Body size of fossil Pediastrum in lake sediments as an indicator of temperature variation

Abstract

Reliable paleotemperature proxies can potentially help resolve the Holocene temperature conundrum. We investigated the Pediastrum body size of a set of lakes in northern China and found that the body size generally increased with annual and summer temperature, rather than with pH, water depth or salinity. The body size variations of fossil Pediastrum in the sediments of Bosten Lake, in Xinjiang, China, were comparable with several independent paleotemperature records for the past 2000 years, with larger body sizes occurring during warm periods, and vice versa. Therefore, we propose that the body size of fossil Pediastrum in the sediments of mid-latitude freshwater lakes is a reliable temperature proxy. The temperature sensitivity of Pediastrum body size may be related to the longer growth season and higher growth rate of green algae under climatic warming.