褐藻類ワカメ・カジメ遊走子の着生と成長,生残および成熟に及ぼす海底堆積粒子の影響

概要

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From the point of view that the desolation of seaweed-beds was largely due to increased quantities of micro-particles suspended in water and/or deposited on the seabed, the influence exerted on sedimentation velocity and zoospore insertions of brown algae by suspended matter was examined in our previous report. In this report, the influence exerted on the insertion of zoospores, germination, servival, and maturation of gametophytes of brown algae in accordance with quantities of sediments has been studied. Both Undaria pinnatifida and Ecklonia cava are employed also for the experiments of this time as samples. If the number of zoosporei nsertions under conditions of no sediments adhering to the substrate is taken to be 100%, it decreases to 50% when a sediment quantity of 0.5mg/cm2 (i.e. approx. 0.008mm in thickness) is deposited on the substrate, and no zoospore insertions take place when the sediment deposition becomes as much as 3mg/cmz. Following a similar way of thinking in respect to the germination of their gametophytes, it (i.e. 100%) also decreases to approx. 40% under conditions of 1mg/cm2, and no germination takes place under conditions of 10mg/cm2. Their survival rate also decreases to approx. 50% under conditions of 1mg/cm2, and there are no survivals at all under conditions of 10mg/cm2. Their maturation rate also reduces to approx. 50% under conditions of 0.25mg/cm2, and no maturation develops under conditions of 1mg/cm2.