Graduate School of Biosphere Science, Hiroshima University, Hiroshima, 739-8528, Japan.
Graduate School of Informatics, Kyoto University, Kyoto, 606-8501, Japan.
Sci Rep. 2017 Jun 20;7(1):3895. doi: 10.1038/s41598-017-04217-3.
The majority of surveys on food webs of aquatic ecosystems have been conducted during the day owning to difficulties in sampling animals at night. In this study, to examine diurnal changes in predator-prey interactions in a temperate seagrass Zostera marina bed, a quantitative day/night survey of fish, the dominant animal community, coupled with acoustic telemetry of their predators, was conducted. The number of species, abundance, and biomass of piscivorous predators and mean trophic level during the night were significantly higher than those in the day in all seasons. Analysis of the stomach contents of 182 piscivorous predators showed that no fish predation occurred during the day whereas predation occurred during the night in winter, spring, and summer. Acoustic telemetry demonstrated nocturnal visits by dominant piscivorous fish species (rockfishes and conger eel) to the seagrass bed. We conclude that the nocturnal visits by piscivorous fishes increased the predation risk and trophic level in the fish nursery. The ecological functions of seagrass beds should be reevaluated accounting for day/night changes in food webs; these areas serve as nurseries for juvenile and small-sized fishes during the day and as foraging grounds for predators during the night.
由于夜间采样动物存在困难，大多数水生生态系统食物网的调查都是在白天进行的。在这项研究中，为了研究温带海草床中捕食者-猎物相互作用的昼夜变化，对鱼类（占主导地位的动物群落）进行了定量的日夜调查，并结合了对其捕食者的声学遥测。在所有季节，夜间的物种数量、丰度和生物量以及平均营养水平均显著高于白天。对 182 种肉食性捕食者的胃内容物分析表明，冬季、春季和夏季白天没有鱼类捕食，而夜间有捕食。声学遥测表明，主要肉食性鱼类（石斑鱼和鳗鱼）在夜间会光顾海草床。我们得出结论，肉食性鱼类的夜间访问增加了鱼类托儿所的捕食风险和营养水平。应考虑食物网的昼夜变化来重新评估海草床的生态功能；这些区域白天是幼鱼和小鱼的托儿所，晚上是捕食者的觅食地。
