Seasonal variation of carbon of Bacteria, Synechococcus, ANF,HNF,Phyioplankton, and Zooplankton
were investigated in Ise Bay, in 1995. In addition, estimated production rates of Bacteria,
Synechococcus, phyioplankton, and grazing rates of HNF, zooplankton. Using these results, we
approximate production rates of each food chain. In this place, we categorized lOum or less
phytoplankton Bacteria Synechococcusand ANF as a producer of Microbial food chain, and cat
egorized other producers as a producer of grazing food chain. Then, we compared and examined
that interrelationship between each microorganism and environment factor.
As a result of this research, water temperature and grazing pressure by HNF were important as
change factor of Bacteria, and grazing pressure of HNF and Oikopleura were important as
Synechococcus. The microbial food chain/grazing food chain production ratio was 0.66 on the
whole, grazing food chain was more important, but microbial food chain was more important in
September and December. On the other hand, dominant species of the zooplankton were Penilia
avimstris (CLADOCERA), and Bivalve larva and Oithonadavisae (COPEPODA) when produc
tion of Bacteria, Synechococcus, etc. was the highest in summer. P. avirostris and Bivalve larva
are herbivorous pico- nano, nanoplankton feeder, and O.davisae is omnivorous nano-microplankton
feeder. The grazing rates of these dominant species occupied 86% (in August, and the whole
67%) to the grazing rates of the whole zooplankton, and the seasonal variation was similar to
change of production rates of Microbial food chain. These results suggest production of a Micro
bial food chain links to production of zooplankton. On the other hand, zooplankton population
and that species composition were seasonal changing so that food can be used effectively.
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