摘要:

For the first timeGalaxias fasciatusGray were observed spawning. The spawning sites were among flooded terrestrial vegetation along the margins of a stream during the peak of a flood. Spawning appeared to be a communal event and the fish were vulnerable to eel(Anguilla dieffenbachii)predation at the time. This spawning behaviour may have some effect on the survival of the young and therefore their subsequent whitebait run.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515955

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

As with other benthic fish which bury themselves in sand, inGenyagnus monopterygiusit is the branchiostegal apparatus which makes the major contribution to ventilation of the gills. The prolonged abduction of the branchiostegal membranes draws water in through the mouth, and exhaled water moves away from the fish through mucus‐lined channels in the sand. The steady and continuous flow of water during ventilation may avoid detection of the stargazer by prey or predators. Associated with its sluggish habits and the low gill surface area available for gas exchange,Genyagnushas a low rate of oxygen consumption (15.8 ml kg‐1h‐1for a 100 g fish at 17°C). At partial pressures of oxygen (PO2) below 6 kPa (45 mm Hg) oxygen consumption is reduced, but the fish does not emerge from the sand until the PO2falls below 2 kPa. There is evidence that the fish can sustain an oxygen debt. Respiration in the stargazer is discussed in relation to the fish's ability to withstand temporary hypoxia when it is stranded above the water level in the intertidal zone.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515956

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Dense aggregations of large ovigerous female rock lobsters,Jasus edwardsii,observed by divers at several places around central New Zealand, are described. Such aggregations are typically seen in late winter in areas of strong tidal water movements, and in the absence of suitable shelter they take the form of defensive circles and heaps. We suggest that this behaviour may facilitate rapid dispersal of newly hatched larvae.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515957

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The biology of an unfished population of the paua,Haliotis irisMartyn, in Peraki Bay, Banks Peninsula, was studied from 1973 to 1976. In February 1976 the population consisted of about 179 000 animals on 4.5 km of coastline. The length/frequency distribution was strongly skewed to the left, indicating an accumulation of old individuals and a recent history of low recruitment. Growth of animals <70 mm long was determined from changes in length frequency, and of larger animals by the analysis of tag returns. The mean parameters of the von Bertalanffy growth equation for the study population areK= 0.163 and L = 131.9 mm. Both are lower than those reported for paua in a more typical habitat near Kaikoura. The annual instantaneous natural mortality rate, as estimated by several methods from population size structure and individual growth rate data, is about 0.1. Spawning was monitored during the breeding seasons of 4 years. Spawning on Banks Peninsula failed to occur during 2 years, and the failure during 1 year was geographically widespread. No explanation for these spawning failures can be offered. The length at first maturity was the same at Peraki Bay and Kaikoura, despite a much lower growth rate and fecundity at Peraki Bay. Recruitment was 2000–5000 2‐year‐olds per year and either recruitment is largely independent of local spawning success or significant spawning occurs outside the currently accepted breeding season.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515958

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A population model is developed and used in conjunction with the results of a study of an unexploited population of paua(Haliotis irisMartyn) to examine the historical pattern of recruitment and yield per recruit. AsH. iriscannot yet be aged, the population model uses size rather than age classes, but is structurally similar to the Leslie matrix model. Simulations suggest that the observed population size structure resulted from a short (about 5 year) period of high recruitment, preceded and followed by longer periods of low recruitment. Yield per recruit analysis shows that the present minimum legal size for the fishery (127 mm) provides close to the maximum yield per recruit for most stocks, although yield per recruit could be increased in some areas by a reduction in minimum legal size.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515959

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Plaxiphora boydenin.sp. from wave‐exposed rocky shores of southern New Zealand is described and illustrated. This is the first published record of the genus from the New Zealand mainland.P. boydeniis readily distinguished from the 2 other New Zealand species of the genus, which occur in the subantarctic region, by the absence of bristle‐tufts on the girdle.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515960

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The New Zealand mangrove,Avicennia marinavar.resinifera,grows close to the latitudinal limit of mangroves. Nevertheless, litter‐fall studies in Tuff Crater, Auckland (36°48’ S, 174°45’ E), using litter‐fall bag and plot techniques, indicate that the mangroves are very productive. Litter fall beneath 2 distinct growth forms of the mangrove is seasonal, with peak fall at the time of fruit production in summer. Beneath the taller mangroves of the creek banks (3.5–4.0 m tall) annual total dry weight of litter fall is estimated as 8.10±2.74 t ha‐1a‐1, whereas beneath the lower, stunted mangroves of the flats (<1.0 m tall), the total is estimated as 3.65 t ha‐1a‐1. The values from the taller mangroves are higher than litter fall recorded beneathAvicenniaat similar latitudes in Australia, and lie within the range reported from mangroves in Queensland, Florida, and elsewhere. They suggest that, in terms of litter, mangroves may be one of the most productive forest types in New Zealand. The rate of decomposition of mangrove leaves, using the litter bag technique, was rapid, with half of the ash‐free weight being lost in 6–8 weeks. Differences between decomposition rates in summer and in winter appear to be small, and site‐specific differences were not discernible.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515961

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Inflow into Lake Tekapo is dominated by the glacially‐fed headwater Godley River. Measurements of water temperature and transmissivity at periods of seasonal maxima and minima provide data on dispersion of river water entering the lake. During spring, lake waters warming from isothermal winter conditions receive turbid cold meltwater which interflows or underflows down‐slope to the deepest basin to pond against the rising lake floor. Waters stratify weakly in summer, and turbid inflowing water interflows. In winter, near isothermal lake water receives cold clear water underflowing to the deepest basin. In all seasons inflowing water is deflected towards the eastern side of the lake by Coriolis force. Diurnal changes in inflow across the Godley delta in spring are complex, with interflow and overflow influenced by heating of waters flowing over wide, braided river channels. In winter, underflows are strongest in early morning when inflows are coldest, and they weaken through the day as river waters warm.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515962

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Temperature and suspended particulate matter concentrations are used to identify lake‐river interactions in Lake Wakatipu. Results from sampling at seasonal maxima and minima of water temperature and inflow, in conjunction with density estimates, suggest that both annual and diurnal cycles from inflow from the predominant headwaters are generated. From mid autumn to mid spring, underflows predominate; in summer, river water may warm sufficiently to allow inflowing water to interflow or overflow. In summer the large diurnal temperature range in the rivers sets up a diurnal cycle of inflows, with underflow in the early morning, progressing through to interflows and finally overflows in the middle of the day, before returning to underflows again at night. In winter, when river temperatures remain low throughout the day, inflowing water underflows continuously. Floods normally enter as turbid underflows, disrupting the diurnal summer cycle and strengthening the underflows of winter. Flood underflows reach speeds of over 20cm s‐1and carry particulate material over 60 km downslope into the deepest basin.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515963

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A linearised model of Csanady (1976) for the time‐averaged mean flow on a continental shelf is applied to the New Zealand west coast continental shelf. The means are time averages over time scales that are long relative to that of local atmospheric forcing. Forcing of the flow is via the sea surface elevation (specified from deep ocean steric levelling with adjustment for boundary effects), mean winds, and thermohaline forcing (specified by observations and determined by the strong fluctuating flow, the time average of which is the weaker mean flow). The main flow components are found generally to be caused by forcing by the sea surface elevation and local winds. North of latitude 42°30'S the mean sea surface slopes down towards the south, with an associated southward‐directed flow component; south of 42°30'S it slopes down towards the north with an associated northward‐directed flow component. On the northwest coast of the South Island the predominant north‐eastward‐directed wind produces a northeastward along‐shore flow component. On the west coast of the North Island north of Cape Egmont the predominant onshore wind produces a flow towards the north. Thermohaline forcing leads to a southward along‐shore flow decreasing to zero near the sea floor.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515964

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor