North Carolina State University, United States.
North Carolina State University, United States.
Aquat Toxicol. 2020 Apr;221:105405. doi: 10.1016/j.aquatox.2020.105405. Epub 2020 Jan 24.
Many freshwater ecosystems are becoming saltier and/or warmer, but our understanding of how these factors interact and affect the physiology and life history outcomes of most aquatic species remain unknown. We hypothesize that temperature modulates ion transport rates. Since ion transport is energetically expensive, increases in salinity and/or temperature may influence ion flux rates and ultimately, organismal performance. Radiotracer (Na, SO, and Ca) experiments with lab-reared mayflies (N. triangulifer) and other field-collected insects showed that increasing temperature generally increased ion transport rates. For example, increasing temperature from 15 °C to 25 °C, increased Na uptake rates by two-fold (p < 0.0001) and SO uptake rates by four-fold (p < 0.0001) in the caddisfly, Hydropsyche sparna. Smaller changes in Na and SO uptake rates were observed in the mayflies, Isonychia sayi and Maccaffertium sp., suggesting species-specific differences in the thermal sensitivity of ion transport. Finally, we demonstrated that the toxicity of SO was influenced by temperature profoundly in a 96-h bioassay. Under the saltiest conditions (1500 mg L SO), mayfly survival was 78 % at 15 °C, but only 44 % at 25 °C (p < 0.0036). Conceivably, the energetic cost of osmoregulation in warmer, saltier environments may cause significant major ion toxicity in certain freshwater insects.
许多淡水生态系统变得更加咸和/或温暖，但我们对这些因素如何相互作用以及影响大多数水生物种的生理和生活史结果的了解仍然未知。我们假设温度调节离子转运速率。由于离子转运是能量密集型的，盐度和/或温度的增加可能会影响离子通量率，并最终影响生物体的表现。使用实验室饲养的蜉蝣（N. triangulifer）和其他野外采集的昆虫进行放射性示踪剂（Na、SO 和 Ca）实验表明，温度升高通常会增加离子转运速率。例如，将温度从 15°C 升高到 25°C，可使毛翅目 Hydropsyche sparna 的 Na 摄取率增加一倍（p < 0.0001），SO 摄取率增加四倍（p < 0.0001）。在蜉蝣 Isonychia sayi 和 Maccaffertium sp. 中，Na 和 SO 摄取率的变化较小，这表明离子转运的热敏感性存在物种特异性差异。最后，我们证明 SO 的毒性在 96 小时生物测定中受温度的强烈影响。在最咸的条件下（1500mg L SO），蜉蝣在 15°C 时的存活率为 78%，但在 25°C 时仅为 44%（p < 0.0036）。可以想象，在温暖、咸水环境中渗透压调节的能量成本可能会导致某些淡水昆虫产生严重的主要离子毒性。
