Fungal spore seasons advanced across the US over two decades of climate change

Ruoyu Wu, Yiluan Song, Jennifer Head, Daniel S.W. Katz, Kabir G. Peay, Kerby Shedden, Kai Zhu
Ruoyu Wu was a Master's student at the University of Michigan, now a Ph.D student at the University of Florida.
Manuscript under review
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Highlights

  • The onset of both ecological and allergenic fungal spore seasons has advanced across the US from 2003 to 2022.
  • Concurrently, the overall intensity of fungal spore seasons has seen a decline.
  • Earlier onset of ecological spore seasons was correlated with higher temperature and lower precipitation.
  • Lower spore season intensity was correlated with lower precipitation.

Abstract

Phenological shifts due to climate change have been extensively studied in plants and animals, yet the responses of fungal spores—crucial organisms that play important roles in ecosystems and act as airborne allergens—remain understudied. This knowledge gap in global change biology hinders our understanding of its ecological and public health implications. To bridge this gap, we first acquired a long-term (2003 — 2022), and large-scale (the continental US) dataset of airborne fungal spores collected by the US National Allergy Bureau. We then extracted ten metrics describing the phenology (e.g., start and end of season) and intensity (e.g., peak concentration and integral) of fungal spore seasons using both ecological and public health approaches, defined as percentiles of total spore concentration and allergenic thresholds of spore concentration, respectively. Using linear mixed effects models, we quantified annual temporal shifts in these metrics across the continental US. We revealed that the onset of the spore season has significantly advanced from both ecological (11 days, 95% confidence interval: 0.4 — 23 days) and public health (22 days, 6 — 38 days) perspectives over two decades. Nevertheless, the total spore concentration in an annual cycle and in a spore allergy season tended to decrease over time. The earlier start of the spore season was significantly correlated with climatic variables, such as warmer temperatures and altered precipitations. Overall, our findings suggest possible climate-driven advanced fungal spore seasons, highlighting the importance of climate change mitigation and adaptation in public health decision-making.

Characterizing fungal spore seasons

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Fungal spore calendar for ten sampling stations.

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Definition and numerical summary of ten fungal spore metrics.

Shifts in fungal spore seasons

Relationship with climatic factors

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Regression coefficients of spore season metrics against climatic variables.

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