Daily, Monthly and Yearly Variability in Recruitment of a Guild of Coral Reef Fishes

Abstract

Temporal variability in recruitment of a guild of pomacentrid fishes inhabiting small patch reefs and corals in the lagoon of One Tree Reef, Great Barrier Reef, was examined. The entire population of newly recruited pomacentrids on 66 sites was censused in situ at approximately 4 to 8 wk intervals from June 1976 to February 1979 and in April-May of 1980. Recruitment was seasonal, with all but 1 species recruiting primarily over summer. Rates of recruitment during summer were not constant but pulsed, with perhaps monthly frequency. One regularly-timed pulse (mid-summer) was studied in detail over 3 yr Calendric timing of the pulse was remarkably constant from year to year, with no clear relationship between recruitment and the time of the lunar month. Maximum daily rate of recruitment during the mid-summer pulse varied 15-fold between years. The size of pulses varied as much as &fold within years and the same pulses varied as much as 6-fold among years. Annual recruitment of the common species varied as much as an order of magnitude over a 4 yr period. The data indicate that (1) a large pulse of recruitment in 1 yr does not necessarily mean that other pulses in the same year will b e similarly large; (2) 1 large pulse alone is sufficient to make total recruitment in a year unusually successful; (3) while a good year for recruitment of 1 species may also b e exceptionally good for other species, it need not necessarily be a good year for all species of the same guild.