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Comparing the behavioural thermoregulation response to heat stress by Atlantic salmon parr ( Salmo salar ) in two rivers
Author(s) -
Corey Emily,
Linnansaari Tommi,
Dugdale Stephen J.,
Bergeron Normand,
Gendron JeanFrançois,
Lapointe Michel,
Cunjak Richard A.
Publication year - 2020
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12487
Subject(s) - salmo , thermoregulation , heat stress , juvenile , environmental science , ecology , air temperature , degree (music) , biology , fishery , geography , zoology , fish <actinopterygii> , meteorology , physics , acoustics
Climate change is expected to increase the frequency and magnitude of extreme thermal events in rivers. The Little Southwest Miramichi River (LSWM) and the Ouelle River (OR) are two Atlantic salmon ( Salmo salar ) rivers located in eastern Canada, where in recent years, water temperatures have exceeded known thermal limits (~23°C). Once temperature surpasses this threshold, juvenile salmon exploit thermal heterogeneity to behaviourally thermoregulate, forming aggregations in coolwater refuges. This study aimed to determine whether the behavioural thermoregulation response is universal across rivers, arising from common thermal cues. We detailed the temperature and discharge patterns of two geographically distinct rivers from 2010 to 2012 and compared these with aggregation onset temperature. PIT telemetry and snorkelling were used to confirm the presence of aggregations. Mean daily maximum temperature in 2010 was significantly greater in the OR versus the LSWM ( p = 0.005), but not in other years ( p = 0.090–0.353). Aggregations occurred on 14 and 9 occasions in the OR and LSWM respectively. Temperature at onset of aggregation was significantly greater in the OR ( T onset = 28.3°C) than in the LSWM ( T onset = 27.3°C; p = 0.049). Logistic regression models varied by river and were able to predict the probability of aggregation based on the preceding number of hours >23°C ( R 2 = 0.61 & 0.65; P 50 = 27.4°C & 28.9°C; in the OR and LSWM respectively). These results imply the preceding local thermal regime may influence behaviour and indicate a degree of phenotypic plasticity, illustrating a need for localised management strategies.