Diel and lunar patterns of reproduction in the Caribbean and Pacific sergeant major damselfishes Abudefduf saxatilis and A. troschelii

Abstract

Diel and lunar reproductive patterns of the Caribbean and Pacific sergeant major damselfishes Abudefduf saxatilis and A. troschelii respectively, were studied i the San Blas and Northern Perls Islands of Panama in 1981 and 1982. These are sister-species that have diverged since the uplift of the isthmus of Panama. Caribbean A. saxatilis females typically complete spawning in the nests of males earlier in the morning than do Pacific A. troschelii females. Spawning is rarely observed during the afternoon. Hatching occurs four or five days after spawning in the Caribbean species, and after four days in the Pacific species. In both, fry hatch during the hour following sunset. There also are differences in lunar patterns of spawning between the two species. The Caribbean A. saxatilis spawns throughout the month, exhibiting no lunar periodicity. In the Pacific A. troschelii spawns within nine days on either side of new moon. During the wet season, reproductive activity at a site spans three or four days, but is extended to eight or more days during dry season upwelling in the Bay of Panama. Thus, reproductive synchrony is much greater within than between colonies of the Pacific sergeant major, particularly in the wet season. Reproductive synchrony in the Pacific sergeant major might be beneficial because fry hatching at dusk encounter favorable tides for transport away from reef-based predators around new moon, or because reproductive synchrony reduces the risk of predation on unhatched embryos in nests guarded by males. Tidal amplitude and the rate of predation on embryos in nests are greater in the Pacific.