Abstract

The relative importance of predatory decapod crustaceans in sedimentary communities depends on the spatial variability in their abundance and composition. At the scale of a fjord, such spatial patterns could be related to sill-mediated larval supply. This study examines larval and adult distributions of abundant predatory decapods at six representative sites in a sub-arctic Newfoundland fjord during three consecutive summers. Adult snow crab (Chionoecetes opilio) and toad crab (Hyas coarctatus, H. araneus) characterized outer areas of the fjord, whereas pandalid shrimp (Pandalus montagui) dominated inner areas, and rock crab (Cancer irroratus) showed only minor spatial differences. Multivariate analysis and nonparametric comparisons of larval abundance and composition suggest that the sill separating inner and outer areas of the fjord results in differences in larval supply that correspond to adult abundances for at least two of the species analyzed here: snow crab and pandalid shrimp. Although larval abundance was not related to adult distribution when all zoeal stages were considered, correspondence between larval and adult patterns emerged when only late stages (zoeae ≥ II) were included in the multivariate analyses. Nonparametric comparisons supported these results, indicating significant differences in larval abundance inside and outside the sill for corresponding species and stages. Our results suggest that larval supply may play a critical role in establishing adult spatial patterns at the scale of the entire fjord for some species, but a less relevant role at the finer scale represented by the sites and habitats located at each side of the sill.

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