Squat lobster assemblages on seamounts differ from some, but not all, deep-sea habitats of comparable depth


Ashley A. Rowden, National Institute of Water & Atmospheric Research, Private Bag 14-901, Wellington, New Zealand.
E-mail: a.rowden@niwa.co.nz


This study was carried out to test the hypothesis that benthic communities on seamounts are distinct from those of other deep-sea habitats at comparable depths. Analysis of the squat lobster fauna of deep-sea habitats in the Southwestern Pacific revealed that the species composition of assemblages on seamounts was not statistically dissimilar from assemblages on slope and plateau habitat at comparable depths. However, compositional differences were observed between seamount and rise and ridge habitat. Differences in assemblage composition between seamount and ridge habitat were statistically significant for two of the four ridge systems examined. Assemblages on seamounts that were distinct from non-seamount ridge habitat were typically dominated by small-bodied species with an abbreviated larval stage. Various environmental variables were correlated with the observed assemblage patterns observed; depth-related variables may account for differences between seamount and rise assemblages, whilst differences in POC flux likely play a role in determining the assemblage compositional patterns between seamount and non-seamount ridge habitat. Extensive pre-analysis data treatment was required to ensure that multivariate analyses of assemblage data from seamount and non-seamount habitats were robust. Our results confirm the findings of recent studies that found no compositional differences in assemblages from seamount and slope habitats, and support the idea that dissimilarity between seamount assemblages on different ridge systems increases with geographic distance. Further research will be required before the generality of these findings can be confirmed.