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Research Commons is the University of Waikato's open access research repository, housing research publications and theses produced by the University's staff and students.

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Importance of stream-wetland refuges for kōaro populations: Are wetlands overlooked climate refugia for kōaro (Galaxias brevipinnis) due to underestimation of their ecological flexibility?
(The University of Waikato, 2026) Kahotea, Josette; Burdon, Frank
Wetlands are widely valued in conservation and restoration, yet their ecological role when connected to lakes is often misunderstood in the management of freshwater fish. Rather than functioning simply as hydrological buffers for lake catchments, wetlands may serve as critical refugia for native fishes under increasing pressure from climatic variability and invasive predators. I investigated whether the spring-fed Millar Road Wetland (MRW), located on the margin of Lake Ōkāreka (Rotorua Te Arawa Lakes, Aotearoa), supports a persistent population of kōaro (Galaxias brevipinnis Günther, 1866). A key objective of my research was to examine the mechanisms underpinning the potential refuge function of the wetland. By integrating year-round population monitoring, mark–recapture analysis, environmental modelling, and stable isotope analysis, I assessed demographic stability, predator limitation, and trophic structure of kōaro in this habitat. The MRW supported a resident, multi-cohort kōaro population exhibiting seasonal recruitment, positive allometric growth, and stable body condition across years. Mark-recapture data indicated close site fidelity and continued individual growth, while interannual comparisons demonstrated stable adult size structure despite evidence for variable juvenile recruitment. Other notable members of the MRW community included common bullies (Gobiomorphus cotidianus McDowall, 1975) and kōura (Paranephrops planifrons White, 1842). Although juvenile rainbow trout (Oncorhynchus mykiss Walbaum, 1792) appear to enter the wetland periodically, their occurrence was spatially restricted to upstream areas and may be strongly mediated by hydrological connectivity. Episodic dissolved oxygen minima and shallow, structurally complex habitat likely constrain trout residency and growth, while kōaro were able to persist in the wetland across seasons. Stable isotope analysis revealed strong trophic differentiation: kōaro were supported predominantly by allochthonous carbon, largely via detritivorous aquatic insects, whereas common bullies relied on autochthonous benthic production. I hypothesised that this energy-channel partitioning of the food web reduces exploitative competition and helps explain the coexistence of these two native fish species at relatively high densities. Together, these findings suggest that the role of the MRW as a refuge emerges not from absolute predator exclusion, but from a locally-dependent balance between hydrological connectivity, environmental filtering, habitat structure, and trophic organisation. Connectivity in the wetland is both essential and risky: it sustains demographic exchange with the lake whilst periodically permitting an invasive, non-native predator access, yet environmental harshness limits sustained trout establishment, and asymmetric tolerances allow kōaro to persist. In a climate-sensitive species such as kōaro, the persistence of a robust wetland population highlights the potential importance of small, groundwater-fed systems as dynamic refugia within invaded landscapes. Protecting and restoring similar wetlands may therefore play a critical role in safeguarding native freshwater biodiversity under ongoing climatic and hydrological change in Aotearoa.
Structural origins of catastrophic forgetting in self-supervised continual learning: A directional and curvature-based analysis of the learning signal
(The University of Waikato, 2026) Huang, Rucheng; Pfahringer, Bernhard
Catastrophic forgetting remains a fundamental challenge in continual learning, where acquiring new knowledge systematically degrades previously learned representations. While existing approaches primarily mitigate this by imposing architectural constraints or using data replay strategies, they offer limited theoretical insight into why and how parameter updates interfere with consolidated knowledge structures. This thesis proposes a structured analytical lens to examine the collision between new and old knowledge at the level of parameter updates, feature representations, and low-dimensional learning signals. Rather than introducing a new method, we seek to characterize the geometric conditions under which gradient updates pose the greatest risk to previously learned structure. Specifically, we hypothesize that forgetting is governed by the degree to which parameter updates project onto high-curvature regions of the old task's loss landscape, namely those directions along which the old loss function is most sensitive to perturbation. We derive a theoretical bound that isolates this curvature-projection term as the dominant factor driving representational forgetting, and empirically verify both the structural conditions under which this bound holds and its statistical relationship with observed forgetting. To ground this analysis in a concrete and mechanistically interpretable setting, we adopt SwAV, a representative self-supervised contrastive learning framework, as our experimental substrate. We leverage SwAV's internal prototype assignment process as a low-dimensional learning signal that faithfully reflects the underlying representational dynamics, allowing the theoretical bound to be expressed and studied in a tractable, interpretable form. Building on this, we further consider whether the second-order sensitivity structure of old knowledge, when projected into a lower-dimensional subspace, retains meaningful geometric differentiation between sensitive and insensitive directions. Our experiments confirm that such a structure persists at low dimensionality and that SwAV's learning signal selectively engages it. We observe that interference with prior knowledge is measurably reduced when the energy of the new task's low-dimensional signal concentrates along axes that carry less of the old task's curvature structure, rather than along regions of high coupling.
Bridging the gap: An exploration into the experiences and challenges faced by new educators and their mentors in Aotearoa New Zealand
(The University of Waikato, 2026) Heng, Marnie; Peters, Sally; Carss, Wendy Diane
This research study provides an exploration into current beginning teacher mentoring relationships, with a focus on identifying the experiences and challenges faced by both beginning and mentor teachers. The purpose of this research was to identify key trends in data and possible implications to support the ongoing growth, consistency and quality of mentoring provided in primary schools in Aotearoa New Zealand. This inquiry not only focused on the beginning teachers' growth and successful transition into their new community of practice, but also on the support in place for mentor teachers to effectively meet the needs of their beginning teachers and provide quality mentoring. This study contributes to the field of mentoring research by providing a key focus on mentor experiences and perspectives in mentoring relationships that are limited in both domestic and international academic research. Situated in a constructivist paradigm driven by a ‘Communities of Practice’ (Lave & Wenger, 1991) theoretical approach, the design of the research was sectioned into two phases. Phase 1 consisted of a mixed method approach using a survey (N=24) as the data collection tool to analyse recent beginning and mentor teacher experiences. Phase 2 followed a qualitative case study approach allowing for in-depth investigation and analysis of the dyadic relationship between two pairs of current beginning and mentor teachers. Case study data were collected through semi-structured interviews and questionnaires. The findings from this data extend understanding of the inconsistencies in beginning teacher experiences by examining the policy frameworks and practical approaches mentor teachers draw upon. Key findings highlighted that even positive mentoring experiences were bound by the same challenges regarding a lack of support and structure surrounding the mentoring experience and dyadic relationship. Findings highlighted the lack of clarity in the current policy framework; minimal access and availability of professional development opportunities for both beginning and mentor teachers; and a lack of theoretical understanding of the principles underpinning the educative mentoring approach. These findings were grouped into positive impacts on mentoring experiences and challenges impacting the success of mentoring experiences, which were then discussed in relation to domestic and international research findings. The existing and proposed mentoring and induction programmes in Aotearoa New Zealand provide broad guidance, yet challenges remain interpreting policy into effective mentoring practices. This thesis argues that effective implementation of educative mentoring practices (Feiman-Nemser, 2001) necessitates a structured mentoring design. The implications of these additions would have significant benefits to the practical application of mentoring practices and procedures within the beginning and mentor teacher relationship. Further practical implications from my study including training and support, considered mentor selection, and stronger dialogue between universities and school communities of practice would contribute to higher consistency in the quality of mentoring provided nationally.
Trends in sediment geochemistry along the fluvial to marine transition of the Waihou River, Aotearoa New Zealand
(The University of Waikato, 2025) Greaves, Nicole; La Croix, Andrew D.
The nuances of the dynamic changes in the water chemistry and sediment deposition within the fluvial to marine transition zone (FMTZ) are difficult and time consuming to capture within water samples as due to the constantly changing nature. Marine water intrusion up rivers changes along short time scales of minutes, hours, and days to months and years. To be able to accurately capture the extent and changes that occur along the FMTZ would provide vital environmental and depositional information regarding river health, temporal variations and forming depositional environments. The use of geochemical sediment proxies as a measure of marine water intrusion upstream is an ongoing topic of research with many potential proxies investigated throughout literature. However, the identification of proxies that represent not only the general movement from fresh to brackish to marine conditions but can also be used to distinguish a gradient along river position as recording the finer changes in water chemistry have yet to be demonstrated within literature. This study aims to identify whether the dynamics of marine water intrusion are recorded through sediment geochemistry or physical properties along a gradient and to assess the uses for the proxies identified, creating an assemblage of proxies to be utilised within future study. Sediment proxies of grainsize, percentage mud (%mud), loss on ignition (LOI), strontium and barium ratios (Sr/Ba), carbon isotopes of delta thirteen carbon (δ13C) and carbon and nitrogen ratios (C/N), X-Ray diffraction (XRD) minerology, and X-ray fluorescence (XRF) elements, will be investigated as potential proxies for marine water intrusion up the FMTZ of the lower Waihou River, Aotearoa, New Zealand. This research finds that whilst varying levels of success were demonstrated within literature, many of the tested proxies fail to identify the fluvial to marine transition let alone distinguish a gradient of change through river position. Strontium/Barium ratios are the only proxy to identify a clear relationship with river distance, presenting with a weak to moderate relationship, finding a lack of small scale precision but the larger scale transition was observed. The carbon isotope results presented a negligible relationship but indicated it may have potential use as a proxy, which prompts the need for further study of the usage of this method as a proxy for marine water intrusion. Whilst this study does not claim to disregard the usefulness of these proxies nor their potential for identifying the hydrodynamics of the FMTZ within the sediment, it does stand that little evidence of it has been found within this research and prompts the thorough investigation of the potential held by these proxies both within the Waihou River and various other river systems of varying size and type where processes vary. Consideration to the type of river environments literature seems to focus on is also prompted as to whether these proxies may only be viable under certain conditions.
Leadership responses to giving effect to Te Tiriti o Waitangi for Māori learners: Learning from the stories of leadership navigating the policy to praxis divide to enact Ka Hikitia and realise Māori potential
(The University of Waikato, 2026) Mason, Ngaia; Berryman, Mere; Egan, Margaret
Despite research on educational leadership, a pressing question remains - to what extent does the interface between policy and praxis, impact the leadership of tumuaki (principal) and kaiako (teacher) Māori (indigenous New Zealander), to effectively create opportunities in education that see Māori advantaged and positioned to reach their potential? This research focuses on understanding how the interface between policy and praxis impacts the leadership of two tumuaki and three kaiako Māori. It seeks to determine how their leadership can effectively implement Ka Hikitia - Ka Hāpaitia, to advantage Māori in kura-auraki (mainstream schools) settings. This small-scale research, grounded in culturally responsive methodology, establishes reflexivity which promotes power sharing relationships to weave together both indigenous and western ways of thinking. By gathering the voices of non-Māori (Pākehā first settlers/and or tauiwi later immigrants) tumuaki, kaiako Māori, ākonga Māori (Māori students), and their whānau (family) in semi-structured interviews as individuals or focus groups, the complexities and intricacies at the interface between policy and praxis begin to be revealed. Their experiences reveal deliberate acts of leadership that encompass multiple leadership positions, differentiated by their varying commitment to mahi tahi (work together through relationships of shared endeavour) and cultural recognition of spaces where mana-motuhake (self-determination) can be enacted. The need for ākonga Māori success to be at the forefront of intention, action and policy in Aotearoa (New Zealand) underscores these findings - particularly if we are to see change that respects innate capabilities, cultural potential and mutually beneficial relationships that allow spaces for mana-motuhake. This research aims to influence educational leaders with better understandings of how to sustain and embed the values of Ka Hikitia - Ka Hāpaitia into their kura so that Māori potential is realised. With these understandings, leaders can re-position themselves to more effectively influence and shape the interface between policy, practice and leadership whether they lead in kura-auraki or not.