Maps of Seasonal Variation

Maps of seasonal variation

Here we present seasonal maps of zooplankton abundance. Copepods, amphipods, decapods, and euphausiids are different groups that form part of the total biomass. Neocalanus plumchrus is usually considered the most important copepod and is presented separately. The right-hand subplot shows the annual average over each region (that is, a seasonal average is first computed over each region in the first 3 plots, and then these 3 seasonal values are themselves averaged), with the whole region coloured according to the scale at right. The numbers shown are the actual averages.

Upper panels show the biomasses associated with net tows that sampled the full water column (to within 20 m of the bottom).  Lower panels show biomasses associated with "shallow" tows that capture upper waters only. Shallow tows are more numerous, but may not capture zooplankton that migrate vertically (which can include all of the groups here except the smaller copepods). Both groups of tows include samples taken both during the day and at night, but most of the shallow tows were taken during the day.

 

Zooplankton