Department of River Ecology, Helmholz-Center for Environmental Research-UFZ, Magdeburg, Germany.
Oecologia. 2013 Sep;173(1):281-91. doi: 10.1007/s00442-013-2592-0. Epub 2013 Jan 30.
Shifts in life history traits and in the behaviour of species can potentially alter ecosystem functioning. The reproduction of the central European fire salamander (Salamandra salamandra), which usually deposits its larvae in first-order streams, in small pool and pond-like habitats, is an example of a recent local adaptation in this species. Here we aimed to quantify the direct and indirect effects of the predatory larvae on the aquatic food webs in the ponds and on the flux of matter between the ponds and adjacent terrestrial habitats. Our estimates are based on biomass data of the present pond fauna as well as on the analysis of stomach content data, growth rates and population dynamics of the salamander larvae in pond habitats. By their deposition of larvae in early spring, female fire salamanders import between 0.07 and 2.86 g dry mass m(-2) larval biomass into the ponds. Due to high mortality rates in the larval phase and the relatively small size at metamorphosis of the pond-adapted salamanders compared to stream-adapted ones, the biomass export of the metamorphosed salamanders clearly falls below the initial biomass import. Catastrophic events such as high water temperatures and low oxygen levels may even occasionally result in mass mortalities of salamander larvae and thus in a net 100 % import of the salamander biomass into the pond food webs. Indirect effects further accelerate this net import of matter into the aquatic habitat, e.g. the feeding of salamanders on aquatic insect larvae with the emergence of terrestrial adults-thus preventing export-and on terrestrial organisms that fall on the water surface (supporting import). This study demonstrates that the adaptation of salamanders to pond reproduction can alter food web linkages across ecosystem boundaries by enhancing the flux of materials and energy from terrestrial (i.e. forest) to the aquatic (i.e. pond) habitat.
生活史特征和物种行为的转变可能会改变生态系统的功能。中欧火蝾螈（Salamandra salamandra）的繁殖方式就是该物种最近发生的局部适应的一个例子，它们通常将幼虫产在一级溪流中，而现在它们也会在小池塘和池塘状栖息地繁殖。在这里，我们旨在量化捕食性幼虫对池塘生物群落中的水生食物网以及池塘与相邻陆地栖息地之间物质通量的直接和间接影响。我们的估计是基于池塘现生物种的生物量数据以及对池塘栖息地中蝾螈幼虫的胃内容物数据、生长率和种群动态的分析。通过在早春产卵，雌性火蝾螈将 0.07 到 2.86 克干物质幼虫生物量导入池塘。由于幼虫阶段死亡率高，以及与适应溪流的个体相比，适应池塘的个体在变态时体型相对较小，因此变态后的蝾螈生物量输出明显低于最初的生物量输入。像高温和低氧水平等灾难性事件甚至可能偶尔导致大量的幼虫死亡，从而导致蝾螈生物量 100%净输入到池塘食物网中。间接影响进一步加速了物质向水生栖息地的净输入，例如，蝾螈以水生昆虫幼虫为食，这些幼虫会变成陆地成虫（阻止了输出），或者以落在水面上的陆地生物为食（支持了输入）。这项研究表明，蝾螈适应池塘繁殖可以通过增加从陆地（即森林）到水生（即池塘）栖息地的物质和能量通量来改变生态系统边界的食物网联系。
