Plankton biomass and productivity in the seas around Hokkaido

A review of the marine plankton biomass and productivity around Hokkaido (Japan) is presented. The seasonal maximum values of the phytoplankton biomass (chlorophyll-a concentration in the euphotic layer) were found to be 5 mg chl-a m super(-3) on an average in Mar on the Pacific coast of southern Hokkaido, 3 mg m3 in Feb to Mar in Funka Bay and 2 mg m super(-3) in Apr. in Ishikari Bay. The maximum mean values of the biomass of meso- and macrozooplankton collected mainly with a Norpac net (0.3-mm mesh aperture) at depth < 150 m were all found in Apr. They were 500 mg wet wt m3 in Ishikari Bay, 700 mg m super(-3) in the coastal area off eastern Hokkaido, 200 mg m super(-3) off southern Hokkaido and 300 mg m super(-3) in Funka Bay. Some estimated and measured values of the primary and secondary productivity are illustrated and tabulated on the basis of previous studies.