Evidence of high annual growth rate for lichens in the maritime Antarctic

Abstract

On Livingston Island (South Shetland Islands, Antarctica) young moraines, now roughly 45 years old, were investigated in 1991 and 2002. More than 500 thalli of the 6 most abundant species, Acarospora macrocyclos, Bellemerea sp. Buellia latemarginata, Caloplaca sublobulata, Rhizocarpon geographicum and Usnea antarctica, previously measured in 1991, were measured again in 2002, which allowed an accurate measure of thallus growth rates. From our results, we believe it important to emphasize that: (1) lichen colonization probably took place at the end of the 1950s, soon after the last glacier retreat. (2) No relation between thallus growth rate and boulder size could be established. (3) Higher annual growth rates than those previously estimated were observed for R. geographicum and Bellemerea sp. and the former had one of the highest growth rates ever reported for this species. We speculate whether this high growth rate may be related to the rapid retreat of the Livingston Island ice cap and glaciers during the last recent years, and which have been attributed to climate warming on the Antarctic Peninsula region.