摘要:

The larval shells ofPaphies ventricosa,reared to settlement in the hatchery, are similar in longitudinal profile to shells of some other mactracean larvae; the umbo‐stage larval shells are nearly round with the anterior margin less broadly curved than the posterior margin, the anterior end is longer than the posterior end, and the umbo is broadly rounded. Straight‐hinge larvae had total lengths up to 149 μm, and total heights up to 126 μm, and umbo larvae had total lengths up to 320 μm, and total heights up to 282 μm. The larvae settled in about 22 days at a size of about 270 μm. The larval hinge structure bears some similarities to those of other mactracean larvae.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515967

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Various morphological and physiological features ofSypharochiton pelliserpentis(Quoy & Gaimard, 1835) were examined in relation to the different physico‐chemical characteristics experienced at 4 sites on Kaikoura Peninsula and 2 sites in the Avon‐Heathcote Estuary. Body water content of chitons from high‐shore exposed and estuarine rocky sites was significantly greater (P<0.005) and desiccation rates were significantly less (P<0.05) than those of chitons from low‐shore marine sites and an estuarine mudflat. The percentage of body water loss causing death was greatest for high‐shore marine chitons and least for estuarine chitons. Estuarine chitons had relatively more gill tissue than marine individuals. Body shape appeared to be correlated with intensity of wave action, and narrow animals were found in more wave‐exposed areas. Variations in radula length showed no clear‐cut trends among localities.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515968

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The effects of the 3 main wastewater discharges on the benthic fauna of the Manawatu River were studied between March 1979 and January 1980. At least 4 replicate Surber samples were taken from each of 6 sites, on 5 occasions during this period.Deleatidiumsp. (Ephemeroptera),Hydorasp. (Coleoptera), and the Chironomidae were the most useful indicator organisms, according to a ranking system based on the occurrence of significant differences (P<0.05) between populations at different sites. These taxa exhibited significant differences between sites in about 70% of all inter‐site comparisons, using Mann‐Whitney U‐tests. The Coefficient of Similarity was successful at summarising the comparisons between the clean‐water and down‐stream sites, ranging between 95% similarity to the clean‐water site for a recovery site in winter, and less than 10% similarity to the clean water site for the lower reaches in summer. It is suggested that relative indices may be more appropriate than absolute indices for measuring water pollution. Water quality, indicated by species diversity, was generally good (allowing for the effects of agricultural runoff), although midsummer organic loading induced marked changes in benthic species composition, including the disappearance ofDeleatidiumsp. from several sites.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515969

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The invertebrate fauna colonising wooden blocks placed in a beech forest stream was studied over a period of 1 year. At least 31 species were taken during the course of the study, with 3 species of Chironomidae predominating numerically. Most species were associated principally with fine particulate matter (FPM) deposited on the upper surfaces of blocks, although a stonefly,Spaniocerca zelandica,was most abundant on the barer surfaces. Of the Chironomidae,Paucispinig‐era approximataandPolypedilum canumhad clearly defined life history patterns with emergence from February to April and October to January, respectively.Psectrocladiussp. had a poorly defined life history. Gut contents of 16 insect species showed that 4 were predominantly predatory, and the remainder were detritivores. The latter could be categorised as shredders (large particle detritivores) or collector‐browsers which mainly ingested particles in the dominant (<50 μm) size range. Oxygen consumption by fine stream sediments was similar at different times of year which suggests that the food quality of detritus may tie relatively constant at all times.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515970

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Energy contents of several freshwater animal species collected from Lake Ellesmere, Canterbury, were determined by bomb calorimetry. Values are shown to vary seasonally and between size classes. Because of this variability the use of a single energy value of an organism in an energetics study is not recommended.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515971

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Eight marine species of the Dinoflagel‐late genusDinophysisare recorded from New Zealand coastal waters. Some notes are given on the morphology and range of variation in the New Zealand specimens as seen in the scanning electron microscope.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515972

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Parameters of community structure (species composition and relative abundance, number of taxa, diversity, evenness, and cell density) were measured for a mudflat diatom community in the Avon‐Heathcote estuary, New Zealand. Fifty three diatom species were identified: 25 taxa (species and varieties) are new New Zealand records. The Shannon‐Wiener information index(H')was 3.46, indicating high diversity. Evenness (J') ranged from 0.57–0.67. The association between the biomass of the pulmonate gastropod,Amphibola crenata,and benthic diatom community structure was studied using large open enclosures (4.0 m2) to manipulate snail biomass. Community structure was compared at 0, 5 (natural biomass), and 10 gA. crenatadry weight per m. A similarity index (SIMI=0.88–0.95), as well asH’andJ’indicated close similarity between the diatom assemblages within all enclosures, but number of taxa increased from 33 to 49 with increasing snail biomass. Cell densities were significantly lower at high snail biomass (6088 valves per mm2) compared to enclosures with no snails (10 110 valves per mm ).A. crenatahad a higher ratio of diatom fragments to whole diatom valves in its faeces (2.42) than in its crop (0.55), indicating that it is capable of fragmenting diatoms.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515973

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Concentrations of microbial ATP in 15 New Zealand lakes were determined using 2 extraction techniques. ATP was found in both the paniculate (>0.45 μm) and dissolved (<0.45 μm) fractions of the water samples. Higher concentrations of paniculate ATP were obtained when ATP was extracted directly from freshwater samples rather than following pre‐concentration on to membrane filters. Recovery of particulate ATP declined with increasing volumes of sample filtered. The magnitude of the filtration effect varied unpredictably between lakes and within lakes with time. Corrections for the presence of dissolved ATP were necessary before estimates of particulate ATP could be made by the direct extraction technique. Concentrations of dissolved ATP up to 1.2 μg L‐1were observed. The direct extraction technique is recommended for more accurate determination of particulate ATP in New Zealand freshwaters.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515974

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A baseline groundwater quality survey of 120 household wells in an unsewered area at Yaldhurst, near Christchurch, was carried out between September and December, 1976. Ammonia‐N levels were below the detection limit (0.02 g m‐3) in all samples. Nitrate‐N, conductivity, and chloride levels tended to vary according to well depth and location, being lower in the deeper wells and in wells located in an area of shallow, stony soils. Approximately 33% of the wells contained coliform bacteria, faecal coliform bacteria or faecal streptococci. A subset of 25 wells was sampled fortnightly from January to August 1977. From January to June, mean nitrate‐N and conductivity levels remained stable at approximately 1.5 g m‐3and 11.2 mS m‐1respectively. An increase in these levels to 3.3 g m‐3and 15.8 mS m‐1in July‐August corresponded with a rise in the water table. Leaching losses from soils probably accounted for most of the nitrate entering the Yaldhurst aquifers, the contribution by septic tank systems being estimated at 20–30%. No direct evidence of contamination of the wells by septic tank effluent was found, although 23 of the 25 wells exhibited intermittent contamination by indicator bacteria throughout the 8 month sampling programme. Although a localised health hazard may exist, septic tank systems in the area were not considered likely to constitute a health threat to the confined aquifers underlying Christchurch city.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515975

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The chemical quality of the Waiohewa stream, Rotorua, was assessed from the results of 2 longitudinal surveys in summer 1978–79. In particular, changes in nitrogen concentration were examined. The quantity of ammonia increased downstream from unmonitored geothermal inputs, but, after dilution and neutralisation by a larger inflow of freshwater, considerable proportions of ammonia were converted to nitrate. In the first survey ammonia concentrations decreased from 4.48 to 2.47 g m‐3and nitrate concentrations increased from 0.59 to 1.13 g‐3in a 3‐km stretch of the stream. Mass flow calculations show that nitrification could account for at least 55% of the ammonia decrease, the rest probably being lost through assimilation or denitrification. Laboratory incubation experiments showed that nitrification occurred in the stream bed. The geothermal waters contained low concentrations of boron (1.1–4.0 g m‐3), filterable mercury (0.1–0.8 mg m‐3) and arsenic (10–14 mg m‐3).

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515976

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor