Fungal colonization of exotic substrates in Antarctica

Throughout the history of polar exploration and up to recent times, wood and other exotic materials have been brought to the Antarctic continent and left there. While the possible transportation of exotic fungal species on these materials is sometimes considered, the effects of these exotic substrates on indigenous fungal communities have not been previously evaluated. This study reports results from seven plots where organic materials were used in baiting studies to determine the fungal diversity present in soils. Four plots were on islands in the Palmer Archipelago on the Antarctic Peninsula and three at Ross Island, Antarctica. Samples of sterile wood and cellulose with and without nutrients added were buried in soil and left for either two or four years before being removed and evaluated for fungal colonization. There was a significant increase in fungal colony-forming units (CFU) from soil in direct contact with introduced, sterile wood and cellulose substrates compared to background soil levels. The type of substrate, 2 or 4 year incubation period in the field, or nutrient addition did not have a significant effect on culturable densities in soil. Fungal abundance on soil adhering to substrates was found to be similar to that found in non-polar soils indicating that lack of organic material may be the most significant limiting factor affecting densities of Antarctic fungal populations. Based on a high degree of colonization, these exotic substrates appear to have a significant effect on indigenous soil fungal abundance.