Department of Biological Sciences, University of Victoria, Victoria, British Columbia, Canada V8P 5C2.
UWA Oceans Institute, School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia.
Proc Biol Sci. 2023 Apr 12;290(1996):20230209. doi: 10.1098/rspb.2023.0209.
Multiple anthropogenic stressors co-occur ubiquitously in natural ecosystems. However, multiple stressor studies often produce conflicting results, potentially because the nature and direction of stressor interactions depends upon the strength of the underlying stressors. Here, we first examine how coral α- and β-diversities vary across sites spanning a gradient of chronic local anthropogenic stress before and after a prolonged marine heatwave. Developing a multiple stressor framework that encompasses non-discrete stressors, we then examine interactions between the continuous and discrete stressors. We provide evidence of additive effects, antagonistic interactions (with heatwave-driven turnover in coral community composition diminishing as the continuous stressor increased), and tipping points (at which the response of coral Hill-richness to stressors changed from additive to near synergistic). We show that community-level responses to multiple stressors can vary, and even change qualitatively, with stressor intensity, underscoring the importance of examining complex, but realistic continuous stressors to understand stressor interactions and their ecological impacts.
多种人为压力因素普遍存在于自然生态系统中。然而，多项压力因素研究经常产生相互矛盾的结果，这可能是因为压力因素相互作用的性质和方向取决于潜在压力因素的强度。在这里，我们首先研究了在长期海洋热浪前后，跨越慢性局部人为压力梯度的地点，珊瑚 α 和 β 多样性如何变化。通过建立一个包含非离散压力因素的多压力因素框架，我们然后研究了连续压力因素和离散压力因素之间的相互作用。我们提供了加性效应、拮抗相互作用（随着连续压力因素的增加，热浪驱动的珊瑚群落组成的周转率降低）和临界点（珊瑚丰富度对压力因素的响应从加性变为近协同作用的点）的证据。我们表明，对多种压力因素的群落水平响应可能会随着压力因素强度的变化而变化，甚至会发生质的变化，这突出了研究复杂但现实的连续压力因素对于理解压力因素相互作用及其生态影响的重要性。
