Trophic cascades in rocky shore tide pools: distinguishing lethal and nonlethal effects
Trophic cascades in rocky shore tide pools: distinguishing lethal and nonlethal effects
复制标题
岩石海岸潮汐池中的营养级联：区分致命和非致命效应
DOI：
10.1007/s00442-004-1512-8
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发表时间：
2004
期刊：
影响因子：
2.7
通讯作者：
B. Silliman
中科院分区：
文献类型：
--
作者：
G. Trussell;P. Ewanchuk;M. Bertness;B. Silliman
捕食者对猎物密度的影响可以通过营养级联对猎物资源的丰富性产生积极的间接影响。这一概念强烈影响了当代人们对社区结构的看法。然而，捕食者也可以通过诱导猎物特征的变化来传递间接影响。我们表明，仅仅是捕食者风险线索的存在就可以在岩石海岸潮汐池塘中引发营养级联。在大型(平均表面积=9平方米)天然潮汐池塘中，我们操纵螃蟹密度及其觅食能力，以考察致命性(密度介导型)和非致命性(性状介导型)捕食者效应对藻类群落发展的相对重要性。我们发现，感知捕食风险与直接捕食处理一样降低了钉螺密度，表明青蟹捕食不是调控当地钉螺密度的重要因素。相反，蜗牛迁徙离开当地的螃蟹似乎是调节当地蜗牛密度的最重要因素。因此，短命绿藻在捕食风险和直接捕食处理中的丰度相似，表明蟹类对蜗牛的摄食在营养级联中的中介作用最小。对捕食者诱导的猎物行为变化所传递的特征中介效应的日益关注，可能会改变我们对捕食者如何对群落结构施加强大影响的看法。
The effects of predators on the density of their prey can have positive indirect effects on the abundance of the prey’s resource via a trophic cascade. This concept has strongly influenced contemporary views of how communities are structured. However, predators also can transmit indirect effects by inducing changes in prey traits. We show that the mere presence of predator risk cues can initiate a trophic cascade in rocky shore tide pools. In large (mean surface area =9 m2), natural tide pools, we manipulated crab density and their foraging ability to examine the relative importance of lethal (density-mediated) and non-lethal (trait-mediated) predator effects to algal community development. We found that perceived predation risk reduced snail density as much as the direct predation treatment, showing that green crab predation was not an important factor regulating local snail density. Instead, snail emigration away from resident crabs appears to be the most important factor regulating local snail density. As a result, the abundance of ephemeral green algae was similar in the predation risk and direct predation treatments, suggesting that the consumption of snails by crabs plays a minimal role in mediating the trophic cascade. Increased attention to trait-mediated effects that are transmitted by predator-induced changes in prey behavior may change our view of how predators exert their strong influence on community structure.