Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
DiSTeM, CoNISMa, University of Palermo, Palermo, Italy.
Glob Chang Biol. 2018 Jan;24(1):e112-e127. doi: 10.1111/gcb.13856. Epub 2017 Sep 11.
Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO change and, if high pCO is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO stress, or are worsened by departures from prior high pCO conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments along a shallow water volcanic pCO gradient to assess the importance of the timing and duration of high pCO exposure (i.e., discrete events at different stages of successional development vs. continuous exposure) on patterns of colonization and succession in a benthic fouling community. We show that succession at the acidified site was initially delayed (less community change by 8 weeks) but then caught up over the next 4 weeks. These changes in succession led to homogenization of communities maintained in or transplanted to acidified conditions, and altered community structure in ways that reflected both short- and longer-term acidification history. These community shifts are likely a result of interspecific variability in response to increased pCO and changes in species interactions. High pCO altered biofilm development, allowing serpulids to do best at the acidified site by the end of the experiment, although early (pretransplant) negative effects of pCO on recruitment of these worms were still detectable. The ascidians Diplosoma sp. and Botryllus sp. settled later and were more tolerant to acidification. Overall, transient and persistent acidification-driven changes in the biofouling community, via both past and more recent exposure, could have important implications for ecosystem function and food web dynamics.
海洋酸化可能对海洋群落和生态系统动态产生深远的影响，但由于难以在生态系统层面上操纵 pCO 来模拟不同时间尺度上发生的现实波动，其全部影响仍未得到充分理解。特别不清楚处于不同发育阶段的群落对中等规模 pCO 变化的反应有多快，如果在演替过程中高 pCO 得到缓解，过去的酸化影响是否会持续存在，是否会因 pCO 缓解而逆转，或者是否会因偏离生物已经适应的先前高 pCO 条件而恶化。在这里，我们使用浅海水域火山 pCO 梯度的互惠移植实验来评估高 pCO 暴露的时间和持续时间（即演替过程中不同阶段的离散事件与连续暴露）对底栖生物结垢群落定殖和演替模式的重要性。我们表明，酸化地点的演替最初被延迟（8 周内群落变化较少），但随后在接下来的 4 周内赶上。这些演替变化导致在酸化条件下维持或移植的群落同质化，并以反映短期和长期酸化历史的方式改变群落结构。这些群落变化可能是由于对增加的 pCO 的种间变异性和物种相互作用的变化导致的。高 pCO 改变了生物膜的发育，使盘管虫在实验结束时在酸化地点表现最好，尽管在移植前 pCO 对这些蠕虫的早期招募仍有负面影响。尾索动物 Diplosoma sp. 和 Botryllus sp. 后来定居，并对酸化更耐受。总的来说，生物结垢群落因过去和最近的暴露而导致的短暂和持续的酸化驱动变化，可能对生态系统功能和食物网动态产生重要影响。
