Fungi in Antarctica: A circumpolar study of biodiversity in soils and historic structures.

摘要

The results from investigations reported in this dissertation provide important new information on fungi found in Antarctica and their role in the degradation of historic wood as well as factors that influence their distribution and abundance. This dissertation has 4 chapters that report different investigations that were carried out in Antarctica. The first is a survey of fungal diversity found at historic sites on the Antarctic Peninsula. The second chapter details results from wood and cellulose fungal baiting traps on Ross Island and the Antarctic Peninsula. The third chapter is a wide ranging survey of fungal soil biodiversity found on Ross Island, the Antarctic Peninsula, and the Dry Valleys as well as evaluation of soil characteristics which are correlated with fungal abundance. The fourth chapter is a report on the current condition of East Base, the oldest standing US base in Antarctica and an important Polar heritage site.;Antarctica is the most remote and isolated continent on Earth and is generally thought to have low biodiversity due to environmental extremes. These relatively simple ecosystems are important to study because they can be used to improve understanding of more complex systems world-wide that are difficult to analyze directly. The isolation of the continent, extreme environmental conditions and the lack of functional redundancy in ecosystem processes make it particularly vulnerable to human disturbance and require improved understanding. The results of this research support the hypothesis that fungal abundance and distribution are generally linked to the presence of primary producers and their effect on carbon and nitrogen quantities in the soil. Experiments introducing sterile plant-derived nutrient sources (wood and cellulose) to soils resulted in increased fungal abundance up to three to four orders of magnitude greater than background soil levels. This suggests that the extremes of the Antarctic environment (low moisture, high salinity, cold temperatures) are primarily affecting fungi by limiting the distribution of flora and direct effects on the fungi are relatively less important as these indigenous soil fungi appear well adapted to Antarctic environment.;A survey of fungal diversity near historic sites and areas where materials were introduced to the Antarctic Peninsula reveals a very similar composition to those affecting historic sites on Ross Island. The fungi found in greatest abundance were species of Geomyces and Cadophora. These two genera also formed a large percentage of the fungal colonization of buried nutrient substrates. The frequent reports of these fungi from many areas in Antarctica and the large diversity of species found indicates they are well adapted to their environment and suggests they are indigenous to Antarctica. The dominance of these fungi on human-introduced material indicates direct human influences may be of more benefit to generalist indigenous decomposer fungi which are pre-adapted to the environmental extremes rather than human-introduced fungi which may be better adapted to utilizing these substrates but not well adapted to the Antarctic environment. It also supports the hypothesis of indigenous Antarctic fungi being primarily limited by nutrient availability.