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Variations in water temperatures and levels in the St. Lawrence River (Québec, Canada) and potential implications for three common fish species

Hudon, C. et Armellin, A. et Gagnon, P. et Patoine, A. (2009). Variations in water temperatures and levels in the St. Lawrence River (Québec, Canada) and potential implications for three common fish species. Hydrobiologia , 647 (1). p. 145-161. DOI: 10.1007/s10750-009-9922-6.

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The implications for fish populations of long- (multi-decadal, 1919–2007), medium- (inter-annual) and short-term (seasonal, daily) variations in water temperatures and levels were examined in the St. Lawrence River (SLR). The effects of the seasonal thermal regime of the SLR and its tributaries on the thermal budgets of resident and migrating fish were contrasted. Over the 1919–2007 period, the mean annual water level in Montreal declined significantly; for a discharge of 8,000 m3 s­¯­1, levels dropped steadily by about 3.6 cm year ­¯­1 between 1955 and 1982, coinciding with the period of major shoreline alteration and channel excavation. Between 1960 and 2007, the annual water temperature of the SLR rose by 1.3°C (0.027°C year­¯­1); none of the 10 coldest years and six of the 10 warmest years were observed since 1981. Temperature differences between the warmest and coolest years were greatest in spring and fall (by about 2.5°C); fish growing season (>5°C) was longer by 5 weeks and represented 20% more degree-days for the warmest years. In comparison with its tributaries, SLR water was slower to warm up in the spring but remained warmer in the fall: fish migrating seasonally between water masses could thus enhance or reduce their thermal budgets by 1–2°C daily. Northern pike recruitment years (year-class strength index [YCSI] values above the time series median) were best with June water levels >4.9 m IGLD85 (International Great Lakes Datum of 1985), combined with June air temperatures >18.6°C. For yellow perch, water temperatures >16.2°C in June alone explained six out of the eight best recruitment years in the time series. Conversely, an episode of massive carp mortality in 2001 exemplifies the inherent risk of using shallow flooded habitats for spawning when rapidly dropping levels coincide with hot, sunny weather. The effects of water temperature and level, singly and in combination, thus appear to be critical variables in determining successful fish recruitment in shallow riparian areas which constitute the most important yet the most elusive fish spawning and nursery habitats.

Type de document: Article scientifique
Statut du texte intégral: Autre
Mots-clés libres: Climate change, Level, Water temperature, Time series, Fish populations, Perch, Pike, Carp, St. Lawrence River
Sujets: 2. Milieu physique > 2.4. Hydrologie
4. Faune > 4.2. Poisson
8. Impacts et monitoring > 8.4. Population de perchaude
9. Nouvelles pressions > 9.1. Changement climatique
Date de dépôt: 09 août 2016 15:51
Dernière modification: 09 août 2016 15:51

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