Browsing by Subject "Historic"

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    Diversity and characterization of wood decay fungi from historic wood in Antarctica
    (2013-07) Held, Benjamin William
    Compared to other biomes, very little is known about fungal diversity in Antarctica and how these important organisms function in this unusual ecosystem. The studies presented in this dissertation are focused on the fungi found in wood on Deception Island (an active volcano), Antarctica, their phylogenetic diversity and role as important decomposers in the polar environment. A diverse fungal assemblage of known wood decay fungi is reported from historic wood in structures at Deception Island, Antarctica as well as the discovery of several undescribed species. The major group of wood decay fungi found was Cadophora species which have been found in other geographic regions of Antarctica causing a soft-rot type of decay in introduced woods. Unlike other areas of Antarctica that have been studied, several filamentous basidiomycetes (Hypochniciellum spp. and Pholiota spp.) were also identified that have different modes of degradation including brown and white rot. The conservation of these historic structures poses difficult challenges because of their polar location and geothermal activity. Lahars have partially buried many of the structures. The buried environment and moist, warm soils are conditions conducive for fungal growth facilitate deterioration by the fungi described. In addition, the diverse assemblage of decay fungi add to the difficulty of conserving these important polar heritage sites. A number of studies have identified Cadophora species, mainly in association with wood, from many areas of Antarctica. A phylogenetic study using four gene regions identifies a diverse group of Cadophora spp. present at different sites in Antarctica (Ross Sea, Peninsula). Cadophora malorum, C. fastigiata sensu stricto, and C. luteo-olivacea were very similar phylogenetically in these gene regions. Undescribed species were also discovered that were closely related to C. fastigiata. Decay studies showed that nearly all the species were able to cause a soft rot type of decay in birch wood wafers and were able to tolerate high levels of salt and copper sulphate. These studies support information that Cadophora spp. are well adapted to thrive in extreme conditions and appear to be important decomposers in these biomes.
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    Fungi in Antarctica: a circumpolar study of biodiversity in soils and historic structures.
    (2010-07) Arenz, Brett Evan
    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.
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    Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Lake Sediment Study
    (University of Minnesota Duluth, 2019-12) Zanko, Lawrence M; Reavie, Euan D; Post, Sara P
    Atmospheric deposition of airborne particulate matter such as fugitive dust contributes to sediment that accumulates at the bottom of a lake. Because of this phenomenon, lake sediment can provide an historic mineralogical and chemical record of what may have been in the air at the time of its atmospheric deposition. This point is important, because the NRRI’s role in the Minnesota Taconite Workers Health Study (MTWHS) was to not only help answer the question “What is in the air?” by conducting present-day in-plant and community air sampling, but – and even more challengingly – to potentially answer the question “What was in the air, when?” by collecting and analyzing historic samples. Lake sediment was the only historic sampling medium available that could allow the investigators to make an attempt to assess what might have been present in the air in the past on Minnesota’s Mesabi Iron Range (MIR). The NRRI therefore core-sampled, age-dated, and characterized intervals of sediment from two MIR lakes – Silver Lake in Virginia, on the central MIR, and “North-of-Snort” Lake on the eastern end of the MIR, near Babbitt (Fig. i). The objective was to determine if fugitive mineral dust generated by past iron ore/taconite mining activity could be discerned in mineral particulate matter (PM) deposited and preserved in the sediment of both lakes.