Czerniawski Robert, Sługocki Łukasz, Kowalska-Góralska Monika
Department of General Zoology, University of Szczecin, Szczecin, Poland.
Centre of Molecular Biology and Biotechnology, University of Szczecin, Szczecin, Poland.
PLoS One. 2016 Jul 8;11(7):e0158837. doi: 10.1371/journal.pone.0158837. eCollection 2016.
The reduced zooplankton abundance at the outlet sections of lakes depends on the occurrence of preying fry. Therefore, light conditions can play a major role in the drift of zooplankton along river outlets. The aim of this study was to determine the influence of diurnal light conditions on the decline of zooplankton densities at lake outlets. Photosynthetically active radiation (PAR) levels were measured to determine their effect on the rate of reduced zooplankton abundance. Cladocerans and copepods showed a significantly greater reduction in abundance than rotifers and nauplii. A significant positive relationship was observed between the PAR levels and the reduced abundance of Asplanchna sp., small cladocerans, large cladocerans and Copepoda at the lake outlets. Among the rotifers, small pelagic rotifers drifted the farthest at all hours of the day. Large crustaceans, especially the large cladocerans and copepodites and adult copepods, had the lowest chance of dispersing over a wide area. Our results indicate that light conditions play an important role in the reduction of zooplankton abundance at lake outlets and have an indirect influence on the downstream food web.
湖泊出水口处浮游动物数量的减少取决于捕食性鱼苗的出现。因此，光照条件在浮游动物沿河流出水口的漂移过程中可能起主要作用。本研究的目的是确定昼夜光照条件对湖泊出水口浮游动物密度下降的影响。测量光合有效辐射（PAR）水平以确定其对浮游动物数量减少速率的影响。枝角类和桡足类的数量减少幅度明显大于轮虫和无节幼体。在湖泊出水口，PAR水平与湖泊出水口处阿斯普蓝氏轮虫、小型枝角类、大型枝角类和桡足类数量的减少之间存在显著的正相关关系。在轮虫中，小型浮游轮虫在一天中的所有时间里漂移得最远。大型甲壳类动物，尤其是大型枝角类、桡足幼体和成体桡足类，在广泛区域扩散的机会最低。我们的结果表明，光照条件在湖泊出水口浮游动物数量的减少中起重要作用，并对下游食物网产生间接影响。
