Feeding of zoopalnkton and micronekton in the deepsea ecosystem

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1) Collections were made of deep sea benthopelagic organisms in the Sagami Bay, Japan using a newly-develope multiple plankton sampler (DTMPS) attacged to the deep tow system. Tows were made as close to the sea floor as the terrain would allow, maintaining a distance of 0.5-3.0m above the bottom. Benthopelagic organisms were effectively collected by this sampler enough to estimate their biomass. Benthopelagic biomass, including megaplankton (> 2cm), ranged from 4.0-43.3g/1000m^3 and excluding megaplankton 4.0-22.6g/1000m^3. Biomass decreased exponentially with depth but showed a clearly different slope than that of pelagic biomass. Assuming that the benthopelagic biomass does not change substantially by area or season, the percentage of benthopelagic biomass to surface biomass ranged from about 5 to 30 %, with an average of 15 % in Sagami Bay.2) The delta^<15>N valus of micronekton collected from Sagami Bay ranges from 9.4 to 14.2 @91. The ^<15>N values of the micronekton. Gonostoma gracile, increased with growth (9.4 to 12.6 @91) and it seems that males, before sex reversal, and females cinsume different food organisms.3) The C/N ratio of meso- and bathypelgic copepods which did not the vertical migration, is almost constant at any season and area. But this ratio of Neocalnus cristatus which was shown remarkable ontogenetic migration, decreased with depth. Many fragments of phytoplankton which were caused by fecal pellet, were recognized under SEM observation.