Warmer and more variable temperatures have been implicated in the recent decline of Atlantic salmon (Salmo salar) in Eastern Canada. To date, we know little on how ecologically relevant thermal fluctuations affect swimming performance in fishes. The goal of this study is to determine the effects of warm versus cool diel thermal variability on swimming efficiency and the speed limit for sustainable aerobically fueled swimming. We acclimated wild S. salar juveniles to a cool and a warm ecologically realistic diel thermal profile (16-21 and 19-24°C), and then tested individuals over a common acute change in temperature (16-24°C). We measured metabolic rate and swimming kinematics at a range of swimming speeds, at five temperatures (16, 18, 20, 22, and 24°C) and calculated swimming efficiency. Our temperature acclimation did not appear to significantly affect energetic and kinematic swimming efficiency, but acute exposure to high temperature did increase overall metabolic rate. It appears that wild S. salar can swim efficiently and sustainably during both acute cool and warm exposures, and after acclimation to diel thermal variation of 16-21 or 19-24°C.
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http://dx.doi.org/10.1111/jfb.15996 | DOI Listing |
J Fish Biol
November 2024
Department of Biology, Mount Allison University, New Brunswick, Canada.
Proc Biol Sci
November 2024
Wildlife Ecology and Conservation, University of Florida, 110 Newins-Ziegler Hall PO, Gainesville, FL 32611, USA.
Thermoregulatory behaviour determines an organism's body temperature and therefore its physiological condition, and may differ for organisms situated across climate gradients. Species' preferred or selected temperatures may be higher in warmer locations-referred to as coadaptation-or lower in warmer temperatures-countergradient variation. Here, we tested if rainforest amphibians exhibited coadaptation or countergradient thermal selection across an underappreciated spatial climate gradient (vertical height from forest floor to canopy) and separating diel activity (diurnal versus nocturnal behaviour).
View Article and Find Full Text PDFSci Rep
October 2024
Department of Biology, University of Rome Tor Vergata, Rome, Italy.
Sci Total Environ
December 2024
Yunnan Key Laboratory of Ecological Protection and Resource Utilization of River-lake Networks, Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Sciences, Yunnan University, Kunming 650500, China; Department of Ecoscience, Aarhus University, Aarhus 8000, Denmark; Department of Biology, Limnology Laboratory, Üniversiteler Mahallesi, Middle East Technical University, Çankaya, Ankara 06800, Turkey; Sino-Danish Centre for Education and Research (SDC), Beijing 100049, China.
Deep chlorophyll maximum (DCM), a chlorophyll peak in the water column, has important implications for biogeochemical cycles, energy flow and water surface algal blooms in deep lakes. However, how an observed periodically asymmetric DCM response to environmental variables remains unclear, limiting our in-depth understanding and effective eco-environmental management of deep lakes. Based on both monthly field investigations in 2021 and diel continuous observations in 2021-2023 in clear, monomictic Lake Fuxian, Southwest China, the temporal dynamics and drivers of DCM were examined and periodic features of DCM were found, with a formation period (FP, February-July) and a weakening period (WP, August-December).
View Article and Find Full Text PDFJ Therm Biol
October 2024
Department of Biology, McGill University, Montreal, QC, Canada.
Deforestation can increase light penetration and runoff entering adjacent freshwaters leading to increased average water temperature, stronger diel temperature fluctuations, and increased water turbidity. Changes in temperature extremes (particularly upper peaks) are important for fishes as their body temperature and rate of oxygen consumption varies with environmental temperature. Here, we compare effects of diel-fluctuating versus stable water temperature regimes on the behaviour and upper thermal tolerance (measured as Critical Thermal Maximum, CT) of the Bluntnose Minnow, Pimephales notatus.
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