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Item Benthic nutrient release from Auckland dune lakes(Report, Environmental Research Institute, The University of Waikato, 2025)New Zealand’s freshwater lakes are under pressure from land use intensification, discharge of nutrient contaminants and over-allocation of groundwater resources. Dune lakes are comparatively rare ecosystems formed by wind-blown sand which creates depressions or water impoundments. Often isolated and diversity depauperate, their geomorphological features can make them particularly vulnerable to anthropogenic eutrophication. Ecological models provide a tool for assessing potential strategies for remediation of lake eutrophication. However, they require an understanding of the drivers of water quality decline, including external and internal nutrient loading. The University of Waikato was contracted by Auckland Council to assess lake littoral groundwater infiltration rates and sediment nutrient release rates in seven dune lakes to support the development of ecological models for the lakes. Littoral groundwater infiltration was measured using custom moulded clear acrylic domes fitted with valves which allowed water passage into an attached collection bag. The chambers were deployed in the winter and of late spring of 2023. Depending on lake size and site suitability, between one and four chambers were deployed in the littoral zone (generally ~0.5m depth) of each lake and left in place for 24 hours. Net groundwater efflux was not detected by any of the chambers, while groundwater infiltration rates ranged from 1.0–7.4 L m-2 day-1. Assessment of groundwater nutrient concentrations was not feasible due to the volume of the chamber (16 L) and the deployment period required to determine infiltration rates. Littoral groundwater infiltration likely constitutes a significant proportion of the inflow to these lakes, and rates appear to be volumetrically proportional to the linear distance to the catchment boundary from the point of sampling, and to variance in catchment rainfall. Littoral infiltration rates responded quickly (<24 hours) to total precipitation preceding sampling; however, this may be partially due to the higher-than-average rainfall and soil saturation during the 2023 survey period. Sediment nutrient release rates were determined using benthic incubation chambers deployed at or near the deepest point of each lake during the spring of 2023. Four dark chambers were deployed in each lake for between 32–68 hours, water samples were pumped from each chamber and analysed for dissolved nutrients. Lakes Kawaupaku, Ōkaihau, Te Kanae and Whatihua were strongly stratified with anoxic bottom waters and sediment nutrient release rates could not be determined. Bottom water samples taken at the time of chamber deployment in these lakes found ammonium and nitrate concentrations were high (>0.2 mg N L-1) but dissolved reactive phosphorus (DRP) concentrations were near or below detection limits (<0.004 mg P L-1); indicating that internal lake phosphorus loading was likely limited in comparison to nitrogen loading. The shallow, polymictic nature of the Tomarata, Spectacle and Slipper lakes provided more suitable conditions for determination of in situ sediment nutrient fluxes, although a second deployment in Lake Tomarata was conducted in August 2024. The measured nutrient flux rates, maximum nutrient flux rates and half saturation constants for ammonium and dissolved reactive phosphorus are presented in the table below. The low phosphorus release rates may be due to low external phosphorus loading, associated with episodic sediment loading from the mostly ephemeral surface inflows to the lakes. These findings align with previous work carried out in Lake Tomarata demonstrating the sedimental total phosphorus (TP) pool to have a low redox sensitive phosphorus fraction despite sediment iron content being reasonably high (Waters, 2022). Prolonged stratification of lakes Kawaupaku, Ōkaihau, Te Kanae and Whatihua provided limited opportunity to directly assess internal nutrient loading. However, external phosphorus loading to these lakes is likely to be constrained as they are primarily groundwater fed with small, ephemeral surface inflows. In addition, hypolimnetic DRP concentrations and sediment phosphorus release rates determined for lakes Tomarata, Slipper and Spectacle indicate that internal phosphorus loading is low compared to other New Zealand lakes. External nitrogen loading is likely to be more substantial than phosphorus loading, but internal loading also appears to be lower than average. These findings underscore the distinct processes driving nitrogen and phosphorus loading, and consequently nutrient concentrations in the lakes studied. They also provide data critical for the parameterisation of subsequent water quality models, which might be used to inform land use practices through comprehensive scenario testing of various management options.Publication The role of Chaetopterus sp. in reshaping sediment characteristics and benthic communities in Queen Charlotte Sound(Thesis, The University of Waikato, 2025)Soft-sediment habitats are critical to marine ecosystems, supporting diverse benthic communities and key processes such as nutrient cycling, sediment stabilisation, and energy transfer. Among these habitats, tube-building polychaetes like Chaetopterus act as ecosystem engineers, modifying sediment properties and influencing community structure and functioning. This study investigated the ecological impacts of Chaetopterus in East Bay, Queen Charlotte Sound, focusing on its role in sediment modification, macrofaunal biodiversity, and functional group composition. Field surveys were conducted across ten paired Chaetopterus and control sites, selected to capture a gradient in tube mat density and depth. At each site, five sediment and macrofaunal samples were collected using coring techniques, enabling a robust comparison of Chaetopterus-modified and unmodified habitats. Results showed significantly higher organic content (3.1% ± 0.2 vs. 2.0% ± 0.1) and mud content (19.8% ± 2.0 vs. 7.7% ± 0.5) in Chaetopterus habitats, highlighting its role in sediment enrichment and stabilisation. Macrofaunal communities exhibited significantly greater species richness (20.0 ± 0.8 vs. 14.5 ± 0.7 species per core) and diversity (Shannon diversity: 2.48 ± 0.05 vs. 2.16 ± 0.06), driven by increased structural complexity and organic matter retention. Functional group analysis revealed a shift towards surface-oriented taxa in Chaetopterus habitats, including increased surface-feeding deposit feeders (e.g., amphipods) and scavengers (e.g., Halicarcinus cookii), alongside a relative reduction in deeper-burrowing taxa such as bioturbating polychaetes (Prionospio multicristata) and burrowing bivalves (Tawera spissa). This suggests that Chaetopterus tube mats promote surface-associated processes like organic matter turnover and detritus retention, while potentially suppressing sediment-mixing and oxygenation functions. Chaetopterus habitats exhibited significantly lower dispersion (PERMDISP), indicating more functionally homogeneous assemblages compared to control sites, where greater within-group variability reflected a broader range of functional traits, including suspension feeders and opportunistic burrowers (e.g., Phoxocephalidae amphipods). Chaetopterus density was significantly correlated with macrofaunal community composition, reinforcing the role of tube mats as a key driver of functional trait distributions. However, the extent of these effects varied across sites, suggesting that local environmental factors, particularly sediment properties (mud content, organic matter) and Chaetopterus density, mediate its influence on benthic communities. These findings advance understanding of habitat-modifying polychaetes by demonstrating that Chaetopterus effects are highly context-dependent, shaped by habitat × site interactions and environmental conditions. While previous studies have identified Chaetopterus as a biodiversity enhancer, this study highlights its dual role as both a facilitator of surfacedominated processes and a potential suppressor of deeper sediment functions. These findings provide critical insights into its ecological role within New Zealand's coastal ecosystems and underscore the need for site-specific management strategies that balance local biodiversity benefits with broader ecosystem functions.Publication Food from the sea: Contesting the blue economy through indigenous stories, livelihoods, and kinship in Lembata Island, East Nusa Tenggara, Indonesia(Thesis, The University of Waikato, 2024)Food from the Sea: Contesting the Blue Economy through Indigenous Stories, Livelihoods and Kinship in Lembata critically examines the intersections between Indonesia’s Blue Economy programme and Indigenous marine governance, focusing on the Lamaholot communities in Lembata, East Nusa Tenggara, Indonesia. Drawing on qualitative research inspired by ethnographic methodologies (participant observation, semi-structured interviews, and focus group discussion), the study explores how traditional ecological knowledge, cultural practices and livelihoods are maintained or disrupted by top-down marine policies. This research shows a disjuncture between the Blue Economy agenda and Indigenous practices rooted in communal stewardship and spiritual ties to land and sea. While Blue Economy initiatives promote sustainability and economic growth, the implementation often marginalises Indigenous and small-scale fishers, threatening food sovereignty and traditional governance. By investigating local responses, including resistance and negotiation, this thesis highlights the concept of blue justice and advocates for inclusive, community-led marine governance. The findings challenge dominant development narratives and contribute to debates on environmental justice, resource access, and Indigenous rights in the context of marine conservation and economic policy.Publication An exploration of different outlooks on science: towards an understanding of the under-representation of girls, and of Maori and Pacific Island students, in science(Thesis, The University of Waikato, 1984)The research reported here was undertaken as a supplementary study to the Learning in Science Project conducted at Waikato University (1979-1981) and sought to understand why girls, Maori and Pacific Island students, are under-represented in the sciences. Two distinctive, but complementary, perspectives were developed; one qualitative, the other quantitative, to provide data from which an understanding of the problem was sought. The qualitative perspective was provided by using a Kelly Repertory Grid methodology and intensive individual interviews with 26 students (and many of their parents) carefully chosen to provide a reasonably heterogeneous sample of students from a variety of different schools, of both sexes, of the three major ethnic groups (European, Maori, and Pacific Island), and from each of the four middle-school form levels (Fl to F4, inclusively). The quantitative perspective was provided by a series of empirical measures chosen, not only to identify the students for the qualitative sample but also, to investigate particular variables suggested by the literature search to have possible implications for the teaching and learning of science. The resultant analyses suggested the sex differences in the students’ outlooks on science could be accounted for by the existence of a broad based ‘gender-related inequality’ in the way science is presented to them by the communication media, home, and school. Similarly, the ethnic differences in students’ outlooks on science could be accounted for by the ‘cultural inequality’ present in New Zealand society which was identified in the way many of the Polynesian students and their parents, perceived the products, processes, and practitioners of science. The simplification presented here masks the complexity of the issues involved but, series of educational within these two broad postulates, a series of educational recommendations was suggested for affecting current educational practices identified as maintaining (or even creating) the existing under-representation of girls, Maori and Pacific Island students in the sciences. These included: (i) Student beliefs about science need to be explored, challenged, modified, and/or extended (ii) Students’ perceptions of other people’s views need to be identified, explored, challenged and/or extended (iii) Teachers’ styles of teaching science need to be examined (iv) Parents’ own outlooks on science need to be developed. This research has emphasised the need to have all students, but particularly girls, Maori, and Pacific Island students, develop positive outlooks on science in order that the current imbalance of girls and Polynesians in the sciences be redressed.Publication Kinetic studies of cyclisations of 2'-hydroxychalcones and derivatives(Thesis, The University of Waikato, 1980)The rates of cyclisation of various 2'-hydroxychalcones to the equilibrium mixture of chalcone and flavanone have been determined over the pH range in which the chalcones undergo ionisation. The compounds studied were 2'-hydroxy-, 2'-hydroxy-5', 6'-benzo-, 2',4'-dihydroxy-, 2'-hydroxy-4'-methoxy-, 2'-hydroxy-6'-methoxy-, and 2'-hydroxy-4', 6'-dimethylchalcone. In each case the observed first order rate constant has been fitted to a theoretical pH-rate profile based on the equation kₒbₛ = kfCH + k’fC⁻ + k’’ {OH⁻} where k is the rate constant for the cyclisation of neutral chalcone (fCH is the fraction of neutral chalcone), k' is the rate constant for the cyclisation of the ionised chalcone (fC⁻ is the fraction of ionised chalcone), and k" is a measure of the rate in the reverse reaction. The expression implies that the reaction in the forward direction can proceed from neutral or ionised chalcone, and in the reverse direction through the reaction of flavanone with hydroxide ion. In all cases the forward reaction of the ionised chalcone (k') is very much faster than that of the neutral species (k). Weak catalysis by some buffer species has been detected but the origin of this catalysis has not been pursued in detail. Comparisons are made between the forward and reverse rate constants for the different chalcones in order to see how they are affected by different A-ring substituents. It is observed that electron releasing groups at the 4'- or 6'- positions decrease the rate. This diminution in the observed rate is particularly pronounced with 6'-substituents, and is considered as possibly due to the steric and/or electrostatic interaction of this substituent with the carbonyl group an interaction that could force the carbonyl group to lie out of the plane of the A-ring thereby changing rates of reactions by electronic or steric effects. The first kinetic study of the reactivity of a 2'-hydroxychalcone epoxide is reported. The variation of the rate of cyclisation of the parent epoxide, 2'-hydroxychalcone epoxide, to 3-hydroxyflavanone in water, over the range pH 1 - 6.5, is shown to be consistent with the rate equation. Rate = 0.235 [Epoxide]{H⁺} + 1.85 x 10⁶ [Expoxide] {OH⁻} mol 1⁻¹s⁻¹ This shows the epoxide to be very unstable at or above neutral pH, and suggests that such compounds, if they do occur, as has often been suggested, as intermediates in flavanoid biosynthesis would probably be very difficult to isolate. Their detection under the basic conditions of either the Algar-Flynn-Oyamada oxidation of 2'-hydroxychalcones, or the formation of aurones from certain 2'-hydroxychalcone dibromides, both reactions in which they have been suggested as intermediates, would be equally unlikely : based on a suggested mechanism, the parent epoxide of this study can be predicted to have a half-life at pH 10 of the order of a few milliseconds. The first determination of the ratio of E- and Z-2'-hydroxy-α-bromochalcones formed directly from a 2'-hydroxychalcone dibromide is described. Combined kinetic and spectrophotometric measurements give the yield (%) of E- and Z-2'-hydroxy-α-bromochalcone as 35 ± 2 and 63 ± 8 respectively for the reaction of erythro-2'-hydroxychalcone dibromide in 4:1 ethanol-water buffered at pH 7.88 with N-ethylmorpholine. Direct cyclisation of the dibromo compound, if it occurs at all, is only a very minor route to 3-bromoflavanone. The lack of any detected dependence buffer concentrations of the rate constants or of the proportions of the E- and Z-isomers formed suggest, an E1cв mechanism rather than an E2. However, with the particular elimination involved (i.e. a double bond being formed α, β to a carbonyl group) there is precedence for small catalysis by N-alkylmorpholines and therefore, it is not certain that the lack of measurable buffer catalysis does in fact mean a total lack of catalysis. Further, if the elimination is in fact by an E1cв type mechanism, a carbanion is not necessarily involved, as the elimination could proceed from the phenolate ion as conjugate base, the phenoxide group acting in place of an external base. An El mechanism is excluded on kinetic grounds.
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