We assessed the in situ daily primary production, photosynthetic efficiency, and xanthophyll cycling of a temperate coral, Cladocora caespitosa , during the summer using an in situ incubation chamber equipped with temperature, oxygen, light, salinity, and pH sensors. During sunny days, photosynthetic carbon (C) production rates of C. caespitosa can be as high as those measured for tropical corals and rapidly follow changes in...