Celestial Mechanics, Sea-Level Changes, and Intertidal Ecology.

Celestial mechanics has long been known to affect life on Earth, but exploration of these influences has been hampered by long temporal scales and complex biological relations. Here we report on a periodic fluctuation in tidal exposure driven by the 18.6-y oscillation of the moon's orbital inclination, which can change by almost 50% the average time that intertidal organisms are exposed to air. The temperature of nearshore water and the upper limits to mussels are shown to vary with the lunar oscillation. Such variation challenges the value of ecological and physiological generalizations based on snapshot measures, and highlights the value of long-term studies.