摘要:

A total of 227 fish species, representing 113 families, are recorded from the Chatham Islands area (c. 860 km east of New Zealand): 148 are first records for the area and two,Scopelarchoides krefftiJohnson (Scopelarchidae) andOneirodes whitleyiBertelsen & Pietsch (Oneirodidae), are first records for New Zealand. Forty‐two species are identified from a single commercial trawling operation off the Chatham Islands; 13 of these species include juveniles. Notes are given on taxonomy, nomenclature, and distribution for selected fishes. Major conclusions reached are: some prominent New Zealand species are notably absent from the Chathams list, but many more fish species remain to be collected from the area; no endemic species are recognised; the observed abundance of juvenile fishes supports the hypothesis of larval transport from New Zealand to the Chathams by ocean currents; the main affinity of the fish fauna is with widespread and central New Zealand waters; small northern and southern elements present do not differ significantly in size or composition from northern and southern elements present in central New Zealand waters; and the fish fauna probably originated relatively recently from mainland NewZealandwaters.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516450

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The distribution of phytoplankton and the diversity of environmental conditions for their growth around the South Island, New Zealand, were examined in May 1989 by way of chlorophyllafluorescence profiling in combination with discrete sample analysis of nutrients and particulates, CTD‐profiles, and concurrent satellite images of sea surface temperature (SST). A composite of 7 overlaid SST images from the period of the cruise emphasised the strong north‐south and east‐west gradients in the oceanic environment. Water column sampling coupled with SST imagery was used to examine the frontal structure in Cook Strait, upwelling along the West Coast, gradients across the Solander Trough and through Foveaux Strait, and oceanographic features associated with the Subtropical Convergence off the East Coast and over Chatham Rise. A correlation analysis of the near‐surface water properties showed the zonal relationships between nutrients, nutrient ratios, and temperature, but also underscored the strong local influence of freshwater inputs around the South Island coastline. An analysis of the in vivo fluorescence data revealed large site‐to‐site differences in the fluorescence yield per unit extracted chlorophylla.The yield varied systematically with changes in the physical and biological environment across the Subtropical Convergence.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516451

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Sediments from Lake Te Anau comprise predominantly mineral components derived from the breakdown and weathering of the surrounding metamorphic country rocks, and a smaller biogenic silica component (mainly diatoms). Sedimentological and micropalaeontological analyses permit the differentiation of the samples into two types. First, sediments from river deltas and headwaters are characterised by high inputs of organic matter (up to 9%) and sandy to gravelly material. The amount of diatoms in these sediments (0.5–1% by volume) is by far outweighed by clastic components. Second, sediments from deep basins are more fine‐grained and fairly uniform in mineral and grain size composition with a relatively high organic carbon content (1–2%) in the clay fraction. The diatom content in the deep basin sediments is on average higher (5–10% by volume) than in the headwater samples owing to less dilution by clastic components. Nonetheless, the sediments in most of the lake basins appear to be predominantly allogenic. Endmember analysis of the compositional data groups the clastic sediments into five types depending on the surrounding source rocks for these sediments. The remoteness of the lake, the composition of its sediments, and their predominantly allogenic nature suggest that the lake could serve as a baseline for future global pollution studies.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516452

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Sewage effluent was diverted away from Lake Horowhenua in 1987, and external loads of nitrogen and phosphorus are estimated to have since dropped by about 20% and 90%, respectively. Lakewater quality was monitored sporadically before 1984, and routinely since then. In the first 3 years since diversion, water quality in the winter has not improved (levels of TP, TN, chlorophyll a, and Secchi depth unchanged), although DRP levels are now low. Summer chlorophyllalevel has halved, and it covaries significantly with TN level which has also fallen substantially. Summer TP and DRP levels have also more than halved, but remain very high (mean TP 420 mg m−3), primarily because of a large internal P load. Water clarity is still poor because levels of inorganic suspensoids and detritus have remained high.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516453

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

SCUBA records on the distribution and abundance of macrophytes in Lake Rotorua show marked changes between 1980 and 1988. Extensive weed beds ofLagorosiphon major(Ridley) Wager, present since the mid‐1950s, disappeared from the lake by 1982. The loss of theL. majorweed beds coincided with marked reductions in water clarity in the early 1980s and with a storm in April 1982.Egeria densaPlanchon spread rapidly from a small infestation in July 1983 to become the most abundant macrophyte in the lake by December 1988 (occupying about 475 ha), equivalent to the historicL. majorweed beds. We predict thatE. densawill be dispersed to become a major problem weed in other Rotorua lakes in the future.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516454

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Growth rates of shortfinned eels(Anguilla australis)from various locations in the Waikato basin, New Zealand, were determined by otolith examination. Two colour‐morphs from the Whangamarino Swamp exhibited different growth rates. Dark‐coloured eels (96% of the catch in low water levels) resided in the swamp; their growth was much slower than that of light‐coloured eels (40% of the catch in floods) which probably entered this habitat in flood waters from Lake Waikare, the Whangamarino River, or main wetland channels. Overall, growth rates were fastest in Lake Waikare followed by Lake Waahi, Lake Whangape, and Hakarimata pastoral streams. Dark‐coloured swamp eels were the slowest growing. Relative annual length increments ranged between 10 and 47 mm. Fast growth of eels in Lake Waikare may be the result of low densities owing to poor recruitment and heavy fishing pressure in recent years. Estimated age at threshold commercial size varied by 11 years throughout the Waikato.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516455

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Scales were taken from adult rainbow trout(Oncorhynchus mykiss, previouslySalmo gairdneri)from the Waimarino, Tokaanu, and Hinemaiaia Rivers; these are tributaries of Lake Taupo, New Zealand. The scales showed both widely‐spaced outer, and narrowly‐spaced inner, circulus zones. Although there were no among‐population differences in average circulus spacing in the outer growth zone, there were significant among‐population differences in the inner zone; these two zones are suggested to represent (common) lake and natal‐stream rearing, respectively. The back‐calculated minimum and average lengths at migration of juveniles from stream to lake was similar for all three populations (c. 94 mm and 140 mm, respectively) but there were significant among‐population differences in age at emigration. The scale patterns and stream sampling suggested that most Hinemaiaia River rainbow trout left the river within the first year whereas much higher proportions of juveniles in the other two streams overwintered before emigrating in their second year.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516456

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Life history and production of aDeleatidiumspecies (lilligroup) (Ephemeroptera: Leptophlebiidae) was studied for a 12‐month period in a flood‐prone river in the South Island, New Zealand in 1985–86. Mean larval density was highest (9170–18 580 m2) following a long period (> 5 months) of low stable flow (< 30 m3s−1), but typically ranged from 3550 to 4310 m−2. The annual cycle ofDeleatidiumwas difficult to interpret but there appeared to be two overlapping, poorly synchronised generations each year. Production of the winter generation calculated using the Size‐frequency method (51.40 g DW m−2), was five times higher than that of the summer generation (9.17 g DW m2) and annual production was 60.57 g DW m−2. Mean biomass of the winter generation (7.59 g DW m−2) was higher than that of the summer generation (0.87 g DW m−2) but the production to biomass ratio (P/B) of the summer generation (10.54) exceeded that of the winter generation (6.77). The ability to feed on low‐biomass epilithic layers, behavioural responses that minimise population losses during floods, and flexible life history patterns enable this species to attain high annual production in a physically harsh environment.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516457

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An artificial substratum invertebrate sampler, designed to mimic bryophytes, is described and evaluated. Invertebrate and algal colonisation of these structures was rapid, and invertebrate abundance peaked after 4 weeks. Following an exposure period of 2 months, total invertebrate density, taxonomic richness, and densities of many taxa were similar to those usually found on natural bryophytes, although densities of Nematoda,Limonia hudsoni(Tipulidae), and an empidid were lower. Taxa that are characteristic of riffles (e.g.,Deleatidiwnsp. andNesameletussp. (Ephemeroptera), orStenoperla prasinaandZelandobiussp. (Plecoptera) did not colonise the “stems” of the artificial bryophytes very extensively, but were present on the bases of these structures and on the underlying bedrock. TWINSPAN classifications identified a strong similarity between faunas of the artificial bryophytes and their real counterparts, but dissimilarity to faunas associated with riffles. Thus, the artificial bryophytes successfully mimicked their real counterparts as a habitat for invertebrate assemblages.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516458

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516459

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor