Abstract
The quality of the surrounding environment significantly impacts lichen diversity and composition, but crustose lichens, particularly those in disturbed environments, can persist. Although the effects of habitat disturbances on the morphology, anatomy, chemical composition, and fertility of lichen species have not been extensively researched, understanding their mechanisms is crucial for understanding their persistence in their environment. The study aimed to identify common lichen species in polluted and semi-polluted environments and compare their morphology, anatomy, chemical composition, and fertility. A two-kilometer stretch along the road that passes through the University of Peradeniya was selected as the semi-disturbed site based on previous records, while the area around Kandy Lake was designated as the polluted site. Using conventional keys, lichen species were identified, and using a hand lens, dissecting microscope, and compound microscope, the morphological traits of the thallus, apothecia, soredia, and isidia, as well as the anatomical features of the thallus, apothecia, and ascospores, were compared between the two sites. Thin-layer chromatography was used to separate and elucidate the secondary metabolites of lichen. Thirty-nine species were discovered on the university site, 15 in the area around Kandy Lake, and species gathered from both locations shared commonalities, including Physcia sp., Parmotrema sp., Lecanora sp., Graphis sp., and Lepraria sp. The color difference between all species, as measured by mean dE, is visible to the naked eye and changes from a pale to a dark hue from a semi-disturbed site to a polluted one. In comparison to disturbed sites, the majority of species displayed an increased mean area in semi-polluted sites. Layer thickness increases or decreases depending on how well each layer can withstand disruptions. Depsinose has been recognized as a potential class of metabolites generated by lichens present in both locations. Only lake sites exhibit toxic metal compounds, as opposed to semi-disturbed sites. Every pH value was acidic, and most species at the lake site had more acidic pH than those at the university site. There is no specific trend in apothecial number and ascospore numbers in common lichen species in both sites. The current study showed that changes in certain morphological and anatomical biochemical characteristics can be triggered by the environment, suggesting that the quality of the environment significantly affects the growth and reproductive success of lichens, thereby survival or extinction, and proposed that bioindicator and bioaccumulator species concerning the changes occurred.