Guenther Rebecca, Miklasz Kevin, Carrington Emily, Martone Patrick T
Botany Department and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4.
Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington, 98250, USA.
J Phycol. 2018 Apr;54(2):153-158. doi: 10.1111/jpy.12614.
Early life stages of marine organisms are predicted to be vulnerable to ocean acidification. For macroalgae, reproduction and population persistence rely on spores to settle, adhere and continue the algal life cycle, yet the effect of ocean acidification on this critical life stage has been largely overlooked. We explicitly tested the biomechanical impact of reduced pH on early spore adhesion. We developed a shear flume to examine the effect of reduced pH on spore attachment time and strength in two intertidal rhodophyte macroalgae, one calcified (Corallina vancouveriensis) and one noncalcified (Polyostea robusta). Reduced pH delayed spore attachment of both species by 40%-52% and weakened attachment strength in C. vancouveriensis, causing spores to dislodge at lower flow-induced shear forces, but had no effect on the attachment strength of P. robusta. Results are consistent with our prediction that reduced pH disrupts proper curing and gel formation of spore adhesives (anionic polysaccharides and glycoproteins) via protonation and cation displacement, although experimental verification is needed. Our results demonstrate that ocean acidification negatively, and differentially, impacts spore adhesion in two macroalgae. If results hold in field conditions, reduced ocean pH has the potential to impact macroalgal communities via spore dysfunction, regardless of the physiological tolerance of mature thalli.
海洋生物的早期生命阶段预计容易受到海洋酸化的影响。对于大型藻类来说，繁殖和种群延续依赖于孢子的沉降、附着并继续藻类的生命周期，然而海洋酸化对这个关键生命阶段的影响在很大程度上被忽视了。我们明确测试了pH值降低对早期孢子附着的生物力学影响。我们开发了一个剪切水槽，以研究pH值降低对两种潮间带红藻大型藻类孢子附着时间和强度的影响，一种是钙化的（温哥华珊瑚藻），一种是非钙化的（粗壮多管藻）。pH值降低使两种藻类的孢子附着延迟了40%-52%，并削弱了温哥华珊瑚藻的附着强度，导致孢子在较低的水流诱导剪切力下脱落，但对粗壮多管藻的附着强度没有影响。结果与我们的预测一致，即pH值降低会通过质子化和阳离子置换破坏孢子粘合剂（阴离子多糖和糖蛋白）的正常固化和凝胶形成，尽管还需要实验验证。我们的结果表明，海洋酸化对两种大型藻类的孢子附着产生了负面且不同的影响。如果这些结果在野外条件下成立，海洋pH值降低有可能通过孢子功能障碍影响大型藻类群落，而不管成熟藻体的生理耐受性如何。
