To investigate the puzzle of whether metabolic rate depression is involved in winter dormancy in fishes, we studied the cunner (Tautogolabrus adspersus), an abundant western North Atlantic wrasse. Like other temperate wrasses [16,29,30], cunner are winter-dormant: they seek refuge within the substrate and become inactive when the ocean cools below approximately 5°C in autumn, and emerge at approximately 5°C the following early summer [31–33]. This winter dormancy in cunner has been associated with a large decrease in metabolic rate that occurs rapidly (within hours) below 5°C and is maintained over the winter [ten,18]. The Q10 of metabolic rate over the transition from active to dormant temperatures has been reported to be greater than 10 in cunner, as in other winter-dormant wrasses , whereas at warmer active temperatures, the Q10 is between 2 and 3, a typical value for fishes [10,34]. Based on this, and consistent with simultaneous reductions in tissue protein synthesis and suppression of appetite and digestion [33,36,37], metabolic rate depression has been implicated as a central component of winter dormancy in cunner. Using cunner as a model, we investigated the hypothesis that the mechanism underlying the energy savings (i.e. low metabolic rate) of winter dormancy in fishes is not metabolic rate depression, but rather a behavioural reduction in activity. We carried out three experiments using automated optical respirometry to allow for multi-day, high-resolution monitoring of whole-animal oxygen consumption rate ( ; a proxy for metabolic rate) even at frigid temperatures. In experiment 1, we examined the influence of acute exposure to low winter temperature on the diel cycle of metabolic rate. In experiment 2, we examined the effect of acute exposure to darkness and low temperature, which are characteristic of the winter refuge, on the diel cycle of metabolic rate and spontaneous activity (measured simultaneously). In experiment 3, we investigated whether chronic acclimation to low temperature can trigger a metabolic rate depression. If metabolic rate depression is involved in winter dormancy, we predicted that the thermal sensitivity (i.e. Q10) of metabolic rate would remain high at all times when cooled Dating-App für über 50 below approximately 5°C, including when fish are at rest (i.e. at their SMR at night, as cunner are active during the day ). Alternatively, if reduced activity explains energy savings under winter dormancy, then the thermal sensitivity of metabolic rate during resting periods would indicate physico-chemical effects alone (Q10 ? 2–3) regardless of acute or chronic cold exposure and, in experiment 2, variation in activity would largely explain variation in metabolic rate.
(a) Dogs
Adult cunner out-of combined men and women was in fact captured that have hoop barriers within the summer 2013 when you look at the Conception Bay (47°37?42? Letter, 52°51?31? W), Newfoundland, Canada. The new seafood was in fact moved to holding tanks within Sea Sciences Heart (OSC), Memorial University out of Newfoundland, supplied with flow-through, temperature-regulated seawater (8–10°C) and you may met with a cold weather photoperiod (eleven L : 13 D). New fish was indeed fed to help you satiation weekly with sliced herring.
Teenager cunner from combined sexes was indeed the fresh new 2013 kiddies from insane-caught mothers away from Placentia Bay (47°42?47? Letter, 53°58?06? W) and you may Conception Bay, Newfoundland. Spawning, hatching and rearing taken place within OSC at 15°C and you can several L : twelve D photoperiod. 3 months just before tests, juveniles was indeed moved to holding tanks, given disperse-owing to, temperature-controlled seawater (8–10°C) lower than a winter photoperiod (eleven L : 13 D), and given lifeless pellets (Gemma; Skretting, St Andrews, NB, Canada).
dos. Material and methods
A keen 11 L : thirteen D photoperiod was used in the research since it takes place inside the southeastern Newfoundland, whenever cunner was energetic but preparing to go into dormancy (October; sea temperature: approx. 9°C and you can cooling) or in winter months dormancy (February; approx. 0°C) [31–33]. Studies were presented anywhere between , into the regular Newfoundland dormancy several months (November–June) .