1995 Fiscal Year Final Research Report Summary
Effects of underwater brightness on behavior of Japanese spiny lobsters.
| Project/Area Number |
06660234
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Mie University |
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Principal Investigator |
KOIKE Takashi Mie Univ.Fac.Bioresources, Associate Professor, 生物資源学部, 助教授 (60093126)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Spiny lobster / Behavior / Daily rhythm / Automatic recording sistem / Daytime brightness / nighttime brightness / Circadian rhythm |
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| Research Abstract |
Japanese spiny lobsters (Panulirus japonicus) have a nocturnal habit, and their activity is high in nighttime and low in daytime. We produced diurnal brightness change with a 12 hour bright period (daytime) and a 12 hour dark period (nighttime) artificially in our experimental tank, and observed the diurnal variation of the spiny lobster activities. The lobster activity was detected by measuring tension of wire which hangth the lobster cage. Under a standard condition with 3.3 x 10^2 1x daytimebrightness and 0 1x nighttime brightness, spiny lobsters exhibit clear diurnal variation pattern almost in phase with the brightness change. When the nighttime brightness is higher than a value of about 1.8 x 10^<-4> 1x, the night time activity is considerably suppressed. This value corresponds to the threshold value speparating the active and inactive regime of the nighttime activity of the spiny lobster. After the daytime brightness is changed from the standard value to 0 1x, the phase of the diurnal variation pattern is shifted and its period becomes 23 hours rather than 24 hours. By using is nature, the minimum daytime brightness recognizable to spiny lobsters is estimated to be about 2.3 x 10^<-5> 1x.
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