GROWTH RATE AND BEHAVIOR OVER 20 YEARS IN THE CRUSTOSE LICHEN HAEMATOMMA ERYTHROMMA AT ELEPHANT ISLAND, ANTARCTICA

Abstract

Antarctica is one of the most extreme environments on the planet considering the climatic conditions. This greatly limits the development of plants, and is reflected in slow growth, especially in the lichens present in this environment. Haematomma erythromma is a nitrophile lichen easily identifiable by its color and was the species chosen to evaluate growth in Antarctica. Using a plastic sheet, squares of 20 x 20 cm were placed on eight different rocks with crustose lichen communities and the species found were drawn in 1992 and in 2012. The location chosen for the survey was Stinker Point, on Elephant Island, north of the South Shetland Archipelago. After 20 years and evaluating 178 thalli, H. erythromma grew 0.2 to 0.7 mm/year, one of the slowest among Antarctic lichens. The thallus growth is mainly oriented West/Northwest, against prevailing wind direction, probably due to nutrient carried form a penguin rockery nearby. New thalli formed during this evaluation and the old ones also grew to connect each other, resulting in a confluent larger thallus. The new thalli grew mostly over Xanthoria elegans (Link.) Th. Fr., Rhizoplaca aspidophora (Vain.) Redón and Buellia spp. demonstrating that H. erythromma is capable of colonize areas with other lichen species coverage. The growth to be confluent with other thalli and the wind orientation are novelties to this species of lichen.