Elucidation of "Isoyake" phenomenon: Study on allelochemicals of coralline red algae
| Project/Area Number |
09660217
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fisheries chemistry
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SUZUKI Minoru Hokkaido Univ., Grad. School of Env. Earth Science, 大学院・地球環境科学研究科, 助教授 (30000855)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Isoyake / Coralline red alga / Epiphytic diatom / Sea urchin / A1lelochemicals / Kombu / Glyceroglycolipid |
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| Research Abstract |
As one of the causative agents of "Isoyake" phenomenon, we hypothesized that some allelochemicals produced by coralline red algae play an important role in maintaining Isoyake. In order to prove this, we investigated coralline algal metabolites which suppress growth of Laminaria algae, attract sea urchin larvae, induce larval settlement and metamorphosis in sea urchin, and stimulate feeding of sea urchins.
Our results show that numerous sea urchins of Strongylocentrotus nudus continually inhabit coralline flats in Isoyake areas because coralline red alga, Lithophyllum yessoense, produces allelochemicals such as glycoglycerolipids that attract planktonic larvae of sea urchins, induce their settlement and metamorphosis, and stimulate feeding in juvenile and adult sea urchins. Therefore, sea urchins aggregate in large numbers at calm coralline flats and Isoyake is apparently maintained by destructive grazing of juvenile macralgae by them. On the other hand, at low seawater temperature herbivores, such as sea urchins, tend to reduce the grazing pressure toward macroalgae, including the kelp community. At low seawater temperature, temperate coralline red algae may slow down their growth and secondary metabolism. The reduced activity of secondary metabolism may lead to low production of allelochemicals that suppress the development and growth of Laminaria sporelings. Hence, Laminaria zoospores settling on coralline red algae may develop normally, leading to the recovery of kelp beds in coralline flats of Isoyake areas in the southwest coast of Hokkaido.
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Report
(4 results)
Research Products
(6 results)
