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Featured Application: Preliminary testing and educational purposes. In earthquake geotechnical engineering, physical model experiments have proven to be significant and valuable in understanding the complex physics and engineering behaviors of prototype undrained soils in fields. An executed literature review indicated that large-scale physical model testing, such as shaking table (ST) and centrifuge devices, have associated advantages and limitations. The current paper presents the design, fabrication, and calibration of a 600N-capacity, small-scale, one-directional (1-D) laboratory ST device that enables quick and valuable assessment of soil liquefaction mechanisms. The dynamically induced porewater pressure (PWP) generation characteristics of sand soil mixed with different percentage weights of clay were evaluated and illustrated as a case study for testing the ST device's performance. The east coast sand (ECS) of New Zealand's North Island was mixed with different percentages of kaolinite clay to produce five variants of ECS (00, 05, 10, 20, 25, and 30). Three input sine wave ground motions of a constant frequency of 10 Hz and amplitudes of 2, 3, and 4 were applied and classified in the current study as low, intermediate, and moderate ground motions, respectively, to evaluate the evolution of the dynamic excess pore pressures in the soil samples. The results indicated that the clean ECS and mixed samples with lower clay content (ECS00, ECS05, ECS10, and ECS15) produced the highest excess PWP throughout the three shaking cycles, with higher tendencies of contraction and liquefaction properties. On the other hand, soil samples with a higher percentage of clay (ECS20 and ECS20) yielded the lowest PWP, with softening and dilative properties. [ABSTRACT FROM AUTHOR]

The northern Hikurangi subduction margin hosts slow slip events (SSEs), which are exceptionally shallow (<15 km). The sedimentary sequence on the incoming plate is therefore representative of the shallow fault material where the SSEs will take place once they enter the subduction zone. Knowledge about the frictional behavior of these sediments is required to know which lithologies are capable of hosting SSEs, and what mechanisms are causing them. Frictional behavior is material specific and depends on sliding velocity, but it is unknown how these natural sediments behave at plate‐rate velocities. We performed laboratory shearing experiments testing the major lithologies sampled during International Ocean Discovery Program (IODP) Expedition 375, at velocities ranging from the plate convergence rate at the Hikurangi margin (5 cm/year), up to those characteristics of the shallow SSEs (160 and 530 cm/year), under simulated in‐situ as well as standardized conditions. We find that the calcite‐rich pelagic sediments are relatively strong and display the velocity‐weakening frictional behavior required for slip events, whereas other lithologies are weaker and show velocity‐neutral to velocity‐strengthening friction. We observe spontaneous laboratory SSEs in the calcareous pelagic sediments, which show partial locking in between sliding events, consistent with the interpretation of SSEs within the spectrum of slow to fast earthquakes. For the Hikurangi margin, our results suggest that SSE occurrence requires the stronger carbonate‐rich unit to be incorporated into the plate‐boundary fault zone, which we suggest occurs because the rough incoming plate introduces geometrical complexity into the fault zone. Plain Language Summary: In the Hikurangi subduction zone, located offshore the east coast of the North Island of New Zealand, the movement between the downgoing and overriding tectonic plates can occur as slow slip events (SSEs). During SSEs the two plates move relative to each other, a process in many aspects similar to ordinary earthquakes, except SSEs take weeks instead of seconds and no ground‐shaking can be felt on the surface. SSEs occur in many subduction zones worldwide, but at the Hikurangi margin they occur shallow, relatively often and close to many mostly land‐based GPS stations that track the movement of the two plates, which makes them ideal to study. A recent research expedition (IODP Expedition 375) drilled the stack of sediments going into the subduction zone to learn more about the circumstances that control where and when SSEs occur. In this paper, we test all the major different sediment types going into the subduction fault zone to find out which one of them is responsible for the SSEs. Using a laboratory device that mimics the subduction zone, we find that sediments containing the mineral calcite cause slip events that are similar to the SSEs observed in the Hikurangi margin. Key Points: Spontaneous laboratory slow slip events (SSEs) suggest the shallow Hikurangi SSEs are favored in carbonate‐rich sedimentsRate‐and‐state friction and critical stiffness theory can partly explain SSEs, but they can occur under velocity‐strengthening conditionsSSE generation in Hikurangi is probably related to heterogeneity in the plate‐boundary fault zone [ABSTRACT FROM AUTHOR]

In the Māori world, people move backwards into the future. The past is on the horizon, we can see it, we know it. The future remains uncertain, we must sharpen our senses and proceed with caution. This article contends that a change of perspective is the most powerful tool to identify multiple ethical implications when conducting research in settings characterized by unfolding processes that weave together human interventions and non-human agency. Walking backwards and based on ethnographic fieldwork in Māori lands, scientific laboratories, research nurseries, and healthy and declining forest in the upper North Island of New Zealand, this paper reflects on the ethical issues that arise from meeting in the field with scientists, Indigenous experts, lethal microorganisms, and giant ancient trees, while also considering the evidence of past multispecies encounters and the uncertainty of future ones. Aware that most of the terrestrial biomass remains outside the field of vision of institutional review boards, this article argues for the adoption of a broader conception of ethics, not as a human construct associated with the production of knowledge, but rather as an essential component of all interdependencies that make life possible on Earth. [ABSTRACT FROM AUTHOR]

This paper presents the current state of knowledge of the Aotearoa New Zealand last interglacial (marine isotope stage 5, MIS 5, sensu lato) sea-level record compiled within the framework of the World Atlas of Last Interglacial Shorelines (WALIS) database. A total of 77 relative sea-level (RSL) indicators (direct, marine-limiting, and terrestrial-limiting points), commonly in association with marine terraces, were identified from over 120 studies reviewed. Extensive coastal deformation around New Zealand has prompted research focused on active tectonics, the scale of which overprints the sea-level record in most regions. The ranges of last interglacial palaeo-shoreline elevations are significant on both the North Island (276.8 ± 10.0 to - 94.2 ± 10.6 ma.m.s.l. , above mean sea level) and South Island (165.8 ± 2.0 to - 70.0 ± 10.3 ma.m.s.l.) and have been used to estimate rates of vertical land movement; however, in many instances there is a lack of adequate description and age constraint for high-quality RSL indicators. Identified RSL indicators are correlated with MIS 5, MIS 5e, MIS 5c, and MIS 5a and indicate the potential for the New Zealand sea-level record to inform sea-level fluctuation and climatic change within MIS 5. The Northland Region of the North Island and southeastern South Island, historically considered stable, have the potential to provide a regional sea-level curve, minimally impacted by glacio- and hydro-isostatic adjustment (GIA) and reflecting near-eustatic fluctuations in a remote location of the South Pacific, across broad degrees of latitude; however, additional records from these regions are needed. Future work requires modern analogue information, heights above a defined sea-level datum, better stratigraphic descriptions, and use of improved geochronological methods. The database presented in this study is available open access at this link: https://doi.org/10.5281/zenodo.4590188 (Ryan et al., 2020a). [ABSTRACT FROM AUTHOR]

This paper focuses on the small-strain shear modulus (Gmax) of natural pumiceous (NP) sands, a type of crushable volcanic soil commonly found in the North Island of New Zealand. These sands are also compressible and lightweight, resulting in difficulty to accurately evaluate their geotechnical properties. To better understand the Gmax dependency of these NP sands on effective confining pressure (σc′) and void ratio (e), bender element tests are performed on three types of locally sourced NP sands and, for comparison purposes, similar tests are conducted on hard-grained Toyoura sand. The results illustrate that the Gmax of NP sands are considerably lower than that of Toyoura sand over a wide range of e and σc′. Furthermore, materials with higher pumice content show higher dependency on σc′ and lower dependency on e compared with those with lower pumice content as well as Toyoura sand. Particle characteristics (e.g., particle shape, particle-size distribution, particle crushing, pumice content, compressibility, and fines content) are taken into consideration to explain the different response of the tested materials. [ABSTRACT FROM AUTHOR]

Western Pacific leatherback sea turtles (Dermochelys coriacea) are a priority bycatch mitigation concern due to the projected extinction of the population before the end of the 21st century. The species regularly occurs as bycatch in gillnet and surface longline fisheries. Here, we explore the potential for dynamic ocean management in an emerging hotspot of leatherback sea turtle bycatch in the New Zealand pelagic longline fishery. We compared spatial areas of different sizes built from single oceanographic covariates as well as built from a composite risk surface developed through ensemble random forests. We found that, individually, the Okubo-Weiss parameter, sea surface temperature (SST) anomaly, SST, moon phase, and distance to the SST front were important oceanographic covariates for leatherback sea turtle bycatch. However, the spatial areas built from the composite risk surface were the most effective at discriminating sets with and without bycatch across a range of risk cutoffs. When we also considered implementation metrics of spatial area and coherence as part of performance, the area derived from the composite risk surface with a risk of interaction per set greater than 52% performed best. This spatial area was ephemeral, occurring 1 or 2 weeks each year, and localized, occurring along the north coast of East Cape in the North Island of New Zealand. The apparent presence of discrete spatial areas with elevated risk may be useful to inform future management in the area. Considering implementation metrics in defining utility was useful for identifying tradeoffs between the total size and the underlying covariates delineating a spatial area. As such, we recommend these types of metrics to be included when designing spatial bycatch mitigation strategies elsewhere. [ABSTRACT FROM AUTHOR]

The Hikurangi Margin east of New Zealand's North Island hosts an extensive gas hydrate province with numerous gas hydrate accumulations related to the faulted structure of the accretionary wedge. One such hydrate feature occurs in a small perched upper‐slope basin known as Urutī Basin. We investigated this hydrate accumulation by combining a long‐offset seismic line (10‐km‐long receiver array) with a grid of high‐resolution seismic lines acquired with a 600‐m‐long hydrophone streamer. The long‐offset data enable quantitative velocity analysis, while the high‐resolution data constrain the three‐dimensional geometry of the hydrate accumulation. The sediments in Urutī Basin dip landward due to ongoing deformation of the accretionary wedge. These strata are clearly imaged in seismic data where they cross a distinct bottom simulating reflection (BSR) that dips counterintuitively in the opposite direction to the regional dip of the seafloor. BSR‐derived heat flow estimates reveal a distinct heat flow anomaly that coincides spatially with the upper extent of a landward‐verging thrust fault. We present a conceptual model of this gas hydrate system that highlights the roles of fault‐controlled fluid flow at depth merging into strata‐controlled fluid flow into the hydrate stability zone. The result is a layer‐constrained accumulation of concentrated gas hydrate in the dipping strata. Our study provides new insight into the interplay between deep faulting, fluid flow and gas hydrate formation within an active accretionary margin. Plain Language Summary: Gas hydrates are ice‐like substances in which natural gas molecules are trapped in a cage of water molecules. They exist where the pressure is high, temperature is cold, and enough methane is present. These conditions exist in the marine environment at water depths greater than 300–500 m near sediment‐rich continental margins and in polar regions. It is important to study gas hydrates because they represent a significant part of the Earth's carbon budget and influence the flow of methane into the oceans and atmosphere. In this study, we use the seismic reflection method to generate images of gas‐hydrate‐bearing marine sediments east of New Zealand. Our data reveal an intriguing relationship between deep‐sourced fluid flow upward along a tectonic fault, and shallower flow through dipping sediments. This complex fluid flow pattern has led to disruption of the gas hydrate system and the formation of concentrated gas hydrate deposits within the dipping sediments. Our study highlights the relationships between relatively deep tectonic processes (faulting and fluid flow) and the shallow process of gas hydrate formation in an active subduction zone. Key Points: A distinct gas‐hydrate to free‐gas transition is mapped using high‐ and low‐frequency seismic dataGas and hydrate accumulations in the Urutī Basin are controlled by the structural setting, ongoing deep‐sourced fluid flow, and near surface stratigraphyRegions of high modeled heat flow can be directly related to accumulations of gas and gas hydrates [ABSTRACT FROM AUTHOR]

Continuous-cover forestry (CCF), which maintains a relatively intact forest cover through selective harvesting, has emerged over the last few decades as a popular alternative to rotational forest management (RFM). Coast redwood, which is native to the western United States, grows rapidly in New Zealand and is well suited to CCF as it has high shade tolerance, an ability to coppice from the cut stem, and resistance to pests, diseases, wind and fire. A forest estate model was used to compare the carbon sequestration, timber production and profitability of redwood CCF, RFM and permanent carbon forestry (PCF) regimes at a regional level within New Zealand. Through linear programming, this model optimised carbon accumulation and harvesting decisions across a large forest to meet a series of constraints associated with each regime. All three regimes represented good investment decisions, but CCF had the highest soil expectation value (SEV) within most North Island regions while PCF had a slightly higher SEV within the South Island regions. Under the transitional CCF (CCFt), revenue from carbon initially increased before levelling out at 40 years, after which time a sustainable harvest of high-value timber commenced in perpetuity without additional revenue from carbon. The CCFt regime transitioned to a steady-state condition, with a uniform age class distribution from year 150 onwards (CCFs), after which time a very high SEV was attained that exceeded that of CCFt by four-fold in the North Island (NZD 136,126/ha vs. NZD 34,430/ha) and seven-fold (NZD 44,714 vs. NZD 6267/ha) in the South Island. This study highlights the profitability of managing redwood under CCF and how initial carbon revenue can be used to finance the transition of the forest to a steady-state condition that produces a stream of valuable timber with a very high rate of return. [ABSTRACT FROM AUTHOR]

Popularity of one-way car rentals poses a challenge to rental car fleet management and brings to focus the importance of a strategic decision for rental car operators: whether to implement a single-fleet or a multifleet model. The single-fleet model allows movement of vehicles between regions, whereas the multifleet model does not. It is not obvious whether a single-fleet model is optimal due to its pooling effect, or a multifleet model due to shorter car relocation times. In practice, different rental car operators use different models. To answer this conundrum, we develop two simulation models and compare them in terms of fleet utilisation, branch service level, relocations, and operating profit. We have taken the New Zealand rental car industry as an example as the country consists of two well-defined regions: the North Island and the South Island. The results indicate that a multifleet model has a higher service level at key centres and higher utilisation. At the same time, the single-fleet model is relatively more profitable at the expense of a lower service level in key centres due to vehicles accumulating in the South Island due to a significant volume of one-way southbound travel. Overall, the implementation of either model should depend on the strategic goals of the rental car operator. Our work will be useful for practitioners considering whether or not to pool their fleet when allowing for one-way rentals with subsequent relocation. [ABSTRACT FROM AUTHOR]

This study demonstrates a framework for using high-resolution satellite imagery to automatically map and monitor outbreaks of red needle cast (Phytophthora pluvialis) in planted pine forests. This methodology was tested on five WorldView satellite scenes collected over two sites in the Gisborne Region of New Zealand's North Island. All scenes were acquired in September: four scenes were acquired yearly (2018–2020 and 2022) for Wharerata, while one more was obtained in 2019 for Tauwhareparae. Training areas were selected for each scene using manual delineation combined with pixel-level thresholding rules based on band reflectance values and vegetation indices (selected empirically) to produce 'pure' training pixels for the different classes. A leave-one-scene-out, pixel-based random forest classification approach was then used to classify all images into (i) healthy pine forest, (ii) unhealthy pine forest or (iii) background. The overall accuracy of the models on the internal validation dataset ranged between 92.1% and 93.6%. Overall accuracies calculated for the left-out scenes ranged between 76.3% and 91.1% (mean overall accuracy of 83.8%), while user's and producer's accuracies across the three classes were 60.2–99.0% (71.4–91.8% for unhealthy pine forest) and 54.4–100% (71.9–97.2% for unhealthy pine forest), respectively. This work demonstrates the possibility of using a random forest classifier trained on a set of satellite scenes for the classification of healthy and unhealthy pine forest in new and completely independent scenes. This paves the way for a scalable and largely autonomous forest health monitoring system based on annual acquisitions of high-resolution satellite imagery at the time of peak disease expression, while greatly reducing the need for manual interpretation and delineation. [ABSTRACT FROM AUTHOR]

Contamination of milk and dairy products with pathogenic and spoilage bacteria may result in huge economic loss due to recalls of products. This study aimed to identify spore-forming bacteria from raw milk and characterise those for toxin production and their spoilage ability. Bovine raw milk collected from dairy farms in the Manawatu region of the North Island of New Zealand was tested for the presence of both aerobic and anaerobic spore-forming bacteria using standard culture-based techniques, as well as genomic analysis. The spore-forming bacteria were investigated for the presence of toxin genes and their spoilage potential. A low number of aerobic spore-forming bacteria were detected in raw-milk samples collected from the four farms in summer and winter. The 16S rRNA sequence types similar to important food spoilage bacteria like C. beijerinckii, C. sporogenes, B. licheniformis and members of the Paenibacillus genus, as well as potentially toxigenic bacteria such as B. cereus and C. perfringens were isolated. Genes responsible for important toxin production were present in some of the tested spore-forming bacteria. This pilot study highlights the presence of various spoilage and pathogenic spore-forming bacteria in raw milk from these farms. A low number of spore-forming bacteria indicates the implementation of good hygienic farm practices and management to reduce the contamination of raw milk with spore-forming bacteria. [ABSTRACT FROM AUTHOR]

Marine multichannel and wide‐angle seismic data constrain the distribution of seamounts, sediment cover sequence and crustal structure along a 460 km margin‐parallel transect of the Hikurangi Plateau. Seismic reflection data reveals five seamount up‐to 4.5 km high and 35–75 km wide, with heterogeneous internal velocity structure. Sediment cover decreases south‐to‐north from ∼4.5 km to ∼1–2 km. The Hikurangi Plateau crust (VP 5.5–7.5 km/s) is 11 ± 1 km thick in the south, but thins by 3–4 km further north (∼7–8 km). Gravity models constructed along two seismic lines show the reduction in crustal thickness persists further east, coinciding with a bathymetric scarp. Gravity data suggest the transition in crustal thickness may reflect spatial variability in deformation and lithospheric extension associated with plateau breakup. Variability in the thickness of subducting crust may contribute to differences in megathrust geometry, upper‐plate stress state and high‐rates of contraction and uplift along the southern Hikurangi margin. Plain Language Summary: The thickness of crust arriving at subduction zones exerts a major influence on the configuration, structure, and distribution of stresses at plate boundaries. A region of thickened oceanic crust, the Hikurangi Plateau, is subducting beneath the North Island of New Zealand. To understand the structure of this Plateau, we analyze seismic data along a 460 km long transect, which reveals five large seamounts, and a 3–4 km reduction crustal thickness between the southern and northern areas of the Plateau. Gravity data show this difference is persistent across the plateau and reveal structures suggesting the crust may have thinned when the Hikurangi plateau separated from a second plateau (Manihiki), which is thought to have formed at the same time. We propose that the subduction of thicker crustal along the southern Hikurangi margin may contribute to the shallow angle of the subducting plate, and high rates of uplift and deformation in the overthrusting plate. Key Points: Crustal thickness of the Hikurangi Plateau reduces by ∼30% between the southern (10–11 km) and northern (7–8 km) PlateauCoincident contrasts in plateau fabric may attribute the thickness contrast to rifting from the Manihiki PlateauThickness contrasts may impact the geometry of the subducting plate and rates of upper‐plate compression and uplift along the Hikurangi margin [ABSTRACT FROM AUTHOR]

Slow slip events (SSEs) are geophysical phenomena primarily occurring in subduction zones. These events are often associated with seismic activity and can be detected by Global Positioning System (GPS). However, the relationship between SSEs and seismic activity remains unclear. To further investigate SSEs associated with seismic activity, we conducted SSE detection and inversion for the period from 2019 to 2022 on New Zealand's North Island, where both SSEs and seismic activity frequently occur. By modeling daily GPS coordinate time series from 40 GPS stations and applying the Network Inversion Filter (NIF) method, we obtain surface displacements, cumulative slips, and slip rates for eight shallow SSEs. Subsequently, we conduct a statistical analysis of seismic activity concerning its spatial distribution and frequency before, during, and after SSE occurrences. The results indicate that SSE1 and SSE7 exhibited larger cumulative slips, at 14.35 and 7.20 cm, and surface displacements, at 4.97 and 2.53 cm, respectively. During their occurrences, the seismic frequency noticeably increased to 6.5 and 5.6 events per day in the Eastern Coastal Region (ECR) of New Zealand's North Island. However, the other six SSEs, characterized by cumulative slips of less than 6 cm and maximum surface displacements of less than 2 cm, did not lead to a noticeable increase in seismic frequency during their occurrences in the ECR. In the Main Slip Regions (MSR) of these eight SSEs, a significant upward trend in seismic frequency was observed during their occurrences. Therefore, it can be inferred that in the ECR of New Zealand's North Island, all SSEs result in an increased seismic frequency within their respective MSRs, but only significant SSEs impact the seismic frequency of the ECR. Monitoring shallow SSEs may contribute to the identification and recording of seismic activity. [ABSTRACT FROM AUTHOR]

The dynamics of accretionary prisms and the processes that take place along subduction interfaces are controlled, in part, by the porosity and fluid overpressure of both the forearc wedge and the sediments transported to the system by the subducting plate. The Hikurangi Margin, located offshore the North Island of New Zealand, is a particularly relevant area to investigate the interplay between the consolidation state of incoming plate sediments, dewatering and fluid flow in the accretionary wedge and observed geodetic coupling and megathrust slip behaviour along the plate interface. In its short geographic extent, the margin hosts a diversity of properties that impact subduction processes and that transition from north to south. Its southernmost limit is characterized by frontal accretion, thick sediment subduction, the absence of seafloor roughness, strong interseismic coupling and deep slow slip events. Here we use seafloor magnetotelluric (MT) and controlled-source electromagnetic (CSEM) data collected along a profile through the southern Hikurangi Margin to image the electrical resistivity of the forearc and incoming plate. Resistive anomalies in the shallow forearc likely indicate the presence of gas hydrates, and we relate deeper forerarc resistors to thrust faulting imaged in colocated seismic reflection data. Because MT and CSEM data are highly sensitive to fluid phases in the pore spaces of seafloor sediments and oceanic crust, we convert resistivity to porosity to obtain a representation of fluid distribution along the profile. We show that porosity predicted by the resistivity data can be well fit by an exponential sediment compaction model. By removing this compaction trend from the porosity model, we are able to evaluate the second-order, lateral changes in porosity, an approach that can be applied to EM data sets from other sedimentary basins. Using this porosity anomaly model, we examine the consolidation state of the incoming plate and accretionary wedge sediments. A decrease in porosity observed in the sediments approaching the trench suggests that a protothrust zone is developing ∼25 km seaward of the frontal thrust. Our data also imply that sediments deeper in the accretionary wedge are slightly underconsolidated, which may indicate incomplete drainage and elevated fluid overpressures of the deep wedge. [ABSTRACT FROM AUTHOR]

Amphibians are considered susceptible to a range of potential effects generated by climate change. We applied species distribution model (SDM) techniques to predict future areas of climatic suitability for Archey's and Hochstetter's frogs under two different climate change scenarios using climate variables derived from their existing geographic extent. For Hamilton's frog their current range was too restricted to model future range, so we used past climate data from current strongholds to establish that these sites may not be suitable for this species in the long-term. Model projections for Archey's frog showed the climatically suitable area expanded and extended south as greenhouse gas concentrations increased. Under the mid-range gas concentration scenario, suitable areas were similar in 2040 and 2090, and both had an 88% overlap with the current distribution. Under the high-end gas concentration scenario suitable areas for occupancy were similar to the mid-range concentrations by 2040 (84.6% overlap), but by 2090, while their currently occupied areas remain suitable for occupancy (85.5% overlap), the suitable area stretched south resulting in a large range expansion. For Hochstetter's frog, the predicted climatically suitable area also moved south, but the proportion of their current range able to be occupied lessened as greenhouse gas concentrations increased. With the mid-range concentrations, less than half of their current areas were still suitable to occupy by 2040 and 2090 (46.1% and 35.7% respectively). The high-end greenhouse gas pathway produced a similar outcome by 2040 with only 47.3% of the current occupied area remaining suitable. Under this pathway, by 2090, suitable areas were much further south, and the northern North Island was no longer suitable for Hochstetter's frog. We conclude that a shift from traditional conservation methods will be required to allow Leiopelma species to persist under a changing climate. [ABSTRACT FROM AUTHOR]

Pureora Forest Park is one of the largest remaining and most ecologically and culturally significant areas of the native forest that once clothed almost all the North Island of New Zealand. Systematic logging and the establishment of sawmilling villages began in the Pureora area in the late 1940s. Concern about the effects of logging of virgin forest on native fauna accelerated until 1978, when a widely publicised tree-sitting protest led to a forced moratorium. The settlement that followed stopped the logging, closed the sawmills, and caused mass local unemployment and social conflict. The long-term solution required an integrated approach, reconciling the needs of economic resource utilisation with those of social welfare and biodiversity conservation. This paper describes the processes leading up to the unprecedented financial settlement that saved the forest, plus the details of the compensation package paid to timber companies for broken contracts, and the consequent benefits for conservation and tourism. • Legal protection for endemic forest birds does not include their habitat. • Logging New Zealand old-growth forests made conflict with conservation inevitable. • Forced closure of two logging companies in 1978 cost NZ$7 million in compensation. • But benefits to conservation, tourism, have been far greater ever since. [ABSTRACT FROM AUTHOR]

Sands consisting of pumice particles are found in the northern part of the North Island of New Zealand. These pumice sands are highly crushable, compressible, and lightweight due to the vesicular nature of the particles, making engineering assessment of their properties problematic. When performing geotechnical assessments of these deposits, questions have been asked whether existing empirical correlations derived primarily from normal (hard-grained) soils apply to the crushable natural pumiceous (NP) soils. Such lack of guidance for the geotechnical characterization and liquefaction assessment of NP soils has long been highlighted by the local geotechnical community. In this research, laboratory experiments, such as cyclic triaxial and bender element tests, were performed on reconstituted and high-quality undisturbed NP samples. These were supplemented by field-based shear wave velocity (Vs) profiling conducted at the same sites where the undisturbed samples were collected. For comparison purposes, similar laboratory tests were also performed on the hard-grained Toyoura sand. The laboratory results showed that NP sands have considerably different behavior when compared to Toyoura sand. For instance, NP sands have lower small strain shear modulus (Gmax) and Vs and higher liquefaction resistance under the same level of packing. Next, results from the laboratory studies and field characterization were synthesized considering the effect of various parameters, such as the degree of packing, overburden pressure, and pumice contents, on the liquefaction assessment of NP sands. Based on the results, attempts were made to develop a Vs-based chart to estimate the liquefaction resistance of such problematic soils for use by the geotechnical profession. Finally, the applicability of the proposed Vs-based chart was examined using available case studies from the 1987 Edgecumbe earthquake and then compared with an existing empirical Vs-based method developed for normal sands. The results showed that the proposed approach better reflected the reported liquefaction manifestation at the sites. [ABSTRACT FROM AUTHOR]

A significant portion of New Zealand's beef and sheep pastoral farming systems are located in the East Coast hill country of the North Island. In these landscapes, one of the main drivers of pasture growth is the highly variable soil water content. Decision making about fertiliser applications, stock and feed budgeting are guided by pasture growth models which rely on soil water information. However, due to the difficulties related to conventional soil moisture data collection, soil water dynamics are still poorly understood in hill country. To capture spatial and temporal soil moisture variability on diverse terrain positions, a soil moisture monitoring network was established at the field scale. The Patitapu Soil Moisture Network (PTSMN) is composed of twenty multi-sensor probes, collecting data from four consecutive depths at 0.1 m intervals. The paper describes the PTSMN deployment and the strategic selection of sensor locations through an extensive spatial analysis and discusses the challenges associated with the network deployment in an operating hill country farm. Additionally, we demonstrate the non-normal nature of soil moisture distribution and that Year 1 and Year 2 showed similarly shaped density curves in the 0.2 − 0.4 m soil depths indicating temporal stability. Similar magnitudes of temporal stability suggested the PTMSN is a temporally stable network although stability changed with depth. Results indicated that soil moisture variability decreased with depth and that higher mean soil moisture content was associated with low variability. Descending and ascending transition stages, i.e., drying, and rewetting periods resulted in the highest spatial variability. As PTSMN is a member of the International Soil Moisture Network, the calibrated, quality checked 2-year dataset has been made accessible online. The presented soil moisture dataset is expected to contribute to the research of near-surface and root-zone soil water dynamics and to assist with the establishment of future networks. • A field scale soil moisture sensor network was deployed in hill country. • Spatial analysis provided valuable information for network deployment. • Spatial variability was highest during drying and wetting periods. • The soil moisture network is temporally stable. • A calibrated and quality checked 2-year dataset is accessible online. [ABSTRACT FROM AUTHOR]

Flooding in coastal areas is a major global hazard, made worse during compound flood events, which occur when multiple flood-drivers, such as tide, sea surge, and fluvial and pluvial flooding, coincide. We use 12 sea-level, 2065 rainfall, and 81 river-flow records to assess the dependence of (1) extreme skew-surge and extreme rainfall (pluvial/surface runoff) and (2) extreme skew-surge and extreme river-flow (fluvial discharge) in New Zealand. We found that (1) skew-surge and rainfall and (2) skew-surge and river-flow are significantly, but not strongly, correlated in NZ. When spatially averaged to within 30 km of sea-level gauge location, the correlation was generally significant and positive, but weak with Kendall's rank correlation coefficient τ < 0.3. We identify the weather types driving regional patterns of dependence. Trough weather types were the dominant driver of individual and coincident extreme events. Blocking weather types were associated with the highest extreme skew-surge and rainfall events along the northeast coast of the North Island and, consequently, were associated with a high proportion of coincident skew-surge/rainfall and skew-surge/river-flow events there. These findings have important implications for flood management, emergency response, and the insurance sector because impacts and losses may be correlated in space. Our findings add to a growing understanding of compound flooding worldwide for different geographical and meteorological settings. The positive dependence observed suggests that more attention to compound event probabilities is warranted when undertaking localized coastal-flood modelling. [ABSTRACT FROM AUTHOR]

Kiwi are a unique and emblematic group of birds endemic to New Zealand. Deep-time evolutionary relationships among the five extant kiwi species have been difficult to resolve, in part due to the absence of pre-Quaternary fossils to inform speciation events. Here, we utilise single representative nuclear genomes of all five extant kiwi species (great spotted kiwi, little spotted kiwi, Okarito brown kiwi, North Island brown kiwi, and southern brown kiwi) and investigate their evolutionary histories with phylogenomic, genetic diversity, and deep-time (past million years) demographic analyses. We uncover relatively low levels of gene-tree phylogenetic discordance across the genomes, suggesting clear distinction between species. However, we also find indications of post-divergence gene flow, concordant with recent reports of interspecific hybrids. The four species for which unbiased levels of genetic diversity could be calculated, due to the availability of reference assemblies (all species except the southern brown kiwi), show relatively low levels of genetic diversity, which we suggest reflects a combination of older environmental as well as more recent anthropogenic influence. In addition, we suggest hypotheses regarding the impact of known past environmental events, such as volcanic eruptions and glacial periods, on the similarities and differences observed in the demographic histories of the five kiwi species over the past million years. [ABSTRACT FROM AUTHOR]

The current geothermal and volcanic activity in the North Island of New Zealand is explained as a consequence of Pacific and Australian plate interactions over the last 20 million years. The primary hypothesis is that the Kermadec subduction zone has for the last 20 million years or more been retreating in a south-easterly direction at about five centimetres per year. It is surmised that this motion and interaction with another subduction zone almost at right angles to it under the North Island resulted in plate tearing due to the incompatibility of the plate geometry where these subduction zones interacted. The nature and consequences of this plate tearing are partially revealed in published maps of the plate currently under the North Island. If the subducted parts of this plate, as shown in Eiby's maps, [G. A. Eiby, "The New Zealand sub-crustal rift", New Zeal. J. Geol. Geophy. 7 (1964) 109-133] are straightened, then the plate edge lies on a curve giving a rough picture of their position before being torn and subducted by the Kermadec trench motion. This map of the tear suggests the shape of the edge of a missing plate segment torn from the plate, and implies a rotation of the upper North Island, clockwise approximately 20 degrees, about a point just south of the Thames estuary. A consequence of this plate tearing is that the solid retreating crustal wave generating magma pressure beneath the crest of the solid wave has the potential to inject significant basaltic magma into the crust through the tears. These intrusive magma fluxes have the ability to generate geothermal fields and rhyolitic lavas from crustal melts. This could explain the geothermal activity along the Coromandel peninsula five to seven million years ago, the ignimbrite outcrops about Lake Taupo and the current geothermal and volcanic activity stretching from Taupo to Rotorua. [ABSTRACT FROM AUTHOR]

Seismic and geodetic examinations of the Hikurangi subduction zone (HSZ) indicate a remarkably diverse and complex system. Here, we investigate the 3-D P -wave velocity structure of the HSZ by applying an iterative, nested regional-global tomographic algorithm. The new model reveals enhanced details of seismic variations along the HSZ. We also relocate over 57 000 earthquakes using this newly developed 3-D model and then further improve the relative locations for 75 per cent of the seismicity using waveform cross-correlation. Double seismic zone characteristics, including occurrence, depth distribution and thickness change along the strike of the HSZ. An aseismic but fast Vp zone separates the upper and lower planes of seismicity in the southern and northern North Island. The upper plane of seismicity correlates with low Vp zones below the slab interface, indicating fluid-rich channels formed on top and/or within a dehydrated crust. A broad low Vp zone is resolved in the lower part of the subducting slab that could indicate hydrous mineral breakdown in the slab mantle. In the northern North Island and southern North Island, the lower plane of seismicity mostly correlates with the top of these low Vp zones. The comparison between the thermal model and the lower plane of seismicity in the northern North Island supports dehydration in the lower part of the slab. The mantle wedge of the Taupo volcanic zone (TVZ) is characterized by a low velocity zone underlying the volcanic front (fluid-driven partial melting), a fast velocity anomaly in the forearc mantle (a stagnant cold nose) and an underlying low velocity zone within the slab (fluids from dehydration). These arc-related anomalies are the strongest beneath the central TVZ with known extensive volcanism. The shallow seismicity (<40 km depth) correlates with geological terranes in the overlying plate. The aseismic impermeable terranes, such as the Rakaia terrane, may affect the fluid transport at the plate interface and seismicity in the overlying plate, which is consistent with previous studies. The deep slow slip events (25–60 km depths) mapped in the Kaimanawa, Manawatu and Kapiti regions coincide with low Vp anomalies. These new insights on the structure along the HSZ highlight the change in the locus of seismicity and dehydration at depth that is governed by significant variations in spatial and probably temporal attributes of subduction zone processes. [ABSTRACT FROM AUTHOR]

Nonindigenous members of the Daphnia pulex complex have been found in many lakes in New Zealand (NZ) in the past 20 years, suggesting a recent invasion. However, very little is known about the precise phylogenetic origin of invasive Daphnia, whether each lake is invaded by a single clone or multiple clones, the lineage of the invasive clones, and whether they are obligately asexual clones. Furthermore, the source and time of arrival of the invasive genotype(s) are unclear. We address these questions by genomic sequencing of Daphnia populations from 13 lakes in the South Island and 1 lake in the North Island, NZ. All biallelic sites in these NZ populations have similar numbers of reads for the two parental alleles, suggesting each NZ population originates from a single asexual clone. Based on 25,643 monomorphic lineage‐specific markers, the invasive Daphnia in the South Island were found to be Daphnia pulicaria Forbes, while those in the North Island are hybrids of D. pulicaria Forbes and D. cf. pulex sensu Hebert. Both the South and North Island Daphnia are phylogenetically clustered with North American Daphnia, thereby suggesting their North American origins. We found also that all South Island clones contain identical mitochondrial genomes, suggesting the origin and proliferation from a single founder clone, which we experimentally verified to be an obligate asexual. Estimates from molecular data imply a colonization time for the South Island clones of ~ 60 years ago, with a likely invasion route associated with the introduction of salmonids from North America. [ABSTRACT FROM AUTHOR]

Abutilon theophrasti (velvetleaf, butterprint), a problematic weed of crops in some temperate countries, was introduced into New Zealand in 1948 as a potential fibre crop. It has naturalised in the North Island in the Waikato and Auckland regions but its status at the many sites where it was inadvertently sown in 2015 as a contaminant of Beta vulgaris seed lines remains unknown. To determine the potential distribution of the species in New Zealand we used an existing and a newly developed climate niche model, both constructed using the modelling software CLIMEX and a current global climate surface dataset. The Holt & Boose model, published in 2000, fitted only 54% of the known 3825 global occurrences of the species. It predicts that most of the North Island is climatically optimal and that most of the South Island is unsuitable. By contrast, the new model, parameterised using a geographically wider set of global occurrences, fitted 98% of the global occurrences. This more robust model predicts that almost all New Zealand, including all agricultural land, is currently climatically suitable for the species. We conclude that velvetleaf could become a weed throughout the country. [ABSTRACT FROM AUTHOR]

We constrain orientations of the horizontal stress field from borehole image data in a transect across the Hikurangi Subduction Margin. This region experiences NW‐SE convergence and is the site of recurrent slow slip events. The direction of the horizontal maximum stress is E‐W at an active splay thrust fault near the subduction margin trench. This trend changes to NNW‐SSE in a forearc trench slope basin on the offshore accretionary wedge, and to NE‐SW in the onshore forearc. Multiple, tectonic, and geological processes, either individually or in concert, may explain this variability. The observed offshore to onshore stress rotation may reflect a change from dominantly compressional tectonics at the deformation front, to a strike‐slip and/or extensional tectonic regime closer to the Taupo Volcanic Zone, further inland. In addition, the offshore stress may be affected by topography and/or stress rotation around subducting seamounts, and/or temporal stress changes during the slow slip cycle. Plain Language Summary: Using geophysical images captured from the inside of boreholes drilled across the Hikurangi Subduction Margin, an area that experiences slow earthquakes, we describe variability in the direction of modern day maximum horizontal tectonic forces (stress) at this collisional plate boundary. Changes in the direction of maximum horizontal stress occur as you move from the plate boundary toward the onshore region of New Zealand's North Island. We suggest a range of possible tectonic and geological processes that either individually or in concert may explain our observed stress direction variations. This includes changing tectonic regimes as you move away from the plate boundary, topography, and effects on the stress field caused by the presence of subducting seamounts, and changing stress conditions related to the intermittent activity of slow earthquakes. Key Points: Maximum horizontal stress directions vary in a transect across the Hikurangi Subduction MarginStress orientations suggest a change occurs moving from offshore to onshore associated with changing dominant tectonic regimeOffshore stress variation may be caused by a number of specific tectonic and geological causes [ABSTRACT FROM AUTHOR]

A 4-month time series of water column temperature structure on the shelf of North Island New Zealand is used to calculate the energy in the internal tide as stratification evolved between spring and summer. Average total energy in the internal tidal wave was 200 J m−2, with peaks reaching 600 J m−2. Wave energy was weakly correlated with stratification (r = 0.2) and with the spring-neap cycle of tidal currents (r = 0.17). Overall there was little predictability in internal tide behaviour in response to the physical environment. Reduction in wave energy was associated with a downwelling-favourable wind event which reduced stratification by mixing and by removing deeper water off the shelf. Vertical eddy diffusivity driven by internal wave dissipation ranged between 5.6 × 10−5 and 3.2 × 10−4 m2 s−1. Combined with nitrate data this diffusivity resulted in diapycnal nitrate fluxes towards the sea surface of 1.6–2.2 mmol m−2 day−1. Strong stratification in summer reduced the eddy diffusivity but had little effect on nitrate flux as a strengthened vertical nitrate gradient compensated for the reduced diffusivity. This compensation will be important when predicting how stronger stratification in a warmer climate might alter diapycnal nutrient supplies to the upper ocean. [ABSTRACT FROM AUTHOR]

This review summarises the ecology and biology of the North Island New Zealand endemic evergreen epiphytic shrub Pittosporum kirkii Hook.f. ex Kirk (Pittosporaceae). While mainly found as an epiphyte associated with other nest epiphytes such as Astelia spp., it also exhibits rupestral and terrestrial lifestyles. Pittosporum kirkii is distinguished from other members of New Zealand Pittosporum by distinctive thick, fleshy, coriaceous leaves, which may assist survival in water-stressed habitats. Water availability is speculated to be the most limiting factor across all of the habitats that P. kirkii occupies and when under water stress, the species utilises a desiccation postponement strategy. Pittosporum kirkii has a restricted distribution with strong habitat preferences restricting it to upper lowland and lower montane mainly old-growth forest ecosystems of the upper North Island. The highest probabilities of P. kirkii occurrence lie within mean annual temperature between 7.8°C and 15.6°C, mean annual rainfall between 1172 and 4432 mm, mean minimum solar radiation in the coldest month between 4.8 and 6.6 MJ/m2/day, and vapour pressure deficits between 0.15 and 0.39 kPa. Pittosporum kirkii is currently listed as at risk–declining and qualified as data-poor and partial decline because of a lack of autecological information. Palatability to introduced brushtail possums and forest clearance have been suggested as the main agents of decline. Due to significant morphological differences between mainland New Zealand and Great Barrier Island/Aotea populations, further study is warranted to determine distinctness. Including P. kirkii in restoration plans and conservation monitoring is recommended in areas where it naturally occurs as this species is recognised as an indicator of overall forest health. Further detailed research on P. kirkii would be invaluable to fill the current gap in knowledge on its ongoing threats, sexual expression, pollination and seed dispersal. [ABSTRACT FROM AUTHOR]

The only complete inventory of New Zealand glaciers was based on aerial photography starting in 1978. While there have been partial updates using 2002 and 2009 satellite data, most glaciers are still represented by the 1978 outlines in contemporary global glacier databases. The objective of this project is to establish an updated glacier inventory for New Zealand. We have used Landsat 8 OLI satellite imagery from February and March 2016 for delineating clean glaciers using a semi-automatic band ratio method and debris-covered glaciers using a maximum likelihood classification. The outlines have been checked against Sentinel-2 MSI data, which have a higher resolution. Manual post processing was necessary due to misclassifications (e.g. lakes, clouds), mapping in shadowed areas, and combining the clean and debris-covered parts into single glaciers. New Zealand glaciers cover an area of 794 ± 34 km2 in 2016 with a debris-covered area of 10%. Of the 2918 glaciers, seven glaciers are >10 km2 while 71% is <0.1 km2. The debris cover on those largest glaciers is >40%. Only 15 glaciers are located on the North Island. For a selection of glaciers, we were able to calculate the area reduction between the 1978 and 2016 inventories. [ABSTRACT FROM AUTHOR]

We analyse deformation bands related to horizontal contraction with an intermittent period of horizontal extension in Miocene turbidites of the Whakataki Formation south of Castlepoint, Wairarapa, North Island, New Zealand. In the Whakataki Formation, three sets of cataclastic deformation bands are identified: (1) normal-sense compactional shear bands (CSBs), (2) reverse-sense CSBs, and (3) reverse-sense shear-enhanced compaction bands (SECBs). During extension, CSBs are associated with normal faults. When propagating through clay-rich interbeds, extensional bands are characterised by clay smear and grain size reduction. During contraction, sandstone-dominated sequences host SECBs, and rare CSBs, that are generally distributed in pervasive patterns. A quantitative spacing analysis shows that most outcrops are characterised by mixed spatial distributions of deformation bands, interpreted as a consequence of overprint due to progressive deformation or distinct multiple generations of deformation bands from different deformation phases. As many deformation bands are parallel to adjacent juvenile normal faults and reverse faults, bands are likely precursors to faults. With progressive deformation, the linkage of distributed deformation bands across sedimentary beds occurs to form through-going faults. During this process, bands associated with the wall-, tip-, and interaction-damage zones overprint earlier distributions resulting in complex spatial patterns. Regularly spaced bands are pervasively distributed when far away from faults. Microstructural analysis shows that all deformation bands form by inelastic pore collapse and grain crushing with an absolute reduction in porosity relative to the host rock between 5 % and 14 %. Hence, deformation bands likely act as fluid flow barriers. Faults and their associated damage zones exhibit a spacing of 9 m on the scale of 10 km and are more commonly observed in areas characterised by higher mudstone-to-sandstone ratios. As a result, extensive clay smear is common in these faults, enhancing the sealing capacity of faults. Therefore, the formation of deformation bands and faults leads to progressive flow compartmentalisation from the scale of 9 m down to about 10 cm – the typical spacing of distributed, regularly spaced deformation bands. [ABSTRACT FROM AUTHOR]

The subfamily Lechytiinae is reported from New Zealand for the first time. A new species, Lechytia novaezealandiae sp. nov., is described and illustrated from Lake Waikare in Waikato District, North Island. In addition, a key to species in the genus Lechytia from Asia, Australia, and New Zealand is included. [ABSTRACT FROM AUTHOR]

We develop and verify an automated workflow for full-waveform tomography based on spectral element and adjoint methods. We choose the North Island, New Zealand as a study area because of its high seismicity, extensive seismic network, and the availability of a candidate ray tomography starting model. To assess the accuracy of this model, we simulated 250 regional earthquakes using a spectral element solver, and compared the resulting synthetics with recorded waveforms. In a 10–30 s passband, reasonable cross-correlation phase and amplitude misfits exist between data and synthetics, whereas at 2–30 s, waveform misalignment is severe enough that meaningful cross-correlation measurements are no longer possible. To improve the velocity model at these short periods, we created an automated inversion framework based on existing tools for signal processing, phase measurement, nonlinear optimization, and workflow management. To verify the inversion framework, we performed a realistic synthetic inversion for 3-D checkerboard structure and analyzed model recovery, misfit reduction, and waveform improvement. The results of this analysis show that the source–receiver distribution within the chosen domain is capable of resolving velocity anomalies in regions of sufficient data coverage, and of magnitudes comparable to those expected in a real seismic inversion. Along with this finding, the relative ease of use and reliability of the workflow motivates future efforts targeting a high-resolution (2–30 s), large-scale (>50 000 measurements) seismic inversion for the North Island. Updated models from such an inversion are expected to improve ground motion predictions, constrain complex velocity structures, and advance understanding of New Zealand tectonics. [ABSTRACT FROM AUTHOR]

Population control of invasive mammal pests is an ongoing process in many conservation projects. In New Zealand, introduced wild domestic cats and mustelids have a severe impact on biodiversity, and methods to reduce and maintain predator populations to low levels have been developed involving poisoning and trapping. Such conservation efforts often run on limited funds, so ways to minimize costs while not compromising their effectiveness are constantly being sought. Here we report on a case example in a 150 km2 area in the North Island, New Zealand, where high predator numbers were reduced by 70-80% in an initial 'knockdown' trapping program, using the full set of traps available in the fixed network and frequent checks, and then maintained at low density using maintenance trapping with less frequent checking. We developed and applied a simulation model of predator captures, based on trapping data, to investigate the effect on control efficacy of varying numbers of trap sites and numbers of traps per site. Included in the simulations were captures of other, non-target, introduced mammals. Simulations indicated that there are potentially significant savings to be made, at least in the maintenance phase of a long-term predator control programme, by first reducing the number of traps in large-scale networks without dramatically reducing efficacy, and then, possibly, re-locating traps according to spatial heterogeneity in observed captures of the target species. [ABSTRACT FROM AUTHOR]

The planting of degraded land with tree plantations may be effective at improving land use sustainability and profitability but it can also have significant effects on stream hydrology. In this paired catchment study, we report the stream hydrological response to partial (62%) afforestation of a steep pastoral catchment in the western Waikato Region, North Island, New Zealand. We comprehensively analyse the hydrological regime changes over a 23-year period (including eight years before pine planting) with reference to a native-forested 'control' catchment. Our results show that afforestation has markedly affected stream hydrology. Seven years after planting, the total annual runoff was 380 mm lower than predicted for the catchment in pasture. Two phases of plantation thinning resulted in the difference between measured and predicted runoff reducing to only 129 mm. Peak flows reduced by ∼50% while total stormflow reduced by ∼30% – which we attribute to canopy interception attenuating and delaying water yield. The impact of plantation establishment on low flows is not so clear, although afforestation appears to have reduced low flows by ∼25%. This study provides information on the hydrological impact of afforestation within a hitherto poorly-represented New Zealand environment (i.e. high rainfall, sedimentary lithology-based, North Island hill country). [ABSTRACT FROM AUTHOR]

Ocellularia (Graphidaceae) is a genus of crustose lichens comprising c.200 species, four known from Australia and New Zealand. Based on recent collections from northern North Island, we describe a fifth species Ocellularia jacinda-arderniae, which is a member of the O. bicuspidata complex. This complex is characterised by peculiar, appendiculate ascospores and a psoromic acid chemistry. Two further undescribed species of this complex, one from North Island and one from South Island, are discussed but left undescribed pending further study. Based on our findings, we provide a revised assessment of New Zealand Ocellularia. Of the four species included in the most recent Flora of New Zealand Lichens from 2007, three do not belong in that genus and the identification of the fourth is incorrect; instead, the following four taxa are recognised: O. jacinda-arderniae, O. aff. dolichotata, O. aff. bicuspidata (a) (South Island; OTA 58820) and O. aff. bicuspidata (b) (North Island; UNITEC 10818). This leads to the somewhat unusual situation that a presumably known genus biota in New Zealand is entirely replaced by names of a new species and three provisional identifications. The following new combination is introduced: Schizotrema concentricum (Stirt.) Lücking comb. nov. In addition, the name Thelotrema manosporum (C. Knight.) Hellb. is given as the correct name for the New Zealand taxon previously identified as T. monosporum Nyl., and the name T. monosporoides Nyl. [syn.: O. monosporoides (Nyl.) Hale] is established as a taxonomic synonym of T. manosporum, leaving two New Zealand species of Thelotrema with large, brown ascospores, namely T. manosporum and T. saxatile C. Knight. The situation of the genus Ocellularia highlights the need for detailed taxonomic revision of understudied lichen groups in New Zealand, especially as these and related genera in the Graphidaceae are excellent indicators of forest health and can be used for monitoring purposes. [ABSTRACT FROM AUTHOR]

Overbank fine sediment deposition in the lower Oroua River leads to decreased flood capacity between stopbanks and increased flood risk. Identifying the dominant sources of erosion contributing to this deposited sediment can inform targeting of erosion management strategies most likely to reduce deposition. Sediment fingerprinting quantifies proportional contributions of catchment sources to suspended and deposited sediment transported downstream. Here, it is used to determine source contributions to recent overbank sediment deposits in the lower Oroua River, North Island, New Zealand. The analysis comprised six sources (channel bank; greywacke mountain range; hill subsurface; hill surface; mudstone; and, unconsolidated sand/silt) and two particle size fractions (< 63 µm and 125-300 µm) using bulk geochemical and radionuclide tracers. The dominant contributions to overbank deposition for the < 63 µm size fraction, which represents 42% of the deposits, are estimated to be from unconsolidated sand/silt (36 ± 8%) and hill subsurface (27 ± 8%), followed by channel bank (12 ± 12%), mudstone (11 ± 8%), hill surface (11 ± 6%), and greywacke mountain range (3 ± 4%). The overbank deposits for the 125-300 µm sediment fraction, which represents 28% of the deposits, show a different order of dominance with the largest contributions from hill subsurface (37 ± 7%) and channel bank (27 ± 10%), followed by mountain range (17 ± 10%), unconsolidated sand/silt (10 ± 7%), mudstone (7 ± 6%), and hill surface (2 ± 4%). Combining these two size fractions by their proportions in the overbank sediment provides an overall sediment source contribution of hill subsurface (31 or 38%), unconsolidated sand/silt (26 or 29%), channel bank (18%), mudstone (9 or 10%), mountain range (9 or 15 %), and hill surface (7 or 8%) (including/excluding channel bank, respectively). Hill subsurface, which represents shallow landslides in steep hill country, is a significant sediment source for both particle size ranges. Therefore, targeting erosion from this source is likely to have the most significant impact on sediment supply to overbank deposition. Differences in source contribution estimates for the two particle size fractions may reflect the composition of source material, variation in erosion and deposition processes, and discrimination challenges caused by channel bank sediment. These differences highlight the importance of accounting for particle size distributions when using sediment fingerprinting. Particle size also needs to be considered when implementing erosion management strategies because sources may have disproportionate downstream impacts depending on their particle size distribution and the aim of the mitigation. Specific sediment yield was estimated using sediment fingerprinting results distributed across a slope-weighted model of catchment outlet sediment yield. The highest specific sediment yield is from unconsolidated sand/silt (1,900 t km-2 yr-1), followed by mudstone (1,100 t km-2 yr-1) and hill subsurface (1,000 t km-2 yr-1). The presentation of sediment fingerprinting outputs can be improved by incorporating results into spatial modelling to produce maps of sediment yield. [ABSTRACT FROM AUTHOR]

Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave. Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (δ18O , δD , d-excess parameter, δ17O , and 17Oexcess) and elemental (Mg/Ca and Sr/Ca) analysis. The monitoring included spot measurements of drip rates and cave air CO2 concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry. Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water δ18O values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. Mg/Ca and Sr/Ca ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of effective infiltration, and is weakest during the wet austral winter (July–September). The Sr/Ca ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower Sr/Ca in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes. [ABSTRACT FROM AUTHOR]

Chromadorina is a globally distributed, largely marine nematode genus frequently found on a variety of organisms, including macro- and microalgae and crustaceans, as well as artificial substrates such as settlement plates and ship hulls. Here, Chromadorina tangaroa sp. nov. is described from filamentous seaweed growing on the hull of RV Tangaroa anchored in Wellington, North Island of New Zealand. It is characterized by body length 763–1,086 mm, and pore of secretory-excretory system located at or near level of teeth. Males have spicules with rounded capitulum followed by a narrower shaft and blade tapered distally, a gubernaculum as long as the spicules, and three cup-shaped precloacal supplements, and females are characterized by a cuticularized prevulvar pad, vagina located at 46–48% of body length from anterior, and vagina anteriorly directed. Chromadorina tangaroa sp. nov. is the first species of the genus to be described from New Zealand, but it is unclear whether it is native to the region because it may have dispersed as part of ship hull biofouling communities. Long-distance transport of nematodes through ship hull biofouling may be a common occurrence, but too little is known about the occurrence of nematodes on ship hulls to gauge the potential effect of shipping on nematode species distributions. [ABSTRACT FROM AUTHOR]

Fluid injection for geothermal production has the potential to produce subsidence and microseismicity that can incur heavy financial cost or hazard. Due to this, novel ways to monitor subsurface deformation to supplement existing methods are highly sought after. We use seismic ambient noise to obtain time-dependent measurements of shear velocity within the geothermal reservoirs of Rotokawa and Ngatamariki, two producing geothermal fields in the Taupō Volcanic Zone located in the central North Island of New Zealand and operated by Mercury Energy. We investigate the relationship between shear wave velocity changes and geothermal injection by selecting time periods at the fields when injection and production volumes were significantly altered: 2009–2010 at Rotokawa, when geothermal injection was quadrupled due to the start-up of a new power station, and 2012–2013 at Ngatamariki, the beginning of geothermal injection for electricity production at that field. Shear wave velocity changes are computed from the ambient noise cross-correlation coda using the Moving Window Cross-Spectral (MWCS) technique, with a reference stack encompassing all data prior to the change in injection rate and moving stacks of 10–50 d. Gradual positive and negative shear velocity changes with a periodicity of approximately 12 months were observed at both sites, with maximum amplitude of 0.06 ± 0.04 and –0.08 ± 0.03 per cent at Rotokawa and 0.07 ± 0.03 and –0.06 ± 0.02 per cent at Ngatamariki. We hypothesize that these changes are due to seasonal rainfall, as seismic velocities computed by ambient noise are sensitive to the filling and emptying of near-surface pore space. In addition to these gradual responses, we found several sharp negative changes in velocity that reach minimum values over a few days and then gradually equilibrate to prior values over a few weeks. The amplitude of these responses is between –0.03 and –0.07 per cent and coincides with regional and local earthquakes. We hypothesize that these responses are primarily produced by the creation of new fractures, the same mechanism that produces gradual groundwater level decreases at regional distances from earthquake epicentres. We analyse a periodic signal within the time-delay measurements and determine that it is at least in part caused by the MWCS window size smoothing the cross-coherence of the ambient seismic signal. We do not observe shear wave velocity changes coinciding with geothermal injection, which may suggest that the signal has lower amplitude compared to the seasonal and seismic responses. We use bandstop filters and polynomial curve fitting to remove the contribution of the seasonal signal, but see no evidence of a shear wave velocity response due to geothermal fluid injection. [ABSTRACT FROM AUTHOR]

Coastal flooding is a major global hazard, yet few studies have examined the spatial and temporal characteristics of extreme sea level and associated coastal flooding. Here we analyse sea-level records around the coast of New Zealand (NZ) to quantify extreme storm-tide and skew-surge frequency and magnitude. We identify the relative magnitude of sea-level components contributing to 85 extreme sea level and 135 extreme skew-surge events recorded in NZ since 1900. We then examine the spatial and temporal clustering of these extreme storm-tide and skew-surge events and identify typical storm tracks and weather types associated with the spatial clusters of extreme events. We find that most extreme storm tides were driven by moderate skew surges combined with high perigean spring tides. The spring–neap tidal cycle, coupled with a moderate surge climatology, prevents successive extreme storm-tide events from happening within 4–10 d of each other, and generally there are at least 10 d between extreme storm-tide events. This is similar to findings from the UK (Haigh et al., 2016), despite NZ having smaller tides. Extreme events more commonly impacted the east coast of the North Island of NZ during blocking weather types, and the South Island and west coast of the North Island during trough weather types. The seasonal distribution of both extreme storm-tide and skew-surge events closely follows the seasonal pattern of mean sea-level anomaly (MSLA) – MSLA was positive in 92 % of all extreme storm-tide events and in 88 % of all extreme skew-surge events. The strong influence of low-amplitude (-0.06 to 0.28 m) MSLA on the timing of extreme events shows that mean sea-level rise (SLR) of similarly small height will drive rapid increases in the frequency of presently rare extreme sea levels. These findings have important implications for flood management, emergency response and the insurance sector, because impacts and losses may be correlated in space and time. [ABSTRACT FROM AUTHOR]

Controlled and natural source seismic data are used to build a 3‐D P wave model for southern North Island, New Zealand, where the Pacific Plate subducts beneath the Australian Plate at a rate of ~41 mm/year. Our analysis reveals an abrupt along‐strike transition in overthrusting plate structure within Cook Strait. Contrasts in properties (Vp, Vp/Vs, and Qs) likely reflects the degree of deformation in the Australian Plate, where the Alpine‐Wairau and Awatere Faults mark the northern boundary of a terrane that has undergone >50° of clockwise vertical‐axis rotation since the early Miocene. Heterogeneity of the crustal transition is likely associated with changes in frictional and elastic properties that may impact elastic stress accumulation and inhibit southward propagation of megathrust earthquakes. Low connectivity of faults in Cook Strait is consistent with the heterogeneity we observe and may promote complex earthquake triggering by lateral stress loading during earthquakes or slow slip events. Plain Language Summary: Subduction zones produce the largest earthquakes and tsunami on Earth and knowledge of structures and physical rock properties at subducting margins will inform how and where strain is accumulated, as well as how stress is relieved. Combined information from earthquakes, seismic data, gravity observations, and geological mapping constrain a new 3‐D subduction zone image at the southern Hikurangi margin, central New Zealand, where the Pacific Plate dives beneath the Australian Plate. The image reveals an abrupt inherited along‐strike transition in the upper Australian Plate structure through Cook Strait. The region is notable because the 2016 magnitude 7.8 Kaikōura earthquake ruptured more than a dozen faults in northern South Island, south of Cook Strait, and triggered large afterslip on the subduction interface. However, the Kaikōura earthquake afterslip did not extend across the Cook Strait transition, into the southern North Island, where the subduction interface is currently strongly coupled or locked. Our work offers new insights suggesting that structure and frictional properties of the overthrusting upper plate might also limit the lateral extent of rupture in future earthquakes on the southern Hikurangi subduction zone. Key Points: The 3‐D velocity images and residual gravity anomalies reveal along‐strike transition in upper plate structure along southern Hikurangi marginTransition marks the northern boundary of a tectonic terrane that has undergone clockwise vertical‐axis rotation since early MioceneThe structure and frictional properties of the upper plate may control megathrust coupling and seismogenic behavior in southern Hikurangi [ABSTRACT FROM AUTHOR]

Mafic magmatism of the rifting Taupo Volcanic Zone (TVZ) of the North Island, New Zealand, is volumetrically minor, but is thought to tap the material that provides the heat source for voluminous rhyolite production through partial melting of the crust, which ultimately results in very large volume explosive eruptions. We have studied the major and trace element chemistry of 14 mafic samples from across the entire TVZ, and the U isotopic composition of whole-rocks, groundmasses and separates of mafic mineral phases from a selection of nine samples (with the remaining five too sparsely phyric for mineral separation). Some minerals yield significant 234U enrichments despite groundmass and whole-rock close to 238U–234U secular equilibrium, pointing to uptake of variably hydrothermally altered antecrystic minerals prior to the eruption of originally sparsely phyric to aphyric mafic magmas. However, incompatible trace element patterns indicate that there are three chemically distinct groups of samples, and that samples may be used to derive primary melt compositions. We employ the latest version of the Arc Basalt Simulator (ABS5) to forward model these compositions, deriving mantle source parameters including mantle fertility, slab liquid flux, mantle volatile content, degree of melting, and P – T conditions of melt segregation. We show that mafic rocks erupted in areas of old, now inactive calderas constitute low-degree, deep melts, whereas those in areas of active caldera-volcanism are high-degree partial melts segregated from a less depleted source at an intermediate depth. Finally, high-Mg basaltic andesites erupted in the SW and NE of the TVZ point to a fertile, shallow mantle source. Our data are consistent with a petrogenetic model in which mantle melting is dominated by decompression, rather than fluid fluxing, and progresses from shallow to deeper levels with time. Melt volumes initially increase to a tipping point, at which large-scale crustal melting and caldera volcanism become prominent, and then decrease owing to progressive depletion of the mantle wedge by melting, resulting in the dearth of heat provided and eventual cessation of very large volume rhyolitic volcanism. ABS5 modelling therefore supports the notion of a direct link between the chemistry of recently erupted mafic magmas and the long-term activity and evolution of rhyolitic volcanism in the TVZ. [ABSTRACT FROM AUTHOR]

According to the most recent (2005) compendium on the history of the European hedgehog (Erinaceus europaeus) in New Zealand, this small insectivorous mammal was first brought from Europe to the South Island in the 19th century. This introduction has been presumed to be the source of hedgehogs that subsequently spread to the North Island. This view was informed by the absence of hedgehogs in the North Island throughout the 19th century and no evidence of direct shipments of hedgehogs from overseas to the North Island. Molecular data have challenged this view and suggested that not only was the North Island colonised independently from overseas, but hedgehogs also first became established in the North rather than in the South Island. If true, this finding indicates that the historical record collected by previous researchers might be incomplete. In the present study, based primarily on newspaper articles, we fill this gap by documenting four pre-1900 shipments of hedgehogs to the North Island, thereby confirming the independent colonisation of the North Island. However, we also report on several relocations from established populations in Canterbury (South Island) to regions on the North Island, and none in the opposite direction. We illustrate the importance of linking observational and molecular data with historical records when interpreting the introduction pathways of introduced species. [ABSTRACT FROM AUTHOR]

This study examined long-term stability in water quality of Lake Okataina, North Island, New Zealand, inferred from sediments deposited from 1836 to 2009, during which time there was a pyroclastic volcanic eruption (Tarawera 1886) and successive introductions of invasive mammals. Multiple geochemical proxies were analysed stratigraphically for organic matter loading, primary productivity, redox potential and phosphorus retention capacity. Organic matter loading to the lake is mostly authochthonous (algae) although there was increased allochthonous (terrestrial) loading immediately after the Tarawera eruption. After 1920, there was a sustained increase in inorganic erosion flux. Primary productivity appeared to increase considerably about 1960, but has remained relatively unchanged more recently. Our results suggest that the lake could recover from the impact of the volcanic eruption within a few decades, but the introduction of mammals may affect its resilience and lead to more pervasive impacts on the biogeochemistry. [ABSTRACT FROM AUTHOR]

Dougherty, A.J. and Nichol, S.L., 2007. 3-D Stratigraphic models of a composite barrier system, northern New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 922 – 926. Gold Coast, Australia, ISSN 0749-0208 This paper presents for the first time, detailed three-dimensional stratigraphic models of both the Holocene and Pleistocene components of a double barrier using ground-penetrating radar. The study focuses on a composite Quaternary barrier system located in Bream Bay, north-east North Island, New Zealand. This coastal compartment maintains a mesotidal environment with low to moderate wave energy. The Holocene barrier has prograded over the last 6500 years during a relative sea-level still stand, or at most 2 metre fall, resulting in a hummocky dune morphology. In contrast, the Pleistocene barrier was formed during rapid sea-level fall towards the end of the Last Interglacial (oxygen isotope 5e to 5a), which resulted in a forced regression producing linear beach ridges. The sublithified nature of these barrier sediments is conducive to utilising both coring and ground-penetrating radar techniques. This study uses standard sedimentological analysis to ground-truth multiple GPR transects collected over the width of both barriers. This method was employed in order to reconstruct the subsurface stratigraphy in detail and to compare barrier structure over the timescale of successive sea-level highstands. The resulting two- and three-dimensional GPR records all show detailed stratigraphy of a regressive facies succession with similar architecture. However, slight differences in spacing and geometry between beach facies were detected in association with the different dune morphologies from each timeframe. While both beach facies are laterally continuous and dipping in a seaward direction, the Holocene stratigraphy exhibits a more closely-spaced, curvilinear cross-sectional geometry consisting of medium sand and shells; whereas the Pleistocene barrier beachface is highlighted by heavy mineral-rich, fine-grained sands showing a similar concave shape in the large scale, but at a more regularly-spaced interval associated with individual beach ridges. The replication of this stratigraphic form at successive sea-level highstands within the beachface indicates that present-day intermediate nearshore conditions are similar to those of the last interglacial highstand. The overall evolutionary sequence for each barrier differs in width, morphology and stratigraphy due to a combination of factors, including variations in sediment supply, accommodation space, and relative sea level within successive highstands. [ABSTRACT FROM AUTHOR]

Critically endangered Māui dolphin (Cephalorhynchus hectori maui) are found exclusively off the west coast of New Zealand's North Island. One important data gap troubling efforts to reduce the current unsustainable level of bycatch is the limited information on the offshore and alongshore limits of their range. Passive acoustic monitoring studies could address this data gap, but Māui dolphin habitat is dominated by a sandy substrate that can shift greatly in the strong local currents. In February 2016, a short pilot CPOD deployment was thus attempted as a first step to see if the equipment could be deployed and recovered in the area and if the data collected would be viable, with a second unit deployed inside a harbour for comparison with earlier TPOD data. The pilot was largely successful, and roughly 11% of all minutes in the core habitat location contained detections of clicks attributed to Māui dolphin. A visual inspection of the data suggests some trends with diel and tidal patterns. Further work of this type is thus recommended. [ABSTRACT FROM AUTHOR]

Biomonitoring is a common method to monitor environmental change in river ecosystems, a key advantage of biomonitoring over snap-shot physicochemical monitoring is that it provides a more stable, long-term insight into change that is also effects-based. In New Zealand, the main biomonitoring method is a macroinvertebrate sensitivity scoring index, with little established methods available for biomonitoring of fish. This study models the contemporary distribution of common freshwater fish and then uses those models to predict freshwater fish assemblages for each river reach under reference conditions. Comparison of current fish assemblages with those predicted in reference conditions (as observed/expected (O/E) ratios) may provide a suitable option for freshwater fish biomonitoring. Most of the fish communities throughout the central North Island and lower reaches show substantial deviation from the modelled reference community. Most of this deviation is explained by nutrient enrichment, followed by downstream barriers (i.e. dams) and loss of riparian vegetation. The presence of modelled introduced species had relatively little impact on the presence of the modelled native fish. The maps of O/E fish assemblage may provide a rapid way to identify potential restoration sites. [ABSTRACT FROM AUTHOR]

Understanding how genetic diversity is maintained within populations is central to evolutionary biology. Research on colour polymorphism (CP), which typically has a genetic basis, can shed light on this issue. However, because gene flow can homogenise genetic variation, understanding population connectivity is critical in examining the maintenance of polymorphisms. In this study we assess the utility of genotyping-bysequencing to resolve gene flow, and provide a preliminary investigation into the genetic basis of CP in Isocladus armatus, an endemic New Zealand marine isopod. Analysis of the genetic variation in 4,000 single nucleotide polymorphisms (SNPs) within and among populations and colour morphs revealed large differences in gene flow across two spatial scales. Marine isopods, which lack a pelagic larval phase, are typically assumed to exhibit greater population structuring than marine invertebrates possessing a biphasic life cycle. However, we found high gene flow rates and no genetic subdivision between two North Island populations situated 8 km apart. This suggests that I. armatus is capable of substantial dispersal along coastlines. In contrast, we identified a strong genetic disjunction between North and South Island populations. This result is similar to those reported in other New Zealand marine species, and is congruent with the presence of a geophysical barrier to dispersal down the east coast of New Zealand. We also found some support for a genetic basis to colouration evidenced by positive FST outlier tests, with two SNPs in particular showing strong association to the expression of a striped morph. Our study provides one of the first population genomic studies of a marine organism in New Zealand, and suggests that genotyping-by-sequencing can be a good alternative to more traditional investigations based on traditional markers such as microsatellites. Our study provides a foundation for further development of a highly tractable system for research on the evolutionary maintenance of CP. [ABSTRACT FROM AUTHOR]

Biomonitoring is a common method to monitor environmental change in river ecosystems, a key advantage of biomonitoring over snap-shot physicochemical monitoring is that it provides a more stable, long-term insight into change that is also effects-based. In New Zealand, the main biomonitoring method is a macroinvertebrate sensitivity scoring index, with little established methods available for biomonitoring of fish. This study models the contemporary distribution of common freshwater fish and then uses those models to predict freshwater fish assemblages for each river reach under reference conditions. Comparison of current fish assemblages with those predicted in reference conditions (as observed/ expected (O/E) ratios) may provide a suitable option for freshwater fish biomonitoring. Most of the fish communities throughout the central North Island and lower reaches show substantial deviation from the modelled reference community. Most of this deviation is explained by nutrient enrichment, followed by downstream barriers (i.e. dams) and loss of riparian vegetation. The presence of modelled introduced species had relatively little impact on the presence of the modelled native fish. The maps of O/E fish assemblage may provide a rapid way to identify potential restoration sites. [ABSTRACT FROM AUTHOR]

We compare sediment vertical methane flux off the Mahia Peninsula, on the Hikurangi Margin, east of New Zealand's North Island, with a combination of geochemical, multichannel seismic and sub-bottom profiler data. Stable carbon isotope data provided an overview of methane contributions to shallow sediment carbon pools. Methane varied considerably in concentration and vertical flux across stations in close proximities. At two Mahia transects, methane profiles correlated well with integrated seismic and TOPAS data for predicting vertical methane migration rates from deep to shallow sediment. However, at our "control site", where no seismic blanking or indications of vertical gas migration were observed, geochemical data were similar to the two Mahia transect lines. This apparent mismatch between seismic and geochemistry data suggests a potential to underestimate gas hydrate volumes based on standard seismic data interpretations. To accurately assess global gas hydrate deposits, multiple approaches for initial assessment, e.g., seismic data interpretation, heatflow profiling and controlled-source electromagnetics, should be compared to geochemical sediment and porewater profiles. A more thorough data matrix will provide better accuracy in gas hydrate volume for modeling climate change and potential available energy content. [ABSTRACT FROM AUTHOR]