Lunar periodicity in the spawning of yellowtail damselfish,Microspathodon chrysurus

Synopsis The reproductive behavior of yellowtail damselfish,Microspathodon chrysurus, was studied off the Caribbean coast of Panama to determine if there is a lunar spawning cycle. Male damselfish prepare nest sites on dead coral surfaces within their permanent feeding territories. Spawning occurs at sunrise and lasts for approximately one hour. Males defend the eggs until hatching, which occurs before the morning of the sixth day of incubation. Males spawn only once a day, but may spawn many times within each reproductive phase. Reproductive activity is highest in the time periods from full to new moon. The timing of this lunar cycle differs from those reported for other marine fishes. The spawning pattern is not consistent with common explanations for lunar periodicity that are based on the role of tides or moonlight. Some implications of these results for the organization of tropical reef communities are discussed.