Diatom Response to Global Warming in Douhu Lake, Southeast China

Abstract

A large number of lacustrine sedimentary records indicate that global warming is the main factor leading to significant changes in diatom communities in lakes of the northern hemisphere. However, due to the intensification of human activities since 1850, some scholars have emphasized that the increasing lake trophic level may be the main reason for the changes in diatom communities. The debate is ongoing. In order to avoid falling into the complex relationship between diatom changes and the seasonal cycle that characterizes lakes in mid and high latitudes, we chose a lake located at a low latitude, where the relationship between diatoms and temperature is not indirect but direct. The diatom record spans the past ca. 100 years and reveals that the abundance of Aulacoseira granulata increased from 1900 until 1985, replacing the previously dominant Aulacoseira ambigua. These changes are in agreement with the increasing trend in global temperature. Since 1985, the percentages of the small-celled Discostella stelligera and the benthic diatom Navicula heimansioides have increased, while Aulacoseira granulata has decreased. This latest shift is caused by further global warming. We conclude that warming is the main factor leading to changing diatom communities in Douhu Lake.

Application of a Diatom Transfer Function to Quantitative Paleoclimatic Reconstruction — A Case Study of Yunlong Lake, Southwest China

“…Diatoms in lakes, especially planktonic diatoms, are very sensitive to temperature changes (Smol and Douglas, 2007;Rühland et al, 2015), including direct and indirect responses (Zou et al, 2018). For example, recent global warming has led to the predominance of the warm-preference planktonic diatom Aulacoseira granulata in Douhu Lake in China (Li et al, 2021), and this preference was also evidenced by an investigation on the seasonal diatom succession of Yunlong Lake in China (Zou et al, 2018), which indicated a direct response of diatoms to temperature. Meanwhile, global warming has greatly reduced the length of the ice-cover period of high-latitude lakes, and intensified the thermal stratification of temperate lakes, which has led to blooming of the cyclotelloid diatom taxa (Wang et al, 2012;Rühland et al, 2015), this is an indirect climatic response.…”