Plankton
biomass of whole taxa (from phytoplankton to metazooplankton)
was evaluated for whole water column (0-5800 m) at four stations covering from
subarctic to subtropical western North Pacific Ocean
Throughout
the taxa, plankton biomass density decreased with increasing depth, while their
decreasing rate is varied with taxa: heterotrophic bacteria < protozooplankton
< phytoplankton < metazooplankton
Latitudinal
changes in taxonomic composition of planktonic biomass were present. Thus, metazooplankton
dominated in the subarctic region, while heterotrophic bacteria and protozooplankton
dominated in the subtropical region
For
calanoid copepods (dominant component of metazooplankton),
species diversity formed peaks at mesopelagic (200-1000 m) layers.
Within
the same genus, vertical distribution was separated with species down to the
greater depths.
Life
cycle of suspension feeding copepods living at 500-1000 m had clear seasonal
pattern, with their reproduction corresponded with the spring phytoplankton
bloom at surface later.
This
correspondence of reproduction timing of deep-sea copepods may related with
seasonal changes in their food which provided by sinking particles from surface
layer.
Calanoid
copepods are estimated to be consume 32% of sinking particule
flux throughout the water column.
