Experimental design
The experiment was carried out at two ponds (pond ID 217 and 218) located at the Cornell University Experimental Ponds Facility in Ithaca, NY, USA during June 4 to August 28, 2016 (Fig. 1). Each pond has a 0.09 ha surface area (30 × 30 m) and 1.5 m deep. To initiate the experiment, we equally divide each of the two ponds into four sections using vinyl coated canvas curtains, and randomly assigned the four sections to either high shade (64% shading), mid shade (47% shading), low shade (33% shading), or no shade treatments (no shading). Shading in each treatment was made using opaque floating mats (6 m diameter as in Fig. 1 of Yamamichi et al., 2018). Details of the experimental design are described in supplementary methods.