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: Scaffolding with and through videos: An example of ICT-TPACK

authors: Otrel-Cass, Kathrin

subjects: New Zealand

abstract: In New Zealand and internationally claims are being made about the potential for information and communication technologies (ICTs) to transform teaching and learning. However, the theoretical underpinnings explaining the complex interplay between the content, pedagogy and technology a teacher needs to consider must be expanded. This article explicates theoretical and practical ideas related to teachers’ application of their ICT technology, pedagogy, and content knowledge (TPACK) in science. The article unpacks the social and technological dimensions of teachers’ use of TPACK when they use digital videos to scaffold learning. It showcases the intricate interplay between teachers’ knowledge about content, digital video technology, and students’ learning needs based on a qualitative study of two science teachers and their students in a New Zealand primary school.

text: Scaffolding with and through videos: An example of ICT-TPACK In New Zealand and internationally claims are being made about the potential for information and communication technologies (ICTs) to transform teaching and learning. However, the theoretical underpinnings explaining the complex interplay between the content, pedagogy and technology a teacher needs to consider must be expanded. This article explicates theoretical and practical ideas related to teachers’ application of their ICT technology, pedagogy, and content knowledge (TPACK) in science. The article unpacks the social and technological dimensions of teachers’ use of TPACK when they use digital videos to scaffold learning. It showcases the intricate interplay between teachers’ knowledge about content, digital video technology, and students’ learning needs based on a qualitative study of two science teachers and their students in a New Zealand primary school.

year: 2012

title: A path to lotions and potions: Ngāti te Maunga ahi kā use of rongoā for hapū wellbeing

authors: Diamond, Kiri

subjects: rongoā

abstract: The research aimed to determine the challenges and improvements required during the implementation of the rongoā programme. The rongoā programme was based on a papakāinga near a marae, in a semi-rural location with difficult access. Participatory action research and autoethnography methods were used with the ahi kā (local residence) to develop a programme that would fulfil the hapū ora (extended family wellbeing) goals.  The goals of the programme were: for the ahi kā to use rongoā (modalities of health) confidently for their wellbeing; consistently use a Facebook page to learn and share information and to develop a database of the local rongoā rākau (medicinal plant). The ahi kā identified a further question to ask Facebook members to understand what motivated their participation and a survey was conducted. The ahi kā also wanted to understand the local doctor’s view on rongoā and its context on health provision in their area. An interview was conducted and the survey and interview added to the understanding of what the ahi kā could do to improve theirs and the hapū whānau (group extended family) wellbeing.
The findings of the research highlighted the complexities that arise from conducting research in a bicultural space where a common understanding of cultural knowledge is assumed to be homogenous. A shared history with colonisation and religious beliefs brought to the forefront the multiplicity Māori work through to determine a shared hapū identity. Based on an understanding of Māori principle values and tikanga (ways of enacting values), as understood by ahi kā, transformed a programme of learning how to make lotions and potions for the ahi kā, into influencing hapū members to change their attitudes and behaviours to their environment and their wellbeing.
This research highlighted the role that ahi kā hold as keepers of cultural knowledge that is rooted in the papakāinga through ancestral links that informs the identity of a hapū. Learning how to use rongoā provided ahi kā a platform to learn a new skill while helping the hapū heal through connecting with the identity and land of the hapū they belong to.

text: A path to lotions and potions: Ngāti te Maunga ahi kā use of rongoā for hapū wellbeing The research aimed to determine the challenges and improvements required during the implementation of the rongoā programme. The rongoā programme was based on a papakāinga near a marae, in a semi-rural location with difficult access. Participatory action research and autoethnography methods were used with the ahi kā (local residence) to develop a programme that would fulfil the hapū ora (extended family wellbeing) goals.  The goals of the programme were: for the ahi kā to use rongoā (modalities of health) confidently for their wellbeing; consistently use a Facebook page to learn and share information and to develop a database of the local rongoā rākau (medicinal plant). The ahi kā identified a further question to ask Facebook members to understand what motivated their participation and a survey was conducted. The ahi kā also wanted to understand the local doctor’s view on rongoā and its context on health provision in their area. An interview was conducted and the survey and interview added to the understanding of what the ahi kā could do to improve theirs and the hapū whānau (group extended family) wellbeing.
The findings of the research highlighted the complexities that arise from conducting research in a bicultural space where a common understanding of cultural knowledge is assumed to be homogenous. A shared history with colonisation and religious beliefs brought to the forefront the multiplicity Māori work through to determine a shared hapū identity. Based on an understanding of Māori principle values and tikanga (ways of enacting values), as understood by ahi kā, transformed a programme of learning how to make lotions and potions for the ahi kā, into influencing hapū members to change their attitudes and behaviours to their environment and their wellbeing.
This research highlighted the role that ahi kā hold as keepers of cultural knowledge that is rooted in the papakāinga through ancestral links that informs the identity of a hapū. Learning how to use rongoā provided ahi kā a platform to learn a new skill while helping the hapū heal through connecting with the identity and land of the hapū they belong to.

year: 2019