摘要:

The age and growth of alpine galaxias(Galaxias paucispondylus)and longjawed galaxias(G. prognathus)were determined from samples of fish collected from the Rangitata River, Canterbury, New Zealand. Both species are small (total length up to 112 mm and 87 mm respectively), slender fish with entirely freshwater life histories. Aged from sagittal otoliths, the majority of fish were age 0+and age 1+, although alpine galaxias up to age 4+and longjawed galaxias up to age 3+were found. Growth of both species was greatest during their first year of life. Alpine galaxias continued to grow in subsequent years, but fish of ages 2+, 3+, and 4+were exclusively females. Longjawed galaxias showed little increase in length after their first year of growth, but for all ages > 0+the females were significantly larger than males. Overall, both species are not only similar to each other, but also similar to the dwarf galaxias (G.divergens)and the common river galaxias (G.vulgaris), particularly in terms of their size, habitat, diet, and the age structure of populations.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516410

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of land use on fish community structure was examined at fifty‐five sites in tributaries draining exotic, indigenous forest and pastoral catchments in the Hakarimata range in March and April 1987. Using a model containing percentage woody debris, temperature, and substrate coarseness, 76% of the sites were classified into correct land uses by discriminant analysis. This indicated that differences in stream habitat, and hence of the fish fauna, were related to effects of changed land use rather than other confounding physical or geographical features of the streams in the catchments. Tributaries in indigenous forest were numerically dominated by banded kokopu(Galaxias fasciatus)and longfinned eel(Anguilla dieffenbachii), with redfinned bully(Gobiomorphus huttoni)and giant kokopu (G.argenteus)occasionally being caught. Pastoral streams below the forest generally supported higher densities and contained more species including the forested species above, Cran's bully(G. basalis), and shortfinned eel (A.australis). As the amount of indigenous forest in the catchment decreased the fauna became less abundant and less diverse and was dominated by both species of eel and Cran's bully.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516411

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Measurements of arsenic concentrations in macrophytes, sediments, fish, and water were made in Lake Rotoroa (37°48'S, 175°16'30"E) and nearby Lake Rotokauri in April and June 1983. Lake Rotoroa, which had been sprayed with sodium arsenite in 1959 to control problem growths of aquatic weeds, showed elevated concentrations of As in its macrophytes (193–1200 mg (kg dry wt)−1) and surficial sediments (540–780 mg (kg dry wt)−1) compared to lake Rotokauri (< 20 and 16.5–40 mg (kg dry wt)−1, respectively). The levels of As recorded in the macrophytes and sediments of Lake Rotoroa were between one and two orders of magnitude greater than those reported from studies of uncontaminated lakes and in the high range of those recorded for lakes subject to geothermal influences or inputs from mining and industry. Sediment As concentrations in Lake Rotoroa were also greater than values reported for seven North American lakes subject to multiple applications of sodium arsenite herbicides. All fish tissues sampled had As concentrations below 1 mg (kg wet wt)−1suggesting minimal accumulation, and levels in the lakes waters were below 0.01 g m−3.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516412

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The rnacrophyte communities present in Lake Parkinson (37°19'S 174O41'E), a 1.9 ha eutrophic sand‐dune lake, are described 5 years after removal of grass carp(Ctenopharyngodon idellaVal; 218 kg ha−1). Eradication of the adventive submerged speciesEgeria densaPlanchon (dependenton vegetative reproduction from stem fragments) as a result of grass carp stocking led to the re‐establishment of a predominantly native macrophyte association from seeds, spores, and buried rhizomes after grass carp removal. EmergentEleocharis sphacelataR. Br. re‐established around the lake margins and throughout the lake's shallow southwestern arm, whereas submerged communities domin ated byPotamogeton ochreatusRaoul andNitella hookeriA. Br. grew to a maximum depth of 5 m.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516413

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Off Westland in February 1982, ciliated protozoans were numerically most abundant and accounted for >95% of the microzooplankton assemblage. Naked oligotrichs dominated these ciliated protozoans, particularly in offshore waters, where phytoflagellates were most abundant. Tinlinnids were relatively more abundant inshore.Stenosomella nivalis, a tintinnid with silica‐encrusted bowl, dominated an upwelling station close to Wanganui Bluff.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516414

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The possible effects that marine reserve protection has had on densities of some reef fish and large invertebrates were investigated near Leigh (north‐eastern New Zealand) by a series of sampling programmes between 1976 and 1988. Fish counts at intervals during the 6 years after the initial establishment of the Cape Rodney to Okakari Point Marine Reserve in 1975 suggested that red moki (Cheilodactylus spectabilis)had increased in abundance whereas five others had remained at approximately constant densities. A comparison of data between 1978 and 1988 also revealed few consistent differences in fish abundances. A detailed survey in 1988 between sites inside and outside the marine reserve showed no clear patterns for sea urchins(Evechinus chloroticus)and several fish; trends for increased abundances in the marine reserve of fish such as snapperPagrus (=Chrysophrys) auratus, blue cod(Parapercis colias), and red moki; a very striking increase in numbers of rock lobsters(Jasus edwardsii)within the marine reserve; and an obvious trend for increased size of snapper in the marine reserve. Most of the trends, however, were not statistically significant, owing largely to the low power of the tests used. Although it is now generally accepted that the creation of marine reserves such as the one at Leigh results in increased abundances of certain organisms, our study highlights the difficulty of rigorously demonstrating this, especially for patchily distributed and mobile fish species.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516415

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The New Zealand big‐handed crab,Heteroziusrotundifrons, shows a full flexion display when mildly disturbed and a full extension lateral merus display in response to strong or prolonged disturbance. The full extension display is unusual since the crab maintains a cataleptic state during the display, which long outlasts the period of stimulation (maximum display time observed was 2612s). Tactile and disequilibrium stimulate on were most effective; their effects appeared additive. Light and water jets were less effective. Statocysts provide the major sensory input during disequilibrium stimulation. Dactyl closure reflexes of the claws were less frequent than normal during the full extension display. It is suggested that the function of this display is to render the crab unpalatable to intertidal fish predators.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516416

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

During March‐April 1983, measurements of14C uptake rate in both light and dark bottles were made on 276 sea‐surface samples distributed across a plume of upwelled water, from the northwest of South Island to the Taranaki Bight, New Zealand. The non‐photosynthetic14C uptake in the dark was extremely variable andoftenahigh(2–88%) proportion of the photosynihetic uptake in die light. Dark and light uptake was broadly related to the extent of spread of upwelled water. Within the plume there was a trend for both increasing phytoplanktonic biomass (as chlorophylla)and ammonium concentration to enhance dark uptake, but therapidity with which environmental conditions changed within the plume probably obscured aclose correlation between variables. High dark14C uptake probably mainly resulted from high bacterial nitrification rates, when average nitrification may have been c. 7% of total nitrogen uptake, plus some uptake by nitrogen‐deficient algae. Dark14C uptake varied too much for it to be used to adjust light14C uptake to estimate primary production.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516417

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Spectral analyses of water‐level oscillations in Wellington Harbour during the 1960 Chilean and 1964 Alaskan tsunamis are given. The results are used to define the periods for the three longest‐period characteristic oscillation modes. Some implications for future tsunamis are discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516418

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The <20 μm fractions of 72 sediment samples from Pauatahanui and Porirua Inlets of Porirua Harbour have been analysed for eight elements and the results compared between the two inlets. Co,Ni,Fe, and Mn occur in similar abundances in sediments from the two inlets and show no evidence of contamination. Cr concentration is somewhat higher in sediments from Pauatahanui Inlet and again shows no evidence of contamination. Cu concentration is significantly higher in sediments of Porirua Inlet and two samples taken in the vicinity of Porirua City are in the class uncontaminated to moderately contaminated. Pb and Zn show significantly higher concentrations in sediments from Porirua Inlet. Sediments in the vicinity of Porirua City attain the category moderately to strongly contaminated for Pb and moderately contaminated for Zn. No evidence of heavy‐metal contamination is seen in sediments in the vicinity of State Highway 1. Heavy‐metal pollution in Porirua Harbour therefore appears to be restricted to Pb, Zn, and, to a lesser extent, Cu, and occurs in Porirua Inlet in the vicinity of Porirua City.

ISSN:0028-8330    

DOI:10.1080/00288330.1990.9516419

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor