title: Integrative analysis of stressor gradients reveals multiple discrete trait‐defined axes underlie community assembly

authors: Barrett, Isabelle C.

abstract: The generalizable functional attributes of organisms (traits) relate strongly to their environment across multiple levels of biological organization, making trait-based approaches a powerful mechanistic framework to understand species distributions and community composition in relation to environmental change. To investigate how a wide range of stressor types shape stream macroinvertebrate communities, we conducted an integrative analysis using community and taxon trait information across drying, flooding, eutrophication, fine sediment, and acid mine drainage (AMD) gradients. Each gradient spanned relatively unimpacted to severely impacted sites. To characterize community change in response to stressors, we incorporated abundance-based trait information from all stressor gradients in a single trait-based ordination (nonmetric multidimensional scaling), defining the trait space within which each stressor gradient acted. We hypothesized that different stressors would apply different environmental filters, moving communities along distinct axes in trait space and resulting in communities with definable trait combinations. Particularly strong relationships were associated with anthropogenically derived stressors (fine sediment, eutrophication, and AMD) compared to natural stressors (drying and flooding). Anthropogenic stressors instigated significant movement of communities along multiple axes in trait space, likely driven by limited adaptation to these novel stressors. We demonstrate that trait-based analysis of communities across multiple stressor gradients can support a more comprehensive understanding of how community composition changes than taxonomic methods or investigation of a single stressor type, and could underpin community-focused management actions.

text: Integrative analysis of stressor gradients reveals multiple discrete trait‐defined axes underlie community assembly The generalizable functional attributes of organisms (traits) relate strongly to their environment across multiple levels of biological organization, making trait-based approaches a powerful mechanistic framework to understand species distributions and community composition in relation to environmental change. To investigate how a wide range of stressor types shape stream macroinvertebrate communities, we conducted an integrative analysis using community and taxon trait information across drying, flooding, eutrophication, fine sediment, and acid mine drainage (AMD) gradients. Each gradient spanned relatively unimpacted to severely impacted sites. To characterize community change in response to stressors, we incorporated abundance-based trait information from all stressor gradients in a single trait-based ordination (nonmetric multidimensional scaling), defining the trait space within which each stressor gradient acted. We hypothesized that different stressors would apply different environmental filters, moving communities along distinct axes in trait space and resulting in communities with definable trait combinations. Particularly strong relationships were associated with anthropogenically derived stressors (fine sediment, eutrophication, and AMD) compared to natural stressors (drying and flooding). Anthropogenic stressors instigated significant movement of communities along multiple axes in trait space, likely driven by limited adaptation to these novel stressors. We demonstrate that trait-based analysis of communities across multiple stressor gradients can support a more comprehensive understanding of how community composition changes than taxonomic methods or investigation of a single stressor type, and could underpin community-focused management actions.

year: 2022

title: Paleoenvironmental Variability during the Middle Miocene Climatic Optimum Reconstructed using a Lake Sediment Record from the Otago Region, New Zealand

authors: Garrity, Francis David Alain

subjects: Miocene

abstract: Climate archives indicate that the varied interaction of several cycles across a range of timescales exerted a prevailing control on climate throughout the Holocene and Pleistocene. However, due to the scarcity of highly resolved lacustrine records, it has so far been difficult to recognize sub-Milankovitch scale cycles in earlier epochs. Climate variability during the Middle Miocene was particularly extensive, and included the Miocene Climatic Optimum, representing the maximum temperatures experienced during the Cenozoic. A high resolution account of Southern Hemisphere paleoenvironmental variability during the Miocene Climatic Optimum has never previously been produced and is thus of significant importance.
The Hindon Maar diatomite is a laminated lacustrine deposit dominated by Aulacoseira Spp. diatoms. This lake formed due to a phreatomagmatic eruption as part of the Waipiata volcanic field, and accumulated during the Langhian Age (~15.2 Ma; Middle Miocene) in the Otago region of New Zealand. A high-resolution multi-proxy analysis was conducted on a 10.8-m-long core of this annually resolved lake sediment, which varve thicknesses suggest represents 7600 years of deposition. Gamma density, magnetic susceptibility, CIELAB L*a*b* colour, particle size, compositional data and petrographic images were collected. Compositional data included biogenic silica, total organic carbon and schist, determined using Fourier transform infrared spectroscopy.
Principal components analysis of these variables enabled the identification of underlying processes which I interpret to represent precipitation, wind speed and temperature. Aulacoseira Spp. diatoms are highly sensitive to variations in wind speed, and thus most changes in lake productivity reflect wind strength changes relating to underlying cyclicity. In addition, electrofacies analysis is used to identify six reoccurring and persisting paleoenvironmental states. Based on electrofacies analysis of principal component factor scores, a high resolution reconstruction is proposed and related to the underlying cyclical factors.
It is suggested that wind strength on this time scale during the Middle Miocene may partially respond to the interaction of two solar cycles and one orbital cycle. These are the DeVries cycle (200 years), the Hallstatt cycle (2300 years) and precession (~26000 years). These cycles and others were identified using a combination of sum of sinusoidal signal analysis, Tukey-Hamming spectral analysis and wavelet transformations. Peaks in these cycles thus likely generated warm conditions, causing prevailing westerly winds to move northwards and intensify, whilst troughs correspond to a decline in oceanic temperatures and wind speeds. This investigation therefore demonstrates the influence of sub-Milankovitch scale cycles and solar forcing on conditions during the Miocene Climatic Optimum for the first time in the Southern Hemisphere.

text: Paleoenvironmental Variability during the Middle Miocene Climatic Optimum Reconstructed using a Lake Sediment Record from the Otago Region, New Zealand Climate archives indicate that the varied interaction of several cycles across a range of timescales exerted a prevailing control on climate throughout the Holocene and Pleistocene. However, due to the scarcity of highly resolved lacustrine records, it has so far been difficult to recognize sub-Milankovitch scale cycles in earlier epochs. Climate variability during the Middle Miocene was particularly extensive, and included the Miocene Climatic Optimum, representing the maximum temperatures experienced during the Cenozoic. A high resolution account of Southern Hemisphere paleoenvironmental variability during the Miocene Climatic Optimum has never previously been produced and is thus of significant importance.
The Hindon Maar diatomite is a laminated lacustrine deposit dominated by Aulacoseira Spp. diatoms. This lake formed due to a phreatomagmatic eruption as part of the Waipiata volcanic field, and accumulated during the Langhian Age (~15.2 Ma; Middle Miocene) in the Otago region of New Zealand. A high-resolution multi-proxy analysis was conducted on a 10.8-m-long core of this annually resolved lake sediment, which varve thicknesses suggest represents 7600 years of deposition. Gamma density, magnetic susceptibility, CIELAB L*a*b* colour, particle size, compositional data and petrographic images were collected. Compositional data included biogenic silica, total organic carbon and schist, determined using Fourier transform infrared spectroscopy.
Principal components analysis of these variables enabled the identification of underlying processes which I interpret to represent precipitation, wind speed and temperature. Aulacoseira Spp. diatoms are highly sensitive to variations in wind speed, and thus most changes in lake productivity reflect wind strength changes relating to underlying cyclicity. In addition, electrofacies analysis is used to identify six reoccurring and persisting paleoenvironmental states. Based on electrofacies analysis of principal component factor scores, a high resolution reconstruction is proposed and related to the underlying cyclical factors.
It is suggested that wind strength on this time scale during the Middle Miocene may partially respond to the interaction of two solar cycles and one orbital cycle. These are the DeVries cycle (200 years), the Hallstatt cycle (2300 years) and precession (~26000 years). These cycles and others were identified using a combination of sum of sinusoidal signal analysis, Tukey-Hamming spectral analysis and wavelet transformations. Peaks in these cycles thus likely generated warm conditions, causing prevailing westerly winds to move northwards and intensify, whilst troughs correspond to a decline in oceanic temperatures and wind speeds. This investigation therefore demonstrates the influence of sub-Milankovitch scale cycles and solar forcing on conditions during the Miocene Climatic Optimum for the first time in the Southern Hemisphere.

year: 2017

title: Participatory data design: managing data sovereignty in IoT solutions

authors: Bowen, Judy

subjects: computer science

abstract: Within the software engineering community, deciding how to collect, store and use personal data has become about more than just understanding our users. This paper considers ethical data use which includes cultural considerations and data ownership rights. We discuss indigenous data sovereignty as a concept and how it potentially impacts technological solutions that gather personal data from users. We propose an extension to typical user-centred design processes which we call participatory data design. This incorporates the use of frameworks and tools that specifically focus on managing data within the cultural context it is gathered from. We also present a specific example of how we have used this approach in the context of a data collection project from M¯aori workers in New Zealand forestry. We conclude with a discussion of the wider implications of this approach.

text: Participatory data design: managing data sovereignty in IoT solutions Within the software engineering community, deciding how to collect, store and use personal data has become about more than just understanding our users. This paper considers ethical data use which includes cultural considerations and data ownership rights. We discuss indigenous data sovereignty as a concept and how it potentially impacts technological solutions that gather personal data from users. We propose an extension to typical user-centred design processes which we call participatory data design. This incorporates the use of frameworks and tools that specifically focus on managing data within the cultural context it is gathered from. We also present a specific example of how we have used this approach in the context of a data collection project from M¯aori workers in New Zealand forestry. We conclude with a discussion of the wider implications of this approach.

year: 2022