Multiple environmental stressors, including nutrient effluents (i.e. nitrates [$\text{N}{\text{O}}_3^{-}$]) and altered pH regimes, influence the persistence of freshwater species in anthropogenically disturbed habitats. Independently, nitrate and low pH affect energy allocation by increasing maintenance costs and disrupting oxygen uptake, which ultimately results in impacts upon whole animal performance. However, the interaction between these two stressors has not been characterised. To address this, the effects of nitrate and pH and their interaction on aerobic scope and physiological performance were investigated in the blueclaw crayfish, Cherax destructor. Crayfish were exposed to a 2 × 3 factorial combination, with two pH levels (pH 5.0 and 7.0) and three nitrate concentrations (0, 50 and 100 mg L⁻¹$\text{N}{\text{O}}_3^{-}$). Crayfish were exposed to experimental conditions for 65 days and growth and survival were monitored. Aerobic scope (i.e. maximal – standard oxygen uptake) was measured at six time points (1, 3, 5, 7, 14, and 21 days) during exposure to experimental treatments. Crayfish performance was assessed after 28 days, by measuring chelae strength and whole animal activity capacity via the righting response. Survival was reduced in crayfish exposed to pH 5.0, but there was no exacerbation of this effect by exposure to high nitrate levels. Aerobic scope was compromised by the interaction between low pH and nitrate and resulted in prolonged elevations of standard oxygen uptake rates. Exposure to nitrate alone affected aerobic scope, causing a 59% reduction in maximum oxygen uptake. Reduced aerobic capacity translated to reduced chelae strength and righting capacity. Together, these data show that low pH and elevated nitrate levels reduce aerobic scope and translate to poorer performance in C. destructor, which may have the potential to affect organismal fitness in disturbed habitats.

多种环境压力源，包括营养废水（即硝酸盐[$\text{ñ}{\text{Ø}}_3^{-}$]）和改变的pH值会影响人为干扰的栖息地中淡水物种的持久性。硝酸盐和低pH值会独立地通过增加维护成本和破坏氧气吸收来影响能量分配，最终影响整个动物的生长。但是，这两个压力源之间的相互作用尚未得到表征。为了解决这个问题，研究了蓝爪小龙虾（Cherax破坏者）中硝酸盐和pH值及其相互作用对有氧范围和生理性能的影响。小龙虾暴露于2×3分解因子组合下，具有两个pH值（pH 5.0和7.0）和三个硝酸盐浓度（0、50和100 mg L ^-1$\text{ñ}{\text{Ø}}_3^{-}$）。小龙虾暴露于实验条件下65天，并监测其生长和存活率。在暴露于实验治疗期间的六个时间点（1、3、5、7、14和21天）测量有氧运动范围（即最大-标准氧气吸收）。28天后，通过扶正响应测量螯合强度和整个动物的活动能力，从而评估了小龙虾的生产性能。暴露于pH 5.0的小龙虾的存活率降低，但是暴露于高硝酸盐水平不会加剧这种作用。低pH与硝酸盐之间的相互作用损害了有氧作用范围，并导致标准氧气吸收率的持续升高。单独暴露于硝酸盐会影响有氧运动范围，从而使最大摄氧量减少59％。有氧能力降低导致螯合强度和扶正能力降低。这些数据加在一起表明，低pH值和升高的硝酸盐水平会降低有氧运动范围，并转化为较差的性能。C.破坏者，可能在受干扰的生境中影响生物适应性。