West Coast Of South Island Research Articles

Yellow substance in coastal and marine waters round the South Island, New Zealand

Abstract Yellow substance, the single largest component of dissolved organic matter in natural waters, is often the most important blue‐light‐absorbing constituent. The spectral absorption of yellow substance was measured by spectrophotometry in coastal (including fiord) and marine waters round toe South Island of New Zealand on Cruise 2027 (May 1989) of the RV Rapuhia; this examined a wide range of optical variables in relation to primary productivity and water mass characteristics. The spectral absorption by yellow substance fitted an exponential model, as is typical, and the spectral slope parameter varied only slightly (mean = 0.015 nm−1, standard deviation = 0.002 nm−1 ) for oceanic waters in the range 300–460 nm. The concentration of yellow substance, indicated by the absorption coefficient of filtrates at 440 nm (g440), varied more than two orders of magnitude, from 0.014 m−1 in the cold subantarctic water south‐east of the South Island, to 1.8 m−1 in humic‐stained surface water in Doubtful Sound. In marine waters, g440 was fairly tightly distributed around a mean of 0.06 m−1 ‐a value typical in sea waters. g440 did not correlate with phytoplankton pigment content of marine waters, probably because most of the yellow substance was old material, derived from terrestial production or long past marine production. Nor was g440 correlated with salinity. But there was a weak (probably incidental) correlation with temperature (r = +0.57), with higher values of yellow substance in the relatively warm waters along the South Island west coast than in the colder waters off the east coast. The concentration of yellow substance explained nearly half of the total variation in light (PAR) absorption at the stations visited.

Vegetation of a coastal sand dune system in southern New Zealand

The introduction of vigorous exotic species has destroyed much of the native sand dune vegetation along the coasts of South Island, New Zealand. However, some dunes built by the native cyperad Desmoschoenus spiralis still remain in the southwest.The dunes at Cole Creek, on the West coast of South Island, were chosen as a relatively pristine study area. 15 transects were laid through semi‐fixed dunes into dwarf forest. Environmental measurements were taken at regular intervals through the dunes: pH, soil moisture, organic matter, conductivity, nutrient status and elevation. Classification and ordination of these data demonstrated that two major environmental areas were present ‐ open dune and dwarf forest ‐ with an abrupt ecotone between them. Vegetation analyses revealed a loosely‐banded pattern, parallel to the sea. Vegetation types with few but constant species such as Desmoschoenus spiralis and Calystegia soldanella, predominated in the open dune. Forest species were rarely found seaward of the dune/forest boundary, though there was evidence the Spatial Mass Effect was operating.Multiple regression and canonical correlation of the vegetation and environmental factors showed that the main factors affecting vegetation patterns were the environmental complex related to distance from the sea, elevation above mean tide, soil alkalinity and moisture.

Historical monitoring of heavy metals in kahikatea ring wood in Christchurch, New Zealand

Tree ring wood was sampled from kahikatea trees in urban Christchurch, New Zealand, and from a background area on the west coast of South Island, New Zealand. The elements lead, cadmium, zinc, copper and manganese were analyzed in the wood using atomic absorption spectroscopy. Comparisons between the concentrations of the metals in the urban and background tree ring wood indicate a significant increase in lead, copper, zinc and cadmium since around 1860-70 for the urban trees. This can be accounted for by the start of urbanization and industrialization in Christchurch with the arrival of settlers from the United Kingdom. In the case of lead, a further increase occurred around 1950 corresponding to the escalating use of the motor car and leaded petrol. Manganese levels tended to fall from the late 19th century and may be associated with the draining of the swampy land in the city. It is suggested that the lead and cadmium in the trees mainly came from the incorporation of aerosol trapped by the bark, whereas the other three metals were probably mainly derived from the soil.

Fission‐track analysis of Tertiary uplift history of granitic basement in the Victoria Range, West Coast, New Zealand

Abstract Basement rocks of Paleogene sedimentary basins form the present physiographic highs on the West Coast of South Island, New Zealand. Apatite and zircon fission‐track ages of these basement rocks allow interpretations to be made on the depths of Paleogene burial and the Miocene uplift history of the Victoria Range. Apparent apatite fission‐track ages increase generally with elevation from 10 to 37 Ma. The ages of the high‐altitude samples represent uplift of rocks that have been only partially annealed during burial, while the young samples (i.e., those between 10 and 16 Ma) have been buried sufficiently deeply to allow annealing of all pre‐existing tracks. A rapid uplift pulse at this time reflects a major phase of compressional tectonics. Zircon ages also exhibit a general altitudinal correlation, but are not fully reset, and hence indicate that burial was to depths of less than 8 km.

Coastal-Trapped Waves on the West Coast of South Island, New Zealand

The coastal ocean response to wind forcing on the west coast continental shelf of South Island, New Zealand is examined using current, sea level and wind observations. Weather band motions over the northern region of the shelf appear to be dominated by the response to wind-forced flux through Cook Strait. Through-strait forcing is still evident in the currents of the southern region but west coast alongshore wind-forcing is also important. Most of the variance of nearshore weather band currents in the northern region of the shelf can be described in terms of coastal-trapped waves (CTWs). A fit of CTW modes 1 and 2 to the observations in that region indicates the equal importance of both modes, in agreement with the theories of strait-generated CTWS. Farther south, the across-shelf depth profile alters dramatically such that CTW structures change from being almost barotropic in the northern region to highly baroclinic. This rapid change in topography suggests that considerable scattering of CTWs might occur, a hypothesis which is supported by current observations in the southern region of the shelf.

Movements and possible stock relationships of the New Zealand barracouta,Thrysites atun,from tag returns

Abstract BetweenMarch 1984 and January 1987, 4097 barracouta were tagged to determine movements and possible stock relationships. Forty‐two recaptures have been recorded, with a greatest minimum distance travelled of 500 nautical miles and maximum time at liberty of 398 days. Most fish were tagged on the east coast of the South Island, New Zealand, and were recaptured along the east coasts of the North and South Islands. These movements appear to coincide with seasonal spawning migrations. It was not possible to determine stock relationships from this study alone but, in combination with the results of other research and commercial data, the existence of at least 3 separate spawing stocks is suggested: east coast North and South Islands; west coast South Island; and Chatham Islands. The relationship of west coast North Island and southern South Island barracouta to these suggested stocks is unclear.

Occurrence of hoki(Macruronus novaezelandiae)eggs and larvae in eastern Cook Strait

Abstract The presence of planktonic eggs and larvae of hoki (Macruronus novaezelandiae) in the Cook Strait region is recorded for the first time. Maximum hoki egg density found in samples collected from Cook Strait in September 1986 was 6813 per 100 m3. This is higher than egg densities recorded from the west coast South Island hoki spawning area. Most (95%) of the eggs were 1.5–3.0 days old. Maximum density of hoki larvae was 474 per 100 m3, with greatest recorded abundance in the 20–40 m depth range. Most of the larvae were over 5 days old. Depth and current considerations suggest that the seafloor canyons in eastern Cook Strait (Nicholson, Wairarapa, and Cook Strait Canyons) are likely spawning areas. The possibility that spawning of hoki in Cook Strait has occurred previously is discussed.

Input of river-derived sediment to the New Zealand continental shelf: II mineralogy and composition

Clay mineralogies and elemental compositions of river-borne sediments from New Zealand were examined as indicators of likely sources of the lithogenous component of sediments on the continental shelf. Relative occurrences of kaolin and smectite enabled the rivers to be fitted into three main groups. These correspond closely with geography as follows: (1) most of the rivers from North Island; (2) all the rivers from the north-east coast of South Island; (3) most of the rivers from the remainder of South Island. Elemental analyses of their sediments also led to a geographical grouping of rivers. Six main groups resulted from a Q-mode cluster analysis of elemental compositions. These were: the northernmost river (Wairoa River); the east coast of North Island; the west coast of North Island; the east coast of South Island; the south-east and west coasts of South Island; the west coast of South Island. There is substantial overlap between the groupings by clay mineralogy and by composition. The results can be interpreted mainly in terms of the geologies of source areas. Exceptions to regional trends reflect either an unusual geology in the source areas or low sediment loads, where soils contribute significantly to the sediments. The terrigenous component of offshore sediments and New Zealand riverine sediments have similar compositions, suggesting that the former are derived in a relatively unmodified form from riverine sediments.

The Use of the Word ‘Pakihi’ on the South Island West Coast in the Nineteenth Century

The Use of the Word ‘Pakihi’ on the South Island West Coast in the Nineteenth Century

Phosphorus requirements of grazed pasture on pakihi and recent soils of the South Island west coast

Abstract Trials on an Addison gley podzol and a Hokitika recent soil determined the production responses to applied superphosphate of pasture under sheep grazing over a 5-year period. Rates of 20 and 22 kg effective (i.e., citric acid soluble) P/ha resulted in 86 and 98% of maximum pasture production for the Addison and Hokitika soils, respectively. These rates were similar to predicted maintenance rates of 19 and 25 kg effective P/ha from the Computerised Fertiliser Advisory Scheme of the New Zealand Ministry of Agriculture and Fisheries. Pasture production was maintained at Olsen P levels of 8 μg/ml for the Addison soil and 22 μg/ml for the Hokitika soil, differing from the predicted Olsen P level of 17 μg/ml. When compared with earlier mowing-only trials with clippings returned, the use of short grazing durations at high sheep stocking densities and 4–6 week regrowth intervals resulted in similar pasture yield responses to added phosphorus.

Spectrophotometric determination of dissolved organic carbon in some South Island streams and rivers (note)

Abstract Absorbance at 360 nm and dissolved organic carbon (DOC) concentration were measured on 47 filtered water samples collected from streams and rivers of the west coast of South Island, New Zealand. The regression equation (DOC (g m‐3) = 59.6 Abs1 cm + 1.9) calculated from the data, reliably predicted DOC concentration within the range 1.6–43.2 gm‐3. This relationship is similar to that found fsr some Venezuelan and south‐eastern United Stales waters indicating that it may have widespread utility for estimating DOC concentrations in soft waters where DOC is dominated by humic substances

Oceanic exchange variability across the continental slope west coast, South Island, New Zealand

Abstract Current observations taken at depths between 630 and 830 m from the west coast South Island continental slope exhibit one‐ to four‐weekly periodicities superimposed on the semi‐diurnal tide. These variable flows at 630 m and otter large, longer‐timescale events have a significart onshore/offshore component of flow which leads to a similar transport of alongshore momentum and heat.

Effects of mowing interval, return of clippings, and potassium fertiliser on production and botanical composition of pasture in a mowing trial

Abstract In many small plot mowing trials on the South Island west coast, ryegrass (Lolium perenne L.)-white clover (Trifolium repens L.) swards have become dominated by unsown grasses. To investigate whether this botanical change was caused by mowing interval, the amount of clippings returned, or the rate of basal potassium fertiliser, a 3-year mowing trial was conducted. Increasing the mowing interval from 3 weeks to 6 weeks increased pasture yield by 48%. Associated with this was an increase in ryegrass and clover content of the pasture and a decrease in other grasses. The amount of clippings returned (70 v. 100%) and rate of potassium fertiliser application (50 v. 200 kg K/ha) had little influence on pasture yield or botanical composition.

Vitamin B12and copper in blood serum and liver of hoggets in relation to cobalt and copper status of west coast South Island soils and pastures

Abstract This study assessed the status of cobalt (Co) and copper (Cu) in yellow-brown earth (YBE) and pakihi soils, in pasture growing on these soils, and in serum and liver of lambs grazing for a year on the pasture. There had been no application of Co or Cu to YBE soils except in one instance, whereas these elements had been applied to pakihi soils at various times within the previous eight years since pasture establishment. Co in pasture was usually in the ‘adequate’ reference range category, although most of the soils were in the ‘responsive’ category. Cu in pasture was in the ‘marginal’ reference range. Co (as vitamin B12) was usually adequate in serum and in liver. Cu was marginal in serum, but adequate in liver. There was only one pakihi soil — the Moana soil at Bell Hill — where, despite recent topdressing with CoSO4, Co levels in liver were consistently in the marginal range.

Chemical soil test prediction of pasture responses to potassium on recent soils of the South Island west coast

Abstract Pasture yield responses to potassium (K) fertiliser were measured at 13 sites which had low levels of exchangeable K but varying amounts of non-exchangeable K. Of soil tests which measured available K (STK), exchangeable K (Kex), and non-exchangeable but plant-available K (TPBK) in the top 7.5 cm of soil, Kex gave the best correlation with relative yield. Further down the profile where exchangeable levels were low but non-exchangeable K levels were very high, only the TPBK test indicated the size of this potential source of K. Information from these soil tests can be used in mathematical models to predict fertiliser requirements for pasture.

Energy transfer through the shelf benthos off the west coast of South Island, New Zealand

Abstract Carbon‐flow pathways are proposed for the muddy‐shelf benthos off the coast of West‐land and north‐west Nelson, New Zealand (southeastern Tasman Sea). They are largely from bio‐mass estimates of sediment bacteria (adenosine triphosphate assay), meiofauna, macrofauna, and demersal fish, and literature values of production/ biomass ratios and energy transfer efficiencies. It is assumed that benthic secondary production (deposit‐feeder dominated) is mediated largely by microbial production, estimated for the upper 2 cm of sediment, as 39 gC m‐2 y‐1. About half this production may be required by benthic invertebrates: meiofaunal production, provisionally estimated as 3.6 gC m‐2 y‐1 consuming 12 gC m‐2 y‐1 and macrofaunal production, at 1.8 gC m‐2y‐1 using 6 gC m‐2y‐1. Bottom‐feeding fish, with a production of at least 0.05 gC m‐2 y‐1 are estimated to consume 0.5 gC m‐2 y‐1. The dominant source of energy for the benthos is pelagic primary production, estimated to average 182 gC m‐2 y‐1 on the shelf, a...

One to four weekly currents on the west coast South island New Zealand continental slope

Current meter measurements from the west coast South Island New Zealand continental slope exhibit flows with dominant time scales of between 1 and 4 weeks as well as the expected diurnal and semidiurnal tides. The alongshore Doodson filtered daily mean flow components are marginally correlated with the alongshore wind. The onshore flow components are marginally correlated with the envelope of the square of the semidiurnal and diurnal tidal flow, which is taken as a measure of energy loss from the tide. Observations from the southern flank of the Challenger Plateau, 200 km north of the continental slope observations and further offshore, also exhibit similar long-period variations. However, here the alongshore flow is more strongly correlated with alongshore wind than at the southern site.

Sediment texture of the continental shelf and upper slope off the west coast of South Island, New Zealand

Abstract Surface sediments on the continental shelf and upper slope off the west coast of the South Island, New Zealand, from north of Karamea Bight (40°45'S) to the Whataroa River mouth (43°07'S) consist almost entirely of sands and muds. Inshore (< 50 m depth) sediment is predominantly fine sand to coarse silt. Silt‐clay content increases towards mid‐shelf depths, and areas of mud occur at depths of about 90–140 m. Sediments tend to become coarser again on the outer shelf, and sandy mud or muddy sand covers the outer shelf and upper slope. The west coast shelf experiences a high input of fluvial sediment, probably c. 12–26 × 106 tonnes y‐1 for the study area. Sedimentation rate on the shelf is estimated to average at least 1–2 mm y‐1. Sedimentation is probably appreciably lower than this in the north of the area and higher in the south, and this is reflected in shelf grain‐size parameters and sediment carbonate content. There are north‐to‐south decreases in mean grain size and in the ranges of sorting a...

Input of river-derived sediment to the New Zealand continental shelf: I. Mass

The input of river-borne sediments to the New Zealand continental shelf has been calculated for all the major rivers and basins in New Zealand. South Island yields 284 ± 40 × 10 6 tonnes per year of sediment from a land area of 152 977 km 2 and North Island yields 105 ± 9·4 × 10 6 tonnes per year from a land area of 114 621 km 2. Particularly high discharges are noted off the west coast of South Island and east coast of North Island and result in higher offshore sedimentation there. The data are compatible with measured sedimentation rates on the New Zealand continental shelf. The specific sediment yield from South Island is amongst the highest previously recorded.

Microbial nitrogen transformations in sediments and inorganic nitrogen fluxes across the sediment/water interface on the South Island West Coast, New Zealand

In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar C N ratio of 5.9–10.9, and the total N P ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m −2 day −1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m −2 day −1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m −2 day −1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m −2 day −1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m −2 day −1, respectively.