Impacts of regional warming on long‐term hypolimnetic anoxia and dissolved oxygen concentration in a deep lake

摘要: Although few reports have described long-term continuous anoxia in aquatic systems, Lake Ikeda Japan experienced such conditions the hypolimnion from 1990 to 2010. The present study aimed assess temporal fluctuations lake's thermal stability 1978 2011 understand influence of regional climate change on hypolimnetic this lake. Because complete vertical mixing, which supplies dissolved oxygen (DO) hypolimnion, potentially occurs February, we calculated Schmidt index (S) February and compared it with DO dynamics. Vertical water temperature profiles were using a one-dimensional model, temperatures meteorological data used analyse annual temperatures, thermocline depth, variables S. We estimated that mean air volume-weighted increased by 0.028 0.033 °C year−1, respectively, 2011. Between 1986 1990, S abruptly, probably due large upwards trend (+0.239 °C year−1). hypothesize mixing regime lacked overturn took effect at time lasted until 2011, when was particularly small. These results demonstrate abrupt warming late 1980s likely triggered termination caused 21-year period successive Ikeda. conclude lake response rapid shift key factor changing environment winter is critical environmental controlling anoxic deep lakes. Copyright © 2014 John Wiley & Sons, Ltd.