a survey of the aeromycota of urban sydney and its ... · cladosporium, alternaria and penicillium...
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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;
[email protected], [email protected]
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.