Jj. Grover et al., TRANSITION FROM PELAGIC TO DEMERSAL PHASE IN EARLY-JUVENILE NASSAU GROUPER, EPINEPHELUS-STRIATUS, PIGMENTATION, SQUAMATION, AND ONTOGENY OFDIET, Bulletin of marine science, 62(1), 1998, pp. 97-113
Early-juvenile Nassau grouper, Epinephelus striatus, were collected of
fshore, in tidal passes, and in shallow bank habitats in the southern
Exuma Gays, Bahamas, during winter in 1993 and 1994, encompassing a co
mplete transition from pelagic to demersal phase. Collected fish were
examined in terms of pigmentation, squamation, and ontogeny of diet du
ring settlement. While pelagic, during January and February, early juv
eniles were uniform in their pigmentation, but varied considerably in
scale development. Once settled into macroalgal bank habitats, during
February, demersal early juveniles were uniform in scale development,
but varied in pigmentation. Complete settlement pigmentation and scale
development were first observed in February and March, respectively.
The diet of pelagic juveniles was dominated by calanoid and poecilosto
matoid copepods, and decapod larvae. The diet of demersal post-settlem
ent juveniles was dominated by gammaridean amphipods and harpacticoid
copepods. Six months later shortly before E. striatus are thought to v
acate macroalgal habitats, early juveniles were collected, to examine
ontogenetic shifts in diet during their tenure in macroalgae. Although
gammarideans continued to dominate the diet at that time, isopods and
mysids increased in importance, in settlement habitats, feeding succe
ss may be related to the development of settlement coloration. Ecologi
cal adaptation to settlement habitats appears to be relatively rapid:
the transition from pelagic to demersal phase appears to be completed
within I wk.