Insights into thermal sensitivity: Effects of elevated temperature on growth, metabolic rate, and stress responses in Atlantic wolffish (Anarhichas lupus)

Abstract

The Atlantic wolffish (Anarhichas lupus) is a cold-water fish with potential for aquaculture diversification. To unveil the mechanisms underlying the compromised growth in Atlantic wolffish when reared at higher temperatures, we investigated the relationship between temperature, growth rate, aerobic capacity, stress biomarkers, and gut barrier function. Juveniles acclimated to 10°C were maintained at 10°C (control) or exposed to 15°C for either 24 h (acute exposure) or 50 days (chronic exposure). Fish exposed to 15°C exhibited reduced growth, higher standard, and maximum metabolic rates compared to those at 10°C. In the chronically exposed group at 15°C, metabolic rates were lower than those of acutely exposed fish. The absolute aerobic scope exhibited no significant variation in temperatures; however, the factorial scope showed a notable reduction at 15°C in both acute and chronic exposed groups, aligning with a correlated decrease in individual growth rates. Chronic warming led to increased plasma glucose levels, indicating energy mobilization, but cortisol levels were unaffected. Furthermore, chronic warming resulted in reduced intestinal barrier function, as evidenced by increased ion permeability and a negative potential in the serosa layer. We conclude that warming elevates metabolic rates while reducing intestinal barrier function, thus increasing energy expenditure, collectively, limiting energy available for growth at this temperature from increased allostatic load. Thus, juvenile wolffish maintaining their aerobic scope under thermal stress experience slower growth. This research provides insights for improving the welfare and resilience of wolffish in aquaculture at elevated temperatures and understanding their response to increased environmental temperatures.

Keywords: Atlantic wolffish; aerobic scope; barrier function; metabolism; stress; temperature.

FIGURE 1

Standard metabolic rate (SMR) and maximum metabolic rate (MMR) (a), absolute aerobic scope (AAS) (b), and factorial aerobic scope (FAS) (c) in the two experimental treatments following acute (10_A, 15_A, white background) and chronic exposure (10_C and 15_C, shaded background). All values are displayed as mean ± SD (n = 16). Letters (a, b) indicate significant differences between temperature treatments at the corresponding time point, whereas symbols denote time effects specific to each temperature, with # and ## used for time differences at 10°C and † and ‡ for time differences at 15°C.

FIGURE 2

Correlation analysis comparing absolute aerobic scope (AAS) (a), factorial aerobic scope (FAS) (b), and maximum metabolic rate (MMR) (c) with specific growth rate (SGR), as well as correlation analysis comparing MMR against AAS (d) or FAS (e) of individual Atlantic wolffish (n = 16), exposed to 10°C (open circles) and 15°C (dark squares). Pearson's coefficient values and linear regression equations for both temperatures are presented below each graph. Asterisks denote significant correlations.

FIGURE 3

Ussing chambers result in proximal and distal intestine regions of the intestine at 10°C (white) or 15°C (gray) of transepithelial resistance (TER, Ω cm⁻²) (a), transepithelial potential (TEP, mV) (b), short‐circuit current (SCC, μA cm⁻²) (c), mannitol uptake (Papp, cm s⁻¹) (d), and lysine uptake (transport, mol min⁻¹ cm⁻²) (e). All values are displayed as mean ± SD (n = 12). p‐Values for main effects and interactions are given in corners of each graph.