title: The inter-valley soil comparative survey: the ecology of Dry Valley edaphic microbial communities

authors: Lee, Charles Kai-Wu

subjects: Antarctica

abstract: Recent applications of molecular genetics to edaphic microbial communities of the McMurdo Dry Valleys and elsewhere have rejected a long-held belief that Antarctic soils contain extremely limited microbial diversity. The Inter-Valley Soil Comparative Survey aims to elucidate the factors shaping these unique microbial communities and their biogeography by integrating molecular genetic approaches with biogeochemical analyses. Although the microbial communities of Dry Valley soils may be complex, there is little doubt that the ecosystem's food web is relatively simple, and evidence suggests that physicochemical conditions may have the dominant role in shaping microbial communities. To examine this hypothesis, bacterial communities from representative soil samples collected in four geographically disparate Dry Valleys were analyzed using molecular genetic tools, including pyrosequencing of 16S rRNA gene PCR amplicons. Results show that the four communities are structurally and phylogenetically distinct, and possess significantly different levels of diversity. Strikingly, only 2 of 214 phylotypes were found in all four valleys, challenging a widespread assumption that the microbiota of the Dry Valleys is composed of a few cosmopolitan species. Analysis of soil geochemical properties indicated that salt content, alongside altitude and Cu2+, was significantly correlated with differences in microbial communities. Our results indicate that the microbial ecology of Dry Valley soils is highly localized and that physicochemical factors potentially have major roles in shaping the microbiology of ice-free areas of Antarctica. These findings hint at links between Dry Valley glacial geomorphology and microbial ecology, and raise previously unrecognized issues related to environmental management of this unique ecosystem.

text: The inter-valley soil comparative survey: the ecology of Dry Valley edaphic microbial communities Recent applications of molecular genetics to edaphic microbial communities of the McMurdo Dry Valleys and elsewhere have rejected a long-held belief that Antarctic soils contain extremely limited microbial diversity. The Inter-Valley Soil Comparative Survey aims to elucidate the factors shaping these unique microbial communities and their biogeography by integrating molecular genetic approaches with biogeochemical analyses. Although the microbial communities of Dry Valley soils may be complex, there is little doubt that the ecosystem's food web is relatively simple, and evidence suggests that physicochemical conditions may have the dominant role in shaping microbial communities. To examine this hypothesis, bacterial communities from representative soil samples collected in four geographically disparate Dry Valleys were analyzed using molecular genetic tools, including pyrosequencing of 16S rRNA gene PCR amplicons. Results show that the four communities are structurally and phylogenetically distinct, and possess significantly different levels of diversity. Strikingly, only 2 of 214 phylotypes were found in all four valleys, challenging a widespread assumption that the microbiota of the Dry Valleys is composed of a few cosmopolitan species. Analysis of soil geochemical properties indicated that salt content, alongside altitude and Cu2+, was significantly correlated with differences in microbial communities. Our results indicate that the microbial ecology of Dry Valley soils is highly localized and that physicochemical factors potentially have major roles in shaping the microbiology of ice-free areas of Antarctica. These findings hint at links between Dry Valley glacial geomorphology and microbial ecology, and raise previously unrecognized issues related to environmental management of this unique ecosystem.

year: 2011

title: The associations between physical-test performance and match performance in women’s rugby sevens players

authors: Sella, Francesco Stefano

abstract: Evaluating the relationships between physical-test and match performance in team sports could be useful for training prescription and athlete evaluation. Here we investigated these relationships in women’s Rugby Sevens. Thirty provincial-representative players performed Bronco-fitness, countermovement-jump, acceleration, speed, and strength tests within two weeks before a two-day tournament. Match-running and match-action performance measures were provided by GPS units and video analysis. Generalised and general linear mixed models were employed to estimate the effect of a two standard-deviation difference in physical test measures on match measures. Effect magnitudes were assessed via standardisation (using the between player SD) and, for effects on tries scored, also via match winning (based on simulating matches). Evidence for substantial and trivial true magnitudes was provided by one-sided interval-hypothesis tests and Bayesian analysis. There was good evidence of positive effects of many physical-test measures on match high-intensity running, with large effects for jump height and acceleration. There was some evidence of small-moderate positive effects of speed and Bronco, and of small-moderate negative effects of maximal strength and jump height, on match total running and high intensity changes in speed. The evidence was generally inadequate for associations between physical-test measures and match actions, but there was good evidence of small-large positive effects of back squat and jump height on tries scored. Enhancing players’ jump height and back-squat performance might therefore increase the likelihood of match success in women’s Rugby Sevens.

text: The associations between physical-test performance and match performance in women’s rugby sevens players Evaluating the relationships between physical-test and match performance in team sports could be useful for training prescription and athlete evaluation. Here we investigated these relationships in women’s Rugby Sevens. Thirty provincial-representative players performed Bronco-fitness, countermovement-jump, acceleration, speed, and strength tests within two weeks before a two-day tournament. Match-running and match-action performance measures were provided by GPS units and video analysis. Generalised and general linear mixed models were employed to estimate the effect of a two standard-deviation difference in physical test measures on match measures. Effect magnitudes were assessed via standardisation (using the between player SD) and, for effects on tries scored, also via match winning (based on simulating matches). Evidence for substantial and trivial true magnitudes was provided by one-sided interval-hypothesis tests and Bayesian analysis. There was good evidence of positive effects of many physical-test measures on match high-intensity running, with large effects for jump height and acceleration. There was some evidence of small-moderate positive effects of speed and Bronco, and of small-moderate negative effects of maximal strength and jump height, on match total running and high intensity changes in speed. The evidence was generally inadequate for associations between physical-test measures and match actions, but there was good evidence of small-large positive effects of back squat and jump height on tries scored. Enhancing players’ jump height and back-squat performance might therefore increase the likelihood of match success in women’s Rugby Sevens.

year: 2022-11-18

title: The cultural and ecological health of the Tokaanu Stream

authors: Eastwood, Kevin

abstract: Freshwater ecosystems worldwide face increasing threats from human activities like land development and altered flow regimes. These pressures, along with climate change, jeopardize water quality and quantity. Despite these challenges, effective management can improve water quality and habitat, thus sustaining biodiversity and ecosystem services.
Lake Taupō, Aotearoa New Zealand’s largest freshwater lake, holds immense significance for the local iwi, Ngāti Tūwharetoa. The Tokaanu Stream is a tributary of Lake Taupō that was once considered a premier fly-fishing spot. However, the stream has been severely impacted by the Tongariro Power Scheme, which required it to be bisected and channelized to accommodate the Tokaanu tailrace. Coupled with land-use changes in the catchment, these alterations have caused the local hapū, Ngāti Kurauia, who have mana whenua over the lower stream, to raise concerns about its ecological and cultural degradation. To address this problem, I developed a cultural monitoring framework (CMF) in collaboration with Ngāti Kurauia, alongside conventional stream monitoring, at six sites in the lower Tokaanu Stream.
The bespoke CMF was developed through kōrero and wānanga (discussions and workshops) with Ngāti Kurauia. This participatory approach resulted in a CMF with 16 attributes covering vegetation, birdlife, water quality, pollution, engineering, and substrate. Regular assessments revealed a longitudinal decline in stream condition from the most upstream site (Site 1) to the most downstream (Site 6). The state of Site 3 was identified as the most desirable, whilst Site 5 was the most degraded.
Alongside the CMF, I assessed stream health using conventional scientific measures. This monitoring also showed a longitudinal decline in stream ecosystem health moving downstream. Water quality worsened, with indicator bacteria increasing from 45 to 190 CFU/100 ml and total ammoniacal nitrogen from 0.029 to 0.125 g/m3 over the 4 km segment. Deposited fine sediment cover was high, increasing from 69% cover at Site 1 to 83% at Site 6. Cellulose degradation rates (a functional indicator) were diminished at Sites 5 and 6 in both years, even with warming from geothermal springs. Macroinvertebrate communities, monitored in 2023 and 2024, initially showed a linear decline moving downstream in 2023. However, in-stream remediation in early 2024, undertaken by a private contractor, significantly improved macroinvertebrate indicators at impacted sites (Sites 4-6).
The challenges facing the Tokaanu Stream are complex, stemming from geothermal inputs, urbanisation, upstream agriculture, and channelization. Declining water quality may be linked to faulty sewage infrastructure in Tokaanu Village. The stream's diversion includes a tailrace spillway that prevents larger downstream flows, potentially reducing scouring events crucial for natural sediment dynamics. These changes have significant ecological and cultural ramifications for Ngāti Kurauia.
To better understand and address these issues, I argue for an additional downstream State of the Environment (SOE) monitoring site. The current site, near the upstream spring, fails to capture the full impact of catchment inputs, including diffuse pollution from Tokaanu Village and altered sediment dynamics from the diversion. An additional SOE site, coupled with the findings of my thesis, would provide crucial knowledge to support efforts in restoring the Tokaanu Stream's ecological health and the mana of Ngāti Kurauia.

text: The cultural and ecological health of the Tokaanu Stream Freshwater ecosystems worldwide face increasing threats from human activities like land development and altered flow regimes. These pressures, along with climate change, jeopardize water quality and quantity. Despite these challenges, effective management can improve water quality and habitat, thus sustaining biodiversity and ecosystem services.
Lake Taupō, Aotearoa New Zealand’s largest freshwater lake, holds immense significance for the local iwi, Ngāti Tūwharetoa. The Tokaanu Stream is a tributary of Lake Taupō that was once considered a premier fly-fishing spot. However, the stream has been severely impacted by the Tongariro Power Scheme, which required it to be bisected and channelized to accommodate the Tokaanu tailrace. Coupled with land-use changes in the catchment, these alterations have caused the local hapū, Ngāti Kurauia, who have mana whenua over the lower stream, to raise concerns about its ecological and cultural degradation. To address this problem, I developed a cultural monitoring framework (CMF) in collaboration with Ngāti Kurauia, alongside conventional stream monitoring, at six sites in the lower Tokaanu Stream.
The bespoke CMF was developed through kōrero and wānanga (discussions and workshops) with Ngāti Kurauia. This participatory approach resulted in a CMF with 16 attributes covering vegetation, birdlife, water quality, pollution, engineering, and substrate. Regular assessments revealed a longitudinal decline in stream condition from the most upstream site (Site 1) to the most downstream (Site 6). The state of Site 3 was identified as the most desirable, whilst Site 5 was the most degraded.
Alongside the CMF, I assessed stream health using conventional scientific measures. This monitoring also showed a longitudinal decline in stream ecosystem health moving downstream. Water quality worsened, with indicator bacteria increasing from 45 to 190 CFU/100 ml and total ammoniacal nitrogen from 0.029 to 0.125 g/m3 over the 4 km segment. Deposited fine sediment cover was high, increasing from 69% cover at Site 1 to 83% at Site 6. Cellulose degradation rates (a functional indicator) were diminished at Sites 5 and 6 in both years, even with warming from geothermal springs. Macroinvertebrate communities, monitored in 2023 and 2024, initially showed a linear decline moving downstream in 2023. However, in-stream remediation in early 2024, undertaken by a private contractor, significantly improved macroinvertebrate indicators at impacted sites (Sites 4-6).
The challenges facing the Tokaanu Stream are complex, stemming from geothermal inputs, urbanisation, upstream agriculture, and channelization. Declining water quality may be linked to faulty sewage infrastructure in Tokaanu Village. The stream's diversion includes a tailrace spillway that prevents larger downstream flows, potentially reducing scouring events crucial for natural sediment dynamics. These changes have significant ecological and cultural ramifications for Ngāti Kurauia.
To better understand and address these issues, I argue for an additional downstream State of the Environment (SOE) monitoring site. The current site, near the upstream spring, fails to capture the full impact of catchment inputs, including diffuse pollution from Tokaanu Village and altered sediment dynamics from the diversion. An additional SOE site, coupled with the findings of my thesis, would provide crucial knowledge to support efforts in restoring the Tokaanu Stream's ecological health and the mana of Ngāti Kurauia.

year: 2025