摘要:

The biomass and species composition of epilithic periphyton in oligotrophic Lake Taupo was measured over a full year. Measurements of photosynthetic carbon uptake were made during summer and early winter. The lake supported a high biomass of epilithic periphyton throughout the year, averaging 100–600 mgm‐2over the 0–35 m water depth and peaking in early summer. Periphyton extended to at least 40 m depth. Depth‐integrated carbon fixation rates of 242–362 mg m‐2h‐1were measured. Periphyton constituted more than 90% of the algal biomass and carbon fixation within the littoral zone, but less than2%of production on a whole‐lake basis. Based on taxonomic composition, periphyton could be divided into three zones, surface (0–2 m), mid water (2–20 m) and deep (> 20 m). The diatomsAulacosira granulata, Rhopalodia novae zealandiae, Epithemia sorex, andFragilariaspp. dominated the deep assemblage,Tolypothrix tenuisandMastogloia ellipticathe mid water, andScytonema, Dichothrix, and filamentous chlorophytes the shallow zone. Indicator pigments, analysed by high‐performance liquid chromatography, confirmed these groupings. Biomass‐specific rates of photosynthesis were low in shallow water (assimilation number ≤ 1 at 1 m depth) and at depths of 20 m and below, photosynthesis was light‐limited. We hypothesise that the periphyton community was slow‐growing and that the high biomass seen at all depths resulted from gradual accrual with low rates of loss.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516592

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The chemical composition of autumn‐shed willow(Salix fragilis)leaves was examined over a 56‐day period of immersion in a stream, and compared with the chemical composition of periphyton. Much of the carbohydrates, phenolic compounds, and tannins were leached from the leaves within the first week. Nitrogen and chlorophyllaconcentrations increased as a percentage of ash‐free dry mass throughout the study period, whereas protein concentration remained relatively constant. In feeding preference studies the larvae of the trichopteranOlinga feredayipreferred 56‐day willow leaves to periphyton, 7‐day, and 28‐day‐incubated leaves. The most notable difference between 56‐day leaves and the other leaves was their lower phenolic content. The preference for 56‐day leaves over periphyton may be related to the high ash content of the periphyton from this stream. We conclude that leaves of introduced willow trees can provide a preferred food source for New Zealand stream macroinvertebrates.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516593

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The first 2 years of monthly‐sampled physico‐chemical data from 77 river and stream sites in New Zealand's National River Water Quality Network are summarised. The data for the major ions, pH, dissolved oxygen, conductivity, clarity, temperature, and NO3‐N from the majority of sites are normally distributed. The data for flow, BOD5, turbidity, absorption coefficients, and total and dissolved nutrients (except for NO3‐N) from most sites are positively skewed. Combined data for all sites are compared with water quality standards and criteria, and “average” world freshwater concentrations. The vast majority of samples are well within accepted standards and criteria for a variety of river water uses and the waters can be classed as being of relatively low ionic strength.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516594

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The first 2 years’ physico‐chemical data from the National River Water Quality Network's 77 river and stream sites were related to environmental variables such as catchment erosion, soil and rock types, and land use. Multivariate analysis reduced the physico‐chemical data to seven groups of determinands: major ions (as indexed by conductivity), P species (DRP and TP), N species (TN and NO3‐N), “organics” (BOD5and NH4‐N), clarity, absorption coefficient (g440), and a combination of DO and pH. The river sites were grouped into nine clusters using these seven determinand groups; 65 sites (containing the most pristine waters, a majority of which are located in the South Island) were contained in just four clusters. Differences between the clusters are best explained by the concentrations of P species and “organics”. Discriminant analysis was used to relate the physico‐chemical site clustering to environmental variables; it indicated that the degree of pasture development and its associated variables (e.g., negligible to moderate erosion, high mean annual water temperature, high percentage recent soils, low mean catchment elevation) are the most important factors affecting water quality.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516595

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The spatial and temporal variability of dissolved reactive silica (DSi) and salinity in Tairua Harbour (Coromandel, New Zealand) were investigated along with that of the riverine inputs and adjacent coastal waters. In all surveys, covering a range of fresh water discharges and seasons, the very high linear correlations between DSi concentration and salinity indicated conservative behaviour, with physical dilution being the only process having any effect on the distribution of DSi in both estuarine and coastal waters. The tidal exchange of DSi, and hence estuarine water, with the coastal water body was high, with around 82% of the incoming flood tide comprising “new” ocean water. This exchange process was strongly influenced by the quasi‐periodic non‐tidal alongshore current, but only weakly by variation in river discharge and tidal range. It appears that complete mixing of fresh water (under normal flow conditions) and riverine solutes occurs over a relatively narrow coastal zone (2–3 km) along this stretch of the Coromandel Peninsula.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516596

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Census data on benthic foraminiferal tests in 56 seafloor sediment samples (high tide to 45 m depth; slightly brackish to normal marine) in Port Pegasus, south‐east Stewart Island, are analysed by cluster analysis. The faunal samples are grouped into six associations: A.Trifarina angulosa/Textularia proxispira/Miliolinella subrotundata—current‐swept passages and adjacent port; B.Notorotalia finlayi/Quinqueloculina delicatula/Nonionella flemingi—muddy fine sand at 22–30 m; C.Notorotalia zelandica/Elphidium novozealandicum—sheltered bays at 2.5–26 m; D.Rosalina bradyi—shallow subtidal amongst rocky reefs; E.Ammonia beccarii/Elphidium advenum depressulum/Haynesina depressula—0.5–6 m, sheltered bays and channels of Cooks Arm; F.Miliammina fusca—brackish, intertidal. In the entrance passages and exposed shelf (5–45 m depth) planktics comprise 15–30% of the total foraminiferal tests. Directly inside the passages in Port Pegasus, planktics comprise 30–65% of the fauna. These are dominated by small species that have been swept inshore by the predominant onshore swells and winds and carried into the port by strong tidal currents before settling out of suspension. The small, calcareous tests of benthicCassidulina carinataandTrifarina angulosaalso have distribution patterns consistent with some current transport into Port Pegasus.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516597

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In laboratory tests, the camouflage crabNotomithrax ursusutilised its algal mask as a source of food. Mask ingestion mainly involved the removal of algae from the carapace, with removal from legs occurring less commonly, implying different rates of algal turnover. When there was no other available source of food, crabs ate an average of 4.1 % of the mask per day but when an alternative source of food (mussel flesh) was available, only 2.8% of the mask was consumed per day. A variety of red, green, and brown algae were consumed. The dual role of the mask means that there is an interaction between camouflage and food storage. Our results suggest that forN. ursus, camouflage is more important because consumption constitutes only a minor part of mask turnover. The evolution of spider crab masking is discussed in relation to the published literature.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516598

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In laboratory tests, the spider crabsNotomithrax ursus, collected near Kaikoura peninsula, South Island, New Zealand, were shown to mask with some species of algae more than others. The types of algae most preferred as masking material were branched algae such asHalopteris spicigeraandCorallina officinalis. Thallose‐like algae such asUlvasp., and strap‐like algae such asCladhymenia oblongifolia, were less preferred. It was also shown that algae with whichN. ursusprefers masking are also the algae thatN. ursusprefers to eat. The conflicting requirements of masking and food storage, and possible reasons for algal choice are discussed.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516599

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Muscle samples were collected from southern bluefin tunaThunnus maccoyiioff New Zealand, from northern bluefin tunaT. thynnusoff Japan, and from specimens recorded as northern bluefin tuna off New Zealand. Electrophoretic analyses of muscle tissues fromT. thynnusandT. maccoyiifound 2 out of 33 enzyme loci with species‐specific gel phenotypes. These two markers were used to identify specimens recorded as “northern” bluefin tuna in the New Zealand fishery. Only two out of 17 “northern” specimens wereT. thynnus.

ISSN:0028-8330    

DOI:10.1080/00288330.1994.9516600

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor