title: Depth-variable settlement patterns and predation influence on newly settled reef fishes (Haemulon spp., Haemulidae).
abstract: During early demersal ontogeny, many marine fishes display complex habitat-use patterns. Grunts of the speciose genus Haemulon are among the most abundant fishes on western North Atlantic coral reefs, with most species settling to shallow habitats (≤12 m). To gain understanding into cross-shelf distributional patterns exhibited by newly settled stages of grunts (<2 cm total length), we examined: 1) depth-specific distributions of congeners at settlement among sites at 8 m, 12 m, and 21 m, and 2) depth-variable predation pressure on newly settled individuals (species pooled). Of the six species identified from collections of newly settled specimens (n = 2125), Haemulon aurolineatum (tomtate), H. flavolineatum (French grunt), and H. striatum (striped grunt) comprised 98% of the total abundance; with the first two species present at all sites. Prevalence of H. aurolineatum and H. flavolineatum decreased substantially from the 8-m site to the two deeper sites. In contrast, H. striatum was absent from the 8-m site and exhibited its highest frequency at the 21-m site. Comparison of newly settled grunt delta density for all species on caged (predator exclusion) and control artificial reefs at the shallowest site (8-m) revealed no difference, while the 12-m and 21-m sites exhibited significantly greater delta densities on the caged treatment. This result, along with significantly higher abundances of co-occurring piscivorous fishes at the deeper sites, indicated lower predation pressure at the 8-m site. This study suggests habitat-use patterns of newly settled stages of some coral reef fishes that undergo ontogenetic shifts are a function of depth-variable predation pressure while, for at least one deeper-water species, proximity to adult habitat appears to be an important factor affecting settlement distribution.
authors.affiliation: Oceanographic Center, National Coral Reef Institute, Nova Southeastern University, Dania Beach, Florida, United States of America. Lance@microwavetelemetry.com
authors.forename: Lance K B
authors.initials: LK
authors.lastname: Jordan
authors.forename: Kenyon C
authors.initials: KC
authors.lastname: Lindeman
authors.forename: Richard E
authors.initials: RE
authors.lastname: Spieler
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D057894:Coral Reefs; D004463:Ecology; D017753:Ecosystem; D005399:Fishes / Q000502:physiology*; D005431:Florida; D015233:Models, Statistical; D011157:Population Dynamics; D011235:Predatory Behavior; D012306:Risk; D013045:Species Specificity