Environmental context determines multi‐trophic effects of consumer species loss
Environmental context determines multi‐trophic effects of consumer species loss
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环境背景决定了消费者物种丧失的多营养效应
DOI：
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发表时间：
2013
影响因子：
11.6
通讯作者：
I. Donohue
中科院分区：
文献类型：
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作者：
Nessa E. O’Connor;I. Donohue
生物多样性的丧失和营养物质的富集是人类对全球生态系统的两个主要影响，但我们对多种压力对自然群落的相互影响以及这与生物多样性和生态系统功能的关系知之甚少。推进我们的理解需要以下几点：（1）纳入自然生态系统中营养级内和营养级之间发生的过程;（2）测试物种损失效应的背景依赖性。我们研究了一个关键的捕食者和两组它的猎物的藻类组合在环境和丰富的营养条件下，在海洋底栖系统的损失的影响，并测试了功能多样性和营养丰富的生态系统功能的损失之间的相互作用。我们发现，丰富的食物网结构相互作用，改变自然群落中物种损失的影响。在环境条件下，初级消费者的损失导致藻类生物量的增加，而捕食者的损失导致藻类生物量的减少（即营养级联）。然而，与预期相反，我们发现营养富集否定了捕食者对藻类的级联效应。此外，藻类组合结构的变化在不同的方式响应贻贝损失，食草动物损失，捕食者损失和营养物质富集，补偿性变化的藻类丰度驱动的不同藻类物种的响应不同的环境条件和存在不同的消费者。我们确定并描述了几种驱动消费者直接和间接影响的情境依赖机制。我们的研究结果强调了在研究潜在的物种冗余时，特别是在不断变化的环境条件下，需要考虑环境背景。此外，基于经验证据的非营养相互作用必须纳入基于食物网的生态模型，以提高对全球变化的社区反应的理解。
Loss of biodiversity and nutrient enrichment are two of the main human impacts on ecosystems globally, yet we understand very little about the interactive effects of multiple stressors on natural communities and how this relates to biodiversity and ecosystem functioning. Advancing our understanding requires the following: (1) incorporation of processes occurring within and among trophic levels in natural ecosystems and (2) tests of context‐dependency of species loss effects. We examined the effects of loss of a key predator and two groups of its prey on algal assemblages at both ambient and enriched nutrient conditions in a marine benthic system and tested for interactions between the loss of functional diversity and nutrient enrichment on ecosystem functioning. We found that enrichment interacted with food web structure to alter the effects of species loss in natural communities. At ambient conditions, the loss of primary consumers led to an increase in biomass of algae, whereas predator loss caused a reduction in algal biomass (i.e. a trophic cascade). However, contrary to expectations, we found that nutrient enrichment negated the cascading effect of predators on algae. Moreover, algal assemblage structure varied in distinct ways in response to mussel loss, grazer loss, predator loss and with nutrient enrichment, with compensatory shifts in algal abundance driven by variation in responses of different algal species to different environmental conditions and the presence of different consumers. We identified and characterized several context‐dependent mechanisms driving direct and indirect effects of consumers. Our findings highlight the need to consider environmental context when examining potential species redundancies in particular with regard to changing environmental conditions. Furthermore, non‐trophic interactions based on empirical evidence must be incorporated into food web‐based ecological models to improve understanding of community responses to global change.