Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia, Canada.
Glob Chang Biol. 2023 Jan;29(1):165-178. doi: 10.1111/gcb.16390. Epub 2022 Aug 25.
Heatwave frequency and intensity will increase as climate change progresses. Intertidal sessile invertebrates, which often form thermally benign microhabitats for associated species, are vulnerable to thermal stress because they have minimal ability to behaviourally thermoregulate. Understanding what factors influence the mortality of biogenic species and how heatwaves might impact their ability to provide habitat is critical. Here, we characterize the community associated with the thatched barnacle, Semibalanus cariosus (Pallass, 1788), in British Columbia (BC), Canada. Then, we investigate what site-level and plot-level environmental factors explained variations in barnacle mortality resulting from an unprecedented regional heatwave in BC, Canada. Furthermore, we used a manipulative shading experiment deployed prior to the heatwave to examine the effect of thermal stress on barnacle survival and recruitment and the barnacle-associated community. We identified 50 taxa inhabiting S. cariosus beds, with variations in community composition between sites. Site-scale variables and algal canopy cover did not predict S. cariosus mortality, but patch-scale variation in substratum orientation did, with more direct solar irradiance corresponding with higher barnacle mortality. The shading experiment demonstrated that S. cariosus survival, barnacle recruitment, and invertebrate community diversity were higher under shades where substratum temperatures were lower. Associated community composition also differed between shaded and non-shaded plots, suggesting S. cariosus was not able to fully buffer acute thermal stress for its associated community. While habitat provisioning by intertidal foundation species is an important source of biodiversity, these species alone may not be enough to prevent substantial community shifts following extreme heatwaves. As heatwaves become more frequent and severe, they may further reduce diversity via the loss of biogenic habitat, and spatial variation in these impacts may be substantial.
热浪的频率和强度将随着气候变化而增加。潮间带固着无脊椎动物通常为相关物种形成热舒适的小生境，但它们很容易受到热胁迫的影响，因为它们的行为热调节能力很小。了解哪些因素会影响生物种的死亡率，以及热浪如何影响它们提供栖息地的能力是至关重要的。在这里，我们描述了加拿大不列颠哥伦比亚省（BC）的那篷藤壶（Semibalanus cariosus）相关群落。然后，我们研究了什么是站点级和图级环境因素解释了前所未有的不列颠哥伦比亚省热浪导致藤壶死亡率的变化。此外，我们在热浪之前使用了一个操纵性遮蔽实验，研究了热应激对藤壶生存和繁殖以及藤壶相关群落的影响。我们确定了 50 种生物栖息在 S. cariosus 床上，不同的生物群落组成存在于不同的地点。站点尺度的变量和藻类冠层覆盖度不能预测 S. cariosus 的死亡率，但斑块尺度上的基底取向变化可以预测，更多的直接太阳辐射对应着更高的藤壶死亡率。遮蔽实验表明，在基底温度较低的遮蔽下，S. cariosus 的存活率、藤壶的繁殖率和无脊椎动物群落的多样性更高。相关群落的组成也在遮蔽和非遮蔽的图块之间存在差异，这表明 S. cariosus 无法完全缓冲其相关群落的急性热应激。虽然潮间带基础物种提供栖息地是生物多样性的一个重要来源，但仅靠这些物种可能不足以防止在极端热浪之后发生重大的群落变化。随着热浪变得更加频繁和严重，它们可能会通过失去生物生境进一步降低多样性，而这些影响的空间变化可能很大。
