Temporal Coupling of Production and Recruitment of Larvae of a Caribbean Reef Fish

Abstract

Variation in larval recruitment is thought to have profound effects on the structure of coral reef fish communities, and planktonic processes often are cited as the major factor controlling the temporal and spatial patterns of such recruitment. We looked at the relationship between temporal patterns of larval production and settlement of planktonic larvae of the Caribbean damselfish Stegastes partitus at one site and attributed any differences to processes acting in the plankton. In doing so we assumed that the pattern of production we observed was representative of the regime that produced fish that settled in the study area. We monitored spawning and larval recruitment continuously for 3 yr. Both spawning and settlement followed (unimodal) lunar cycles, and both activities spanned °3 wk of the lunar month. Although the form of the average settlement cycle matched that of the average production cycle, monthly settlement episodes were shorter and (slightly) more variably timed than equivalent production episodes. Although monthly variability in the magnitude of settlement was fourfold greater than corresponding variability in the magnitude of larval production, monthly settlement success did not vary in an extreme manner. There was no significant correlation between the magnitude of larval production in a month and of settlement the following month. Daily growth increments in the otoliths of settlers indicated that (1) larvae were °5 wk old at settlement, (2) there was low overall variability in age at settlement, (3) there were no differences between the ages of settlers arriving early and late in the monthly settlement period, and (4) age variability among settlers collected on the same day was not different from that among settlers collected on different days. Hence, the basic lunar periodicity of settlement is determined by the periodicity of production of relatively fixed—age settlers. Planktonic processes enhance the temporal variability of settlement, principally by affecting the magnitude of settlement events, but also by influencing the duration and precise timing of monthly settlement episodes. Planktonic processes also determine that most of a month's successful settlers arrive (and are produced) over a few consecutive days and mix cohorts of larvae that are produced on different days. We conclude that the timing and magnitude of settlement are strongly influenced by both production and planktonic processes, and the latter only partly decouple settlement and production.

Larger female fish contribute disproportionately more to self-replenishment

“…In each clutch, three 1 cm 2 replicates were sampled by scuba divers to calculate egg density, which was then multiplied by the total area of the clutch, calculated by pr 2 given that clutches essentially were circular (following Robertson et al [35] Expected values of the mean size of females producing SRs based on the number of eggs they potentially contribute were calculated at each of the six sites included in the analysis ( figure 1). This was achieved by weighting the size of each individual by its estimated fecundity (calculated using the equation provided earlier).…”

Local retention, dispersal and fluctuating connectivity among populations of a coral reef fish

“…Adults spawn demersally following a unimodal lunar cycle with year-round reproduction and seasonal reproductive peaks from April to November (Robertson et al 1988). The males of the species provide parental care to the eggs; however, after hatching (*3.5 days), larvae enter the pelagic environment and the pelagic larval duration ranges between 24 and 40 days (Robertson et al 1988;Wellington and Victor 1989). After settlement, the adults are sedentary, defending small feeding territories indefinitely (Myrberg 1972).…”

Larval growth predicts the recruitment success of a coral reef fish

“…Pelagic juveniles of Acanthurus chirugus settle to benthic reef habitats at night (Robertson et al 1988). To estimate settlement, newly-settled fish were collected each morning from January 1984 to January 1987 from small (40-60 m 2 area) patch reefs in the San Blas Archipelago, Caribbean Panama (see map in Robertson et al 1999).…”