Semester of Graduation
Spring 2023
Degree
Master of Science (MS)
Department
Geology & Geophysics
Document Type
Thesis
Abstract
Fungi play key and specific roles in ecosystems, specifically as many have restricted geographic distributions, known host/substrate preferences, and are important local environmental indicators due to their short dispersal distances. This study of fossil fungi from a time interval of pronounced global warming, the Miocene Climatic Optimum (MCO), allows analysis of fungal response to an analogue for future climate change scenarios. The research presented herein is part of a larger project, Fungi in a Warmer World (FiaWW), which is using globally-distributed sediment samples to provide foundational information on fungal community distribution patterns and will provide the first fungi-based climatological reconstructions for this time period. A probability-based climate reconstruction technique (CREST) provides an accurate plant-based representation of paleoclimate for each MCO locality studied and acts as an external control for the fungi-based paleoclimate reconstructions proposed herein.
For this thesis, 27 samples from middle Miocene cored intervals in the South China Sea (SCS) and 44 samples from McMurdo Sound, Antarctica (SMS) are studied. Although diagenesis likely caused significant impacts to the SCS MCO samples, the fungal assemblage present immediately following the MCO indicates a Köppen–Geiger climate class characterized by tropical to temperate conditions. According to CREST, the reconstructed MCO climate for the nearest landmass to the SCS study site is warmer and drier during the winter, when compared to modern-day climate, with precipitation during the MCO being only 37% of modern-day levels. Fungi are depauperate members of the SMS MCO palynoflora, with a single morphotype present in low abundance and maximum concentration ranging only from 72 to 199 fungi per gram of dried sediments. Apiosporaceae fungi are cosmopolitan and show taxa present during the MCO in Antarctica adapt to a wide range of climate and environmental conditions. CREST reconstructs a warmer and significantly wetter than present paleoclimate in SMS during the MCO, with precipitation being 279% higher than present-day levels. These results demonstrate significant refinement of plant-based paleoclimatic reconstructions and define the first known limitations on fungal paleoclimatic reconstructions: both non-occurrence and preservation bias in marine sediments may preclude the use of terrestrial fungal palynomorphs as paleoclimate indicators in those environments.
Date
4-5-2023
Recommended Citation
Pilie, Mallory, "Evaluating Fungal Population Response to the Miocene Climatic Optimum: High-Resolution Palynological Insights from the South China Sea and McMurdo Sound, Antarctica" (2023). LSU Master's Theses. 5750.
https://repository.lsu.edu/gradschool_theses/5750
Committee Chair
Warny, Sophie
DOI
10.31390/gradschool_theses.5750