摘要:

Current meter moorings were deployed in six locations around the South Island, New Zealand, in 1993 to monitor the Southland Current. Off the eastern shelf of the South Island, the Southland Current is unidirectional, but variable in speed. Mean flows during 6 months at the 100 m isobath off Oamaru and Nugget Pt were 14.4 and 23.8 cm s−1, respectively, with standard deviations of 9 and 14.8 cm s−1. Flows south of Stewart Island, over the Snares Plateau, are more isotropic and considerably weaker, with mean flows typically 3–5 cm s−1.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516693

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Sponges of the order Dictyoceratida are poorly known in southern temperate regions. This paper describes five new species (generaPsammocinia, Thorecta, andThorectandra), from New Zealand coastal waters. These represent new records of all three genera from New Zealand.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516694

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The geographic distributions of 375 reef and reef‐associated fishes are reported for 16 regions ranging from Norfolk and Kermadec Islands in the north to Macquarie Island in the south. Species diversity was greatest at Norfolk Island (228 species) and lowest at Macquarie Island (6 species). Diversity declined linearly with increasing latitude. Most species were either widespread or had very restricted distributions. Widespread species generally ranged from Three Kings Islands to Stewart Island. The most widespread species occurred in 14 of the 16 regions. Species with restricted distributions were mainly tropical or subtropical species that occurred at one or more of Norfolk Island, Kermadec Islands, and North‐East North Island. Principal Components Analysis (PCA) identified eight groups of regions with similar species compositions. These eight groups reflected the latitudinal variation in sea surface temperature. Seven species distributional groups were recognised. Tropical (167 species) and antarctic (4 species) groups were identified using distributional data from the literature. A PCA ordination was carried out on the remaining 204 species and five further species groups were identified: subtropical (77 species), warm temperate (32), widespread (81), cool temperate (10), and subantarctic (4).

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516695

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Over 3000 otoliths and 100 000 length and sex records were examined of southern blue whiting caught from commercial fishing grounds on the Campbell Island Rise, south of New Zealand, during August and September between 1981 and 1989. Ages of juveniles were validated by following modes in length‐frequency data over a 13‐month period between September 1981 and 1982. Ages of adults were validated up to at least 10 years by following strong year classes both from otolith‐based age frequency distributions and from length‐frequency data from 1981 through to 1989. Independent analysis of the length‐frequency data using MULTIFAN further supported the adult otolith ages. Above age 10 there was less confidence in otolith ages, less agreement between readers and a greater degree of bias between readers. When using the data in catch‐at‐age models it is recommended that ages greater than 10 be grouped as a single plus group.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516696

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The diet of chinook salmon in New Zealand coastal waters is described, based on 803 adult salmon taken by commercial bottom trawlers in depths of 40–70 m off the mid‐Canterbury coast during three summers from 1991/92 to 1993/94, and 36 yearlings caught in a shallow coastal embayment in 1992 and 1993. Adult chinook salmon were primarily piscivorous, stout sprat—Sprattus muelleri—comprising 76% of the diet by weight. Pelagic swarming postlarval juveniles of the galatheid crabMunida gregaria, known as red krill, and juvenile hoki,Macruronus novaezelandiae, comprised 18% and 5% of the diet, respectively. Prey diversity was extremely low, both in terms of the number of species consumed (10), and the proportion of stomachs containing a single prey type (81%). Diet showed no relationship to predator size or geographical area. Interannual variabilityof Munidaand hoki in the diet appeared to be related to changes in their abundance. Diet of yearling salmon consisted of several larval fish species and the mysidTenagomysis macropsis. Both adult and yearling chinook salmon appeared to feed opportunistically on a relatively narrow spectrum of pelagic prey close to the ocean floor.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516697

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Plastic resin histology and transmission electron microscopy were used to examine the development of the retina in snapperPagrus auratus(Bloch & Schneider, 1801) larvae before, and at the onset of feeding. Light microscopy was used to examine changes in ocular morphology with increasing body size, in larval, juvenile, and adultP. auratus. There was a 96‐fold increase in eye size, from 0.23 mm diameter in a 4‐day‐old larva (3.42 mm standard length), to a maximum of 22 mm diameter in an adult of 333 mm fork length. Cells of the presumptive optic cup were undifferentiated in fish larvae at the time of hatching. Development of the eye proceeded rapidly so that at 3 days of age, a pigmented cone retina had formed and the optic nerve connected to the optic tectum. On the fourth day after hatching, the lens had become crystalline, and synaptic ribbons and vesicles were present in the cone cell synaptic junctions, indicating that the retina was now functional. This coincided with the onset of feeding behaviour in the fish larvae. Putative rod precursor cells were present in fish at 18 days of age. Juvenile and adult fish had duplex retinae with cones arranged in a regular mosaic in which four equal double cones surrounded a central single cone. Cone ellipsoid diameter increased during eye enlargement to maintain a closely packed array in fish of all sizes. Angular density of cones continued to increase with increasing eye size such that theoretical spatial acuity increased from 2°1′ (Minimum Separable Angle, MSA) in a 4‐day‐old fish, to asymptotic values of between 3′ and 4′ (MSA) in adult fish.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516698

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Chrysochromulina acantha, C. hirta, C. pachycylindra, and C. cf.polylepis(Haptophyceae = Prymnesiophyceae) are new records, based on transmission electron microscopy, for New Zealand coastal waters. The morphology and growth characteristics ofC. acanthaandC. hirta, and of C.simplexandC. ericina(also New Zealand isolates), are described.C. ericinaof the present study has a shorter haptonema (12–24 urn; non‐coiling), larger plate and spine scales, and fewer spine scales (with broader bases), than northern hemisphere isolates. Scales ofC. simplexfit the emended type description, whereas the large spine scales ofC. hirtaare shorter (≤ 11 μm) than the type description (20–30 μm).C. ericinaandC. hirtafall into a temperate (15–20°C), andC. acanthaandC. simplexinto a sub‐tropical (20–25°C), temperature group. All species tested grew well in brackish salinities (c. 23 through to 36);C. hirtagrew optimally at a salinity of 23. All tolerated 25–150 umol m−2s−1photon flux and pH of 7.5 to c. 8.4.C. acanthahad significantly faster growth rates (doublings d−1) with nitrate than with urea or ammonium chloride as nitrogen source, andC. hirtawith urea and ammonium chloride rather than with nitrate; none required selenium. None of the species tested was toxic toArtemia salina. C. ericinaandC.acanthawere phagotrophic. Calcofluor assisted in the identification ofC. quadrikontafrom other spine‐bearing species and FITC‐conjugated wheat germ lectin aided differentiation of theChrysochromulinaspecies fromPrymnesium parvumandP. patelliferum.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516699

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Sea surface temperatures (SSTs) from five coastal sites around New Zealand were compared with SST products from satellite AVHRR (Advanced Very High Resolution Radiometer) measurements between mid 1989 and late 1994. The objectives of this analysis were to test the accuracy and stability of the AVHRR product, and to distinguish how the coastal SST measurements represent the larger coastal areas which the satellite product measures. The AVHRR product is comparable with the coastal data up until mid 1991, after which the AVHRR product is colder by approximately 1°C. The difference peaked in late 1992 and probably died away by late 1993. This may be a result of the eruptions of Mt Pinatubo (June 1991) and/or Cerro Hudson (August 1991). The coastal measurements from relatively exposed sites are representative of the larger coastal regions measured by the satellites. In the case of more enclosed waters, particularly within harbours, the long‐term means of the coastal and AVHRR measurements agree before mid 1991, but the coastal measurements have larger seasonal cycles.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516700

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We measured the seasonal variation in phytoplankton biomass and photosynthesis in three size classes at four contrasting sites in Manukau Harbour during 1993–94. Low levels occurred during winter, when the < 5 μm class dominated (43–51% of chlorophylla, 46–58% of photosynthesis). The 5–22 um class dominated during early summer (47–66%, and 52–71%, respectively), whereas the > 22 μm class dominated during a late summer bloom ofOdontella sinensisand other large diatoms, particularly at the inner harbour sites (41–57%, and 43–61%, respectively). Values of the photosynthetic parameterPmBfor the different size classes were similar. Values ofIkfor the > 22 μm class were 22–44% higher on average than those for both the smaller classes. The ratio of photosynthesis to biomass in the euphotic zone—a simple index of potential growth rate—varied seasonally; but at any given time values for all three size classes were similar. Despite this, during summer the biomass of the smaller size classes increased much less than that of the > 22 μm class, implying the smaller cells were lost at a greater rate then.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516701

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

By use of a modern BOD bottle probe, a digital read‐out meter, and quadruplicate sampling, oxygen concentrations were routinely measured with a precision of ± 0.02 g DO m−3. This level of accuracy permitted measurement of Water Oxygen Demand (WOD), Net Production (NP), and Gross Production (GP) at all depths in the water column of lakes. Sediment Oxygen Demand (SOD) was also measured and found to be small when compared to the total water column oxygen demand in unstratified water but was a significant part of the hypolimnetic oxygen uptake. Measurements of GP were found to correlate closely with primary production values determined independently by means of the14C technique. Significant GP was also found in the hypolimnion of a mesotrophic lake, indicating that WOD does not always provide a measure of hypolimnetic oxygen uptake; net production does so in this situation. Further, WOD was found to decrease by about 20% per day in incubated samples, revealing that WOD incubations should never exceed one day in duration.

ISSN:0028-8330    

DOI:10.1080/00288330.1996.9516702

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor