title: The spatial variability of elemental and isotopic compositions of carbon and nitrogen within sediments in a subtropical mangrove forest

authors: Ramirez-Matiz, Yuliana

subjects: Carbon

abstract: Mangrove forests are coastal habitats, which provide numerous ecosystem services in tropical and temperate regions, including burial and storage of Carbon and Nitrogen in the sediments. In New Zealand mangrove coverage is rapidly expanding throughout muddy coastlines and estuaries, in direct contrast to the current global trend of declining mangrove coverage. In this thesis, we explore the spatial distribution of Carbon and Nitrogen content and isotopic compositions in the sediments of a mangrove forest in New Zealand.

The field site is the Firth of Thames mangrove forest, which has rapidly expanded since around 1950, and now reaches 1 km in width over the southern Firth. Sediment cores with lengths ranging from 34 to 40 cm were collected from twelve across-shore transects and two along-shore transects. At each location, samples were taken from the surface and at depth, resulting in a total of 175 samples, providing substantial spatial coverage across the forest. A number of samples of mangrove vegetation were also collected. Elemental and isotopic analyses were performed on the sediment and vegetation samples. Additionally, grain size, fluorometric determination of Chlorophyll-a pigments and loss on ignition analyses were made on a selected subset of sediment samples. The elemental analyses in sediments showed mean concentrations of 2.09%, 1.59%, and 0.23% of total carbon, organic carbon and nitrogen, respectively, with generally larger concentrations at the surface. The C:N ratios were much larger from tree tissue samples (mean 38.01) relative to sediments (mean of 6.83). The mean δ13C and δ15N values in sediments were -23.04‰ and 8.20‰, respectively, while the mangrove samples were 13C-depleted (mean of -26.89‰) and exhibited a wide range in the Nitrogen isotope composition (values from 4.89-11.94‰).

Surface sediment samples showed a progressive increase of N, C and OC towards the interior of the mangrove forest, a decrease in δ13C values, but no clear spatial pattern was discerned in the depth samples. Despite some scatter, δ15N values were relatively constant in the across-shore direction. The elemental and isotopic concentration in the sediments did not appear to be affected on a large scale by the freshwater discharge, which locally influenced only the concentrations within the sediments on the adjacent riverbanks. Relatively high δ13C values and low C: N ratios indicate the predominance of an allochthonous marine source for carbon in FoT mangrove sediments. Neither algal biomass nor grain size were found to be correlated with OC content in the Firth of Thames sediments. A gross estimate (integrated over the top 10 cm) of C and N stocks was 13.26 t C ha-1 and 1.47 t N ha-1, respectively, thus adding to the recognition of these forests as efficient carbon and nitrogen sinks.

This research contributes to the knowledge of C and N content, sources and burial patterns in subtropical mangrove sediments. Such information is required to underpin environmental management decisions, for example prior to undertaking restoration or removal projects.

text: The spatial variability of elemental and isotopic compositions of carbon and nitrogen within sediments in a subtropical mangrove forest Mangrove forests are coastal habitats, which provide numerous ecosystem services in tropical and temperate regions, including burial and storage of Carbon and Nitrogen in the sediments. In New Zealand mangrove coverage is rapidly expanding throughout muddy coastlines and estuaries, in direct contrast to the current global trend of declining mangrove coverage. In this thesis, we explore the spatial distribution of Carbon and Nitrogen content and isotopic compositions in the sediments of a mangrove forest in New Zealand.

The field site is the Firth of Thames mangrove forest, which has rapidly expanded since around 1950, and now reaches 1 km in width over the southern Firth. Sediment cores with lengths ranging from 34 to 40 cm were collected from twelve across-shore transects and two along-shore transects. At each location, samples were taken from the surface and at depth, resulting in a total of 175 samples, providing substantial spatial coverage across the forest. A number of samples of mangrove vegetation were also collected. Elemental and isotopic analyses were performed on the sediment and vegetation samples. Additionally, grain size, fluorometric determination of Chlorophyll-a pigments and loss on ignition analyses were made on a selected subset of sediment samples. The elemental analyses in sediments showed mean concentrations of 2.09%, 1.59%, and 0.23% of total carbon, organic carbon and nitrogen, respectively, with generally larger concentrations at the surface. The C:N ratios were much larger from tree tissue samples (mean 38.01) relative to sediments (mean of 6.83). The mean δ13C and δ15N values in sediments were -23.04‰ and 8.20‰, respectively, while the mangrove samples were 13C-depleted (mean of -26.89‰) and exhibited a wide range in the Nitrogen isotope composition (values from 4.89-11.94‰).

Surface sediment samples showed a progressive increase of N, C and OC towards the interior of the mangrove forest, a decrease in δ13C values, but no clear spatial pattern was discerned in the depth samples. Despite some scatter, δ15N values were relatively constant in the across-shore direction. The elemental and isotopic concentration in the sediments did not appear to be affected on a large scale by the freshwater discharge, which locally influenced only the concentrations within the sediments on the adjacent riverbanks. Relatively high δ13C values and low C: N ratios indicate the predominance of an allochthonous marine source for carbon in FoT mangrove sediments. Neither algal biomass nor grain size were found to be correlated with OC content in the Firth of Thames sediments. A gross estimate (integrated over the top 10 cm) of C and N stocks was 13.26 t C ha-1 and 1.47 t N ha-1, respectively, thus adding to the recognition of these forests as efficient carbon and nitrogen sinks.

This research contributes to the knowledge of C and N content, sources and burial patterns in subtropical mangrove sediments. Such information is required to underpin environmental management decisions, for example prior to undertaking restoration or removal projects.

year: 2020

title: "Being trans intersects with my cultural identity": Social determinants of mental health among Asian transgender people

authors: Tan, Kyle K. H.

subjects: Social Sciences

abstract: Purpose: While studies on the relationship between social determinants and mental health among transgender people in Asia are increasing, there is a paucity of research on Asian transgender people living in Western countries. This study aimed to examine how social positions (gender, ethnicity, and migrant status) and social determinants of mental health were inter-related for Asian transgender people in Aotearoa/New Zealand.

Methods: We analyzed both quantitative and qualitative data from Asian participants (n=49) who responded to the 2018 Counting Ourselves: Aotearoa New Zealand Trans and Non-Binary Health Survey.

Results: Overall, 35% reported a very high psychological distress level. There were high levels of unmet needs for gender-affirming care, and participants reported a range of negative experiences at health care settings. About two-fifths had been discriminated because of their transgender (42%) or Asian (39%) identities. Fewer than half of participants felt that their family members were supportive of them being transgender (44%), and most reported they had supportive friends (73%). More than two-thirds of participants (68%) had a strong sense of belongingness to the transgender community and 35% reported this for the Asian community. Qualitative findings revealed specific challenges that participants experienced; these included barriers to accessing health care due to their migrant status and language barriers, influences of Asian cultures on mental health experiences, and rejection by family and people in Asian communities.

Conclusion: Our study provides evidence for health care providers, researchers, and policy makers to employ a culturally appropriate lens to improve knowledge about the intersectional experiences of being Asian and transgender.

text: "Being trans intersects with my cultural identity": Social determinants of mental health among Asian transgender people Purpose: While studies on the relationship between social determinants and mental health among transgender people in Asia are increasing, there is a paucity of research on Asian transgender people living in Western countries. This study aimed to examine how social positions (gender, ethnicity, and migrant status) and social determinants of mental health were inter-related for Asian transgender people in Aotearoa/New Zealand.

Methods: We analyzed both quantitative and qualitative data from Asian participants (n=49) who responded to the 2018 Counting Ourselves: Aotearoa New Zealand Trans and Non-Binary Health Survey.

Results: Overall, 35% reported a very high psychological distress level. There were high levels of unmet needs for gender-affirming care, and participants reported a range of negative experiences at health care settings. About two-fifths had been discriminated because of their transgender (42%) or Asian (39%) identities. Fewer than half of participants felt that their family members were supportive of them being transgender (44%), and most reported they had supportive friends (73%). More than two-thirds of participants (68%) had a strong sense of belongingness to the transgender community and 35% reported this for the Asian community. Qualitative findings revealed specific challenges that participants experienced; these included barriers to accessing health care due to their migrant status and language barriers, influences of Asian cultures on mental health experiences, and rejection by family and people in Asian communities.

Conclusion: Our study provides evidence for health care providers, researchers, and policy makers to employ a culturally appropriate lens to improve knowledge about the intersectional experiences of being Asian and transgender.

year: 2021

title: Maori & Psychology Research Unit annual report 2005

authors: Rua, Mohi

subjects: Maori and Psychology Research Unit

abstract: Annual report of the Maori and Psychology Research Unit (MPRU) 2005. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

text: Maori & Psychology Research Unit annual report 2005 Annual report of the Maori and Psychology Research Unit (MPRU) 2005. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

year: 2005