The sensitivity of kelps to elevated temperatures has been linked to recent declines in some kelp populations, with cascading impacts on marine communities. However, it remains unclear how thermal stress affects the ability of kelps to respond to other environmental factors, which could influence their vulnerability to climate change. We investigated the effect of thermal stress on the ability of the bull kelp Nereocystis luetkeana to acclimate to its surrounding hydrodynamic environment through tension‐regulated plasticity in blade morphology. We first determined optimal and stressful temperatures for N. luetkeana by measuring growth over nine temperatures from 5°C to 22°C. We then exposed N. luetkeana blades to a factorial combination of temperature (13°C and 20°C) and tension (0.5 N and 2.0 N) simulating different flow conditions, and measured changes in blade length and width after 7 days. The temperature at which N. luetkeana exhibited maximum growth was estimated to be ~11.9°C, though growth was high over a relatively wide temperature range. When thermally stressed, N. luetkeana maintained morphological responses to simulated high flow, but were inhibited from acclimating to low flow, indicated by an inability of blades to widen. Our results suggest that N. luetkeana in sheltered habitats may be particularly vulnerable to climate warming, where an inability to adjust blade morphology to local hydrodynamic conditions could drive declines at sublethal levels of warming. As ecologically important foundation species, declines in sheltered kelp populations could result in major biodiversity loss and disrupt ecosystem function.

中文翻译：

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升高的温度影响公牛海带（Nereocystis luetkeana，Phaeophyceae）的表型可塑性。

海带对高温的敏感性与一些海带种群的近期减少有关，对海洋社区的影响是连锁的。但是，目前尚不清楚热应力如何影响海带对其他环境因素的反应能力，这可能会影响海带对气候变化的脆弱性。我们通过对叶片形态进行张力调节的可塑性研究了热应力对海带Nereocystis luetkeana适应其周围水动力环境的能力的影响。我们首先通过测量从5°C到22°C的9个温度下的生长情况，来确定luetkeana烟草的最佳温度和胁迫温度。然后，我们暴露了luetkeana猪笼草叶片在温度（13°C和20°C）和张力（0.5 N和2.0 N）的因子组合下模拟不同的流动条件，并在7天后测量了叶片长度和宽度的变化。尽管在相当宽的温度范围内生长很高，但卢埃斯猪笼草显示出最大生长的温度估计为〜11.9 °C。当受到热胁迫时，卢埃斯猪笼草保持对模拟高流量的形态响应，但是由于叶片无法加宽而受到抑制，无法适应低流量。我们的结果表明，N。luetkeana在庇护所的栖息地中，气候变暖尤其容易，在这种情况下，无法根据当地的水动力条件调整叶片形态可能会导致致死水平以下的致残率下降。作为具有重要生态意义的基础物种，庇护海带种群数量的减少可能导致生物多样性的大量丧失并破坏生态系统的功能。