References of "Ovidio, Michaël"
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See detailSeasonal variations of activity pattern of brown trout (Salmo trutta) in a small stream, as determined by radio-telemetry
Ovidio, Michaël ULg; Baras, Etienne; Goffaux, D. et al

in Hydrobiologia (2002), 470(1-3), 195-202

Nine brown trout (27.9-42.8 cm FL, 234-995 g) from the Aisne stream (Belgian Ardenne) were tagged with surgically implanted radio transmitters, and their activity patterns were studied at 10-min intervals ... [more ▼]

Nine brown trout (27.9-42.8 cm FL, 234-995 g) from the Aisne stream (Belgian Ardenne) were tagged with surgically implanted radio transmitters, and their activity patterns were studied at 10-min intervals during twenty-six 24-h cycles from October 1995 to May 1997. The duration and intensity of activity were mainly proportional to water temperature and day length but some differences appeared between individuals. The daily home range in summer was also 3.2 times longer than in winter, and was exploited 2.5 times more intensively. At all seasons, trout were most active at dusk, and seasonal variations in diel patterns consisted mainly in a progressive shift from more crepuscular activity in autumn and winter to more homogenous and intensive activity during spring and summer, but still with a predominance of activity at dusk. This relative consistency of activity rhythm throughout the year was interpreted within the context of foraging risk and efficiency, in view of the scarcity of predators in the Aisne stream, and of drifting macroinvertebrates being consistently more abundant at dusk at all times of the year. However, activity patterns varied substantially between individuals living in different microhabitats, including when fish were investigated on the same day. This suggests that activity patterns are also subordinated to local factors such as habitat structure or abundance of drifting prey. [less ▲]

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See detailL'impact des barrages sur les migrations des poissons
Ovidio, Michaël ULg

in Delbeuck, Claude (Ed.) Paysage (2001)

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See detailA radio-tracking study on the impact of small dams on the conservation of salmonid fish in Southern Belgium.
Ovidio, Michaël ULg; Lambot, Francis; DeBast, Benoît et al

Conference (2000, November)

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See detailRelationship between habitat structure and the mobility of brown trout in a small stream.
Ovidio, Michaël ULg; Brucy, Claire; Philippart, Jean-Claude ULg et al

Conference (2000, September)

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See detailMethodological bias in home range and mobility estimates when locating radio-tagged trout, Salmo trutta, at different time intervals
Ovidio, Michaël ULg; Philippart, Jean-Claude ULg; Baras, Etienne

in Aquatic Living Resources (2000), 13(6), 449-454

Radio tracking has been extensively used to enhance our knowledge on the movement and home range of fish in general and salmonids in particular. However, the use of various temporal sampling protocols is ... [more ▼]

Radio tracking has been extensively used to enhance our knowledge on the movement and home range of fish in general and salmonids in particular. However, the use of various temporal sampling protocols is likely to overlook fish movements, and produce experimental artefacts, the amplitude of which is unknown and may compromise comparison of fish behaviours revealed by different protocols. Starting from a day-by-day tracking study of brown treat in Belgian waters (Aisne stream, nine fish, minimum 39 daily locations per fish), we re-examined their home range and mobility, through a subsampling process, as if the fish had been located at longer time intervals (2-14 days). The estimates from subsamples were compared to the original data set in order to quantify the corresponding reduction of accuracy from observed data, and how far this could be predicted on the basis of locating frequency. The results clearly indicate that all intervals longer than one day generally generate substantial biases (reduction of accuracy from 0 to 82% for home range and from 5 to 92% for mobility) but these can be partly corrected through the use of predictive models. This analysis demonstrates that any comparison between studies relying on different locating frequencies can generate some ambiguity when interpreting biological phenomena or geographical differences. (C) 2000 Ifremer/CNRS/INRA/IRD/Cemagref/Editions scientifrques et medicales Elsevier SAS. [less ▲]

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See detailRelationship between the drift of macroinvertebrates and the activity of brown trout in a small stream
Giroux, F.; Ovidio, Michaël ULg; Philippart, Jean-Claude ULg et al

in Journal of Fish Biology (2000), 56(5), 1248-1257

Brown trout Saline trutta were most active in a small stream at night. dusk and dawn when drift rate was highest, but correlations between hourly drift rates and the trout's activity varied substantially ... [more ▼]

Brown trout Saline trutta were most active in a small stream at night. dusk and dawn when drift rate was highest, but correlations between hourly drift rates and the trout's activity varied substantially between individuals, between different dates for a single individual, and between different periods of the daily cycle. On some occasions. the trout were responsive to the total drift rate, either at night or during the day, and on others to the largest drifting organisms only (terrestrial organisms, adults of Ephemeroptera, Diptera and Trichoptera). The study supports the idea that trout adapt their activity pattern to the abundance of drifting prey, either as generalists towards any organism, or as specialists towards the largest ones. (C) 2000 The Fisheries Society of the British Isles. [less ▲]

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