Omnivory and stability in freshwater habitats: Does theory match reality?
Omnivory and stability in freshwater habitats: Does theory match reality?
复制标题
DOI：
10.1111/fwb.12908
复制
发表时间：
2017-05
影响因子：
2.7
通讯作者：
K. Wootton
中科院分区：
文献类型：
--
作者：
K. Wootton
杂食性在多个营养级上进食，是淡水生态系统的一个普遍特征。了解杂食性在何时何地很重要、其与维持多样性的相关性以及其对生态系统对干扰的反应可能产生的影响，对于淡水生态系统的有效管理是必要的。关于杂食性影响的许多理论预测往往是相互矛盾的，旨在理解杂食性的实证研究一直很困难，并且取决于许多因素。在这里，我综合了理论证据，对杂食动物在淡水生态系统中最重要的位置、它的维持方式以及它对社区的影响做出了五项预测。首先，理论表明，虽然强的杂食性相互作用会破坏稳定，但弱的杂食性相互作用通常会增强稳定性。因此，降低杂食相互作用强度的机制应该有利于它们的发生并增加食物网的稳定性。其次，由于整个食物网的稳定特征，理论上不稳定的杂食性相互作用可能存在于稳定的食物网中。第三，杂食性可能主要在中等生产力水平上持续存在，并且在受干扰的环境中更为常见。第四，杂食可能会降低营养级联的强度。最后，杂食动物通常应该成为更成功的入侵者。这些预测对于有效的淡水管理非常重要，因为降低杂食性相互作用强度的行动，例如为消费者维持栖息地避难所（例如木质残骸和水生植物），可能对于维持生物多样性至关重要。此外，如果杂食动物是更好的入侵者，有效的入侵管理可能会受益于将资源集中在杂食入侵者上，以限制其传播和影响。总体而言，理论和实证研究的综合表明，虽然他们的预测可能经常不一致，但通过更深入的研究，它们在很大程度上是可以调和的，并且可以用来为淡水食物网中杂食动物的谨慎管理提出实际建议。
Omnivory, feeding at more than one trophic level, is a prevalent feature of freshwater ecosystems. Understanding where and when omnivory is important, its relevance for sustaining diversity, and the effect it may have on ecosystem responses to disturbances, are necessary for effective management of freshwater ecosystems. The many theoretical predictions of the effects of omnivory are often contradictory, and empirical studies aimed at understanding omnivory have been difficult and contingent on a number of factors. Here, I synthesise theoretical evidence to generate five predictions of where omnivory will be most important in freshwater ecosystems, how it is maintained and the effect it will have on communities. First, theory indicates that, while strong omnivorous interactions are destabilising, weak omnivorous interactions usually enhance stability. Therefore, mechanisms which decrease the strength of omnivorous interactions should favour their occurrence and increase stability of food webs. Secondly, omnivorous interactions which are theoretically unstable may be found in stable food webs due to stabilising features of the web as a whole. Thirdly, omnivory is likely to persist primarily at intermediate productivity levels and be more common in disturbed environments. Fourthly, omnivory is likely to decrease the strength of trophic cascades. Finally, omnivores should generally make more successful invaders. These predictions are important for effective freshwater management because actions which decrease the strength of omnivorous interactions, such as maintaining habitat refuges for consumers (e.g. woody debris and aquatic plants), may be essential for sustaining biodiversity. In addition, if omnivores make better invaders, effective invasion management may benefit from focussing resources on omnivorous invaders to limit their spread and impact. Overall, this synthesis of theoretical and empirical studies indicates that, while their predictions may be frequently at odds, with deeper investigation they are largely reconcilable and can be used to make practical suggestions for the careful management of omnivory in freshwater food webs.