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首页> 外文期刊>Ecological research >A trophic cascade in a macrophyte-based food web at the land-water ecotone
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A trophic cascade in a macrophyte-based food web at the land-water ecotone

机译：陆水交错带基于植物的食物网中的营养级联

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Trophic cascades may purportedly be more common in aquatic than terrestrial food webs, but her-bivory on freshwater vascular plants has historically been considered low. Water lilies are an exception, suffering severe grazing damage by leaf beetles. To test whether a central prediction of cascade models-that predator effects propagate downwards to plants-operates in a macrophyte-based food web, we experimentally manipulated predation pressure on a key herbivore of water lilies in the littoral zone of a lake in Michigan, USA. Field experiments comprised combinations of caging treatments to alter the number of predators (larvae of the ladybird beetle Coleomegilla maculata) that hunt the grazers of the macrophytes (larvae of the leaf beetles Galerucella nymphaeae) on the leaves of the water lily Nuphar advena. Predatory larvae of the ladybird beetles significantly reduced grazing damage to water-lily leaves by 35-43%. The predators reduced plant damage chiefly via density-mediated effects, when lower densities of grazers translated to significant declines in plant damage. Plant damage caused by the surviving herbivores was less than predicted from individual grazing rates under predator-free conditions. This suggests that trait-mediated effects may possibly also operate in this cascade. The observed strong effect of predators on a non-adjacent trophic level concurs with an essential component of the trophic cascade model, and the cascade occurred at the ecotone between aquatic and terrestrial habitats: Nuphar is an aquatic macro-phyte with emergent and floating leaves, whereas both beetle species are semi-terrestrial and use the dry, emergent and floating leaves of the water lily as habitat. Also, the cascade is underpinned by freshwater macrophytes-a group for which trophic processes have often been underappreciated in the past.
机译：据说营养级联在水生生物中比陆生食物网更为普遍，但从历史上看，其在淡水维管植物上的象牙质很低。睡莲是一个例外，它的叶甲虫对牧草造成了严重破坏。为了测试级联模型的中心预测（即捕食者的作用向下传播到植物）是否在基于大型植物的食物网中运行，我们通过实验控制了美国密歇根州湖沿岸带主要食草动物的捕食压力。 。野外实验包括笼养处理的组合，以改变捕食睡莲Nuphar advena叶片上的大型植物（叶甲虫Galerucella nymphaeae的掠食者）的掠食者（瓢虫甲虫Coleomegilla maculata的幼虫）的数量。瓢虫的掠食性幼虫显着减少了对睡莲叶片的放牧损害，降低了35-43％。掠食者降低密度主要导致密度的下降，主要是通过密度介导的作用来减少植物的损害。在无捕食者的条件下，存活的草食动物造成的植物损害少于个体放牧率所预测的损害。这表明特质介导的作用也可能在此级联中起作用。所观察到的掠食者对非邻近营养水平的强效与营养级联模型的基本组成部分是一致的，并且级联发生在水生和陆地生境之间的过渡带：Nuphar是一种水生大型植物，具有出生叶和浮叶，而这两种甲虫都是半陆生的，并使用睡莲的干燥，出苗和漂浮的叶子作为栖息地。同样，级联是由淡水大型植物支撑的，该类植物的营养过程在过去常常被低估。

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