Zooplankton was counted and identified from three sites over the 5-year period. The net used (200 m Bongo net) was designed to catch meso-zooplankton with an integrated vertical tow through the water column. One net from each of the paired Bongo samples was analysed and the data expressed as numbers per m3. Copepods dominated the zooplankton, with other groups such as salps, krill, appendicularians, cladocerans, chaetognaths and meroplanktonic larvae being seasonally dominant.
Zooplankton were collected with a 2-m long Bongo net (mouth diameter: 75 cm; mesh size: 200 m). The nets were deployed to within 2 m of the seabed and hauled steadily (1 m s-1) back to the surface. On-board, zooplankton samples were anesthetised using soda water and refrigerated. The catches were returned to the laboratory and preserved in 4% formaldehyde. When necessary, samples were subsplit with a Folsom plankton splitter so that between 400 and 1000 individuals were counted. Many groups, including copepods, krill, salps and cladocerans, were identified to species. Other individuals were identified to coarser taxonomic levels.