Severe photobiont injuries of lichens strongly associated with air pollution

The photobiont ultrastructure of the epiphytic lichens Bryoria fuscescens a nd Bryoria fremontii was studied along the pollution gradient from two Cu-N i smelters in Nikel and Monchegorsk in northern Finland and north-western R ussia. The relationship between ultrastructural characteristics of B. fusce scens and environmental factors (i.e. climate, atmospheric SO2 and bark ele ment concentrations) was studied by using a principal component analysis (P CA) aiming to assess the air quality in a northern environment. Based on PC A, increased plasmolysis and mitochondrial changes in the Trebouxia photobi ont were significantly correlated with elevated pollutant concentrations. D egenerated cells, showing altered chloroplasts and electron-translucent pyr enoglobuli, occurred in lichens growing 35-50 km from the Monchegorsk smelt er. Cell wall and cytoplasmic lipid volumes, and size of pyrenoglobuli, pos itively correlated with the distance from the Monchegorsk smelter. Vacuoles and electron-opaque vacuolar deposits were significantly increased at the Finnish site in the vicinity of a pulp mill. Swelling of mitochondrial cris tae and thylakoids showed little correlation with environmental factors, bu t indicated of initial stage of injuries and were observed at several sligh tly polluted sites in northern Finland and north-western Russia. The result s suggest that the severe photobiont injuries of lichens are strongly assoc iated with poor air quality.