Department of Ecology and Biogeography, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Toruń, Poland.
Department of Ecology and Biogeography, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University, Toruń, Poland.
Sci Total Environ. 2019 Sep 20;684:14-22. doi: 10.1016/j.scitotenv.2019.05.280. Epub 2019 May 21.
Due to the widespread use of artificial light, freshwater ecosystems in urban areas at night are often subjected to light of intensities exceeding that of the moonlight. Nocturnal dim light could modify fish behaviour and benefit visual predators because of enhanced foraging success compared to dark nights. However, effects of nocturnal light could be mitigated by the presence of structured habitats providing refuges for prey. We tested in laboratory experiments whether nocturnal light of low intensity (2 lx) increases foraging efficiency of the Eurasian perch (Perca fluviatilis) on invertebrate prey (Gammarus fossarum). The tests were conducted at dusk and night under two light regimes: natural cycle with dark nights and disturbed cycle with artificially illuminated nights, in habitats differing in structural complexity: sand and woody debris. We found that nocturnal illumination significantly enhanced the consumption of gammarids by fish compared to dark nights. In addition, the perch was as effective predator in illuminated nights (2 lx) as at dusk (10 lx). Woody debris provided an effective refuge only in combination with undisturbed darkness, but not in illuminated nights. Our results suggest that nocturnal illumination in aquatic ecosystems may contribute to significant reductions in invertebrate population sizes through fish predation. The loss of darkness reduces the possibility of using shelters by invertebrates and hence the effects of elevated light levels at night could not be mitigated by an increased habitat complexity.
由于人工照明的广泛使用，城市地区的淡水生态系统在夜间经常受到超过月光强度的光照。与黑暗的夜晚相比，夜间微光可能会改变鱼类的行为，并使视觉捕食者受益，因为它们的觅食成功率更高。然而，由于存在为猎物提供避难所的结构化栖息地，夜间光的影响可能会减轻。我们在实验室实验中测试了低强度（2 勒克斯）的夜间光是否会提高欧洲鲈鱼（Perca fluviatilis）对无脊椎动物猎物（Gammarus fossarum）的觅食效率。测试在黄昏和夜间进行，有两种光照条件：自然周期（黑暗的夜晚）和受干扰的周期（人工照明的夜晚），以及两种结构复杂程度不同的栖息地：沙质底质和木质碎屑。我们发现，与黑暗的夜晚相比，夜间照明显著增加了鱼类对水蚤的消耗。此外，鲈鱼在光照的夜晚（2 勒克斯）和黄昏（10 勒克斯）一样有效地捕食。木质碎屑只有在不受干扰的黑暗中才能为鱼类提供有效的避难所，而在光照的夜晚则不能。我们的研究结果表明，水生生态系统中的夜间照明可能会通过鱼类捕食导致无脊椎动物种群数量显著减少。黑暗的丧失减少了无脊椎动物利用避难所的可能性，因此，夜间光照水平的升高不能通过增加栖息地的复杂性来减轻其影响。
