Variable Temperature Stress in the XXXX @entity2199 (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor.

@entity2199 @entity920
UNASSIGNED: A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the @entity2199 @entity2199 responds to @entity920 at constant temperatures (8-24  C) and under fluctuation conditions of low (  4  C) and high (  8  C) amplitude (averages of 12, 16, 20  C and 16  C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12-24  C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8  C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12  C impacted reproduction and body size compared to @entity2199 kept at the matching average constant temperatures. @entity920 exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to @entity920 (EC50 values), was similar at intermediate temperatures (12, 16, 20  C) and higher at 24  C and especially the innately stressful 8  C condition. Temperature variation did not increase @entity920 sensitivity. Indeed under variable conditions including time at the stressful 8  C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher @entity920 concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case.
