Sampaio E, Rodil I F, Vaz-Pinto F, Fernández A, Arenas F
Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; MARE - Marine Environmental Science Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, Cascais 2750-374, Portugal.
Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; Tvärminne Zoological Station, University of Helsinki, Hanko, Finland; Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
Mar Environ Res. 2017 Apr;125:25-33. doi: 10.1016/j.marenvres.2017.01.001. Epub 2017 Jan 6.
Since the past century, rising CO levels have led to global changes (ocean warming and acidification) with subsequent effects on marine ecosystems and organisms. Macroalgae-herbivore interactions have a main role in the regulation of marine community structure (top-down control). Gradients of warming prompt complex non-linear effects on organism metabolism, cascading into altered trophic interactions and community dynamics. However, not much is known on how will acidification and grazer assemblage composition shape these effects. Within this context, we aimed to assess the combined effects of warming gradients and acidification on macroalgae-herbivore interactions, using three cosmopolitan species, abundant in the Iberian Peninsula and closely associated in nature: the amphipod Melita palmata, the gastropod Gibbula umbilicalis, and the green macroalga Ulva rigida. Under two CO treatments (ΔCO ≃ 450 μatm) across a temperature gradient (13.5, 16.6, 19.9 and 22.1 °C), two mesocosm experiments were performed to assess grazer consumption rates and macroalgae-herbivore interaction, respectively. Warming (Experiment I and II) and acidification (Experiment II) prompted negative effects in grazer's survival and species-specific differences in consumption rates. M. palmata was shown to be the stronger grazer per biomass (but not per capita), and also the most affected by climate stressors. Macroalgae-herbivore interaction strength was markedly shaped by the temperature gradient, while simultaneous acidification lowered thermal optimal threshold. In the near future, warming and acidification are likely to strengthen top-down control, but further increases in disturbances may lead to bottom-up regulated communities. Finally, our results suggest that grazer assemblage composition may modulate future macroalgae-herbivore interactions.
自上个世纪以来，不断上升的二氧化碳水平导致了全球变化（海洋变暖和酸化），进而对海洋生态系统和生物产生影响。大型海藻与食草动物的相互作用在海洋群落结构的调节（自上而下的控制）中起着主要作用。变暖梯度对生物体新陈代谢产生复杂的非线性影响，进而影响营养级相互作用和群落动态。然而，关于酸化和食草动物组合组成如何塑造这些影响，我们所知甚少。在此背景下，我们旨在评估变暖梯度和酸化对大型海藻与食草动物相互作用的综合影响，使用三种在伊比利亚半岛丰富且在自然环境中密切相关的世界性物种：双壳类动物梅利塔棕榈虫、腹足类动物脐螺和绿色大型海藻硬石莼。在两个二氧化碳处理水平（ΔCO≃450μatm）下，设置一个温度梯度（13.5、16.6、19.9和22.1°C），分别进行了两个中宇宙实验，以评估食草动物的摄食率和大型海藻与食草动物的相互作用。变暖（实验I和II）和酸化（实验II）对食草动物的存活产生负面影响，并导致摄食率的物种特异性差异。梅利塔棕榈虫被证明是单位生物量（而非人均）更强的食草动物，并且也是受气候压力影响最大的。大型海藻与食草动物的相互作用强度明显受温度梯度影响，而同时酸化降低了热最佳阈值。在不久的将来，变暖和酸化可能会加强自上而下的控制，但干扰的进一步增加可能会导致由自下而上调节的群落。最后，我们的结果表明，食草动物组合组成可能会调节未来大型海藻与食草动物的相互作用。
