Climate change is likely to have large impacts on freshwater biodiversity and ecosystem function, especially in cold-water streams. Ecosystem metabolism is affected by water temperature and discharge, both of which are expected to be affected by climate change and, thus, require long-term monitoring to assess alterations in stream function. This study examined ecosystem metabolism in two branches of a trout stream in Minnesota, USA over 3 years. One branch was warmer, allowing the examination of elevated temperature on metabolism. Dissolved oxygen levels were assessed every 10 min from spring through fall in 2017–2019. Gross primary production (GPP) was higher in the colder branch in all years. GPP in both branches was highest before leaf-out in the spring. Ecosystem respiration (ER) was greater in the warmer stream in two of three years. Both streams were heterotrophic in all years (net ecosystem production—NEP < 0). There were significant effects of temperature and light on GPP, ER, and NEP. Stream discharge had a significant impact on all GPP, ER, and NEP in the colder stream, but only on ER and NEP in the warmer stream. This study indicated that the impacts of temperature, light, and discharge differ among years, and, at least at the local scale, may not follow expected patterns.

中文翻译：

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多年监测冷水流两个分支中的生态系统代谢

气候变化可能会对淡水生物多样性和生态系统功能产生重大影响，尤其是在冷水流中。生态系统的新陈代谢受水温和排放量的影响，预计两者都会受到气候变化的影响，因此，需要进行长期监测以评估河流功能的变化。这项研究调查了美国明尼苏达州鳟鱼流的两个分支中超过3年的生态系统代谢。一个分支较暖和，可以检查高温下的新陈代谢。从2017-2019年春季到秋季，每10分钟评估一次溶解氧水平。在所有年份中，较冷的部门的初级生产总值（GPP）都较高。在春季退出之前，两个分支中的GPP最高。在三年中的两年中，暖流中的生态系统呼吸（ER）更大。两种流在所有年份都是异养的（净生态系统产量-NEP <0）。温度和光对GPP，ER和NEP都有显着影响。流排放对较冷流中的所有GPP，ER和NEP都有重大影响，但仅对较暖流中的ER和NEP具有重大影响。这项研究表明，温度，光和放电的影响在几年之间是不同的，并且至少在本地范围内可能未遵循预期的模式。