Daytime Variations in Phytoplankton Photosynthesis

A study of CO2‐removal during July and August, 1954, under natural conditions in western Lake Erie demonstrated a maximal rate during the hours of 0700–1000 (10 µmoles CO2 absorbed per liter of water per hour), a reduced rate during the hours 1000–1600 (6µmol/L/hr), a slightly negative rate during the daylight hours 1600–1900 (−1 µmol/L/hr), and nighttime negative rates similar to the day‐time positive rates (−6µmol/L/hr).