Fungi in a Warmer World: evaluating fungal biodiversity during the Miocene Climatic Optimum in Southern McMurdo Sound

PILIÉ, MALLORY R; WARNY, SOPHIE; GIBSON, MARTHA E.; NUÑEZ OTAÑO, NOELIA B.; ROMERO, INGRID C.; POUND, MATTHEW J.; O'KEEFE, JENNIFER M.K.

Manizales

Congreso; 54th AASP Meeting - Manizales 2022; 2022

The palynological society

Fungi play a key role in ecosystems; most of themmany are cosmopolitan, but several species taxa have distinctive geographical distributions due to climate and hosts availability. Although they are often overlooked in deep-time palynological preparations, their study in the fossil record is key to better understanding their role in past ecosystems under different climate conditions. Fungal remains are generally deposited close to the source, providing an accurate record of local environmental conditions at the time of deposition. Some fungi have very narrow environmental preferences, such as temperature, humidity, rainfall, and pH. The Middle Miocene Climatic Optimum (MMCO) is considered an excellent analogue for future global climate. Thus, the Fungi in a Warmer World (FiaWW) project is developing a global dataset of fungal diversity and distributions from different sites representative of the MMCO worldwide. Here we present the fungal study results of from the ANDRILL (Antarctic geologic drilling program) 2A core recovered from the southern McMurdo Sound in western Ross Sea, Antarctica. Marine, freshwater, and terrestrial palynomorphs previously analyzed suggest a relatively short period of time during the peak of the MMCO in which the area became suddenly much warmer, with summer temperatures reaching at least 10°C (Warny et al. 2009), and moisture delivery to the Antarctic coast substantially increased (Feakins et al. 2012). Our preliminary results of from the ANDRILL- 2A newly acquired fossil fungal record newly acquired show that fossil fungi are low in diversity and vary in opacity and deterioration throughout the MMCO. The Amerospores are the most common morphotype found belonging to amerospores, which likely suggests a more humid environment. We used the CREST method (Climate Reconstruction SofTware) to re-evaluate the pollen and spore record to provide new paleoclimatic reconstructions. These new CREST analyses provide a mean annual temperature of 10.3°C and a mean annual precipitation of 1147 mm. These parameters are consistent with but add precision to the findings published by Warny et al. 2009 (based on the climatic distribution of Nothofagus, the most abundant remaining plant during the MMCO in the Ross Sea) and Feakins et al. 2012 (based on modeling of hydrogen isotopic data extracted from leaf waxes). Results from this work will aid in determining the impact an increase in global temperatures would have on modern fungi in glacial environments.