Feeding and schooling behaviour of barracouta (Thyrsites atun) off Otago, New Zealand

1998 ◽  
Vol 49 (1) ◽  
pp. 19 ◽  
Author(s):  
Richard L. O'Driscoll
Keyword(s):  
New Zealand ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Fish Population ◽  
Pelagic Fish ◽  
Wild Fish ◽  
Gut Contents ◽  
Side Scan Sonar ◽  
Schooling Behaviour ◽  
The Mean

To test the hypothesis that fish in schools forage more successfully than individual fish, an analysis was made of the stomach contents of barracouta (Thyrsites atun), a facultatively schooling species of fish, in a wild fish population. Schooling (n = 29) and non-schooling (n = 86) barracouta were captured during a side-scan sonar survey of pelagic fish off the coast of Otago, New Zealand. The proportion of fish with empty stomachs was lower and the mean wet mass of gut contents was higher in barracouta from schools. The increased feeding success of fish in schools was due to increased consumption of krill, Nyctiphanes australis. In regions where the density of krill in net tows was high (>1000 individuals km-1 tow length) or moderate (100–1000 individuals km-1), the mean wet mass of krill in the stomachs of schooling barracouta was 2–4 times higher than in the stomachs of non-schooling barracouta. Few schools of barracouta were observed in areas with low densities of krill (<100 individuals km-1). Schooling by barracouta seems to be a feeding strategy to exploit surface swarms of krill.

Contrasting Trophic Level Interactions in Lake St. George and Haynes Lake (Ontario, Canada)

1991 ◽  
Vol 48 (3) ◽  
pp. 356-363 ◽  
Author(s):  
Nathalie Lafontaine ◽  
Donald J. McQueen
Keyword(s):  
Chlorophyll A ◽  
Trophic Level ◽  
Fish Population ◽  
Pelagic Fish ◽  
Strongly Correlated ◽  
Total Zooplankton ◽  
Clear Water ◽  
Southern Ontario ◽  
Water Lake ◽  
Pelagic Communities

Two small, adjacent kettle lakes in southern Ontario were sampled during spring and summer 1987. The data comprised weekly samples of zooplankton and water chemistry, monthly diel assessments of the densities of pelagic fish and zooplankton found at 1-m depth intervals in the water column, and an annual mark and recapture assessment of the entire fish population. The two lakes had very different community structures. Haynes Lake was characterized by high piscivore numbers, few planktivores, a relatively large assemblage of large bodied zooplankton, low chlorophyll a concentrations, and clear water. Lake St. George had a lower piscivore to planktivore ratio, smaller zooplankton, more chlorophyll a, and murkier water. Comparisons of trophic level biomasses for the two lakes suggested that in both communities, the relationships between piscivores and planktivores and between planktivores and zooplankton were strongly correlated with predator abundances. In the more oligotrophy community (Haynes Lake) this influence extended weakly to the phytoplankton, but in the more eutrophic system, little of the variability in chlorophyll a with respect to total phosphorus could be explained by total zooplankton (or Daphnia) abundance. This suggests that for freshwater pelagic communities, top-down effects may be stronger in more oligotrophic systems.

scholarly journals On some continuous observations of the rate of dissipation of electric charges in the open air

1905 ◽  
Vol 76 (508) ◽  
pp. 152-159 ◽  
Keyword(s):  
New Zealand ◽  
Individual Values ◽  
Similar Work ◽  
Maximum Value ◽  
Variable Quantity ◽  
The Mean ◽  
Atmospheric Conductivity ◽  
Rate Of Dissipation ◽  
The Individual ◽  
Sea Coast

During the latter part of 1902 and the early months of 1903 I resolved to take as many observations of the rates of dissipation of positive and negative electric charges as possible, and to continue them over the whole 24 hours of the day, and, when opportunity offered, over longer periods. There appeared to be little information regarding the rate of dispersion during the night hours. At about the same time that these observations were being made, Nilsson was doing similar work at Upsala, and found a noticeable maximum value for atmospheric conductivity at about midnight. The observations were made on the Canterbury Plains of New Zealand, at a station about 20 feet above sea-level and about five miles due west from the sea coast. The apparatus used was Elster and Geitel’s Zerstreuungs- apparat , and the formula of reduction used was that given by them, viz:- E = 1/ t log V 0 /V- n / t ' log V' 0 /V' . In this formula E is proportional to the conductivity of the gas surrounding the instrument—for positive or negative charges, as the case may be. The constant “ n ” = ratio of capacity without cylinder ____________________________________ capacity with cylinder was determined by me to be 0·47, as the instrument was always used, with the protecting cover. The cover was always at one height above the base of the instrument, and was set so as to be as nearly co-axial with the discharging cylinder as could be judged by eye. No attempt was made to determine the actual capacity of the condenser cylinder and protecting cover, which would be a somewhat variable quantity owing- (1) to the differences on different days in attempting to cause the two to be co-axial; (2) to a certain amount of looseness in the fit of the shank of the cylinder on to its hole. The value above given for “ n "is the mean of several deter­minations made with different settings of the cover and cylinder. The individual values of “ n ” varied over about 0.03.

Methane emissions from young and mature dairy cattle

2016 ◽  
Vol 56 (11) ◽  
pp. 1897 ◽  
Author(s):  
C. A. Ramírez-Restrepo ◽  
H. Clark ◽  
S. Muetzel
Keyword(s):  
New Zealand ◽  
Emission Factor ◽  
Dry Matter ◽  
Sulfur Hexafluoride ◽  
Dry Matter Intake ◽  
Tracer Technique ◽  
Ch4 Emissions ◽  
Dairy Heifers ◽  
Age Related ◽  
The Mean

Daily methane (CH4) emissions (g) and CH4 yield (g/kg dry matter intake) were measured from 10 dairy heifers (<1 year old) and nine rumen-fistulated cows (>6 years old) fed ryegrass (Lolium perenne) chaffage indoors. The CH4 emissions were estimated using the sulfur hexafluoride tracer technique in four ~5-day periods beginning in June 2008 and repeated 4, 6 and 7 months later. Respiratory chambers were used in four ~13-day periods beginning in November 2008 and repeated 2, 5 and 6 months later. Third and fourth sulfur hexafluoride tracer periods overlapped with the first and second chamber measurement periods, respectively. Averaged over the four measurement periods the CH4 yields determined using both techniques were similar for heifers and cows. The mean CH4 yield estimated by the sulfur hexafluoride tracer technique was 25.3 ± 0.52 for heifers and 24.1 ± 0.55 for mature cows, whereas the mean CH4 yield measured in respiratory chambers was 23.7 ± 0.66 for heifers and 23.6 ± 0.66 for mature cows. Averaged over the eight measurements irrespective of technique, CH4 yields for heifers (24.5 ± 0.42) and cows (23.8 ± 0.43) were similar. There was also no difference between CH4 methods for assessing CH4 yield during the overlapping measurement periods. It was concluded that no consistent differences in CH4 yield existed between heifers and mature cows. Therefore, we do not recommend adoption of an age-related emission factor for cattle in the national inventory calculations for New Zealand.

Ingesta particle size, food handling and ingestion in the tammar wallaby (Macropus eugenii Desmarest)

1999 ◽  
Vol 47 (1) ◽  
pp. 75 ◽  
Author(s):  
R. G. Lentle ◽  
K. J. Stafford ◽  
M. A. Potter ◽  
B. P. Springett ◽  
S. Haslett
Keyword(s):  
Particle Size ◽  
New Zealand ◽  
Particle Size Distribution ◽  
Stomach Contents ◽  
Tammar Wallaby ◽  
Food Handling ◽  
Macropus Eugenii ◽  
Food Particles ◽  
Chewing Rates ◽  
Free Ranging

The particle size distribution of stomach contents from 25 tammar wallabies (Macropus eugenii Desmarest) shot in the Okataina State Forest and adjoining farmland near Rotorua, New Zealand, were determined. There was a greater percentage of finer, and a smaller percentage of larger, particles than reported in the stomach contents of larger macropods. The chewing and biting activities of four free-ranging tammars fitted with radio-microphone collars were monitored. Chewing rates (chews per minute) were similar to those of other small herbivorous vertebrates. There were significantly lower rates of chewing and higher chew-to- bite ratios when browsing than when grazing. Observations of browsing by three captive tammars showed inefficient handling by mutually opposed palms and digitopalmar grip, resulting in low rates of ingestion. We suggest that tammars lower the time necessary for fermentation of food by reducing the size of food particles, and that their choice between graze and browse is influenced by food handling and chewing investment.

scholarly journals Antibody level of New Zealand children immunized with the triple vaccine DTP (diphtheria-tetanus-pertussis)

1988 ◽  
Vol 101 (2) ◽  
pp. 405-410 ◽  
Author(s):  
R. C. H Lau
Keyword(s):  
New Zealand ◽  
Immunosorbent Assay ◽  
Antibody Level ◽  
Herd Immunity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Igg Antibody ◽  
Immunization Strategy ◽  
The Mean ◽  
Antibody Levels

SUMMARYEnzyme-linked immunosorbent assay (ELISA) tests were used to measure IgG antibody levels in 2638 New Zealand children who had been immunized with the triple vaccine DTP. The percentage of children immune to diphtheria decreased with age. The percentage of children immune to tetanus varied from 67.1 to 55.0%. The percentage of children with measurable antibody to pertussis increased with age. The mean percentages of children with measurable antibody or immunity to one or more DTP components were 34.2% (with 3 components), 34.4% (2 components), and 78.1% (1 component). It appears the immunization strategy for diphtheria and tetanus is satisfactory for herd immunity in New Zealand children. However, the current pertussis strategy may not be providing adequate immunity to 5-year-olds in this country.

scholarly journals Schooling behaviour of small pelagic fish: phenotypic expression of independent stimuli

2007 ◽  
Vol 334 ◽  
pp. 263-272 ◽  
Author(s):  
P Brehmer ◽  
F Gerlotto ◽  
C Laurent ◽  
P Cotel ◽  
A Achury ◽  
...  
Keyword(s):  
Phenotypic Expression ◽  
Pelagic Fish ◽  
Small Pelagic Fish ◽  
Schooling Behaviour

scholarly journals Attenuation of peak ground accelerations in some recent New Zealand earthquakes

1993 ◽  
Vol 26 (1) ◽  
pp. 3-13 ◽  
Author(s):  
D. J. Dowrick ◽  
S. Sritharan
Keyword(s):  
New Zealand ◽  
Strong Motion ◽  
Medium Size ◽  
Data Sets ◽  
Fault Rupture ◽  
Motion Data ◽  
Peak Ground Accelerations ◽  
The Mean ◽  
Using Data ◽  
Event Based

The attenuation of peak ground accelerations was studied for eight New Zealand earthquakes which occurred in the period 1987 to 1991. These events were of medium size with moment magnitudes in the range Mw = 5.8 - 6.7, with depth to centroids of the fault rupture ranging from 4 to 60 km. Attenuation of peak ground accelerations was examined for each event, based on the slope distance from the rupture surface to each strong motion data site. The mean regression attenuation curve for each event was compared with those derived by others using data sets from other parts of the world, allowance being made for source mechanism and depth. Excepting the 1988 Te Anau event, the other seven New Zealand events as a set closely match a Japanese model, but give significantly stronger accelerations than those predicted by the models from western USA and Europe.

scholarly journals A new genus and species of eomysticetid (Cetacea: Mysticeti) and a reinterpretation of ‘Mauicetus’ lophocephalus Marples, 1956: transitional baleen whales from the upper Oligocene of New Zealand

2018 ◽  
Author(s):  
Robert Boessenecker ◽  
R. Ewan Fordyce
Keyword(s):  
Phylogenetic Analysis ◽  
New Zealand ◽  
Temporomandibular Joint ◽  
New Genus ◽  
Feeding Strategy ◽  
Thoracic Vertebrae ◽  
New Genus And Species ◽  
Baleen Whales ◽  
Upper Oligocene ◽  
Lunge Feeding

The early evolution of toothless baleen whales (Chaeomysticeti) remains elusive despite a robust record of Eocene-Oligocene archaeocetes and toothed mysticetes. Eomysticetids, a group of archaic longirostrine and putatively toothless baleen whales fill in a crucial morphological gap between well-known toothed mysticetes and more crownward Neogene Mysticeti. A historically important but perplexing cetacean is “Mauicetus” lophocephalus (upper Oligocene South Island, New Zealand). The discovery of new skulls and skeletons of eomysticetids from the Oligocene Kokoamu Greensand and Otekaike Limestone permit a redescription and modern reinterpretation of “Mauicetus” lophocephalus, and indicating that this species may have retained adult teeth. A new genus and species, Tokarahia kauaeroa, is erected on the basis of a well-preserved subadult to adult skull with mandibles, tympanoperiotics, and cervical and thoracic vertebrae, ribs, sternum, and forelimbs from the Otekaike Limestone (&gt;25.2 Ma). “Mauicetus” lophocephalus is relatively similar and recombined as Tokarahia lophocephalus. Phylogenetic analysis supports inclusion of Tokarahia within the Eomysticetidae alongside Eomysticetus, Micromysticetus, Yamatocetus, and Tohoraata, and strongly supports monophyly of Eomysticetidae. Tokarahia lacked extreme rostral kinesis of extant Mysticeti and primitively retained a delicate archaeocete-like posterior mandible and synovial temporomandibular joint, suggesting that Tokarahia was capable of at most, limited lunge feeding in contrast to extant Balaenopteridae, and utilized an alternative as-yet unspecified feeding strategy.

scholarly journals Ecological impact and spread of an invasive paper wasp in New Zealand (Hymenoptera: Vespidae)

2021 ◽  
Author(s):  
Matthew Howse
Keyword(s):  
At Risk ◽  
Invasive Species ◽  
New Zealand ◽  
Ecological Impact ◽  
Diet Analysis ◽  
Paper Wasp ◽  
Gut Contents ◽  
Suitable Habitat ◽  
The South ◽  
The North

<p><b>Social wasps are considered among the most successful and impactful invasive species in the world. One species, Polistes dominula has spread from its native Mediterranean range to every continent except Antarctica. This wasp reached New Zealand in the last decade where it has established in the north of the South Island, however, reports of its presence are increasing throughout the country. Due to its recent arrival in New Zealand, little is known about where this species is likely to establish or what impacts it may have on local insect communities. In this thesis, I conducted two studies to investigate these questions, providing valuable information that may inform future management of this invasive species. </b></p><p>In chapter 2, I used two bioclimatic modelling methods to predict areas of suitable habitat across four regions in the southern hemisphere. These models were informed by global temperature and precipitation data as well as global distribution occurrence data of P. dominula. These data were used to estimate conditions most highly correlated with the presence of this wasp. The models identified large areas across the target regions that were climatically suitable for the establishment of P. dominula. Many of these areas are not known to currently contain populations of this species, representing habitat potentially vulnerable to further invasion by P. dominula. Areas across South America, South Africa and Australia were predicted to be climatically suitable. In New Zealand, much of the North Island and eastern parts of the South Island were predicted to be suitable habitat for this wasp. These results suggest that P. dominula could potentially establish across more of the country and expand its invaded range. Information provided by these models may guide conservation and biosecurity management by highlighting key areas where prevention and mitigation should be prioritized. </p><p>In chapter 3, I used molecular diet analysis to investigate the range of prey being utilised by P. dominula in New Zealand. Using DNA barcoding, larval gut contents of P. dominula and another closely related species, Polistes chinensis, were analysed to identify what species were present in the diet of both wasps. Butterflies and moths (Lepidoptera) were found to be the most highly represented order in both species’ diets. True bugs (Hemiptera) and flies (Diptera) were also abundant. Both wasps were shown to consume a range of native and introduced species including a number of agricultural pests. P. dominula was found to utilise a wider range of prey than P. chinensis. This more diverse prey range, combined with known differences in nesting behaviour, suggest that P. dominula may represent a more significant threat to invertebrate diversity than the already well-established P. chinensis. These results may inform conservation and biosecurity managers on which species are most at risk where this new invasive wasp becomes established. </p><p>This thesis provides insights into the potential impacts of a new invasive species to New Zealand. Both chapters represent the first time that these methods have been used to study P. dominula. This work highlights the need for continued monitoring of wasp populations throughout New Zealand, especially in regions highlighted as vulnerable to P. dominula establishment. We also suggest the need to prioritise the conservation of ‘at-risk’ species in coastal and human-altered habitats. Increased public engagement through the citizen-science initiatives should be encouraged while more research into management and control methods is recommended.</p>

scholarly journals Effects of urban pollution on UV spectral irradiances

2008 ◽  
Vol 8 (2) ◽  
pp. 7149-7188 ◽  
Author(s):  
R. L. McKenzie ◽  
C. Weinreis ◽  
P. V. Johnston ◽  
B. Liley ◽  
H. Shiona ◽  
...  
Keyword(s):  
Boundary Layer ◽  
New Zealand ◽  
Tropospheric Ozone ◽  
Urban Pollution ◽  
Supplementary Data ◽  
Spectral Measurements ◽  
Spectral Signatures ◽  
Polluted Sites ◽  
The Mean ◽  
Pristine Site

Abstract. Spectral measurements of UV irradiances at Tokyo are compared with corresponding measurements at a pristine site (Lauder New Zealand) to identify the causes of the reductions in urban UV irradiances, and to quantify their effects. Tropospheric extinctions in Tokyo were found to be up to ~40% greater than at Lauder. Most of these differences can be explained by differences in cloud and aerosols, but ozone differences are also important in the summer. Examining spectral signatures of tropospheric transmission of both sites shows that reductions due to mean NO2 and SO2 amounts are generally small. However, at times the amount of NO2 can be 20 times higher than the mean amount, and on these days it can decrease the UV-A irradiance up to 50%. If SO2 shows comparable day to day variability, it would contribute to significant reductions in UV-B irradiances. The results indicate that at Tokyo, interactions between the larger burden of tropospheric ozone and aerosols also have a significant effect. These results have important implications for our ability to accurately retrieve surface UV irradiances at polluted sites from satellites that use backscattered UV. Supplementary data characterising these boundary layer effects are probably needed.

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