Changes in balance of light and nutrient inputs induce stoichiometric plasticity of primary producers in aquatic food web. Generally, algal species produce high P content cells under low-light and vice versa when P supply is limited. Algal food with high P content improves growth rate of zooplankton. Accordingly, zooplankton abundance increase in spite of the decreasing primary productions under low-light in P-limited condition. However, this paradoxical bottom-up effects has been studied in a small scale with structurally simple communities.

To clarify how changes in balance of light:nutrient input alter trophic structures of complex communities, we experimentally manipulated input of irradiance (100, 44 and 25%) into 6 P-limited ponds with 0.1 ha and 1.5 m deep where the communities was composed of natural benthic and planktonic organisms. Then, we monitored periodically biotic and abiotic variables for 81 days in summer 2015. We will present how abundance and C:P ratios of primary producers and abundance of zooplankton responded to the shading in the natural ponds.