Green macroalga Ulva lactuca Linnaeus and red macroalga Ahnfeltiopsis flabelliformis (Harvey) Masuda were cultured in CO₂-enriched seawater (including 5-10 times CO₂ than normal seawater) (CSW) and normal seawater (NSW) for a week, respectively. We compared daily growth rate (DGR), morphology and intracellular soluble proteins between CSW- and NSW-cultured thalli. DGR of CSW-cultured thalli was higher than NSW-cultured thalli in both U. lactuca (1.2 times) and A. flabelliformis (1.7 times). Morphology of A. flabelliformis in CSW-cultured thalli had much branchlets issued from lateral portion of branches than that in NSW-cultured thalli. In comparison of intracellular soluble protein, we detected specific protein in CSW-cultured thalli in both U. lactuca (33 kDa) and A. flabelliformis (60 kDa) by bi-dimensional electrophoresis.

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Algal succession after removal of Strongylocentrotus nudus population from the sea urchin-dominated barren ground (ISOYAKE) was observed on the coasts of Sai, Shimokita Peninsula, Japan, in order to clarify the procedures for the restoration of edible seaweed communities of Saccharina japonica. Strongylocentrotus nudus population (c.a. 44k-194k) was removed from the eight areas (1.2-4.15 ha) of the depth of 4-13 m in each year of 1994 to 2001. Standing crops and covered ranges of seaweed were measured from February 1995 to June 2002 in the S. nudus removal and non-removal area, respectively. Young sporophytes of S. japonica occurred on February 1995 in the removal area of S. nudus population that was removed on September 1994. After that, S. japonica dominated the standing crops of seaweeds and the maximum standing crop of 10.1kg/m² was recognized on June 1996. Dominant communities of S. japonica occurred also in other seven removal areas within a year from the removal of S. nudus population. And the S. japonica communities were observed successively for a maximum of eight years, though S. nudus swarmed to graze on them. On the other hand, ISOYAKE had continued in the non-removal area. From these results, the S. japonica communities were considered to be restored by the removal of S. nudus population from ISOYAKE on this investigation coast.

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The effect of edible blue-green algae, Nostoc flagelliforme, Nostoc commune, and Aphanothece sacrum on the infection of Listeria monocytogenes was studied in mice. Fiveweek-old male ddY mice were administered orally with the hot-water extract of these algae (0.2 ml/day) for 7 days, and then inoculated intravenously with L. monocytogenes. The number of L. monocytogenes in spleen was counted on day 3. The hot-water extract of these algae showed the tendency to inhibit the growth of L. monocytogenes in spleen.

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We investigated the effect of Fe(II) for the growth of Ulva prolifera O. F. Müller in outdoor tanks cultivation in deep seawater (DSW) by adding bags containing chipped Fe(II), “Ion Culture” (Tôyô glass co. Ltd., Tokyo). The daily growth rates of U. prolifera in only DSW (control culture) were 23.3 % (winter) to 71.0 % (summer), however, it reached 28.1 % in DSW with 30 g “Ion Culture” (winter) to 100.5 % in DSW with 120 g “Ion Culture” (summer). The concentration of Fe(II) rose in proportion to quantity of “Ion Culture”. These results indicated that Fe(II) dissolved from “Ion Culture” stimulated growth of U. prolifera.

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