摘要:

The prevalence, intensity, abundance, and densityof Anisakislarval infection of four species of New Zealand fish and one species of squid were determined. In order of intensity of infection these were: barracouta(Thyristes atun), tarakihi(Nemadactylus macropterus), red cod(Pseudophycis bachus), red gurnard(Chelidonichthys kumu), and arrow squid(Nototodarus solanii). Some data on infections in monkfish(Kathetostoma giganteum)are also presented. There was no evidence of postmortem migration of larvae in red cod, red gurnard, or barracouta. The larvae did excapsulate postmortem and the excapsulation was less in fish kept on ice. The majority of larvae were associated with the visceral organs and membranes (98.5% or more of the total worm burden). However, a proportion of all fish species examined had small numbers of larvae in the fillets and these may pose a risk to human health.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516907

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effects of wastewater discharge in an artificially confined wetland, Turangi land treatment facility, New Zealand, were investigated by measuring the changes in water and sediment chemistry in the land treatment facility. Analysis of surface water shows that the treatment facility is effective at removing BOD5(85%), but not NH4‐N, SO4, PO4‐P, and total suspended solids. Surface flow measurements indicate that the effluent flows through the confined wetland in less than a day. The retention time is too short to allow exchange between wetland vegetation and effluent, thus preventing efficient contaminant removal. The change in land use c. 30 years ago associated with the construction of the land treatment facility is reflected in a change in stratigraphy and sediment chemistry. Elevated sulphur and zinc concentrations in sediments are attributed to sewage effluent discharge, and indicate that soil uptake is taking place.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516908

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The relative abundance of different‐sizedAnisops wakefieldiin a small, fishless pond was determined from sweep‐net samples taken along one open‐water and two shoreline transects at noon on two dates, and at noon and midnight on a third date. During the day, large individuals occurred only along the shore, whereas smaller ones occurred both along the shore and in open water. At night, large individuals also occurred in the open water. The diurnal size‐class segregation suggests that young individuals migrate into less preferred, open water to avoid interference and cannibalism from larger individuals. The shoreline may be preferred during the day because it provides greater food resources or a refuge from visually feeding avian predators. Laboratory experiments in containers with floating aquatic plants at one end complemented the field data. When alone, both small and largeA. wakefieldisought cover during the day and moved into open water at night. During the day, the presence of large individuals induced small ones to move into open water. The results of this study on a notonectid population are consistent with some earlier ones in demonstrating that interactions between large and small size classes may lead to pronounced spatial segregation of size classes, and show for the first time that spatial distributional patterns during the day and night may be very different.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516909

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The poeciliid fish,Phalloceros caudimaculatus(commonly referred to as the “caudo"), is recorded from the wild for the first time, occurring in stock‐water troughs on a farm near Kamo in Northland, New Zealand. The populations in the stock troughs reputedly came from a nearby stream c. 10 years ago, although a preliminary search has failed to reveal them to be there now. Presence of an additional exotic fish in New Zealand fresh waters is a matter for concern, and requires management. To facilitate recognition off.caudimaculatus, and its distinction from other poeciliids present here, a diagnosis is provided to enable identification, together with notes on natural history, and a key for the identification of the five species of Poeciliidae now known from natural waters in New Zealand.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516910

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A small stream in a predominantly dairying catchment in the Waikato region of New Zealand was monitored for 2 years at three sites. Total nitrogen (TN) concentrations were up to 7.09 g m‐3in winter, with the bulk comprising nitrate nitrogen (NO‐3‐N). During summer NO‐3‐N was near zero and TN mostly comprised organic nitrogen. Maximum concentrations of total phosphorus (TP) and dissolved reactive phosphorus (DRP) were 1.64 and 0.555 g m‐3, respectively, and peaks coincided with spring and autumn applications of phosphorus fertiliser. Ammoniacal nitrogen concentrations exceeded 1 g m‐3on several occasions and mean concentrations at the three sites were 0.165–0.272 g m‐3. Faecal coliform and enterococci bacteria concentrations were 64–26000 and 7–23000 cfu per 100 ml, respectively. Specific yields of TN and NO‐3‐N (35.3 and 30.7 kg ha yr‐1, respectively) were much greater than any previously reported for New Zealand pasture catchments, whereas TP and DRP yields (1.16 and 0.54 kg ha yr‐1, respectively) were more in accord with other studies. Greater use of land treatment of liquid wastes will reduce stream inputs of faecal organisms, NH4‐N and P.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516911

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor