Skip to content


  • Stoffwechsel Und Aktivität
  • Open Access

Light and photosynthesis in intertidal benthic diatoms

  • 1
Helgoländer wissenschaftliche Meeresuntersuchungen10:BF01626096


    1. The rate of photosynthesis at varying amounts of natural sunlight has been measured for large pennate littoral diatoms which inhabit the sand flats of Barnstable Harbor, Massachusetts, and which exhibit vertical migration to the surface at low tide.

    2. The algae require only 12 gm. cal./cm.2/hr. to reach their maximum photosynthetic capacity.

    3. Full mid-day summer sunlight (75 gm. cal./cm.2/hr.) results in only a 10% inhibition of maximum photosynthesis.

    4. Measurements of light penetration through the sand in which the diatoms are found indicated 10% of solar radiation reaches 1.5 mm.

    5. At noon on a cloudless mid-summer day these species existing as deep as 3.0 mm. are probably above their compensation level, while those from 2.0 mm. to the surface are able to photosynthesize at 90% or better of their maximum rate.

    6. The photosynthetic efficiency at low light levels enables these diatoms to fix considerable carbon even when the flats are exposed when the sun angle is low.

    7. The migration pattern of these diatoms does not result in significant inhibition of photosynthesis but rather their photosynthetic apparatus is well adapted to such migratory activity.


    • Photosynthesis
    • Vertical Migration
    • Photosynthetic Efficiency
    • Benthic Diatom
    • Natural Sunlight