S. Fukuda results 37
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Seasonal variability and regulation of bacterial production in a shallow eutrophic lakeNARA Subscribed
The seasonal variation of bacterial production (BP) in a shallow, eutrophic Lake Kasumigaura was clarified from 2012 to 2016. During the studied period, BP fluctuated from 1.9 to 138 μ g C L −1 d −1 . There were no significant correlations between BP and bacterial abundance in any season, suggesting a strong top‐down regulation on BP throughout the year. On the other hand, BP was also related to bottom‐up regulation factors su...
Location, size and age at onset of metamorphosis in the Japanese eel Anguilla japonicaNARA Subscribed
This study clarifies the location, size and age at the onset of metamorphosis in Japanese eels Anguilla japonica through oceanic surveys, rearing experiments and analyses of the morphology and otoliths of leptocephali and glass eels. Twenty‐eight metamorphosing leptocephali were collected in the mesoscale eddy region to the east of Taiwan during research expeditions in 2004. Rearing experiments showed that the total length ( L...
Schooling behaviour of juvenile Pacific bluefin tuna Thunnus orientalis depends on their vision developmentNARA Subscribed
The effects of vision development and light intensity on schooling behaviour during growth in juvenile Pacific bluefin tuna Thunnus orientalis were investigated using both behavioural and histological approaches. The schooling behaviour of three age groups [25, 40 and 55 days post hatching (dph)] of juvenile T. orinetalis were examined under various light intensities. Subsequently, schooling variables, such as the nearest neig...
Ontogenetic changes in schooling behaviour during larval and early juvenile stages of Pacific bluefin tuna Thunnus orientalisNARA Subscribed
Schooling was first observed at 25–27 days after hatching (26· 2–33· 8 mm, total length) in the Pacific bluefin tuna Thunnus orientalis . At this time, the mode of swimming changed from intermittent sprinting to continuous cruising, and this allowed the fish to adjust to an inertial hydrodynamic environment.
Schooling behaviour and retinomotor response of juvenile Pacific bluefin tuna Thunnus orientalis under different light intensitiesNARA Subscribed
Schooling behaviour and histological retinal light adaptation in juvenile Pacific bluefin tuna Thunnus orientalis were examined under various light intensities to determine the effect of light intensity on behaviour. After monitoring the schooling behaviour of juveniles 35–36 and 45–46 days post hatching, schooling variables such as nearest neighbour distance and separation swimming index were measured under different light in...
Using stable isotope ratios as a tracer of feeding adaptation in released Japanese flounder Paralichthys olivaceusNARA Subscribed
Release‐recapture experiments were conducted to examine temporal changes of the carbon and nitrogen stable isotope (δ 13 C and δ 15 N) ratios in the muscle tissue of artificially produced Japanese flounder Paralichthys olivaceus , juveniles. About 9000 juveniles (mean ± s . d . 43·3 ± 5·2 mm in standard length and 1·07 ± 0·37 g, n = 15) were released in each of three coastal areas: Chojagasaki, Arasaki and Jogashima with diffe...