Disentangling the effects of cyclical variability in environmental forcing and long‐term climate change on natural communities is a major challenge for ecologists, managers, and policy makers across ecosystems. Here we examined whether the vertical distribution of rocky intertidal taxa has shifted with sea‐level variability occurring at multiple temporal scales and/or long‐term anthropogenic sea‐level rise (SLR). Because of the distinct zonation characteristic of intertidal communities, any shift in tidal dynamics or average sea level is expected to have large impacts on community structure and function. We found that across the Northeast Pacific Coast (NPC), sea level exhibits cyclical seasonal variability, tidal amplitude exhibits ecologically significant variability coherent with the 18.6‐year periodicity of lunar declination, and long‐term sea‐level rise is occurring. Intertidal taxa largely do not exhibit significant vertical distribution shifts coherent with short‐term (monthly to annual) sea‐level variability but do exhibit taxa‐specific vertical distribution shifts coherent with cyclical changes in lunar declination and long‐term SLR at decadal timescales. Finally, our results show that responses to cyclical celestial mechanics and SLR vary among taxa, primarily according to their vertical distribution. Long‐term SLR is occurring on ecologically relevant scales, but the confounding effects of cyclical celestial mechanics make interpreting shifts in zonation or community structure challenging. Such cyclical dynamics alternatingly amplify and dampen long‐term SLR impacts and may modify the impacts of other global change related stressors, such as extreme heat waves and swell events, on intertidal organisms living at the edge of their physiological tolerances. As a result, intertidal communities will likely experience cyclical periods of environmental stress and concomitant nonlinear shifts in structure and function as long‐term climate change continues. Our results demonstrate that consistent, large‐scale monitoring of marine ecosystems is critical for understanding natural variability in communities and documenting long‐term change.

中文翻译：

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岩石潮间带生物的垂直分布随东北太平洋沿岸的海平面变化而变化


理清环境强迫的周期性变化和长期气候变化对自然群落的影响，是生态系统中生态学家、管理者和政策制定者面临的重大挑战。在这里，我们研究了岩石潮间带类群的垂直分布是否随着多个时间尺度上的海平面变化和/或长期人为海平面上升 （SLR） 而发生变化。由于潮间带群落的独特分区特征，预计潮汐动力学或平均海平面的任何变化都会对群落结构和功能产生重大影响。我们发现，在整个东北太平洋海岸 （NPC），海平面表现出周期性的季节性变化，潮汐振幅表现出与 18.6 年月偏角周期一致的生态显着变化，并且海平面正在发生长期上升。潮间带分类群在很大程度上没有表现出与短期（每月到每年）海平面变化相一致的显着垂直分布变化，但确实表现出与月偏角和十年时间尺度上长期 SLR 的周期性变化相一致的分类群特异性垂直分布变化。最后，我们的结果表明，对周期性天体力学和 SLR 的响应因分类群而异，主要取决于它们的垂直分布。长期 SLR 发生在生态相关的尺度上，但周期性天体力学的混杂效应使得解释分区或群落结构的变化具有挑战性。这种周期性动力学交替放大和抑制长期 SLR 影响，并可能改变其他与全球变化相关的压力源（例如极端热浪和涌浪事件）对生活在生理耐受性边缘的潮间带生物的影响。 因此，随着长期气候变化的持续，潮间带群落可能会经历环境压力的周期性时期，并随之而来的结构和功能的非线性变化。我们的结果表明，对海洋生态系统进行一致、大规模的监测对于了解群落的自然变化和记录长期变化至关重要。