Abstract

Information on Western Atlantic snapper species in the southern hemisphere is limited for many species. This study examined habitat use patterns in newly settled, juvenile and adult stages of the dog snapper, Lutjanus jocu, within a larger study of lutjanids across the wide Abrolhos shelf system of east-central Brazil, 18° S. Visual surveys were conducted in rock, forereef, tide pool, and mangrove habitats within widely separate cross-shelf systems (estuarine rivers; inner-shelf reefs, and mid-shelf reefs) to determine larval settlement sites, quantify life stage abundances, and determine distribution. Lutjanus jocu was the most abundant snapper, comprising approx. 80% of all individuals recorded of the seven or more lutjanid species in the area. Density was highest in reef habitats on the inner shelf. There was an increase in size of individuals across the shelf. For example, <7 cm individuals were highly associated with estuarine habitats, whereas older stages (>40 cm) were recorded only on mid-shelf reefs. Individuals between 10-30 cm were most abundant on inner-shelf reefs. Settlement sites include rock piles and mangrove roots in the Rio Caravelas estuary, and potentially shallow forereef areas on the inner-shelf. Constraints on cross-shelf migration include wide softbottom expanses (several 20 km distances) among disparate reefs across the 200 km shelf and high fishing pressure beginning on sub-adults. Relative plasticity in juvenile habitat use is implied by some early results but answers to fundamental questions of ecological structure will require extended observations and manipulations across this large South Atlantic shelf system.

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