported a number of unique or locally rare species and as such contribute to regional species diversity and should be included in conservation planning.