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Euphausiid assemblages of the oceanographically complex north-west marine bioregion of Australia
The north-west marine bioregion of Australia, which includes the waters adjacent to the Kimberley and Ningaloo coasts, is influenced by both the Indian and Pacific Oceans and has high tropical biodiversity, some of which is conserved in a suite of marine protected areas. The epipelagic euphausiid assemblages of this bioregion were investigated and related to physical and biogeochemical properties of the water column as well as food availability. Twentyfive euphausiid species were identified, and included three new records for Australian waters. Pseudeuphausia latifrons was the most abundant species, dominating the shelf waters across both study areas. Stylocheiron carinatum replaced P. latifrons in the deeper waters where species richness was greater. Off Ningaloo, there were higher concentrations of euphausiids and this may be linked to the bathymetry, narrowness of the shelf and resultant effects on oceanography and biogeochemistry. Assemblages were primarily structured by depth but mean seawater density, dissolved oxygen, fluorescence and mesozooplankton abundance also significantly explained some of the variation in euphausiid assemblages. This study has confirmed that the physical and biogeochemical properties of the water column and food availability are recurrent factors influencing euphausiid assemblage variation in the eastern Indian Ocean.
MF16334 Accepted 24 January 2017
© CSIRO 2017