Under-ice respiration rates shift the annual carbon cycle in the mixed layer of an oligotrophic lake from autotrophy to heterotrophy
Under-ice respiration rates shift the annual carbon cycle in the mixed layer of an oligotrophic lake from autotrophy to heterotrophy
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DOI：
10.1080/20442041.2020.1805261
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发表时间：
2020-11-28
期刊：
影响因子：
3.1
通讯作者：
Weathers, Kathleen C.
中科院分区：
文献类型：
--
作者：
Brentrup, Jennifer A.;Richardson, David C.;Weathers, Kathleen C.
生态系统代谢是对水生态系统中碳的产生和呼吸的综合度量。然而，冰下地区和混合期很少取样，因为物流的挑战和低生物活性的假设，导致有限的了解冬季epilimnetic代谢的贡献，每年的碳循环。水生生态系统可以将其从陆地景观中获得的高达76%的碳作为二氧化碳排放到大气中，使其成为地球碳循环的重要贡献者。因此，研究冰下的新陈代谢尤其重要，因为暖冬已经缩短了冰盖，延长了冰的过渡期，可能导致更多的二氧化碳排放。使用连续一年的epilimnetic高频溶解氧数据，我们发现，总初级生产力低，但不存在冰下，并在冰下期结束时增加。尽管冷水温度，冰下呼吸是夏季呼吸的1.2倍，冰和冰关闭期间是重要的贡献者，每年的新陈代谢估计。平均而言，冰下净生态系统生产力（NEP）是负的，相反，积极的NEP的春季和夏季。包括冬季代谢估计翻转年度NEP从自养到异养，表明全年采样是必不可少的准确评估湖泊中的碳循环。
Ecosystem metabolism is an integrative measure of the production and respiration of carbon in aquatic ecosystems. However, under-ice regions and mixing periods are infrequently sampled because of logistical challenges and assumptions of low biological activity, resulting in limited understanding of the contribution of winter epilimnetic metabolism to annual carbon cycling. Aquatic ecosystems can emit up to 76% of the carbon they receive from terrestrial landscapes as carbon dioxide to the atmosphere, making them significant contributors to Earth's carbon cycle. Consequently, studying metabolism under ice is especially important given that warmer winters have already shortened ice cover and lengthened ice transitional periods, potentially resulting in greater carbon dioxide emissions. Using a continuous year of epilimnetic high-frequency dissolved oxygen data, we found that gross primary production was low but not absent under ice and increased during the end of the under-ice period. Despite cold water temperatures, under-ice respiration was 1.2 times higher than summer respiration, and ice-on and ice-off periods were important contributors to annual metabolism estimates. On average, under-ice net ecosystem production (NEP) was negative, in contrast to positive NEP for the spring and summer periods. Including winter metabolism estimates flipped annual NEP from autotrophy to heterotrophy, demonstrating that year-round sampling is essential for accurately assessing carbon cycling in lakes.