Fig. 2: Development of invertebrate indicators of deepwater oxygen availability in Bichelsee and vegetation around the lake during the past 13,000 years.

A Percentages of chironomids relative to all aquatic invertebrate remains. B Log-transformed chironomid influx at high resolution (grey) and with a 9-sample running average (black). C Scores of the first axis of a CCA calculated as in ref. 21 in orange and log-transformed Chaoborus-to-chironomid ratio in blue24. D Rates of change between the chironomid samples. E Selected tree pollen percentages (Alnus glutinosa-type, Fagus sylvatica). The vertical shading shows the three major phases of oxygen availability in Bichelsee (oxygen-rich, hypoxic and variable hypoxic).