Contribution
Habitat separation among three temperate Chaoborus species
Tsalkitzis, Efrosini; Yan, Norman D.; McQueen, Donald J.; Popiel, Stephanie A.; Demers, Eric
Archiv für Hydrobiologie Volume 129 Number 4 (1994), p. 385 - 403
39 références bibliographiques
publié: Feb 23, 1994
DOI: 10.1127/archiv-hydrobiol/129/1994/385
ArtNo. ESP141012904000, Prix: 29.00 €
Abstract
We investigated the hypothesis that larvae of three morphologically different species of Chaoborus, (C. flavicans, C. punctipennis, C. trivittatus) were able to coexist in Ranger Lake, a small Canadian Shield lake, through spatial and temporal niche differentiation. Population censuses from horizontal and vertical transects, suggested that all three species inhabited the water column during both the night and the day, and that they all migrated up in the water column at dusk. C. punctipennis, the smallest species, was consistently found nearer the lake surface than the other two species. C. punctipennis was also found at all stations during the day, while the two other species were concentrated at the deeper stations and were found at the shallow stations only at night. Our results suggest that the horizontal and vertical distribution patterns observed for all three species resulted from migratory responses to potential fish predation and from horizontal drift associated with bulk movements of epilimnetic waters. We suggest that at Ranger Lake, evening migration from the hypolimnion into the epilimnion exposes Chaoborus to wind induced advective currents which carry them onshore. At dawn, downward migration is expected to carry littoral Chaoborus into offshore currents (Stefan et al. 1989) which are created by night-time surface cooling and nearshore downwelling. This results in horizontal movement away from the littoral zone and back into the daytime refuge provided by the hypolimnion.
Mots-clefs
Chaoborus • censuses • fish predation • hypolimnion • migration • Ranger Lake • Canada