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ID 28909
file
title alternative
塩分低下をともなう珪酸塩の供給に対するSi制限Skeletonema costatumの生理的応答
creator
Tsuchiya, Haruhiko
subject
Skeletonema costatum
silicate
salinity
continuous culture
physiology
NDC
Zoology
abstract
Unsteady continuous culture of the diatom Skeletonema costatum, which is a dominant species forming red tides during the warm season in Mikawa Bay, was carried out. From the reported field observations, silicate concentration was considered to be the most plausible factor governing the biomass of S. costatum in the surface layer of the stratified water column. The two possible major processes involved in Si supply, i.e. from the bottom layer by wind mixing and by fresh water runoff, occurring in situ during this season were established by reciprocal replacement with a Si-sufficient media, with or without an accompanying salinity decrease of 5 ‰ to the Si-limited culture of S. costatum. The uptake rate of nitrate and phosphate per cell increased with Si limitation. Silicate limitation also caused several noticeable changes in the morphology of S. costatum. One of these morphological changes, cell elongation, made the cell quota of N and P larger than that of Si. On the other hand, silicate uptake rate per cell showed a sharp increase with increased Si supply and this elevated Si uptake rate was 5-9 fold that under Si-limited conditions. The degree of elevation of Si uptake was higher without an accompanying salinity decrease than with a salinity decrease, indicating that osmotic pressure may not be responsible for the uptake mechanism. Furthermore, Si-limited S. costatum showed higher growth rates when supplied Si with an accompanying salinity decrease than without a salinity decrease. Judging from these results, it is supposed that Si-depleted S. costatum grows faster in situ with Si supplied through river discharge, if the salinity is optimum for S. costatum, than through overturning of the water column due to wind mixing.
journal title
日本プランクトン学会報
volume
Volume 42
issue
Issue 1
start page
1
end page
17
date of issued
1995-07-15
publisher
日本プランクトン学会
issn
0387-8961
ncid
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 1995 The Plankton Society of Japan
department
Graduate School of Biosphere Science



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