Alternaria and Cladosporium fungal spore concentrations in the atmosphere of Tétouan: relationships with meteorological parameters and forecasting models

Abstract

This study aimed to predict daily concentrations of Alternaria and Cladosporium spores in Tétouan (2009–2017) and revealed their near-continuous presence with clear seasonal patterns. Monthly spore integrals (MSIn) were highest from spring to autumn. Alternaria reached its highest values mainly in May–June, with a maximum in June 2010 (5,652 spores*day/m³). Cladosporium showed its highest MSIn values mostly in October, reaching its maximum in 2014 (109,218 spores*day/m³). Since both taxa exhibited two seasonal increases each year, we delineated pre-maximum 1 from the season onset to the first maximum value, and pre-maximum 2 from the subsequent rise to the later seasonal maximum. Pre-maximum 1 showed higher mean concentrations for Alternaria, whereas Cladosporium was higher in pre-maximum 2. During pre-maximum 1, maximum (T_max), mean and minimum temperatures showed significant positive correlations with daily concentrations of both spores. In Pre-maximum 2, temperature exhibited a significant negative correlation for Cladosporium. Correlations with other meteorological parameters were also significant in some cases. For Alternaria, the pre-maximum 1 regression model was the most accurate, explaining 47% of the variability, with T_max as the main predictor and validation in 2015 was satisfactory. For Cladosporium, the best model explained 33.66% of the variability and likewise included T_max as a key predictor. When validated with pre-maximum 2 data from 2016, no significant differences were found between predicted and observed values. Overall, the findings highlight the strong influence of climatic conditions on fungal spore dynamics and provide valuable insights into the ecology of airborne fungi and their potential public health implications.