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In an article published in The Conversation on January 9^th,ÌýProfessor Anson Mackay and Dr George Swann (¹û¶³Ó°Ôº PhD, now Associate Professor at the University of Nottingham) discuss new evidence for the effects of the warming of southern Siberia’s Lake Baikal on some of its unique microscopic plants as they are outcompeted by species not endemic to the lake.

The evidence is taken from mud accumulated at the bottom of the lake, and especially from cores showing long-term trends in a key group of organisms called diatoms.

Earlier work at ¹û¶³Ó°Ôº had predicted that climate change would lead to a decline in Baikal’s large, heavy, slow-growing, endemic diatom species and their replacement by smaller, lighter, faster-growing species.

A new study by colleague Sarah Roberts set out to test this hypothesis as part of her PhD by studying sediment cores from the bottom of the lake, and thus how diatoms had changed over time. She collected cores from exactly the same locations as had Anson for his post-doctoral research 20 years earlier. Her results suggest that in the south of the Lake especially, there had been a significant change in the diatoms since the early 1970s as the lake began to warm and winter ice thinned.

As expected, there had been a decline in diatoms with thick, heavy shells, and an increase in some faster-growing species with lighter shells. More unexpectedly, however, there had also been a decline in other lighter, especially endemic, species.

The paper concludes that the increasing dominance of non-endemic diatom species has the potential to disrupt the lake’s own food web through changes to the types of zooplankton and other fauna that depend on Baikal diatoms. This may, in turn, impact the endemic fish species that feed on zooplankton communities.

Other changes, such as increases in untreated sewage from coastal settlements and rising surface water temperatures, may also have untold consequences on biodiversity in one of the world’s unique ecosystems.

See