In coastal marine environments, physical and biological forces can cause dynamic pH fluctuations from microscale (diffusive boundary layer [DBL]) up to ecosystem‐scale (benthic boundary layer [BBL]). In the face of ocean acidification (OA), such natural pH variations may modulate an organism's response to OA by providing temporal refugia. We investigated the effect of pH fluctuations, generated by the brown alga Fucus serratus' biological activity, on the calcifying epibionts Balanus improvisus and Electra pilosa under OA. For this, both epibionts were grown on inactive and biologically active surfaces and exposed to (1) constant pH scenarios under ambient (pH 8.1) or OA conditions (pH 7.7), or (2) oscillating pH scenarios mimicking BBL conditions at ambient (pH 7.7–8.6) or OA scenarios (pH 7.4–8.2). Furthermore, all treatment combinations were tested at 10°C and 15°C. Against our expectations, OA treatments did not affect epibiont growth under constant or fluctuating (BBL) pH conditions, indicating rather high robustness against predicted OA scenarios. Furthermore, epibiont growth was hampered and not fostered on active surfaces (fluctuating DBL conditions), indicating that fluctuating pH conditions of the DBL with elevated daytime pH do not necessarily provide temporal refugia from OA. In contrast, results indicate that factors other than pH may play larger roles for epibiont growth on macrophytes (e.g., surface characteristics, macrophyte antifouling defense, or dynamics of oxygen and nutrient concentrations). Warming enhanced epibiont growth rates significantly, independently of OA, indicating no synergistic effects of pH treatments and temperature within their natural temperature range.

中文翻译：

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钙化海洋表皮生物对生物pH波动和全球海洋酸化情景的生长响应

在沿海海洋环境中，物理和生物力会导致动态pH波动，从微尺度（扩散边界层[DBL]）到生态系统尺度（底栖边界层[BBL]）。面对海洋酸化（OA），此类自然pH值变化可能会通过提供暂时的抑制作用来调节生物体对OA的反应。我们研究了pH值波动的影响，由褐藻产生的墨角藻锯的钙化epibion​​ts“生物活性，藤improvisus和恋父草在OA下。为此，两种表皮动物都生长在无活性和生物活性的表面上，并暴露于（1）在环境（pH 8.1）或OA条件（pH 7.7）下恒定的pH方案，或（2）在环境（pH）下模拟BBL条件的振荡pH方案7.7–8.6）或OA方案（pH 7.4–8.2）。此外，所有处理组合均在10°C和15°C下测试。与我们的预期相反，在恒定或波动的（BBL）pH条件下，OA处理均不会影响表生子的生长，这表明在预测的OA情况下具有很高的鲁棒性。此外，表观生物的生长受到阻碍，并且没有在活性表面上生长（波动的DBL条件），这表明白天pH升高的DBL的pH条件波动并不一定会导致OA暂时性衰弱。相比之下，结果表明，pH以外的其他因素可能对大型植物的表生生物生长起更大的作用（例如，表面特性，大型植物的防污防御或氧气和养分浓度的动态变化）。升温独立于OA显着提高了表观生物的生长速率，表明pH处理和温度在其自然温度范围内没有协同作用。