Variable versus constant temperature acclimation regimes: Effects on hemoglobin isomorph profile in goldfish,Carassius auratus

Abstract

Goldfish,Carassius auratus, were acclimated for 2 to 3.5 weeks to three temperature regimes: [1] temporally-constant (10, 20 and 30°C), [2] diurnally-cycling (20 ± 10°C) and [3] randomly-fluctuating (± 2°C at approximately 2h intervals between extremes of 10 and 30°C). No significant differences in hematocrit were evident. Hemoglobin levels in fish at constant 30°C and under randomly fluctuating temperature were significantly elevated. Of the three hemoglobin isomorphs observed, the two minor components (G1, G3) tended to decrease in relative abundance with increase in constant temperature, but increased under varying temperature regimes. The converse was true of the principal hemoglobin, G2. Extent of isomorph variation was correlated with extent of temperature variability. These observations confirm that temperature variability significantly effects thermoacclimatory response. The functional significance of changes in isomorph abundances during the acclimatory process is considered.

Regulation of apical H+-ATPase activity and intestinal HCO3−secretion in marine fish osmoregulation

“…While the subsequent application of bafilomycin showed that high salinity increases apical H ϩ secretion, it appears that the regulation of H ϩ secretion and HCO 3 Ϫ secretion are independent. While the critical trigger affecting HCO 3 Ϫ secretion is unknown, slight variations in acclimation temperature may have contributed to our results (15). Activity of the Na ϩ -K ϩ -ATPase is known to decrease at lower temperatures and affect osmoregulatory capacity, but the effect of acclimation temperature on the V-H ϩ -ATPase and SLC26a6 Cl Ϫ /HCO 3 Ϫ exchanger has not been investigated (26).…”

Physiological effects of environmentally relevant, multi-day thermal stress on wild juvenile Atlantic salmon (Salmo salar)

“…However, largely due to practical issues of temperature control in the laboratory, comparatively few studies investigate how temperature cycling, compared to stable acclimation temperatures, affect fish biology (see Threader and Houston, 1983; Houston and Gingras-Bedard, 1994; Mesa et al ., 2002; Narum et al ., 2013; Tunnah et al ., 2017 as examples). Given that water temperatures in traditionally productive Atlantic salmon habitat, such as the Miramichi River, are increasing beyond the presumed thermal limit for this species (Elliott and Elliott, 1995), we were interested in whether the nature of the thermal cycle differentially influenced physiology.…”

Winter survival of age-0 smallmouth bass, Micropterus dolomieu, in north eastern lakes

“…In the cold, under-ice environment of northern lakes, the function of temperature in the mortality process is complex affecting the availability of oxygen for metabolism (Ultsch 1989) and the acclimation process (Houston & Gingras-Bedard 1994, Jobling 1994. Colder temperatures (2 vs. 4°C) can increase mortality of age-0 smallmouth bass (Oliver et al 1979).…”

“…The winter was divided into early, middle, and late periods reflecting declining, stable, and increasing seasonal changes in water temperatures. To search for potential interactions of temperature and survival, we used the overall average temperature, degreedays from 1 January to 1 April (days · temperature when temperature > 0), coefficient of variation (CV -variable temperature effects, Houston & Gingras-Bedard 1994), and slope of the early winter decline in temperature (period of acclimatization sensitivity; Cunjak et al 1987).…”