Newcomb L A, Cannistra A F, Carrington E
Department of Biology, University of Washington, Seattle, Washington 98195, USA.
Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA.
Integr Comp Biol. 2022 Jul 6. doi: 10.1093/icb/icac111.
Organisms rely on the integrity of the structural materials they produce to maintain a broad range of processes, such as acquiring food, resisting predators or withstanding extreme environmental forces. The production and maintenance of these biomaterials, which are often modulated by environmental conditions, can therefore have important consequences for fitness in changing climates. One well-known example of such a biomaterial is mussel byssus, an array of collagen-like fibers (byssal threads) that tethers a bivalve mollusk securely to benthic marine substrates. Byssus strength directly influences mortality from dislodgement, predation or competition and depends on the quantity and quality of byssal threads produced. We compared the temperature sensitivity of byssal attachment strength of two mussel species common to the west coast of North America, Mytilus trossulus and M. galloprovincialis, when exposed to seawater temperatures ranging from 10 to 24˚C in the laboratory. We found the two species attached equally strong in seawater ≤ 18˚C, but higher temperatures caused byssal thread production rate and quality (break force and extensibility) to be greatly reduced in M. trossulus and increased in M. galloprovincialis, leading to a 2 to 10-fold difference in overall byssus strength between the two species. Using this threshold value (18˚C), we mapped habitat for each species along the west coast of North America based on annual patterns in sea surface temperature. Estimated ranges are consistent with the current distribution of the two species and suggest a potential mechanism by which ocean warming could facilitate the northern expansion of M. galloprovincialis and displacement of native M. trossulus populations.
生物体依靠它们所产生的结构材料的完整性来维持广泛的生理过程，比如获取食物、抵御捕食者或承受极端环境力量。这些生物材料的产生和维持通常受环境条件调节，因此在气候变化的情况下可能对适应性产生重要影响。这种生物材料的一个著名例子是贻贝足丝，它是一束类似胶原蛋白的纤维（足丝），能将双壳贝类软体动物牢固地固定在海底海洋基质上。足丝强度直接影响因脱离、捕食或竞争导致的死亡率，并且取决于所产生的足丝的数量和质量。我们在实验室中将北美西海岸常见的两种贻贝，即紫贻贝和地中海贻贝，暴露于10至24˚C的海水温度下，比较了它们足丝附着强度的温度敏感性。我们发现，在海水温度≤18˚C时，这两种贻贝的附着强度相同，但温度升高会导致紫贻贝的足丝产生速率和质量（断裂力和延伸性）大幅降低，而地中海贻贝的足丝产生速率和质量则会增加，导致两种贻贝的整体足丝强度相差2至10倍。利用这个阈值（18˚C），我们根据海表温度的年度模式绘制了北美西海岸每个物种的栖息地分布图。估计范围与这两个物种的当前分布一致，并表明海洋变暖可能促进地中海贻贝向北扩张并取代本地紫贻贝种群的潜在机制。
