2003 Fiscal Year Final Research Report Summary
Study on the biological function of tropical minute rotifers and its application for mass preservation of live food.
| Project/Area Number |
14560155
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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 |
General fisheries
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| Research Institution | Nagasaki University |
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Principal Investigator |
HAGIWARA Atsushi Nagasaki University, Graduate School of Science and Technology, Professor, 大学院・生産科学研究科, 教授 (50208419)
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| Project Period (FY) |
2002 – 2003
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| Keywords | tropical minute rotifers / genetic characteristics / resting egg / low temperature tolerance / low temperature / preservation larval rearing |
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| Research Abstract |
1.Genetic characteristics of SS type rotifers
Crossbreeding experiments were conducted using three rotifer strains from Indonesia, Thai and Spain strains. Rotifer mating behavior involves male contact on female corona, male circling around female lorica and copulation, followed by fertilization. The frequency of mating was monitored and percent fertilization was obtained, by co-culturing 100 females and 50 males in a 5 ml petri dish. In the crossing between SS strains, percent copulation and fertilization were 5.0-16.6% and 7.7-34.7%, respectively. No copulation and fertilization was observed between S and SS strains in this experiment, whereas such cases were reported with other S and SS strains. A large genetic variation probably exists both in S and SS strain groups.
2.Reproduction and mass preservation
SS rotifers could be preserved for 14 days at 10 and 12℃. The addition of gamma-aminobutyric acid at 50 ug/mL increased population growth at 25℃. Significantly higher resting egg production was observed when the culture temperature was changed from 30 to 25℃, than when temperature was kept at 30℃. In the large-scale trial using 500L tanks, rotifers produced 2.6x10^6 resting eggs during a 9-day experiment, which was 1.6 times more than the number of rotifers without temperature change.
3.Larval rearing of grouper using SS rotifers
By maintaining the SS type rotifer density at 3, 10 and 30 ind./ml, ingestion rate of grouper larvae was reduced on day 6 and 7, and total length of larvae on day 7 was also the smallest. After day 8 however, no difference was found among treatments. The lorica size of supplied SS rotifers ranged from 80-156um (average lorica length=114um), while larvae ingested rotifers whose lorica length was from 75 to 138 um (104 um in average). Thus, grouper larvae at this stage could ingest only smaller size class of SS rotifers.
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Research Products
(4 results)
