Environmental and Experimental Botany 52 (2004) 149–159 Physiological attributes of the lichen Cladonia pleurota in heavy metal-rich and control sites near Sudbury (Ont., Canada) M. Baˇ ckor a,∗ , D. Fahselt b a Department of Botany, Institute of Biology and Ecology, Šafárik University, Mánesova 23, 041 67 Košice, Slovak Republic b Department of Biology, University of Western Ontario, London, Ont., Canada N6A 5B7 Accepted 28 January 2004 Abstract The recovery of lichen communities on metal-rich historical ore-roasting beds west of Sudbury has been slow, and our objective was to locate and measure metals in Cladonia pleurota, the most frequently encountered roast bed lichen species. Particulates incorporated into the thallus on or near the roast bed contained high Fe, Al, Cu and Ni, and inductively coupled plasma-atomic emission spectroscopy showed lower concentrations of heavy metals in the control site 60 km upwind than in the roast bed or an immediately adjacent forest. Wavelength-dispersive X-ray spectrometry indicated potentially toxic levels of Cu, Ni, Fe and Al in both the mycobiont and photobiont in the roast bed. The physiology of roast bed lichens was consistent with damage found in metal-treated photobionts in culture: lower concentrations of chlorophyll a, chlorophyll b and total carotenoids on or near the roast bed than in the control site. In addition chlorophyll a on the roast bed was more subject to phaeophytinization and the yield of photosystem II, as measured by F v /F m , was significantly less in both of the metal-rich sites than in the control. Thin-layer densitometry and UV spectrophotometry showed no significant difference in the amount of usnic acid between metal-rich and control sites, but heavy metals were associated with crystals of usnic acid, possibly forming complexes. © 2004 Elsevier B.V. All rights reserved. Keywords: Copper; Nickel; Iron; Lichen substances; Elemental analysis; Chlorophyll a integrity; Chlorophyll a fluorescence; Usnic acid; Photobionts; Soil analysis 1. Introduction The Sudbury area in Central Ontario, Canada, has some of the best known deposits of Ni, Cu, Co and Fe ores in the world (Hutchinson and Symington, 1997), and it is also one of the most ecologically disturbed regions in Canada (Amiro and Courtin, 1981). Dur- ing the past 80 years of mining and smelting, more ∗ Corresponding author. E-mail address: mbackor@kosice.upjs.sk (M. Baˇ ckor). than a 100 million tonnes of sulfur dioxide and tens of thousands of tonnes of Cu, Ni and Fe have been released into the atmosphere from the open roast beds and smelters (Gunn et al., 1995). Eleven roast beds operated in the Sudbury region at one time and the O’Donnell, approximately 20 km west of the city, was the largest (Hutchinson and Symington, 1997). To re- duce the high sulfur content before smelting, ores were first roasted in open beds. O’Donnell roast beds burned continuously throughout the year and sulfur dioxide fumigation, along with particulates containing heavy 0098-8472/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.envexpbot.2004.01.014