title: Seasonal patterns of growth and nutrient status of the macroalga Adamsiella chauvinii (Rhodophyta) in soft sediment environments

authors: Kregting, Louise T.

subjects: Adamsiella chauvinii

abstract: The seasonal growth and nutrient status of the temperate subtidal macroalga Adamsiella chauvinii was determined at three soft sediment sites with different ranges of tidally-driven current speeds. A. chauvinii thalli exhibited maximum growth rates during the late summer (February) and no evidence of nitrogen limited growth in summer as often exhibited by macroalgae growing on hard substrata in temperate environments. We suggest that growth was maintained during the summer period, when seawater nitrogen concentrations were low, by localized sources of ammonium probably produced by sediments and fauna within the canopy. Growth rates were up to 50% lower at the site with the slowest water velocity throughout most of the experimental period. However a greater tissue nitrogen content of A. chauvinii thalli at the slow flow site did not support evidence for mass-transfer limitation. It is suggested that as a consequence of slow flow, sedimentation on blade surfaces reduced the amount of light available for photosynthesis and growth. Lower growth rates at the slow flow site reduced metabolic demand for nutrients resulting in accumulation of tissue nitrogen and phosphate.

text: Seasonal patterns of growth and nutrient status of the macroalga Adamsiella chauvinii (Rhodophyta) in soft sediment environments The seasonal growth and nutrient status of the temperate subtidal macroalga Adamsiella chauvinii was determined at three soft sediment sites with different ranges of tidally-driven current speeds. A. chauvinii thalli exhibited maximum growth rates during the late summer (February) and no evidence of nitrogen limited growth in summer as often exhibited by macroalgae growing on hard substrata in temperate environments. We suggest that growth was maintained during the summer period, when seawater nitrogen concentrations were low, by localized sources of ammonium probably produced by sediments and fauna within the canopy. Growth rates were up to 50% lower at the site with the slowest water velocity throughout most of the experimental period. However a greater tissue nitrogen content of A. chauvinii thalli at the slow flow site did not support evidence for mass-transfer limitation. It is suggested that as a consequence of slow flow, sedimentation on blade surfaces reduced the amount of light available for photosynthesis and growth. Lower growth rates at the slow flow site reduced metabolic demand for nutrients resulting in accumulation of tissue nitrogen and phosphate.

year: 2008

title: Relationship between meteoric ¹⁰Be and NO₃⁻ concentrations in soils along Shackleton Glacier, Antarctica

authors: Diaz, Melisa A.

abstract: Outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced changes in ice thickness greater than other coastal regions of Antarctica during glacial maxima. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, complicating our understanding of ecological succession in TAM soils. Our knowledge of glacial extent on small spatial scales is limited for the TAM, and studies of soil exposure duration and disturbance, in particular, are rare. We collected surface soil samples and, in some places, depth profiles every 5 cm to refusal (up to 30 cm) from 11 ice-free areas along Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet. We explored the relationship between meteoric ¹⁰Be and NO₃⁻ in these soils as a tool for understanding landscape disturbance and wetting history and as exposure proxies. Concentrations of meteoric ¹⁰Be spanned more than an order of magnitude across the region (2.9×108 to 73×108 atoms g⁻¹) and are among the highest measured in polar regions. The concentrations of NO₃⁻ were similarly variable and ranged from ∼ μg g⁻¹ to 15 mg g⁻¹. In examining differences and similarities in the concentrations of ¹⁰Be and NO₃⁻ with depth, we suggest that much of the southern portion of the Shackleton Glacier region has likely developed under a hyper-arid climate regime with minimal disturbance. Finally, we inferred exposure time using ¹⁰Be concentrations. This analysis indicates that the soils we analyzed likely range from recent exposure (following the Last Glacial Maximum) to possibly >6 Myr. We suggest that further testing and interrogation of meteoric ¹⁰Be and NO₃⁻ concentrations and relationships in soils can provide important information regarding landscape development, soil evolution processes, and inferred exposure durations of surfaces in the TAM.

text: Relationship between meteoric ¹⁰Be and NO₃⁻ concentrations in soils along Shackleton Glacier, Antarctica Outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced changes in ice thickness greater than other coastal regions of Antarctica during glacial maxima. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, complicating our understanding of ecological succession in TAM soils. Our knowledge of glacial extent on small spatial scales is limited for the TAM, and studies of soil exposure duration and disturbance, in particular, are rare. We collected surface soil samples and, in some places, depth profiles every 5 cm to refusal (up to 30 cm) from 11 ice-free areas along Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet. We explored the relationship between meteoric ¹⁰Be and NO₃⁻ in these soils as a tool for understanding landscape disturbance and wetting history and as exposure proxies. Concentrations of meteoric ¹⁰Be spanned more than an order of magnitude across the region (2.9×108 to 73×108 atoms g⁻¹) and are among the highest measured in polar regions. The concentrations of NO₃⁻ were similarly variable and ranged from ∼ μg g⁻¹ to 15 mg g⁻¹. In examining differences and similarities in the concentrations of ¹⁰Be and NO₃⁻ with depth, we suggest that much of the southern portion of the Shackleton Glacier region has likely developed under a hyper-arid climate regime with minimal disturbance. Finally, we inferred exposure time using ¹⁰Be concentrations. This analysis indicates that the soils we analyzed likely range from recent exposure (following the Last Glacial Maximum) to possibly >6 Myr. We suggest that further testing and interrogation of meteoric ¹⁰Be and NO₃⁻ concentrations and relationships in soils can provide important information regarding landscape development, soil evolution processes, and inferred exposure durations of surfaces in the TAM.

year: 2021

title: He oranga tō te wai: Māori Pedagogies - A Culturally Responsive View of Aquatic Education and Drowning Prevention in Aotearoa

authors: Haimona, Mark Waihape

abstract: Drowning is a leading cause of accidental death and hospitalisation among Māori in Aotearoa. Drowning reports (Water Safety New Zealand, 2010, 2016, 2019) indicate Māori are over-represented in drowning compared to non-Māori, and on average account for up to a quarter of all drowning fatalities each year. Māori male aged 15-44 years and Māori children under five are most at risk of drowning (WSNZ, 2018, 2). A recent Aotearoa study on children’s water survival skills suggest changes are needed to improve how children develop fundamental aquatic skills and how teachers can best teach those skills (Button et al., 2017). In particular, the teaching of water safety skills for broader use in the open water environments of Aotearoa. 
Māori pedagogies within physical education, health, and education in the outdoors (Hemara, 2000; Jackson et al, 2016; Phillips, 2018) have demonstrated the benefits of Māori teaching methods that foster positive learning outcomes for Māori. (Bishop & Berryman, 2006, 2009). As such, this research investigated core components of Māori pedagogies that can improve aquatic education for Māori. It sought to validate traditional and contemporary aquatic teachings and water safety practices that Māori exercise as an expression of ira tangata (human development) and their relationship with te ao tūroa (the long-standing world). By means of kaupapa Māori research and the development of a new framework - Tāne Whānau Mārama, this thesis offers valuable insights into the importance of culturally responsive pedagogies in aquatic education that will enhance the health, educational achievements, and well-being of Māori whānau and communities.

text: He oranga tō te wai: Māori Pedagogies - A Culturally Responsive View of Aquatic Education and Drowning Prevention in Aotearoa Drowning is a leading cause of accidental death and hospitalisation among Māori in Aotearoa. Drowning reports (Water Safety New Zealand, 2010, 2016, 2019) indicate Māori are over-represented in drowning compared to non-Māori, and on average account for up to a quarter of all drowning fatalities each year. Māori male aged 15-44 years and Māori children under five are most at risk of drowning (WSNZ, 2018, 2). A recent Aotearoa study on children’s water survival skills suggest changes are needed to improve how children develop fundamental aquatic skills and how teachers can best teach those skills (Button et al., 2017). In particular, the teaching of water safety skills for broader use in the open water environments of Aotearoa. 
Māori pedagogies within physical education, health, and education in the outdoors (Hemara, 2000; Jackson et al, 2016; Phillips, 2018) have demonstrated the benefits of Māori teaching methods that foster positive learning outcomes for Māori. (Bishop & Berryman, 2006, 2009). As such, this research investigated core components of Māori pedagogies that can improve aquatic education for Māori. It sought to validate traditional and contemporary aquatic teachings and water safety practices that Māori exercise as an expression of ira tangata (human development) and their relationship with te ao tūroa (the long-standing world). By means of kaupapa Māori research and the development of a new framework - Tāne Whānau Mārama, this thesis offers valuable insights into the importance of culturally responsive pedagogies in aquatic education that will enhance the health, educational achievements, and well-being of Māori whānau and communities.

year: 2023