Replenishment of populations of Caribbean reef fishes: are spatial patterns of recruitment consistent through time?

Many benthic marine invertebrates and demersal fishes produce dispersive, pelagic larvae. Large fluctuations in recruitment - the addition of individuals to the benthic population following settlement - are common both in space and time, and these fluctuations can influence population size and community dynamics. In this report, we examine the recruitment of 14 species of Caribbean reef fishes over four years at 10 sites in the waters around three islands in the US and British Virgin Islands: St. Croix, St. John and Virgin Gorda. We asked: (1) how variable is recruitment?; (2) from where does the variation come (years, islands, sites within islands)?; (3) are spatial patterns consistent through time even if the absolute numbers of recruits are not?; and (4) are there spatial correlations in recruitment among fish species? There was significant spatial and temporal variation in recruitment at the assemblage level. However, we detected two general types of recruitment patterns. Six of the 14 species had spatial patterns that were consistent from year to year. For these species, variation among sites accounted for most of the variance, and the ranking of sites was consistent from year to year as indicated by concordance analysis. Consistent spatial patterns were species specific, however. The other eight species had spatial patterns that were temporally variable. A substantial proportion of the variance was due to the interaction between sites and years. Concordance analysis did not reveal consistent rankings of sites. Principal components analysis indicated some relationships among species in terms of recruitment. For example, all planktivorous species loaded on the same component. These results indicate that deterministic and potentially predictable processes may dictate the pattern of recruitment among sites for some species, while other species have much more variable recruitment. They also indicate that these deterministic processes affect species differently. (C) 1998 Elsevier Science B.V. All rights reserved.