title: Landscape-level variation in stable isotopes of carbon and nitrogen across aquatic ecosystems in New Zealand

authors: Finnerty, Rebecca Catrin

abstract: The stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) are frequently used in food web studies as natural biological indicators for tracking ecological processes, interactions, and energy flows from the basal plant and detrital energy sources to the primary and secondary consumers. The spatial heterogeneity in the ecological, biogeochemical, hydrological, and geomorphological processes of aquatic ecosystems can influence the δ¹³C and δ¹⁵N isotopic baseline of food webs, which directly affect the isotopic composition of primary and secondary consumers. A better understanding of the significant drivers of δ¹³C and δ¹⁵N of aquatic organisms at the landscape scale would facilitate and improve the accuracy of the use of these isotopic ratios as natural tracers.
The main objective of this study was to identify the leading mechanisms influencing the spatial variability of δ¹³C and δ¹⁵N across New Zealand aquatic ecosystems at the landscape scale. The aims of this study were; (1) to review and collate the findings from published stable isotopic studies that investigated the effect of environmental factors on δ¹³C and δ¹⁵N of aquatic organisms, (2) to identify the sources and scales of δ¹³C and δ¹⁵N variability for top-predatory fish across New Zealand lake environments and, (3) to identify the sources and scales of δ¹⁵N variability for top-predatory fish and invertebrates (predatory and non-predatory) across New Zealand stream and river environments. Lake and stream δ¹³C and δ¹⁵N data of aquatic organisms were collated from a range of published and unpublished scientific literature across New Zealand. Data from a total of 88 lakes sourced from 11 publications and 475 stream sites from 15 publications were assessed to investigate the direct and indirect effects of environmental factors on the spatial variability of stable isotopic ratios across lakes and streams. To do so, a combination of correlation analyses, principal component analysis (PCA), and piecewise structural equation modelling (pSEM) were carried out.
The variability of top-predatory fish δ¹³C values across New Zealand lakes was best explained by the morphology of the lake. Fish sampled from lakes with large surface areas and volumes had higher δ¹³C signatures from lakes of smaller morphological size. I hypothesised that larger lakes allow for more influence of δ¹³C-enriched atmospheric CO₂ due to greater equilibration through gas exchange processes and turbulence regimes, contributing to the observed increase in enrichment of fish δ¹³C with lake surface area. The top-predatory fish δ¹⁵N most strongly reflected the watershed land use and showed no apparent relationship with lake size. The variability of non-predatory and predatory invertebrates, and top-predatory fish δ¹⁵N across New Zealand streams was best explained by the local land use in the upstream catchment and the nutrient concentrations, i.e., the total nitrogen and total phosphorus concentrations.
Our findings suggest that δ¹³C and δ¹⁵N respond to different environmental drivers. Carbon isotopic ratios tend to reflect the natural ecosystem properties, whereas nitrogen isotopic ratios respond more readily to the watershed land use. The findings in this study were consistent with previous stable isotopic research conducted in North American and European aquatic ecosystems, which have examined the effects of environmental factors on C and N isotopic ratios among aquatic organisms. An enhanced understanding of the natural ecosystem processes and anthropogenic influences, contributing to the spatial distribution of δ¹³C and δ¹⁵N of aquatic organisms, can improve the study design and interpretation of stable isotopes as a tracer in food web and ecosystem ecology, by taking into account the natural and human-induced spatial and trophic subsidies.

text: Landscape-level variation in stable isotopes of carbon and nitrogen across aquatic ecosystems in New Zealand The stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) are frequently used in food web studies as natural biological indicators for tracking ecological processes, interactions, and energy flows from the basal plant and detrital energy sources to the primary and secondary consumers. The spatial heterogeneity in the ecological, biogeochemical, hydrological, and geomorphological processes of aquatic ecosystems can influence the δ¹³C and δ¹⁵N isotopic baseline of food webs, which directly affect the isotopic composition of primary and secondary consumers. A better understanding of the significant drivers of δ¹³C and δ¹⁵N of aquatic organisms at the landscape scale would facilitate and improve the accuracy of the use of these isotopic ratios as natural tracers.
The main objective of this study was to identify the leading mechanisms influencing the spatial variability of δ¹³C and δ¹⁵N across New Zealand aquatic ecosystems at the landscape scale. The aims of this study were; (1) to review and collate the findings from published stable isotopic studies that investigated the effect of environmental factors on δ¹³C and δ¹⁵N of aquatic organisms, (2) to identify the sources and scales of δ¹³C and δ¹⁵N variability for top-predatory fish across New Zealand lake environments and, (3) to identify the sources and scales of δ¹⁵N variability for top-predatory fish and invertebrates (predatory and non-predatory) across New Zealand stream and river environments. Lake and stream δ¹³C and δ¹⁵N data of aquatic organisms were collated from a range of published and unpublished scientific literature across New Zealand. Data from a total of 88 lakes sourced from 11 publications and 475 stream sites from 15 publications were assessed to investigate the direct and indirect effects of environmental factors on the spatial variability of stable isotopic ratios across lakes and streams. To do so, a combination of correlation analyses, principal component analysis (PCA), and piecewise structural equation modelling (pSEM) were carried out.
The variability of top-predatory fish δ¹³C values across New Zealand lakes was best explained by the morphology of the lake. Fish sampled from lakes with large surface areas and volumes had higher δ¹³C signatures from lakes of smaller morphological size. I hypothesised that larger lakes allow for more influence of δ¹³C-enriched atmospheric CO₂ due to greater equilibration through gas exchange processes and turbulence regimes, contributing to the observed increase in enrichment of fish δ¹³C with lake surface area. The top-predatory fish δ¹⁵N most strongly reflected the watershed land use and showed no apparent relationship with lake size. The variability of non-predatory and predatory invertebrates, and top-predatory fish δ¹⁵N across New Zealand streams was best explained by the local land use in the upstream catchment and the nutrient concentrations, i.e., the total nitrogen and total phosphorus concentrations.
Our findings suggest that δ¹³C and δ¹⁵N respond to different environmental drivers. Carbon isotopic ratios tend to reflect the natural ecosystem properties, whereas nitrogen isotopic ratios respond more readily to the watershed land use. The findings in this study were consistent with previous stable isotopic research conducted in North American and European aquatic ecosystems, which have examined the effects of environmental factors on C and N isotopic ratios among aquatic organisms. An enhanced understanding of the natural ecosystem processes and anthropogenic influences, contributing to the spatial distribution of δ¹³C and δ¹⁵N of aquatic organisms, can improve the study design and interpretation of stable isotopes as a tracer in food web and ecosystem ecology, by taking into account the natural and human-induced spatial and trophic subsidies.

year: 2022

title: Social media and body image: It's complicated

authors: Elliott, Darren Jack

subjects: Body image

abstract: Body image is an important dimension of life, and in a media-saturated world, we are supposedly surrounded by images of 'idealised' physical body types that are harmful to people's body image. Many theories have been put forward to account for the growing idealisation of 'thin' and 'toned' women and 'lean' and 'muscular' men. Historically, psychological body image research has reliably linked exposure to 'ideal' bodies in mainstream 'traditional' media (along with moderating processes of internalisation, self-comparison, and objectification) and experiences of body image dissatisfaction; for increasingly diverse populations of women and men across the lifespan. In recent years, researchers have turned their attention to social media's impact on body image. Some quantitative and correlational studies suggest that social media use is associated with body image dissatisfaction and, in some instances, further intensifies its scope and scale. Findings also contend that social media can promote body image satisfaction by enabling the distribution and consumption of alternative, 'realistic' body types and body positive content.

This thesis suggests inconsistent, and binary findings come from the limited and partial ways research often conceptualise and analyse the relationship between social media and body image. Studies are typically based on singular aspects of social media (i.e. exposure to particular pages or technological affordances) and often overemphasise body image as a static, cross-situational trait, ignoring its complex and situational-specific nature. The current study counters this by bringing together the critical psychological view that body image is complex, multidimensional, and fluid and contemporary Screen and Media scholarship that emphasises how people can simultaneously be users of and used by social media. I combine these two perspectives to critically explore how people experience their body image through social media in ambivalent ways and how social media can enable and challenge the process of developing positive body image experiences.

Specifically, I take a Critical Realist informed, qualitative approach to exploring how the social and technological affordances of social media ('Facebook' and 'Instagram') shape attitudinal body image (thoughts, feelings and behaviours relating to research respondents' physical appearance and embodiment) of adult, New Zealand and Australian women and men who are actively using social media to improve their body image. The research findings draw from an online survey of 552 respondents and 30 semi-structured interviews that highlight the simultaneous risks, rewards, and ever-present tensions - which, I argue, are inherently characteristic of the reflexive relationship between particularly situated individuals, social media, and body image.

text: Social media and body image: It's complicated Body image is an important dimension of life, and in a media-saturated world, we are supposedly surrounded by images of 'idealised' physical body types that are harmful to people's body image. Many theories have been put forward to account for the growing idealisation of 'thin' and 'toned' women and 'lean' and 'muscular' men. Historically, psychological body image research has reliably linked exposure to 'ideal' bodies in mainstream 'traditional' media (along with moderating processes of internalisation, self-comparison, and objectification) and experiences of body image dissatisfaction; for increasingly diverse populations of women and men across the lifespan. In recent years, researchers have turned their attention to social media's impact on body image. Some quantitative and correlational studies suggest that social media use is associated with body image dissatisfaction and, in some instances, further intensifies its scope and scale. Findings also contend that social media can promote body image satisfaction by enabling the distribution and consumption of alternative, 'realistic' body types and body positive content.

This thesis suggests inconsistent, and binary findings come from the limited and partial ways research often conceptualise and analyse the relationship between social media and body image. Studies are typically based on singular aspects of social media (i.e. exposure to particular pages or technological affordances) and often overemphasise body image as a static, cross-situational trait, ignoring its complex and situational-specific nature. The current study counters this by bringing together the critical psychological view that body image is complex, multidimensional, and fluid and contemporary Screen and Media scholarship that emphasises how people can simultaneously be users of and used by social media. I combine these two perspectives to critically explore how people experience their body image through social media in ambivalent ways and how social media can enable and challenge the process of developing positive body image experiences.

Specifically, I take a Critical Realist informed, qualitative approach to exploring how the social and technological affordances of social media ('Facebook' and 'Instagram') shape attitudinal body image (thoughts, feelings and behaviours relating to research respondents' physical appearance and embodiment) of adult, New Zealand and Australian women and men who are actively using social media to improve their body image. The research findings draw from an online survey of 552 respondents and 30 semi-structured interviews that highlight the simultaneous risks, rewards, and ever-present tensions - which, I argue, are inherently characteristic of the reflexive relationship between particularly situated individuals, social media, and body image.

year: 2022

title: The coastal habitats of Tairawhiti: A review of the scientific, local, and customary knowledge

authors: Ross, Philip M.

abstract: In Aotearoa/New Zealand, regional councils and unitary authorities have a range of responsibilities for decision making in the coastal and marine area (CMA). The New Zealand Coastal Policy Statement (2010), in policy 11, sets out requirements for avoiding significant adverse effects on species, habitats and ecosystems, and section 67 of the Resource Management Act (1991) indicates that regional plans must give effect to the New Zealand Coastal Policy Statement. For regional councils to be able to successfully manage indigenous marine biodiversity (composed of species, habitats and ecosystems) they must have some understanding of the types of biodiversity present within a region’s CMA, and knowledge of the spatial distribution of that biodiversity. For regions such as Auckland and Northland biodiversity in the CMA has been relatively well described. For example, the Department of Conservation has compiled a marine habitat map for the Northland section of the Northeast Marine Bioregion, which covers an area of 1.34 million hectares of coastal habitat from Ahipara to Mangawhai (https://www.nrc.govt.nz/resource-library-summary/research-and-reports/coastal/).
This knowledge makes it much easier for councils to develop coastal plans that provide appropriate protections and management outcomes. In other regions, less information is available which can make it difficult to put in place appropriate environmental management.
The Gisborne Region (Tairawhiti) is a region for which there is comparatively little information available regarding marine biodiversity and the distribution of coastal habitats. The region has been under-represented in coastal research to date, which is largely a consequence of its remoteness to institutions conducting research in the CMA (Universities, CRIs and other research providers). Consequently the Gisborne District Council (GDC), the unitary authority responsible for Tairawhiti, does not have readily available and robust information about the marine and coastal environments of the region. This lack of knowledge spans the range of coastal habitats which GDC has the task of managing under the Resource Management Act (1991).
As a first step towards gathering the information required to better manage the Tairawhiti CMA, this report collates and summarises the available scientific, local and customary knowledge on the extent, location and state of marine and estuarine habitats within the Tairawhiti region. In addition to the collation of this information, additional objectives for this report include: identifying gaps in the information base; recording information that might explain how pressures and activities within the region may have altered coastal habitats; providing advice on priorities for additional work required to fill knowledge gaps; and where possible, include mātauranga Māori in accordance with tikanga. With this knowledge, GDC will be in a better position to facilitate the development of a Regional Plan for Tairāwhiti to set the strategic direction for growth, development and resource management over the next 30 years.

text: The coastal habitats of Tairawhiti: A review of the scientific, local, and customary knowledge In Aotearoa/New Zealand, regional councils and unitary authorities have a range of responsibilities for decision making in the coastal and marine area (CMA). The New Zealand Coastal Policy Statement (2010), in policy 11, sets out requirements for avoiding significant adverse effects on species, habitats and ecosystems, and section 67 of the Resource Management Act (1991) indicates that regional plans must give effect to the New Zealand Coastal Policy Statement. For regional councils to be able to successfully manage indigenous marine biodiversity (composed of species, habitats and ecosystems) they must have some understanding of the types of biodiversity present within a region’s CMA, and knowledge of the spatial distribution of that biodiversity. For regions such as Auckland and Northland biodiversity in the CMA has been relatively well described. For example, the Department of Conservation has compiled a marine habitat map for the Northland section of the Northeast Marine Bioregion, which covers an area of 1.34 million hectares of coastal habitat from Ahipara to Mangawhai (https://www.nrc.govt.nz/resource-library-summary/research-and-reports/coastal/).
This knowledge makes it much easier for councils to develop coastal plans that provide appropriate protections and management outcomes. In other regions, less information is available which can make it difficult to put in place appropriate environmental management.
The Gisborne Region (Tairawhiti) is a region for which there is comparatively little information available regarding marine biodiversity and the distribution of coastal habitats. The region has been under-represented in coastal research to date, which is largely a consequence of its remoteness to institutions conducting research in the CMA (Universities, CRIs and other research providers). Consequently the Gisborne District Council (GDC), the unitary authority responsible for Tairawhiti, does not have readily available and robust information about the marine and coastal environments of the region. This lack of knowledge spans the range of coastal habitats which GDC has the task of managing under the Resource Management Act (1991).
As a first step towards gathering the information required to better manage the Tairawhiti CMA, this report collates and summarises the available scientific, local and customary knowledge on the extent, location and state of marine and estuarine habitats within the Tairawhiti region. In addition to the collation of this information, additional objectives for this report include: identifying gaps in the information base; recording information that might explain how pressures and activities within the region may have altered coastal habitats; providing advice on priorities for additional work required to fill knowledge gaps; and where possible, include mātauranga Māori in accordance with tikanga. With this knowledge, GDC will be in a better position to facilitate the development of a Regional Plan for Tairāwhiti to set the strategic direction for growth, development and resource management over the next 30 years.

year: 2021