Seasonal variability of palynomorphs in a JT-03 sediment trap setteled in the Japan Trench

• Main Author: 松岡, 數充
• Format: Publication
• Language: Japanese
• Published: 31.01.1992

A JT-03 sediment trap composed of two WHOI Mark VI apparatuses of was settled at depth of -8,798m and -4,260m in the Japan Trench (34° 11.34'N, 114° 59.53'E) from March 15 to November 4, 1988. Only the shallower apparatus was successfully recovered in collecting flux. Organic walled particles collected in that apparatus were investigated palynologically. Palynomorphs (organic-walled particules) consisted mainly of lorica of tintinnids, pollen grains, fern spores, fragments of planktonic crustaceans, fecal pellets, acritarchs and dinoflagellate cysts. The maximum flux of palynomorphs was 10.71 X 10^4 grains/㎡/day which was recorded in samples collected from May 27 to June 13 and the minimum was 0.526X 10^4 grains /㎡/day in samples collected from October 18 to November 4. This variability is clearly due to seasonal abundance of tintinnids, and pollen grains of Pinus and Cryptomeria. Pollen grains of Cryptomeria are spread during their flowering time from early January to early February, and Pinus from late April to early May, on the Pacific side in Japan. The lag in abundance of these pollen grains between flowering and trapping times probably shows the time that the pollen grains are transported from their terrestrial habitat areas to being sunk onto the sea floor through the water column. On the basis of the observation that some fecal pellets contain pollen grains of Pinus and Cryptomeria, the sinking mechanism for these pollen grains in the water column is probably controlled by zooplankton consumers such as copepods, amphipods and others.