IMIS - Marine Research Groups

After the BROKE-West survey of 2006, the original BROKE survey was renamed BROKE-East. The project attempted to explain these patterns in terms of dietary factors and tolerance to different thermohaline regimes. Nearly 2000 individuals, weighing 1210 g, were collected, from approximately 1.5 million m3 of the upper 200 m of ocean, supporting the theory that Antarctic ichthyoplankton has low biomass. The collection consisted mainly of P. antarcticum larvae and juveniles and E. antarctica sub-adults, with a range of other notothenioid fish and myctophids. Three distinct biogeographic zones, with characteristic ichthyo- and zooplankton assemblages were identified. The Oceanic Zone was dominated by myctophids and, in the western reaches, the paralepidid N. coatsi. The Shelf Break Zone was comprised mainly of myctophids, and the juveniles of notothenioid fish. The Shelf Zone consisted of notothenioid juveniles and sub-adults. Characteristic water masses and associated zooplankton assemblages were found throughout these three zones. Analysis of fish stomach contents indicated feeding on locally abundant zooplankton taxa. There was niche-partitioning of prey taxa and size-classes, between both sympatric species and between different ontogenetic stages. Fish distributions corresponded to known patterns, and extended the known geographic range of several species.