Miocene Climatic Optimum fungal record and plant-based CREST climatic reconstruction from Southern McMurdo Sound, Antarctica

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

Journal of Micropalaeontology

Copernicus Publications

Año: 2023

Fungi play key roles in ecosystems; many have restricted geographic distributions, knownhost/substrate preferences, and are important local environmental indicators due to their short dispersal distances. Deep-time studies are necessary to evaluate fungal distribution under global warming events such as those during the middle Miocene. This study of fossil fungi from the Miocene Climatic Optimum (MCO), a time interval of pronounced global warming, provides a unique opportunity to assess fungal response to an analogue for future climate change scenarios.In this study, 44 samples from Southern McMurdo Sound, Antarctica (SMS) provide a new data set of fungal assemblages. With a single morphotype present in low abundance, fungi prove to bedepauperate members of the SMS MCO palynoflora, with maximum concentration ranging only from 72 to 199 fungi per gram of dried sediments. The cosmopolitan nature of the fungi recovered prevented assignment of the assemblage to a narrow Köppen–Geiger climate class. Nevertheless, the analysis shows that the taxa present during the MCO in Antarctica are those adapted to a wide range of climate and environmental conditions. A probability-based climate reconstruction technique (CREST) was applied to provide the most accurate plant-based representation of paleoclimate for this MCO locality. CREST reconstructs a warmer and significantly wetter than present paleoclimate in SMS during the, with precipitation being 279% higher than present-day levels. The CREST reconstructions show the presence of a Cfb Köppen–Geiger climate class during the MCO of SMS. This reconstruction agrees with and enhances the accuracy of previous results completed using various geochemical proxies. These results demonstrate significant refinement of plant-based paleoclimatic reconstructions and define the first known limitations on fungal paleoclimatic reconstructions: both low yield and preservation bias in marine sediments may preclude the use of terrestrial fungal palynomorphs as paleoclimate indicators in those MCO environments.