Isabel Iglesias

Variation assessment of airborne Alternaria and Cladosporium spores at different bioclimatical conditions.

The study of mould spores is of major importance as many fungi can cause considerable economic losses worldwide acting as plant pathogens or triggering respiratory diseases and allergenic processes in humans. Knowledge of spore production relationships to different altitudes or weather patterns can be applied in a more efficient and reliable use of pesticides or improving diagnosis and treatment of respiratory allergic diseases. In this way monitoring of Cladosporium cladosporioides, C. herbarum and Alternaria spp. airborne spores during 2002 was carried out by means of three LANZONI VPPS 2000 pollen traps located in areas of north-west Spain at various altitudes and with various weather patterns. High spore counts were recorded in the late summer and early autumn, with a fairly similar hourly spore-count pattern, increasing the concentrations in the late evening (7-10 p.m.). High spore concentrations were detected in inland rural areas in front of coastal ones. As the continentality index increased, C. cladosporioides spore concentrations rose and Alternaria declined. C. herbarum concentrations increased with increasing height above sea level. The weather factor displaying the strongest positive correlation with mean daily spore counts was temperature. The optimal conditions for high airborne spore concentrations were recorded at temperatures ranging from 23-29 degrees C and RH values of around 80%, followed rapidly by rainfall in Vigo and Ourense and preceded by heavy rain two days prior to recording peak values in Trives.

Seasonal variation of airborne fungal spore concentrations in a vineyard of North-West Spain

Conidial types collected daily in the air above a vineyard in northwest Spain were identified and counted. A total of 26 fungal spore types were recognised; ten of which (Cladosporium, Botrytis, Fusarium-Leptosphaeria type,Torula, Puccinia, Alternaria, Uncinula, Helminthosporium type,Agrocybe andStemphylium) gave a seasonal total concentration exceeding 1000 spores. Seasonal patterns are shown for 12 of the identified taxa.

Airborne concentrations ofBotrytis, Uncinula andPlasmopara spores in a vineyard in Leiro-Ourense (N.W. Spain)

Three important phytopathogenic spores which cause serious fungal diseases on vines (Botrytis, Uncinula andPlasmopara) were monitored from June 2, 1994 to September 21, 1994, in vineyards belonging to ‘Estación de Enoloxía e Viticultura’ of Ponte San Clodio-Leiro (Ourense), one of the most important vine growing areas of northwest of Spain. The concentrations for each of the genera were correlated with rainfall, humidity, maximum, minimum and average temperatures. These meteorological parameters are currently used to determine chemical sprays to be applied to the vines. The aim was to establish the behaviour of airborne concentrations of spores of these taxa during the period from the flowering to harvest because these are the periods of greatest susceptibility to attack by these pathogens.

Study of the pollen emissions of Urticaceae, Plantaginaceae and Poaceae at five sites in western Spain

A comparative study is presented of the pollen emissions of Urticaceae, Plantaginaceae and Poaceae, collected during 1995 with Hirst samplers (Burkard or Lanzoni) at five sites in western Spain: two Mediterranean sites located in the south (Huelva and Seville) and three Atlantic sites in the north (Orense, Vigo and Santiago). The annual pollen of Poaceae and Plantaginaceae collected in the Atlantic cities was found to be twice that in the Mediterranean sites, and the total amount of Urticaceae was higher at sites with an urban environment and subject to sea influence (Vigo, Huelva and Seville). At all the sites, the start of the main pollination periods (MPP) took place in the following order: Urticaceae, Plantaginaceae and Poaceae. It was also observed that the MPP of these three pollen types began earlier in Huelva and Seville, where the mean temperatures necessary for the beginning of pollen emissions are recorded very early. Regarding the variation in pollen concentrations throughout the year, Urticaceae presented peaks of maximum concentration in March (Huelva, Seville, Vigo and Orense) and June (Santiago); Plantaginaceae in March (south) and June (north); and Poaceae in May (south) and June–July (north). At northern sites, pollen emissions of Urticaceae and Plantaginaceae continued throughout the summer, while in the south they decreased considerably from May onwards. From the allergenic point of view, the indices of reactivity described for Urticaceae and Poaceae were exceeded more often at northern sites, in particular at Vigo. The meteorological conditions associated with periods of highest pollen emission of these three herbaceous types are a rise in mean temperature, light or absent rainfall, and abundant sunshine. The statistical correlations between pollen emissions and meteorological factors were not well-defined, either for the stations or for all the taxa, although they were clearer for the Atlantic cities and for Urticaceae.

Allergenic airborne pollen monitoring of Vigo (NW Spain) in 1995–2001

Pollen data from the atmosphere of Vigo, NW Spain was collected using a Hirst type pollen trap over a seven-year period (1995–2001). A total of 56 different pollen types were identified, among which Urticaceae, Poaceae, Betula and Quercus represent the greatest risk for people suffering from allergic rhinitis (hay fever) or other allergic diseases. Although in the atmosphere of Vigo the presence of allergenic pollen is constant throughout the year, the months of March and April account for 40% of the annual total pollen count. Two main risk periods have been identified for asthma and allergies: (1) March – April, and (2) June – July, the latter is of greater importance due to high concentrations of Poaceae pollen. Correlation analysis with meteorological parameters demonstrates that rainfall, relative humidity, maximum temperature, sun hours and north-easterly winds are the main factors influencing the average daily pollen concentrations in the atmosphere.

Aerobiological survey of Alnus pollen in Ourense (N.W. Iberian Peninsula), 1993–2000

Alnus pollen is one of the major components of the aeropalynological spectra during winters in Ourense, with maximum values registered in January and February. This work analyses the intra- and interannual variations within the period 1993–2000, when a volumetric Hirst spore-trap (LANZONI VPPS 2000) was in continuous operation. Statistically significant differences between periods 1996/97 (with a few rainy days), 1998/99, and all the others were observed. The relationships between atmosphere pollen content and the most important meteorological parameters within the same period were studied by means of correlation analysis. Temperature was the most important factor explaining the presence of Alnus pollen in the air. A Scheffes test was carried out before the correlation analysis to establish years corresponding to the same statistical population. The results obtained from both tests were used for a regression analysis to establish the prediction patterns for this taxon. Even when a negative correlation coefficient was presented, the influence of this parameter did not decline. Previous temperatures in the main pollination period, however, were a determinant factor predicting the onset and intensity of Alnus flowering.

The role of stochastic forcing on the behavior of thermohaline circulation.

The nonlinear nature of the climate system suggests that its reactions to unexpected perturbations could be different from the expected ones. In nonlinear science it is recognized as a promising paradigm that stochastic fluctuations can generate order or other counterintuitive effects. Thus, noise sources, adequately coupled to a nonlinear system, may give rise to a rich new phenomenology not present in a deterministic noiseless scenario. In this review we focus attention on thermohaline circulation (THC). THC presents two modes of operation; one state shows active THC and the other inactive. Previous episodes of transitions between both states of THC observed in paleoclimatic records and the influence of this circulation on climate have resulted in detailed investigations on the dynamics of the THC. A weakening or a collapse of this current could trigger the onset of a new Younger Dryas. In this review the introduction of stochastic forcing in key parameters, both in a simple box model and in an earth model of intermediate complexity, provokes a weakening and even a shutdown of the THC. The consequences of this weakening are observed in different variables. The surface air temperature and the sea surface temperature are dominated by cooling of the Northern Hemisphere. Changes in the position of the Intertropical Convergence Zone and in precipitation are observed. There is also an intensification of the North Atlantic Oscillation values during winter. These results reinforce the necessity to consider stochastic sources in climate models to improve our understanding of the climate.