A survey of the aeromycota of urban Sydney and its relationships with environmental

variables

P.J Irga & F. R Torpy

1School of Life Sciences, University of Technology Sydney, Sydney NSW AU;

peter.irga@uts.edu.au, fraser.torpy@uts.edu.au

Abstract

The absence of a comprehensive survey of aeromycota, and the factors that are associated

with the species distribution and density of urban Sydney is lacking. This study determined

the diversity and abundance of outdoor airborne fungal concentrations in urban Sydney.

Several sites with a range of varying characteristics were sampled for culturable airborne

fungi and a range of physiochemical air quality variables monthly for one year.

through multivariate analysis, the primary factors associated with fungal species diversity,

propagule density and species distribution were identified. As has been the case with research

from other cities, there were major seasonal changes in the species distribution detected;

although samples from most months were dominated by Cladosporium spp. and Alternaria

spp. Pathogenic fungi were sparsely distributed in the data set, although Aspergillus spp.

including A. fumigatus was detected in several samples. Grass as a component of urban

forestry was associated with changes in total spore density. Further, the investigation

indicated the potential contribution of senescent leaves to the diversity of airborne fungal

propagules during the season of autumn.

Keywords

Airborne fungi, bioaerosols, seasonal; allergy, risk assessment.

Introduction

Airborne fungal propagules have been comprehensively assessed for every major Australian

city except for Sydney. Only three assessments for Sydney exist (Frey and Durie 1960;

Burton and Katelaris 2014; Torpy & Irga et al. 2013), however these studies have limited

ecological scope and temporal and spatial replication.

Gaps in knowledge for Sydney - what is happening outdoors?

• Diversity and relative abundance of airborne fungal genera in Sydney

• Seasonal variation

• Meteorological relationships

• Potential source relationships

Aims:

1. Determine density and species composition of airborne fungi

2. Map seasonality of outdoor airborne fungi in urban Sydney

3. Map spatial diversity of the aeromycota community across urban Sydney

4. Determine if environmental variables have relationships with mould propagule

density/diversity

Figure 1. Map of Sydney, Australia depicting the locations of sampling sites

Materials and Methods

Eleven sites with a range of varying characteristics were sampled monthly

Airborne fungal samples were collected using a Reuter Centrifugal air sampler.

Greenspace density, relative humidity, rainfall, temperature prevailing wind direction were

also recorded

Statistical analyses

Differences in fungal CFU concentrations across sites and months were examined by general

linear model analyses of variance (ANOVA)

Community differences across months were compared using analyses of similarities

(ANOSIM) using a Euclidean distance similarity matrix.

Similarity percentages analysis (SIMPER) was used to identify genera responsible for

differences across groups (sites and months).

Environmental associations were examined using Pearson correlation coefficients. Stepwise

multiple linear regression was used to determine the relative influence of the environmental

variables on the variance in fungal levels.

Results and Discussion

Increases in fungal density and diversity were observed during summer months, possibly due to

changes in meteorological factors.

There were positive associations between variables that increase during summer in Sydney, such as

temperature and rainfall, and many fungal genera.

There were no differences in community assemblage across sites, however some individual genera

did show trends; Epicoccum was frequently found in Newtown.

There may be a potential urban forestry association with this genus for this particular site, which had

substantial greenspace density.

Newtown samples had higher concentrations, followed by Centennial park, indicating that

greenspace, especially the grass component, could be a major determinant of airborne fungi in

urban areas.

Environmental variables associated with diversity and abundance of fungal propagule loads were;

temperature, wind speed, proximal greenspace.

If the greenspace comprised of grass, stronger associations with the aeromycota were observed.

Figure 3. Temporal relative abundances of fungal genera encountered in Sydney

Australia, averaged across sites.

Figure 4. Average total number of fungal CFU/m3 encountered and average

number of genera encountered across sampling sites.

Figure 5. Spatial relative abundances of fungal genera encountered in Sydney

Australia, averaged across months.

Cladosporium, Alternaria and Penicillium were common across both spatial and temporal

samples.

The diversity of genera resembled the composition of fungi in other city centres across

Australia

Equation 1

Total airborne fungi (CFU m-3) = 16.6a + 138b – 1.9c + 370.1

Where a = Percentage grass cover within 100 m radius, b = Wind speed (m.s-1), c = Total

rainfall in the past month (mm).

Equation 2

Number of genera encountered = 0.218a – 0.207b + 0.0065c + 9.8 Where a = wind speed (m

s-1), b = temperature (oC), c = Total rainfall in the past month (mm).

Focus was paid to Aspergillus spp., due to the human health risks. Aspergillus versicolour

was most prevalent (Table 1). Aspergillus fumigatus was detected much less frequently,

occurring in 1.5% of samples.

This work has been published as:

Irga, P. J. and F. R. Torpy (2015). "A survey of the aeromycota of Sydney and its correspondence

with environmental conditions: grass as a component of urban forestry could be a major

determinant." Aerobiologia: 1-15. DOI 10.1007/s10453-015-9388-0

References

Frey, D., & Durie, E. B. (1960). The incidence of airbourne fungus in Sydney.

Mycopathologia, 13(2), 93-99.

Burton, P. K., & Katelaris, C. H. (2014). Aerobiological survey of fungal spores in Sydney:

seasonal distribution of Didymella and Coprinus spores. In 10th International Congress of

Aerobiology). Campbelltown, Australia.

Torpy, F., Irga, P., Brennan, J., & Burchett, M. (2013). Do indoor plants contribute to the

aeromycota in city buildings? Aerobiologia, 29(3), 321-331.

Acknowledgements: We thank Gemma Armstrong, Ashley NJ Douglas, volunteers and staff

at University of Technology Sydney for their invaluable help.