Central Otago Research Articles

Changes in total soluble solids concentration, fruit acidity, and yeast assimilable nitrogen in response to altered leaf area to fruit weight ratio in Pinot noir

The increasing consumer demand for lower alcohol wine and the need to mitigate against a warming climate presents new challenges for winegrowers and the desire to produce grapes with lower total soluble solids (sugar) or earlier harvesting, while preserving other wine compounds and attributes, particularly for varieties intended for red wine production. We investigated how reducing vine leaf area through shoot trimming and leaf removal, applied at different severities and timings to modify the leaf area to fruit weight (LA) ratio, affects fruit composition for producing lower alcohol quality Pinot noir wine. Shoot trimming treatments (half canopy, H in 2015/16 and 2016/17, and quarter canopy, Q in 2016/17 by alternately removing leaves after trimming shoots to half) were applied shortly before veraison (V-, E-L 34), during veraison (V, E-L 35) and post-veraison (V+, E-L 36) in three different vineyard locations (Marlborough, Canterbury and Central Otago, New Zealand). Untrimmed vines served as the control. Lateral shoots were removed during treatment application, and regrowth was removed to maintain a consistent leaf area. Results showed that reducing the LA:FW ratio delayed the accumulation and concentration of total soluble solids (reduction of 1.0 to 2.7 °Brix) at harvest in all trimmed vines over both seasons. Berry weight, malic acid concentration, titratable acidity, and pH at harvest were unaffected by trimming. At target TSS levels of 18 °Brix (10 % ethanol, v/v) in the Marlborough vineyard and 20 °Brix (11 % v/v) in the Central Otago vineyard, V+ vines showed malic acid and titratable acidity levels comparable to the control. At the Canterbury vineyard, these parameters remained similar across all treatments at 16 °Brix (8.9 % v/v). Yeast-assimilable nitrogen concentration increased (188 to 411 mg/L) in early trimmed vines. At Central Otago, roots showed lower carbohydrate reserves across all trimming treatments, likely due to the high yield at the site, while at Canterbury, trimming did not result in significant differences in carbohydrate reserves, likely due to the low yield at the site. At the Marlborough vineyard, vines trimmed early and more severely had less starch in their roots, while HV+ vines maintained similar levels of starch to controls. In conclusion, halving the canopy post-veraison (HV+, LA 0.70 m²/kg as observed in Marlborough) could be considered a viable viticultural option to lower sugar accumulation, thereby reducing potential alcohol content, without affecting titratable acidity and pH. This practice offers significant potential for adapting to a warming climate and producing lower alcohol Pinot noir wines in a sustainable manner.

Doing dams better? A case study of a proposed pumped hydro scheme at Lake Onslow, Central Otago

AbstractWater resource managers and Geographers share common interests in meeting Sustainable Development Goal Seven (universal access to affordable energy) and addressing climate change. Hydropower plays a key role but dams have environmental, social and cultural consequences. The Hydropower Sustainability Assessment Protocol (HSAP) aims to ensure that dams are built safely and potential impacts are understood. This study of a proposed pumped hydro scheme at Lake Onslow in Central Otago, New Zealand, considers the effectiveness of HSAP. Results reported here show that HSAP works well but that it can also be improved by including new groups of stakeholders and by widening the perception of risks.

A synopsis of the Early Miocene St Bathans Fauna of New Zealand

The St Bathans Fauna, from sites near the village of St Bathans, Central Otago, South Island, is the first substantive pre-Quaternary terrestrial vertebrate fossil fauna discovered in New Zealand. This fauna derives from 33 sites or discrete sedimentary beds located in the lower 50 m of the lacustrine Bannockburn Formation, Manuherikia Group, and is generally accepted as local stage Altonian (19–15.9 Ma; Burdigalian, Early Miocene) in age. Investigations since 2001 have revealed an abundant and diverse fauna from over 9000 catalogued lots that is herein reviewed. Invertebrates notably include eight genera and species of terrestrial molluscs. Among vertebrates, freshwater fish remains dominate with 17 species evidenced by 16,500 analysed otoliths (genera Neochanna, Galaxias, Prototroctes, and Mataichthys) and many thousands of bones. Birds (minimally 45 species, several thousand bones) are the most common non-fish vertebrates, among which waterfowls dominate all assemblages (10 species). Co-occurring with these was a diverse herpetofauna, including undetermined crocodylians and a terrestrial turtle, both absent in Recent faunas. Significantly, the St Bathans Fauna evidences that Zealandia already had all of New Zealand’s ‘old’ endemic Recent taxa (sphenodontids, leiopelmatids, dinornithiforms, apterygids, aptornithids, strigopoid parrots, acanthisittids, and mystacinids) during the Early Miocene. Furthermore, it includes Australasia’s oldest ardeids, two flightless rallids, a novel higher landbird family, a greater diversity of bats, and terrestrial mammals. All sites reflect a single fauna, except that the ducks Manuherikia lacustrina (stratigraphically lower in section) and M. primadividua (higher) have a mutually exclusive distribution that is not yet correlated with any other biotic distribution differences.

Detrital gold morphology and recycling around the early Miocene St Bathans paleovalley, Central Otago, New Zealand

ABSTRACT The St Bathans paleovalley developed as a major southwest-draining fluvial system during early Miocene rejuvenation of the Central Otago landscape. Rounded quartz pebbles and detrital gold were recycled from Eocene quartz pebble conglomerates into the headwaters of this Miocene paleodrainage system on the northern margin of the Otago Schist belt. Gold particle morphology is mostly irregular and rough, locally with relict gold crystal shapes, plus a minor component of well-defined flakes. Incremental rounding and surface deformation at the 10 µm scale has occurred through several recycling events in Central Otago, hindering linkage of Miocene and younger placer gold to ultimate basement sources. More intense deformation of the gold, forming thin flakes, occurred in the lower reaches of the Miocene paleodrainage system as gold was transported >100 km to eastern Southland. Hence, the St Bathans paleovalley has been an important source of gold for historic mining in Central Otago and Southland.

The moa footprints from the Pliocene – early Pleistocene of Kyeburn, Otago, New Zealand

ABSTRACT In March, 2019, a trackway of seven footprints was found at a riverbank outcrop of Maniototo Conglomerate Formation in the Kyeburn River, Central Otago, South Island, New Zealand. In this study, we describe this first known occurrence of moa (Dinornithiformes) footprints to be found and recovered in Te Waipounamu/South Island. Footprints of the trackway were ∼46 mm deep, 272–300 mm wide and 260–294 mm in length. An associated separate footprint was 448 mm wide and 285 mm long. Cosmogenic nuclide dating of adjacent overlying beds from the same formation establishes a mean minimum age of burial age for the tracks of 3.57 Ma (+1.62/−1.18 Ma) with a mode of 2.9 Ma, which we interpret to be Late Pliocene, with a conservative age range of Pliocene to Early Pleistocene. The trackway maker is identified as a moa from the Emeidae family, probably from the genus Pachyornis, with a mean mass of 84.61 kg that was travelling at a speed of 2.61 kmh−1. The single adjacent footprint was made by an individual from the family Dinornithidae, most likely from the genus Dinornis with an estimated mass of 158 kg. These moa footprints represent the second earliest fossil record of moa.

Hydrogeological controls on formation of Patearoa saline site in Central Otago, New Zealand and definition of geoecological salt lines

ABSTRACT The Patearoa saline site in Maniototo basin has developed on variably clay-altered Otago Schist. Decomposition and sedimentary redistribution of schist outcrop components has led to formation of bare soil-free substrates (upper metre scale) with contrasting permeability to rain and shallow groundwater percolation. Relatively impermeable clay-rich substrates, with a surface crust (cm scale) of detrital clay and muscovite, are saline with electrical conductivity (EC) of 1–35 mS/cm and locally hyperalkaline (pH > 10), with evaporative mineral accumulations. These saline substrates are downslope of more permeable substrates consisting of coarse schist debris and fractured outcrops, which have lower salinity (EC < 1 mS/cm) and lower pH (<7). A salt line can be mapped at metre scale between these substrate types on hillsides. The geochemical contrasts across the salt line have strong effects on plant communities that are colonising bare ground. Initial colonisation of bare saline substrates by some plants changes the geochemical signatures of the surficial few centimetres to form proto-soil with lower EC and pH. Proto-soil development facilitates further colonisation by pasture grasses, but the underlying substrates remain saline and highly alkaline. Salt lines similar to the one at Patearoa are mappable elsewhere in the Otago area and constitute fundamental geoecological boundaries.

Phenological development of subterranean clover (Trifolium subterraneum L.) in New Zealand in response to different climate change scenarios

Climate predictions for New Zealand for the coming decades suggest rising temperatures (+0.7–3 °C), increased diurnal temperature and variable precipitation patterns that differ around the country and with seasons. The most common pattern of annual precipitation indicates the largest increases in the west of the South Island and the largest decreases in the east of the North Island and coastal Marlborough. The phenophases of subterranean clover were estimated and quantified using a thermal time-based model under different climate scenarios based on greenhouse gases and aerosol pathways over the 21st century, known as the Representative Concentration Pathways (RCPs), at two periods (mid and end of the century). The estimated flowering (R3) and post- flowering (R6-R11) date change showed a consistent trend across all districts. The largest date advances (≥ 5 days) were predicted for the three current latest flowering districts (Mackenzie, Queenstown and Central Otago). A reduction of the plant’s life cycle, for both ‘Early’ and ‘Late’ maturity cultivars may have undesired consequences for forage yield so genetic material with later flowering dates may be useful. Adaptation strategies to mitigate the future warming effects include using ‘Late’ flowering cultivars and greater use of supplementary feed through summer dry conditions.

Genetic characterization and prevalence of Pseudomonas syringae strains from sweet cherry orchards in New Zealand

AbstractBacterial canker of cherry, caused by Pseudomonas syringae pathovars, is a major constraint to cherry growing in New Zealand. The prevalence of strains from cherry orchards in Central Otago, the main growing area for cherries in New Zealand, was studied, to better understand the epidemiology of the disease. Pseudomonas spp. isolates were collected from symptomatic and asymptomatic cherry tissue from 23 commercial cherry orchards in 2015. Isolates were classified into strains belonging to three different taxonomic groups by determining their phylogeny using the gltA gene sequence for all the strains and multilocus sequence analysis (MLSA) of four housekeeping genes for 35 strains. Pathogenicity of all Central Otago strains was tested on immature cherry fruit to support the phylogenetic classification. The two main taxonomic groups were P. syringae pv. syringae (Pss) and P. syringae pv. morsprunorum race 1 (Psm1), in Phylogroup 2 (PG2) and Phylogroup 3 (PG3), respectively. The third group comprised nonpathogenic strains classified as Pseudomonas spp. Strains of Psm1 formed a monophyletic group, representing an almost clonal population. There was more variation detected within strains of Pss, although they were restricted to group PG2d. Nonpathogenic Pseudomonas spp. and pathogenic Pss and Psm1 strains coexisted in the same orchard. It was concluded that Pss is the predominant pathovar in Central Otago. This is the first detailed study of the P. syringae species complex in cherry orchards in New Zealand and provides the basis for future epidemiology studies.

Basanite cobbles in Pleistocene sediments in Central Otago and their implications for intraplate volcanism and Clutha River paleo-drainage

ABSTRACT The occurrence of volcanic basanite cobbles in Pleistocene terraces at Galloway and in the upper Clutha valley in Central Otago, in an area devoid of known volcanic edifices, has implications for Cenozoic intraplate volcanism and Pleistocene drainage in the region. We present petrographic, mineralogical, whole rock geochemical and Sr-Nd-Pb isotopic data, as well as an 39Ar-40Ar date of 24.4 ± 0.06 Ma, together with mineral analyses of enclosed peridotite xenoliths. We conclude from this dataset that these alkaline basanite cobbles are most likely derived from the Alpine Dike Swarm in northwest Otago, probably in the Lake Wanaka-Hawea-Luggate area, which extends the volcanic field east of its known extent. The pilotaxitic textures and presence of intersertal glass, along with the volume of basanitic material, suggests that the source rocks were likely effusive, which would make this the first such known component of the Alpine Dike Swarm and requires emergent land at that time. The occurrence of the Galloway basanite cobbles implies that Pleistocene Clutha River flowed through or over what is now the Dunstan Range. The young (late Pleistocene) age of all the basanite-bearing gravels means that the basanite cobbles have likely been reworked several times before final deposition.

Hair today, gone tomorrow: Analysing potential mercury exposure in 19th‐century New Zealand gold miners using Laser Ablation‐Inductively Coupled Plasma‐Mass Spectrometry

AbstractToxic metal or element exposure has the potential to cause significant negative health effects in human populations. During the goldrushes of the colonial period, mercury amalgamation was one of the most common methods of extracting gold from alluvial deposits or crushed ore, and exposure to mercury was an occupational health hazard. In this study we examine mercury exposure in mining populations from New Zealand’s first major goldrush, which began in Central Otago in 1861. We explore mercury toxicity through laser ablation inductively coupled mass spectrometric analysis of archaeological hair and sediment samples associated with the Tuapeka goldfields. Our analysis highlights ubiquitous low‐level mercury exposure on the goldfields, as well as one individual with such high mercury concentrations in their hair that we suspect direct mercury intake, perhaps medicinally, rather than from environmental contamination.

Mixed yeast communities contribute to regionally distinct wine attributes

There is evidence that vineyard yeast communities are regionally differentiated, but the extent to which this contributes to wine regional distinctiveness is not yet clear. This study represents the first experimental test of the hypothesis that mixed yeast communities-comprising multiple, region-specific, isolates, and species-contribute to regional wine attributes. Yeast isolates were sourced from uninoculated Pinot Noir fermentations from 17 vineyards across Martinborough, Marlborough, and Central Otago in New Zealand. New methodologies for preparing representative, mixed species inoculum from these significantly differentiated regional yeast communities in a controlled, replicable manner were developed and used to inoculate Pinot Noir ferments. A total of 28 yeast-derived aroma compounds were measured in the resulting wines via headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Yeast community region of origin had a significant impact on wine aroma, explaining ∼10% of the observed variation, which is in line with previous reports of the effects of region-specific Saccharomyces cerevisiae isolates on Sauvignon Blanc ferments. This study shows that regionally distinct, mixed yeast communities can modulate wine aroma compounds in a regionally distinct manner and are in line with the hypothesis that there is a microbial component to regional distinctiveness, or terroir, for New Zealand Pinot Noir.

The ‘Gulliver’ fish fauna of an early Miocene freshwater system of New Zealand; new insights from otoliths from the Bannockburn Formation

ABSTRACT The early Miocene palaeolake Manuherikia in Central Otago, South Island, New Zealand is a prime source for reconstructing the terrestrial and freshwater biota of past Zealandia. Otoliths of fishes that once lived in this lake system were first described in 2012. Here we report the results of extensive additional sampling resulting in a total of 16,500 fish otoliths from a wide set of stratigraphic levels and environmental settings within the Bannockburn Formation near St Bathans. Six new species are described: Galaxias crassus, Galaxias naviculus, Galaxias nitidus, Galaxias polei, Galaxias tholus, Mataichthys asymmetricus. The entire freshwater otolith-based fish fauna of the Bannockburn Formation now encompasses 17 species, 10 in Galaxiidae, 2 in Prototroctidae and 5 in Eleotridae; all families present in the freshwater systems of New Zealand today. Correlation with putative related extant taxa reveal that the fishes from the Bannockburn Formation were relatively large, often at the upper margin of the extant sizes of fishes in the respective groups or even larger. This ‘Gulliver’ fish fauna is consistent with other fossil and extant ‘gulliverisms’ observed in various Zealandian biota. Environmental and putative evolutionary explanations, aspects of the taphocoenosis and possible stratigraphic implications of the otolith assemblages are discussed.

Miocene-Holocene river drainage evolution in Southland, New Zealand, deduced from fish genetics, detrital gold and geology

ABSTRACT We integrate multidisciplinary observations to provide a regional-scale synthesis of river drainage reconfiguration in Southland (New Zealand) between the Miocene and the Holocene. Distributions of sedimentary clasts, including alluvial gold, garnets and chromite, are combined with freshwater fish genetics, surface geomorphology, and basement geology to constrain river drainage directions and interconnections through time. River evolution in much of the South Island has been dominated by localised tectonic uplift linked to distant Alpine Fault tectonism. In the southeast, the rise of ranges between Central Otago and Southland severed initial long-distance southward drainage and gold transport and isolated fish species. Plio-Pleistocene range uplift caused the recycling of older alluvial gold deposits into the new Southland river systems. The most significant Southland drainage reorientations have occurred through the Pleistocene, in parallel with similar processes in Central Otago. In particular, the Pomahaka River has evolved geomorphologically from a Southland-linked catchment to become a major tributary of the Clutha catchment, with associated biological evolution of distinctive endemic freshwater fish.

Trends in agrichemical use on stonefruit orchards in New Zealand from 2004–2019

ABSTRACT Annual spray diaries from orchardists in the two main stonefruit growing regions, Central Otago and Hawke’s Bay, were analysed. The analysis was restricted to products for disease and arthropod pest control. It included apricots, cherries, nectarines, peaches and plums grown as fresh fruit for export and domestic markets, and processing crops. Mean fungicide and bactericide applications declined from 13 to 9/block/year in Central Otago, but rose from 11 to 13 sprays in Hawke’s Bay. Central Otago is drier than Hawke’s Bay and the regional spray programmes now better match the respective climates. Despite large annual variations in rainfall and numbers of brown rot (Monilinia fructicola) infection periods in both regions, there was little correlation with the numbers of fungicides applied that had activity against brown rot. The products used against diseases changed substantially during the study period. Insecticide and miticide sprays averaged 5 applications per year in Central Otago at the start of the study and declined to 4-6/crop/year (overall mean of 4) by 2018–19. Hawke’s Bay growers used 1–3 insecticide sprays per crop (overall mean of 2) throughout the study. The proportion of selective insecticides applied grew in Central Otago, but fell in Hawke’s Bay.

Four new species of Craspedia (Compositae/Asteraceae, Gnaphalieae) from the South Island of New Zealand, all characterised by dark red-purple anthers

ABSTRACT In New Zealand, Craspedia (Compositae/Asteraceae, Gnaphalieae) has much more morphological variation than previously recognised, as demonstrated by suggestions of about 50 informally named putative species and varieties. As part of our research towards a revision of New Zealand Craspedia we have focused here on those plants that can be segregated from other New Zealand species of Craspedia by their dark red-purple anthers. We are describing the four species C. argentea, C. diversicolor, C. rugosa, and C. thinicola from the South Island of New Zealand as new to science. They are recognised based on a morphological assessment of scape, rosette leaf, inflorescence, floret, and achene characters following detailed herbarium, cultivation, and field studies. All four species are threatened. Each is known from a single locality only. Craspedia argentea, endemic to Mahaka Katia Scientific Reserve (Pisa Flats) in Central Otago, has rosette leaves with a dense, silvery, appressed to floccose lanate indumentum. Craspedia diversicolor was once more widespread in the Canterbury plains but is now restricted to Wakanui Gully in Canterbury, where only two plants were found recently. The colour of its rosette leaves varies from olive-green to grey, to dark red. Craspedia rugosa, known only from Cameron Fan, near Lake Heron, in Canterbury, can be distinguished from all other species of Craspedia by its rugose, dark-red-mottled rosette leaves. Craspedia thinicola is confined to the stable deflation hollows at Kaitorete Spit, adjoining Banks Peninsula in Canterbury. Its rosette leaves are covered with a dense, appressed, lanate indumentum. When in the open its leaves are appressed to the ground, with the upper rosette leaves strongly recurved. The formal taxonomic treatments for each species are provided, together with illustrations and descriptions of their morphology, distribution, habitat, phenology, etymology, and cytology, as well as an assessment of their conservation status.

Do Woody Plants Facilitate Herbaceous Plants in Dryland New Zealand?

Aims: Woody plants are postulated to facilitate understory herbaceous plants in arid and semi-arid environments worldwide, the so-called ‘nurse plant’ effect, but this mechanism. has been little studied in the drylands of New Zealand. Indigenous dryland plants postulated to have grown under woody shrubs in New Zealand before European settlement may benefit from their recovery, or even their replacement by exotic substitutes. The aim of this study was to investigate woody pant facilitation of understory herbaceous plants in dryland New Zealand.&#x0D; Study Design: In this study I investigated the effects of canopies of four shrub species – Kunzea serotina, Discaria toumatou, Rosa rubiginosa and Coprosma propinqua – on herbaceous plant species richness, in the presence and absence of rabbit grazing (for K. serotina).&#x0D; Place and Duration of Study: The study was conducted in the drylands of Central Otago, New Zealand, from August 2007 to January 2009.&#x0D; Results: Herbaceous plant species richness was lower under canopies of K. serotina, possibly because the dense canopy shaded the understorey plants. It was higher under C. propinqua, D. toumatou and R. rubiginosa canopies than in their adjacent open grasslands, but for all three species this effect was seen only in winter. Woody plant canopy protection of understorey herbaceous plants against winter frost may explain the effects. Grazing significantly decreased herbaceous plant species richness. Since D. toumatou, R. rubiginosa and C. propinqua showed facilitative effects on herbaceous plant species richness they are possible agents for the restoration of dryland vegetation.&#x0D; Conclusion: I conclude that control of grazing and the protection of these three woody species could be a good management strategy for the maintenance of a predominantly indigenous dryland mixed herbaceous and woody vegetation in Central Otago.

Geochemical evolution of high-pH sodic salt pans in Central Otago, New Zealand

ABSTRACT Soil-free sodic salt pans with local pH >10 have formed on loess and schist-derived clay surfaces in the semi-arid climate of Central Otago. This study identifies evaporative mineral distributions and associated variations in surface geochemistry, and these results are relevant to survival of rare halophytic plants on some of the pans. Evaporative salts on pan surfaces are dominated by NaCl from marine aerosols, and Na-sulphates and Na-carbonates. Some of the Na in evaporites was derived from alteration of schist-derived albite and Na-bearing smectite formed from albite. The high pH pan surfaces result from a combination of long-term (decades to millennia) albite alteration and short-term (minutes to months) Na-carbonate dissolution and recrystallisation. This muscovite is variably cemented by evaporative salts, and some crusts have abundant salt-dissolution voids. High pH has facilitated dissolution of aluminium and silica from albite and smectite, with evaporative precipitation of Al-oxyhydroxide contributing to crust cementation. Different dissolution rates of evaporative minerals during rain events and damp seasons results in differential mobility of salt components downslope. The salt pans are physically and chemically dynamic features that have formed on time scales of decades to centuries.

The politics of water governance in Central Otago, New Zealand: Struggling with a nineteenth century legacy

AbstractToday, in Central Otago, New Zealand, with competing claims for water beyond irrigation, farmers and water conservation interests are at loggerheads, and freshwater management has become a site of intense debate, competition and political action. We comment on the polarised politics of water governance in Central Otago, writing from the perspective of fish and gamebird management. Our commentary is allied to an interpretation of freshwater allocation for irrigation in New Zealand, which emphasises the emergence and dominance of a singular ‘more water’ discourse in rural development in the 2000s.

Wines from the hinterland: comparing availability of local wines on wine lists in two New Zealand tourism destinations

PurposeThis paper aims to situate restaurant experiences and in particular the wines available on wine lists, within the wider context of wine tourism. This is done by examining the wine lists of restaurants in two New Zealand destinations, focusing in particular on the showcasing of “local wines” and the factors behind these offerings, and outlines the potential implications for hospitality managers and a wider academic audience.Design/methodology/approachThe population of restaurants in each destination was identified using online directories, from which a sample of wine lists, comprising 84 in Christchurch and 43 in Queenstown, was systematically analysed to identify number of wines, regional origin, price and other information. Following this, key informant interviews in restaurants in each destination explored decision-making factors in stocking local wines, including consumer base, existing networks and reputation and additional challenges and opportunities.FindingsRestaurants in each destination offered more New Zealand than foreign wines on their lists, though significant regional differences are apparent. Queenstown restaurants offered slightly fewer imported wines and significantly more local (Central Otago) wines than Christchurch restaurants. The global awareness of Central Otago pinot noir is a factor in this wine list representation, but there are also other influences, including the greater concentration of overseas visitors (pre-pandemic) and more significant visibility and greater opportunities for wine tourism experiences within the destination.Originality/valueThis paper represents an important addition to academic research on wine marketing in the on-premise sector of emerging wine regions. This paper also highlights the potential significance of restaurant meals – including wine choices – in overall wine destination experiences and demonstrates differences in approach between restaurants in wine regions of similar size but with different reputations, international visitation and wine tourism infrastructure.

A vanished ecosystem: Sophora microphylla (Kōwhai) dominated forest recorded in mid-late Holocene rock shelters in Central Otago, New Zealand

A vanished ecosystem: Sophora microphylla (Kōwhai) dominated forest recorded in mid-late Holocene rock shelters in Central Otago, New Zealand