Brown Norah E M, Therriault Thomas W, Harley Christopher D G
Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, BC, Canada.
Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Rd, Nanaimo, BC, Canada.
J Anim Ecol. 2016 Sep;85(5):1328-39. doi: 10.1111/1365-2656.12557. Epub 2016 Jul 11.
Increasing levels of CO2 in the atmosphere are affecting ocean chemistry, leading to increased acidification (i.e. decreased pH) and reductions in calcium carbonate saturation state. Many species are likely to respond to acidification, but the direction and magnitude of these responses will be based on interspecific and ontogenetic variation in physiology and the relative importance of calcification. Differential responses to ocean acidification (OA) among species will likely result in important changes in community structure and diversity. To characterize the potential impacts of OA on community composition and structure, we examined the response of a marine fouling community to experimental CO2 enrichment in field-deployed flow-through mesocosm systems. Acidification significantly altered the community structure by altering the relative abundance of species and reduced community variability, resulting in more homogenous biofouling communities from one experimental tile to the next both among and within the acidified mesocosms. Mussel (Mytilus trossulus) recruitment was reduced by over 30% in the elevated CO2 treatment compared to the ambient treatment by the end of the experiment. Strong differences in mussel cover (up to 40% lower in acidified conditions) developed over the second half of the 10-week experiment. Acidification did not appear to affect the mussel growth, as average mussel sizes were similar between treatments at the end of the experiment. Hydroid (Obelia dichotoma) cover was significantly reduced in the elevated CO2 treatment after 8 weeks. Conversely, the percentage cover of bryozoan colonies (Mebranipora membranacea) was higher under acidified conditions with differences becoming apparent after 6 weeks. Neither recruitment nor final size of barnacles (Balanus crenatus) was affected by acidification. By the end of the experiment, diversity was 41% lower in the acidified treatment relative to ambient conditions. Overall, our findings support the general expectation that OA will simplify marine communities by acting on important ecological processes that ultimately determine the community structure and diversity.
大气中二氧化碳水平的不断上升正在影响海洋化学，导致酸化加剧（即pH值降低）以及碳酸钙饱和状态下降。许多物种可能会对酸化做出反应，但这些反应的方向和程度将基于生理特征的种间和个体发育差异以及钙化的相对重要性。物种对海洋酸化（OA）的不同反应可能会导致群落结构和多样性发生重要变化。为了描述OA对群落组成和结构的潜在影响，我们在野外部署的流通式中宇宙系统中，研究了海洋污损生物群落对实验性二氧化碳富集的反应。酸化通过改变物种的相对丰度显著改变了群落结构，并降低了群落变异性，导致在酸化中宇宙内和之间，从一个实验瓦片到下一个实验瓦片的生物污损群落更加同质化。到实验结束时，与环境处理相比，在高二氧化碳处理中贻贝（Mytilus trossulus）的招募减少了30%以上。在为期10周的实验的后半段，贻贝覆盖率出现了强烈差异（在酸化条件下低至40%）。酸化似乎并未影响贻贝的生长，因为在实验结束时各处理之间的贻贝平均大小相似。8周后，在高二氧化碳处理中螅状群体（Obelia dichotoma）的覆盖率显著降低。相反，苔藓虫群落（Mebranipora membranacea）的覆盖率在酸化条件下更高，6周后差异变得明显。藤壶（Balanus crenatus）的招募和最终大小均未受到酸化的影响。到实验结束时，酸化处理中的多样性相对于环境条件降低了41%。总体而言，我们的研究结果支持了一般预期，即OA将通过作用于最终决定群落结构和多样性的重要生态过程来简化海洋群落。
