|Search for homeostasis through time budgeting in Barbus barbus (L.)|
Baras, E. (1993). Search for homeostasis through time budgeting in Barbus barbus (L.), in: Chardon, M. et al. (Ed.) Third Belgian Congress of Zoology, 5-6 November 1993. Belgian Journal of Zoology, 123(Suppl. 1): pp. 5
In: Chardon, M.; Goffinet, G. (Ed.) (1993). Third Belgian Congress of Zoology, 5-6 November 1993. Belgian Journal of Zoology, 123(Suppl. 1). University of Liège: Liège. 109 pp., more
In: Belgian Journal of Zoology. Koninklijke Belgische Vereniging voor Dierkunde = Société royale zoologique de Belgique: Gent. ISSN 0777-6276, more
|Also published as |
- Baras, E. (1993). Search for homeostasis through time budgeting in Barbus barbus (L.). Belg. J. Zool. 123(Suppl. 1): 5, more
Freshwater fish; Homeostasis; Homeostasis; Physiology; Seasonal variations; Temperature effects; Thermoregulation; Barbus barbus (Linnaeus, 1758) [WoRMS]; Belgium, Ourthe R. [Marine Regions]; Fresh water
Although fishes may buffer the natural fluctuations of water temperature through various mechanisms, behavioural thermoregulation may undoubtly be regarded as the basic adaptive response to short term environmental changes. Radio telemetry (40 MHz activity circuit transmitters) was used to define how Barbus barbus (Pisces, Cyprinidae) apportions its time under various thermal conditions throughout the annual cycle. The activities of 21 telemetered fishes (23-53 cm FL) were studied over 24 h cycles (N = 37) and partial cycles (diurnal or nocturnal, N = 80) in the River Ourthe (Southern Belgium, thermal range: 0-25 °C). The daily activity budgets range between 0 and 720 min over the annual cycle and are significantly dependent on water temperature (polynomial regression, R = 0.83, 36 DF). During the autumnal thermal transition (9- 10 °C), the typical bimodal crepuscular rhythm pattern observed in summer turns to a trimodal pattern with the emergence of a diurnal phase. The auroral then crepuscular and finally diumal activity periods progressively vanish as water temperature decreases till the thermallimit for activity (4.0-4.5 °C), when barbels enter a dormancy period. An opposite progressive shift is observed during the spring thermal transition. Although the crepuscular rhythm pattern is consistent throughout summer, water temperature modulates significantly (p < 0.05) the precise timing and respective duration of crepuscular and auroral activities. These results clearly show that the activity budgets, rhythms and timings of B. barbus are modulated by water temperature and suggest a form of homeostasis through time budgeting. The progressive activity shifts demonstrated in B. barbus contrast with the sharp transitions emphasized in Arctic environments and are discussed within the context of homeostasis and adaptation, in parallel with the feeding and diet plasticity in the species.