Human growth has caused an unprecedented increase in artificial light at night (ALAN). In coastal habitats, many species rely on day/night cycles to regulate various aspects of their life history and these cycles can be altered by this stressor. This study assessed the influence of ALAN on the early (cyprid) and late (spat) settlement stages of the acorn barnacle Semibalanus balanoides, a species widely distributed in natural and man-made coastal habitats of the North Atlantic. A newly designed settlement plate, originally for studies in rocky intertidal habitats in the southeast Pacific, was adapted to measure settlement rates on man-made habitats -wharf seawalls- located in Atlantic Canada. Plates equipped with a small LED diode powered by an internal battery (ALAN plates) were used to quantify settlement rates in comparison to plates lacking a light source (controls). These plates were deployed for 6 d in the mid-intertidal levels, where adult barnacles were readily visible. ALAN and control plates collected large number of settlers and showed to be suitable for this type of man-made habitats. The number of early settlers (cyprids) did not differ between plates but the number of late settlers (spat) was significantly lower in ALAN plates than in controls. These results suggest that light pollution has little influence on the early stages of the acorn barnacle settlement but is clearly detrimental to its late stages. As barnacles dominate in many natural and man-made hard substrates, it is likely that ALAN also has indirect effects on community structure.

人类的成长导致夜间人造光（ALAN）的空前增长。在沿海生境中，许多物种依靠昼/夜循环来调节其生活史的各个方面，而这些循环可以被这种压力源改变。这项研究评估了ALAN对橡子藤壶Semibalanus balanoides的早期（塞浦路斯）和晚期（spat）沉降阶段的影响该物种广泛分布于北大西洋的自然和人为沿海栖息地。新设计的沉降板最初用于研究东南太平洋的岩石潮间带栖息地，后来被用来测量位于加拿大大西洋的人工栖息地（码头海堤）的沉降率。与没有光源的板（对照）相比，配备有内部电池供电的小型LED二极管的板（ALAN板）用于量化沉降速率。这些板块在潮间带中水平放置了6天，在那里容易看到成年藤壶。ALAN和控制板收集了大量定居者，并显示适用于此类人造栖息地。平板之间的早期定居者（塞浦路斯）数量没有差异，但ALAN平板中的后期定居者（spat）数量明显低于对照组。这些结果表明，光污染对橡子藤壶沉降的早期几乎没有影响，但显然对其后期有害。由于藤壶在许多天然和人造硬质基质中占主导地位，因此ALAN可能也对群落结构产生间接影响。