title: Investigation into the microbial ecology and persistence of soil taxa through trace-gas oxidation in Tongariro National Park

authors: Peach, Hanna Annette Caroline Georgia

subjects: Trade Gas Oxidation

abstract: Cultivation-dependent and metagenomic surveys of bare, volcanic and hyperarid oligotrophic ecosystems have revealed surprisingly diverse microbial communities¹⁻⁴. The richness of Mt. Tongariro soil communities is surprising considering the extreme environmental parameters. Given that soil moisture on Mt. Tongariro is highly variable dependent on season, and both phototrophic Cyanobacteria and trace gas oxidising taxa from the phyla Actinobacteria, WPS-2 and AD3 are detected in these soils, it is postulated that these taxa alternate as the primary producers in these oligotrophic soils. In this scenario, cyanobacteria are the phototrophic backbone and trace-gas oxidisers use atmospheric trace gases (H₂, CO) as supplemental cell energy for mixotrophic metabolism to persist. Mt. Tongariro soil communities were shown to encode high affinity hydrogenases and carbon monoxide dehydrogenases, which are necessary for atmospheric oxidation of H₂ and CO. This thesis details the microbial ecology and effect of physicochemistry on the alpha and beta diversity of Mt. Tongariro soils. It also addresses microbial persistence by the use oxidation of trace gases H₂ and CO at 4 °C and 60 °C for the South, Red and Central Craters of Mt. Tongariro on the southernmost point of the Taupo Volcanic Centre (TVZ), and control soils from White Island (Whakaari), Mt. Urchin and Mt. Sugarloaf. This preliminary study uncovers the microbial ecology of Mt. Tongariro and other bare, high elevation control soils from around New Zealand. Although, more extensive testing is required such as testing isolated Mt. Tongariro strains to understand whether the thermophilic taxa present are capable of oxidising trace gas, or whether they harbour low affinity enzymes suited to elevated levels of CO and H₂. This study indicates that trace gas oxidation may be an important mechanism for persistence or a dependable source of supplemental energy to specific mixotrophic trace-gas oxidising taxa in all communities from bare, oligotrophic systems.

text: Investigation into the microbial ecology and persistence of soil taxa through trace-gas oxidation in Tongariro National Park Cultivation-dependent and metagenomic surveys of bare, volcanic and hyperarid oligotrophic ecosystems have revealed surprisingly diverse microbial communities¹⁻⁴. The richness of Mt. Tongariro soil communities is surprising considering the extreme environmental parameters. Given that soil moisture on Mt. Tongariro is highly variable dependent on season, and both phototrophic Cyanobacteria and trace gas oxidising taxa from the phyla Actinobacteria, WPS-2 and AD3 are detected in these soils, it is postulated that these taxa alternate as the primary producers in these oligotrophic soils. In this scenario, cyanobacteria are the phototrophic backbone and trace-gas oxidisers use atmospheric trace gases (H₂, CO) as supplemental cell energy for mixotrophic metabolism to persist. Mt. Tongariro soil communities were shown to encode high affinity hydrogenases and carbon monoxide dehydrogenases, which are necessary for atmospheric oxidation of H₂ and CO. This thesis details the microbial ecology and effect of physicochemistry on the alpha and beta diversity of Mt. Tongariro soils. It also addresses microbial persistence by the use oxidation of trace gases H₂ and CO at 4 °C and 60 °C for the South, Red and Central Craters of Mt. Tongariro on the southernmost point of the Taupo Volcanic Centre (TVZ), and control soils from White Island (Whakaari), Mt. Urchin and Mt. Sugarloaf. This preliminary study uncovers the microbial ecology of Mt. Tongariro and other bare, high elevation control soils from around New Zealand. Although, more extensive testing is required such as testing isolated Mt. Tongariro strains to understand whether the thermophilic taxa present are capable of oxidising trace gas, or whether they harbour low affinity enzymes suited to elevated levels of CO and H₂. This study indicates that trace gas oxidation may be an important mechanism for persistence or a dependable source of supplemental energy to specific mixotrophic trace-gas oxidising taxa in all communities from bare, oligotrophic systems.

year: 2019

title: Metabarcoding inventory of an arctic tundra soil ecosystem reveals highly heterogeneous communities at a small scale

authors: Jorna, Jesse

abstract: Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near the Canadian High Arctic Research Station in Cambridge Bay, Nunavut. Invertebrate communities were extracted at a vegetated and non-vegetated site in three replicates and inventoried using 18S metabarcode sequencing. A total of 361 amplicon sequence variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites, and springtails. Most taxa were found only at a single location and even samples from the same site displayed distinct communities, suggesting that belowground species richness in Arctic tundra habitats is highly heterogeneous. Preserving soil biodiversity in a changing Arctic is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

text: Metabarcoding inventory of an arctic tundra soil ecosystem reveals highly heterogeneous communities at a small scale Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near the Canadian High Arctic Research Station in Cambridge Bay, Nunavut. Invertebrate communities were extracted at a vegetated and non-vegetated site in three replicates and inventoried using 18S metabarcode sequencing. A total of 361 amplicon sequence variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites, and springtails. Most taxa were found only at a single location and even samples from the same site displayed distinct communities, suggesting that belowground species richness in Arctic tundra habitats is highly heterogeneous. Preserving soil biodiversity in a changing Arctic is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

year: 2023-05-01

title: Me ko Māui: Harnessing the sun to provide better outcomes for marae and communities

authors: Greensill, Waikauri

abstract: Marae are the cultural centres of Māori communities, providing a space for important gatherings both joyful and sad. With the advent of solar energy capture technologies and rising electricity bills, many marae are becoming interested in whether a solar powered system will be beneficial for them. However, marae have unique electricity demand profiles, distinct from commonly modelled building types such as residential or commercial buildings. It is thus difficult to estimate an appropriate solar and battery system size based on annual or even monthly electricity usage data, which may be the only data readily available, requiring more in-depth analysis at a highly site-specific level to find an answer. This thesis aims to increase understanding around how solar power could benefit marae, first by investigating the characteristic electricity demand profile of marae, then by observing how proposed system configurations meet the demand. The potential community benefits arising from such a system was also investigated. Using a year’s worth of half-hourly data from three marae, five characteristic day types were found in the analysis of the demand profile, namely a “Non-Event” profile that maintained a low baseload and accounted for 70% of the days in a year, a “1-Day Event” profile that lasted only a few hours, and for events spanning multiple days a “Start”, “Middle” and “End” day profile that varied greatly in demand magnitude. The demand profiles were then used to develop an annual demand profile for an average marae that was broadly representative of a wide range of marae. Different configurations of solar and battery powered systems were then applied to the annual demand and a technoeconomic analysis performed to determine whether a specific configuration met the needs of the average marae or not, which then produced a range of acceptable system sizes based on the needs specified. Not many solar and battery configurations resulted in positive economic returns for the marae alone, but widening the scope of the analysis to the surrounding community allows other interests such as local grid resilience to be considered, some of which may justify a marae’s decision to invest in a non-economic system to gain better community benefits. While investigating the use of peer-to-peer energy trading and community energy scenarios, sharing excess energy generated by a system with the wider community was also found to improve the economic outlook of solar for marae.

text: Me ko Māui: Harnessing the sun to provide better outcomes for marae and communities Marae are the cultural centres of Māori communities, providing a space for important gatherings both joyful and sad. With the advent of solar energy capture technologies and rising electricity bills, many marae are becoming interested in whether a solar powered system will be beneficial for them. However, marae have unique electricity demand profiles, distinct from commonly modelled building types such as residential or commercial buildings. It is thus difficult to estimate an appropriate solar and battery system size based on annual or even monthly electricity usage data, which may be the only data readily available, requiring more in-depth analysis at a highly site-specific level to find an answer. This thesis aims to increase understanding around how solar power could benefit marae, first by investigating the characteristic electricity demand profile of marae, then by observing how proposed system configurations meet the demand. The potential community benefits arising from such a system was also investigated. Using a year’s worth of half-hourly data from three marae, five characteristic day types were found in the analysis of the demand profile, namely a “Non-Event” profile that maintained a low baseload and accounted for 70% of the days in a year, a “1-Day Event” profile that lasted only a few hours, and for events spanning multiple days a “Start”, “Middle” and “End” day profile that varied greatly in demand magnitude. The demand profiles were then used to develop an annual demand profile for an average marae that was broadly representative of a wide range of marae. Different configurations of solar and battery powered systems were then applied to the annual demand and a technoeconomic analysis performed to determine whether a specific configuration met the needs of the average marae or not, which then produced a range of acceptable system sizes based on the needs specified. Not many solar and battery configurations resulted in positive economic returns for the marae alone, but widening the scope of the analysis to the surrounding community allows other interests such as local grid resilience to be considered, some of which may justify a marae’s decision to invest in a non-economic system to gain better community benefits. While investigating the use of peer-to-peer energy trading and community energy scenarios, sharing excess energy generated by a system with the wider community was also found to improve the economic outlook of solar for marae.

year: 2024