title: Changes in ecosystem functioning along a eutrophication gradient in Waihī Estuary

authors: Squires, Kit

subjects: Ecosystem functioning

abstract: Soft-sediment coastal ecosystems are important sites for a multitude of ecosystem functions, including primary production, organic matter recycling and nutrient processing. Intertidal areas host an array of fauna and flora that can alter pathways and processes which underpin function, support higher food webs and ecosystem services. Anthropogenic impacts on coastal areas are increasing in frequency and intensity. One of the key pressures to New Zealand estuaries, and globally, is that of increased run-off from land. This can cause 
 eutrophication, which is the ecological response to increased nutrients. Waihī Estuary, in Bay of Plenty, New Zealand, has been influenced by farming intensity, coastal development, and stream channelising, which has increased sediment and nutrient inputs recently and over the past 90 years; resulting in frequent algal blooms. This thesis explores the effect eutrophication is having on ecosystem functioning along a gradient of change.

Field sampling was carried out over summer 2018 and used space as a proxy for time, sampling seven sites over a naturally occurring eutrophication gradient. Solute exchanges (O₂, NH₄⁺-N, PO₄ᶟ⁻-P, NOₓ-N), were measured using benthic flux chambers over one tidal period. At each site, environmental variables and the macrofaunal community were also quantified. Biotic and abiotic drivers of function were examined firstly on a site by site basis, to gain resolution of fine scale flux dynamics. Non-metric distance based linear models were then created to evaluate changes in function across the spectrum of sites using sequential tests where organic matter content was fitted first.

Results from this study indicate increasing organic matter content was a major contributing factor to ecological shifts, cascading biotic and abiotic interactions, and feedback loops. Increasing organic matter content increased sediment oxygen demand to the point of hypoxia (and potentially anoxia), particularly where algal mats (Gracilaria spp.) were present. Gracilaria spp. seemingly capped the sediment, prevented light penetration and significantly influenced sediment oxygen consumption. Photosynthetic efficiency (GPP𝒸ₕₗ ₐ) also decreased with organic matter enrichment. In association with increased sediment oxygen consumption, NH₄⁺-N and PO₄ᶟ⁻-P showed a 2.6 and 2-fold increase in efflux (respectively) under dark conditions. Redox pathways were altered as eutrophication increased and,  ii where oxygen was depleted, NOₓ-N was taken up by sediments and utilised as an electron acceptor.

Organisms responded positively to organic enrichment to a point, but once this threshold was exceeded, taxonomic richness and individual abundance reduced. Although sediment variables explained the greatest proportion of variance in flux models across the gradient, key bioturbating species had disproportionate effects
on solute exchanges. These organisms were sensitive to changes in sediment conditions. The New Zealand cockle Austrovenus stutchburyi and tellinid bivalve Macomona liliana were the first species to decline in response to eutrophication. A. stutchburyi increased NH₄⁺-N efflux, but declined in number with eutrophication, which simultaneously increased NH₄⁺-N efflux. A burrow building polychaete, Ceratonereis spp. enhanced NOₓ-N uptake to sediments indicating nitrificationdenitrification coupling. However the opportunistic amphipod Paracorophium spp. dominated site 4, where increased NOₓ-N efflux (though continuous burrow ventilation) indicated a potentially important species for ammonification and subsequent nitrification.

This study demonstrates how changes in ecosystem functioning due to eutrophication can result in undesirable shifts within estuarine systems. These changes are often difficult to remediate and can impede the services that estuaries provide.

text: Changes in ecosystem functioning along a eutrophication gradient in Waihī Estuary Soft-sediment coastal ecosystems are important sites for a multitude of ecosystem functions, including primary production, organic matter recycling and nutrient processing. Intertidal areas host an array of fauna and flora that can alter pathways and processes which underpin function, support higher food webs and ecosystem services. Anthropogenic impacts on coastal areas are increasing in frequency and intensity. One of the key pressures to New Zealand estuaries, and globally, is that of increased run-off from land. This can cause 
 eutrophication, which is the ecological response to increased nutrients. Waihī Estuary, in Bay of Plenty, New Zealand, has been influenced by farming intensity, coastal development, and stream channelising, which has increased sediment and nutrient inputs recently and over the past 90 years; resulting in frequent algal blooms. This thesis explores the effect eutrophication is having on ecosystem functioning along a gradient of change.

Field sampling was carried out over summer 2018 and used space as a proxy for time, sampling seven sites over a naturally occurring eutrophication gradient. Solute exchanges (O₂, NH₄⁺-N, PO₄ᶟ⁻-P, NOₓ-N), were measured using benthic flux chambers over one tidal period. At each site, environmental variables and the macrofaunal community were also quantified. Biotic and abiotic drivers of function were examined firstly on a site by site basis, to gain resolution of fine scale flux dynamics. Non-metric distance based linear models were then created to evaluate changes in function across the spectrum of sites using sequential tests where organic matter content was fitted first.

Results from this study indicate increasing organic matter content was a major contributing factor to ecological shifts, cascading biotic and abiotic interactions, and feedback loops. Increasing organic matter content increased sediment oxygen demand to the point of hypoxia (and potentially anoxia), particularly where algal mats (Gracilaria spp.) were present. Gracilaria spp. seemingly capped the sediment, prevented light penetration and significantly influenced sediment oxygen consumption. Photosynthetic efficiency (GPP𝒸ₕₗ ₐ) also decreased with organic matter enrichment. In association with increased sediment oxygen consumption, NH₄⁺-N and PO₄ᶟ⁻-P showed a 2.6 and 2-fold increase in efflux (respectively) under dark conditions. Redox pathways were altered as eutrophication increased and,  ii where oxygen was depleted, NOₓ-N was taken up by sediments and utilised as an electron acceptor.

Organisms responded positively to organic enrichment to a point, but once this threshold was exceeded, taxonomic richness and individual abundance reduced. Although sediment variables explained the greatest proportion of variance in flux models across the gradient, key bioturbating species had disproportionate effects
on solute exchanges. These organisms were sensitive to changes in sediment conditions. The New Zealand cockle Austrovenus stutchburyi and tellinid bivalve Macomona liliana were the first species to decline in response to eutrophication. A. stutchburyi increased NH₄⁺-N efflux, but declined in number with eutrophication, which simultaneously increased NH₄⁺-N efflux. A burrow building polychaete, Ceratonereis spp. enhanced NOₓ-N uptake to sediments indicating nitrificationdenitrification coupling. However the opportunistic amphipod Paracorophium spp. dominated site 4, where increased NOₓ-N efflux (though continuous burrow ventilation) indicated a potentially important species for ammonification and subsequent nitrification.

This study demonstrates how changes in ecosystem functioning due to eutrophication can result in undesirable shifts within estuarine systems. These changes are often difficult to remediate and can impede the services that estuaries provide.

year: 2019

title: Axioms for function semigroups with agreement quasi-order

authors: Stokes, Tim E.

subjects: function semigroup

abstract: The agreement quasi-order on pairs of (partial) transformations on a set X is defined as follows: (f, g) ≼ (h, k) if whenever f, g are defined and agree, so do h, k. We axiomatize function semigroups and monoids equipped with this quasi-order, thereby providing a generalisation of first projection quasi-ordered ∩-semigroups of functions. As an application, axiomatizations are obtained for groups and inverse semigroups of injective functions equipped with the quasi-order of fix-set inclusion. All axiomatizations are finite.

text: Axioms for function semigroups with agreement quasi-order The agreement quasi-order on pairs of (partial) transformations on a set X is defined as follows: (f, g) ≼ (h, k) if whenever f, g are defined and agree, so do h, k. We axiomatize function semigroups and monoids equipped with this quasi-order, thereby providing a generalisation of first projection quasi-ordered ∩-semigroups of functions. As an application, axiomatizations are obtained for groups and inverse semigroups of injective functions equipped with the quasi-order of fix-set inclusion. All axiomatizations are finite.

year: 2011

title: Kimihia, rangahaua ngā tikanga heke iho. He taonga huahua e riro mai: Exploring whakapapa as a tool towards a kaupapa Māori assessment framework in early childhood education

authors: Paki, Vanessa Anne

subjects: kaupapa Maori assessment

abstract: This study explores whakapapa as a tool, which can be used as a kaupapa Māori assessment framework in early childhood education, positioning kaupapa Māori theory as a paradigm base underpinning a philosophical and theoretical discourse towards assessment for children's learning. This thesis represents the culmination of a personal and professional journey, derived from the writer's longstanding interest in and commitment to kaupapa Māori early childhood education, and more specifically, philosophies and practices for assessment in this context. The study has canvassed a vast terrain of kaupapa Māori philosophy in its search for a theoretical grounding for a kaupapa Māori assessment framework for early childhood education.
Foundation to the study has been the premise that the notion of whakapapa serves as an overarching philosophical matrix, encompassing the interconnected realms of genealogy, spirituality, and knowledge that precede, surround, and embrace the Māori child. Throughout the thesis, diagrams are employed to demonstrate and model the whakapapa underpinning the conceptualisations being explored. After contextualising the study within a historical overview of the impact of colonisation of kaupapa Māori education and research, it is suggested that a re-examination of key concepts from tikanga Māori will illuminate transformative possibilities applicable to the study's focus on the development of a theoretical base for an assessment tool within kaupapa Māori early childhood settings. Drawing from the literature, the thesis re-positions the view of the Māori child to one of being nurtured within a philosophical construct underpinned and immersed in tikanga such as whakapapa, ira tangata, whanaungatanga, mana and tapu, and ako, providing a strongly Māori theoretical base for the envisioning of the assessment process. The outcome of this study is to propose an assessment framework, which embodies and reflects these core kaupapa Māori philosophies as praxis.

text: Kimihia, rangahaua ngā tikanga heke iho. He taonga huahua e riro mai: Exploring whakapapa as a tool towards a kaupapa Māori assessment framework in early childhood education This study explores whakapapa as a tool, which can be used as a kaupapa Māori assessment framework in early childhood education, positioning kaupapa Māori theory as a paradigm base underpinning a philosophical and theoretical discourse towards assessment for children's learning. This thesis represents the culmination of a personal and professional journey, derived from the writer's longstanding interest in and commitment to kaupapa Māori early childhood education, and more specifically, philosophies and practices for assessment in this context. The study has canvassed a vast terrain of kaupapa Māori philosophy in its search for a theoretical grounding for a kaupapa Māori assessment framework for early childhood education.
Foundation to the study has been the premise that the notion of whakapapa serves as an overarching philosophical matrix, encompassing the interconnected realms of genealogy, spirituality, and knowledge that precede, surround, and embrace the Māori child. Throughout the thesis, diagrams are employed to demonstrate and model the whakapapa underpinning the conceptualisations being explored. After contextualising the study within a historical overview of the impact of colonisation of kaupapa Māori education and research, it is suggested that a re-examination of key concepts from tikanga Māori will illuminate transformative possibilities applicable to the study's focus on the development of a theoretical base for an assessment tool within kaupapa Māori early childhood settings. Drawing from the literature, the thesis re-positions the view of the Māori child to one of being nurtured within a philosophical construct underpinned and immersed in tikanga such as whakapapa, ira tangata, whanaungatanga, mana and tapu, and ako, providing a strongly Māori theoretical base for the envisioning of the assessment process. The outcome of this study is to propose an assessment framework, which embodies and reflects these core kaupapa Māori philosophies as praxis.

year: 2007