Distributions of benthic cells of Skeletonema costatum and Heterosigma akashiwo in Osaka bay [Japan]
1989
Yamochi, S. (Osaka-fu. Fisheries Experiment Station, Misaki (Japan))
The author collected bottom sediment samples at 21 stations of Osaka Bay in June 1986 and October 1987, and examined physico-chemical factors of the sediments and numbers of benthic stage cells of Skeletonema costatum and Heterosigma akashiwo. Benthic cells of S. costatum existed at densities ranging from 2.3 x 10(3) to 4.6 x 10(6) cells.g(-1) wet sediment in June 1986 and from 2.4 x 10(3) to 1.1 x 10(6) cells.g(-1) wet sediment in October 1987. Those of H. akashiwo varied between 5 and 2.7 x 10(2) cells.g(-1) wet sediment in June 1986 and between 27 and 5.4 x 10(3) cells.g(-1) wet sediment in October 1987. Many cells of benthic forms of both species were found in the sea areas where the bottom sediments consisted of gravel or sand. Neither cell numbers of S. costatum nor H. akashiwo had close relationship with ignition loss, Eh, total carbon and total nitrogen contents. But cell numbers of S. costatum tended to decrease when total sulphide content of the sediments exceeded 0.5 - 0.6 mg.g(-1) dry sediment. This suggests that total sulphide or some factors related to total sulphide depress the release of benthic S. costatum cells from the bottom sediment in Osaka Bay
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