Environmental risk assessment in aquatic ecosystems typically uses biomarkers to detect interactions between potential hazards and biological systems. Next to knowing environmental contaminant levels in tissues and the environment, it is important to link to potentially deleterious effects at higher levels of biological organization such as biochemistry, physiology, and overall health status. In this laboratory study we assessed the toxicity of waterborne cadmium (Cd) over an exposure range of 0 - 100 µg l⁻¹ for nine days to the loricariid suckermouth catfish Hypostomus plecostomus. We evaluated the integrated response of the fish at the biochemical to physiological level by means of a suite of tissue biomarkers of exposure and effects, including Cd concentrations in gills, liver metallothioneins (MT) and cholinesterase activity (ChE) in brain, before and after the inhibition of the alkaloid eserine, as well as whole-fish resting oxygen consumption rates and ingestion rate. Tissue biomarkers (MT and ChE) showed a non-monotonic relationship, with maximum/minimum responses at intermediate doses. i.e. 10 and 50 µg l⁻¹, whereas biomarker responses of fish exposed at 100 µg l⁻¹ more closely resembled biomarker responses seen at lower concentrations (< 10 µg l⁻¹). Conversely, the oxygen consumption rate peaked at 100 µg l⁻¹, suggesting a higher metabolic cost for higher metal exposure, with no significant correlation with fish body condition and food intake. Integrated Biomarker Response (IBR) values peaked at the intermediate exposure concentration of 50 µg l⁻¹ Cd. The non-monotonic dose-response of the biochemical biomarkers of exposure, together with the higher metabolic rates of fish exposed to 50 - 100 µg l⁻¹ of Cd and the non-significant effects on the more relevant physiological and histological variables suggests that H. plecostomus is capable of biochemically and physiologically regulating moderately high Cd concentrations, thus representing a suitable indicator organism to monitor metal pollution by Cd.

水生生态系统中的环境风险评估通常使用生物标志物来检测潜在危害和生物系统之间的相互作用。除了了解组织和环境中的环境污染物水平之外，重要的是要与更高水平的生物组织（如生物化学、生理学和整体健康状况）的潜在有害影响联系起来。在这项实验室研究中，我们评估了在 0 - 100 µg l ^-1的暴露范围内持续 9 天的水性镉 (Cd) 对 loricariid 吸嘴鲶Hypostomus plecostomus的毒性. 我们通过一系列暴露和影响的组织生物标志物评估了鱼类在生化水平对生理水平的综合反应，包括前后鳃中的镉浓度、肝脏金属硫蛋白 (MT) 和大脑中的胆碱酯酶活性 (ChE)抑制生物碱丝氨酸，以及整鱼静息耗氧率和摄食率。组织生物标志物（MT 和 ChE）显示出非单调关系，在中等剂量下具有最大/最小反应。即 10 和 50 µg l ^{-1 ，而暴露于 100 µg} l ^-1的鱼的生物标志物反应更接近于在较低浓度下观察到的生物标志物反应（< 10 µg l ^-1）。相反，耗氧率在 100 µg l ^-1时达到峰值，这表明较高的金属暴露会产生较高的代谢成本，与鱼体状况和食物摄入量没有显着相关性。综合生物标志物反应 (IBR) 值在 50 µg l ^-1 Cd的中间暴露浓度达到峰值。暴露的生化生物标志物的非单调剂量反应，以及暴露于 50 - 100 µg l ^-1 Cd 的鱼的较高代谢率以及对更相关的生理和组织学变量的非显着影响表明H . plecostomus能够在生化和生理上调节适度高的 Cd 浓度，因此是监测 Cd 金属污染的合适指示生物。