Ecological Studies on New Zealand Lacustrine Zooplankton with Special Reference to Boeckella propinqua Sars (Copepoda: Calanoida)

1962 ◽  
Vol 13 (2) ◽  
pp. 143 ◽  
Author(s):  
IAE Bayly
Keyword(s):  
New Zealand ◽  
Vertical Distribution ◽  
Lower Limit ◽  
Bimodal Distribution ◽  
Zooplankton Biomass ◽  
Vertical Variation ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Egg Number ◽  
The Vertical Distribution

A study was made of the zooplankton of a small, warm monomictic, closed, alkaline lake. This was located on Mayor Island, an offshore island of the North Island of New Zealand. Morphometric, thermometric, and chemical aspects of this lake are discussed. The vertical distribution of the zooplankton was investigated by the vertical hauling of a closing net and by the horizontal towing of a Clarke Bumpus sampler. The vertical distribution of zooplankton biomass and of the different planktonic crustacean species at different times of the year is discussed. When thermal stratification was well developed, all crustacean and rotatorian species had a very sharply defined lower limit between the upper limit of the metalimnion and the thermocline; minimal population densities existed some distance above this lower limit. A reversed diurnal vertical migration is reported for Daphnia carinata and the mature males of Boeckella propinqua. The following investigations and findings refer to Boeckella propinqua: the vertical distribution of four population components (CI-V, C VI male, male, C VI female, female , and C VI female, female, with eggs) at different times of the year is discussed; departure of sex ratio from 1 : 1 is reported; cyclic seasonal changes, which correlated inversely with temperature during part of the year, occurred in mean length and mean number of eggs in sacs; mean egg number also correlated with mean body length; considerable simultaneous interpopulational variation in mean egg number was found; length measurements of adults from November surface collections showed a bimodal distribution, and at the same time vertical variation occurred in the nature of size-frequency distributions-in both sexes the upper mode was progressively diminished with increasing depth and finally eliminated; in these November collections the percentage of lower modal females with eggs was much smaller than that for upper modal ones; when surface collections showed unimodal size distributions there appeared to be no vertical variation in size-frequency distributions; variation in the lobulation of the last metasomal segment of females is mentioned; the occurrence of a cestode cysticercoid stage in male and female stages CV and VI, and parasitic castration of C VI male, male, is reported. General observations are made on the Rotatoria and the vertical distribution of Filinia longiseta is dealt with. Comparisons are made between the zooplankton of a number of mainland lakes and that of the Mayor Island lake.

Effect of sward height and its clover vertical distribution on the performance of cashmere goats grazing perennial ryegrass/white clover swards during the autumn

1997 ◽  
Vol 1997 ◽  
pp. 172-172
Author(s):  
M. del Pozo ◽  
K. Osoro
Keyword(s):  
New Zealand ◽  
Vertical Distribution ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Northern Spain ◽  
Sward Height ◽  
Cashmere Goats ◽  
The Vertical Distribution ◽  
Clover Pasture

Previous trials performed in temperate sown swards from New Zealand (Clark et al, 1982), from UK (del Pozo and Wright, 1995) and from Spain (Osoro and Martinez, 1995) showed improvements of sward clover contents on grass/clover pastures grazed by goats during the early part of the grazing season. However, this phenomenon might not occur to the same extent during autumn due to clover's poorer competitiviness with ryegrass. Additionally, Merchant and Riach (1994) showed that cashmere goats required pastures with mean sward heights to be above 6 cm to achieve aceptable levels of performance but were not able to considerate the implications of the sward legume content on their liveweight changes. The aim of this study was to investigate the effects of three contrasting sward height regimes and their associated relative changes in the vertical distribution of the sward clover proportion on the performance of cashmere goats grazing during the autumn season a lowland perennial ryegrass/white clover pasture located in Northern Spain.

scholarly journals Studies on New Zealand Bivalve Larvae, with Observations on the Adults, and on the Hydrology of Bay of Islands and Wellington Harbour

2021 ◽  
Author(s):  
◽  
John Duncan Booth
Keyword(s):  
New Zealand ◽  
Vertical Distribution ◽  
Late Stage ◽  
Water Current ◽  
Bivalve Species ◽  
Bivalve Molluscs ◽  
Secchi Disc ◽  
Bivalve Larvae ◽  
The Vertical Distribution ◽  
Made In

<p>1) Observations made on some hydrological parameters at Bay of Islands and Wellington Harbour during 1970-71 are presented and discussed. The parameters include water temperature, salinity, dissolved oxygen content and turbidity. The water current system in Bay of Islands is also discussed and a proposed pattern presented. The hydrology of Bay of Islands and Wellington Harbour are compared. Bay of Islands is topographically lees isolated from oceanic influence than Wellington Harbour, and there is a more marked change from estuarine to oceanic hydrological conditions within the bay. Monthly mean surface seawater tempe ratures at Bay of Islands exceed those of Wellington Harbour by about 4 degrees C. Water temperature stratification is more marked in Bay of Islands than Wellington Harbour, suggesting less efficient water mixing. Salinities are lower in Wellington harbour (normally about 33.5 - 34.5 parts per thousand) than the main basin of Bay of Islands (normally about 3S.5. parts per thousand). Turbidities in estuarine areas of Bay of Islands are similar to those for most of Wellington Harbour ( 3 - 6 metres Secchi Disc visibility values), but are much Less in outer basin areas (Secchi Disc visibility values may exceed 15 metres). Dissolved oxygen content is high in both harbours, frequently exceeding 100 per cent saturation in surface water. The results suggest that although both harbours are hydrologically quite homogeneous, Wellington Harbour is more efficiently mixed than Bay of Islands. (2) Benthic and shore collections of marine bivalve molluscs were made in Bay of Islands, and benthic collections were made in Wellington Harbour, during 1970-72. The species occurring are recorded and discussed, and the distribution of some common species in Wellington Harbour is related to sediment types. A list of bivalve molluscs collected in Bay of Islands is presented, and additional species to previous Wellington Harbour species lists are recorded. Invertebrate marine communities described for New Zealand are discussed, and the bivalve fauna of both harbours is visually compared to these communities. The observations at fifty four anchor dredge benthic stations in Wellington Harbour are then treated statistically, and compared to the visual assessments. It appears that the great variability in Wellington Harbour sediments makes identity of classical communities in the harbour almost impossible. However, station groups (groups of stations with similar bivalve species present) are evident, and their distribution in Wellington Harbour correlate closely to sediment type distribution. Lists of the most abundant bivalve species occurring in both harbours, deduced from all the observations presented in this study, are given. (3) Observations were made on the occurrence of common late stage bivalve larvae in the plankton at Bay of Islands and Wellington Harbour during 1979 - 71. Three stations in Bay of Islands and four stations in Wellington Harbour were sampled approximately monthly. The bivalve larvae in shorter series of plankton samples from Raumati Beach, Dargaville Beach, Mahurangi, Ohiwa Harbour, Raglan Harbour and Kaipara Harbour during 1971 - 72 were also analysed. Twenty-nine species of bivalve larvae from these plankton samples are described. Twenty-three species of late stage bivalve larvae are provisionally identified, the identifications being based on the larval hinge structure, the distribution and abundance of the larvae in relation to adult stocks, and in some cases by correlation with the adult gonad or condition index cycle. The broad seasonal pattern of occurrence of twenty five species of late stage bivalve larvae in the plankton at Bay of Islands, Wellington Harbour and Raumati Beach is presented. (4) Ecological studies made on bivalve larvae at Bay of Islands and Wellington Harbour during 1970 - 71, are presented and compared to other published studies from overseas. Included are observations on the vertical meso-distribution of bivalve larvae over tidal cycles in estuarine and non-estuarine localities of l2m to l5m depth, the daytime vertical meso-distribution of bivalve larvae in non-estuarine water 20m- 30m in depth, the effect of light on the vertical meso-distribution of bivalve larvae in water 15m- 30min depth, and the horizontal mega-distribution of bivalve larvae in Wellington Harbour and Bay of Islands. The observations suggest that in estuarine areas, the effect of alternating tides on the vertical distribution of bivalve larvae far outweighs the effects of any other factors. During the flood tide, bivalve larvae rise from the bottom into the water column and are carried up the estuary by the tide. During the ebb tide the larvae settle and remain on the bottom. In non-estuarine areas, no such vertical migration was observed. Gravity, light and water currents, in particular, affect the vertical distribution of bivalve larvae in these areas. The horizontal mega-distribution of bivalve larvae within Wellington Harbour is fairly uniform. In Bay of Islands, bivalve larvae occur in greatest densities near the shores, while much of the central basin is almost devoid of larvae. This distribution is due to the proximity of the adult stocks to the regions of most larvae, and to the prevailing water current pattern within the bay.</p>

Diffusion from a fixed source at a height of a few hundred feet in the atmosphere

1957 ◽  
Vol 2 (3) ◽  
pp. 299-310 ◽  
Author(s):  
J. S. Hay ◽  
F. Pasquill
Keyword(s):  
Vertical Distribution ◽  
Correlation Coefficient ◽  
Frequency Distribution ◽  
Turbulent Energy ◽  
Airborne Particles ◽  
Frequency Distributions ◽  
Auto Correlation ◽  
The Vertical Distribution ◽  
Shape And Size

The results of measurements of the vertical distribution of airborne particles, released usually at a height of 500 ft., and sampled for periods of about 30 minutes at downwind distances of 100, 300 and 500 metres, are presented and discussed.At all distances the frequency distributions of the particle elevation with respect to the site of release are closely similar in shape and size to the frequency distribution of wind inclination at the site of release. This is interpreted as showing that, despite the uncorrelated effects of small eddies, high correlation was maintained in the motion of a particle, for periods of 1 minute or more, by the dominant action of persistent eddies which contributed heavily to the turbulent energy. In contrast to this result, the wind observations showed that the Eulerian auto-correlation coefficient (Rr) fell to about 0.2 in 10 seconds.

scholarly journals Studies on New Zealand Bivalve Larvae, with Observations on the Adults, and on the Hydrology of Bay of Islands and Wellington Harbour

2021 ◽  
Author(s):  
◽  
John Duncan Booth
Keyword(s):  
New Zealand ◽  
Vertical Distribution ◽  
Late Stage ◽  
Water Current ◽  
Bivalve Species ◽  
Bivalve Molluscs ◽  
Secchi Disc ◽  
Bivalve Larvae ◽  
The Vertical Distribution ◽  
Made In

<p>1) Observations made on some hydrological parameters at Bay of Islands and Wellington Harbour during 1970-71 are presented and discussed. The parameters include water temperature, salinity, dissolved oxygen content and turbidity. The water current system in Bay of Islands is also discussed and a proposed pattern presented. The hydrology of Bay of Islands and Wellington Harbour are compared. Bay of Islands is topographically lees isolated from oceanic influence than Wellington Harbour, and there is a more marked change from estuarine to oceanic hydrological conditions within the bay. Monthly mean surface seawater tempe ratures at Bay of Islands exceed those of Wellington Harbour by about 4 degrees C. Water temperature stratification is more marked in Bay of Islands than Wellington Harbour, suggesting less efficient water mixing. Salinities are lower in Wellington harbour (normally about 33.5 - 34.5 parts per thousand) than the main basin of Bay of Islands (normally about 3S.5. parts per thousand). Turbidities in estuarine areas of Bay of Islands are similar to those for most of Wellington Harbour ( 3 - 6 metres Secchi Disc visibility values), but are much Less in outer basin areas (Secchi Disc visibility values may exceed 15 metres). Dissolved oxygen content is high in both harbours, frequently exceeding 100 per cent saturation in surface water. The results suggest that although both harbours are hydrologically quite homogeneous, Wellington Harbour is more efficiently mixed than Bay of Islands. (2) Benthic and shore collections of marine bivalve molluscs were made in Bay of Islands, and benthic collections were made in Wellington Harbour, during 1970-72. The species occurring are recorded and discussed, and the distribution of some common species in Wellington Harbour is related to sediment types. A list of bivalve molluscs collected in Bay of Islands is presented, and additional species to previous Wellington Harbour species lists are recorded. Invertebrate marine communities described for New Zealand are discussed, and the bivalve fauna of both harbours is visually compared to these communities. The observations at fifty four anchor dredge benthic stations in Wellington Harbour are then treated statistically, and compared to the visual assessments. It appears that the great variability in Wellington Harbour sediments makes identity of classical communities in the harbour almost impossible. However, station groups (groups of stations with similar bivalve species present) are evident, and their distribution in Wellington Harbour correlate closely to sediment type distribution. Lists of the most abundant bivalve species occurring in both harbours, deduced from all the observations presented in this study, are given. (3) Observations were made on the occurrence of common late stage bivalve larvae in the plankton at Bay of Islands and Wellington Harbour during 1979 - 71. Three stations in Bay of Islands and four stations in Wellington Harbour were sampled approximately monthly. The bivalve larvae in shorter series of plankton samples from Raumati Beach, Dargaville Beach, Mahurangi, Ohiwa Harbour, Raglan Harbour and Kaipara Harbour during 1971 - 72 were also analysed. Twenty-nine species of bivalve larvae from these plankton samples are described. Twenty-three species of late stage bivalve larvae are provisionally identified, the identifications being based on the larval hinge structure, the distribution and abundance of the larvae in relation to adult stocks, and in some cases by correlation with the adult gonad or condition index cycle. The broad seasonal pattern of occurrence of twenty five species of late stage bivalve larvae in the plankton at Bay of Islands, Wellington Harbour and Raumati Beach is presented. (4) Ecological studies made on bivalve larvae at Bay of Islands and Wellington Harbour during 1970 - 71, are presented and compared to other published studies from overseas. Included are observations on the vertical meso-distribution of bivalve larvae over tidal cycles in estuarine and non-estuarine localities of l2m to l5m depth, the daytime vertical meso-distribution of bivalve larvae in non-estuarine water 20m- 30m in depth, the effect of light on the vertical meso-distribution of bivalve larvae in water 15m- 30min depth, and the horizontal mega-distribution of bivalve larvae in Wellington Harbour and Bay of Islands. The observations suggest that in estuarine areas, the effect of alternating tides on the vertical distribution of bivalve larvae far outweighs the effects of any other factors. During the flood tide, bivalve larvae rise from the bottom into the water column and are carried up the estuary by the tide. During the ebb tide the larvae settle and remain on the bottom. In non-estuarine areas, no such vertical migration was observed. Gravity, light and water currents, in particular, affect the vertical distribution of bivalve larvae in these areas. The horizontal mega-distribution of bivalve larvae within Wellington Harbour is fairly uniform. In Bay of Islands, bivalve larvae occur in greatest densities near the shores, while much of the central basin is almost devoid of larvae. This distribution is due to the proximity of the adult stocks to the regions of most larvae, and to the prevailing water current pattern within the bay.</p>

Mesozooplankton biomass in the Celtic Sea: a first approach to comparing and combining CPR and LHPR data

1999 ◽  
Vol 79 (1) ◽  
pp. 179-181 ◽  
Author(s):  
S.D. Batten ◽  
A.G. Hirst ◽  
J. Hunter ◽  
R.S. Lampitt
Keyword(s):  
High Resolution ◽  
Vertical Distribution ◽  
Zooplankton Biomass ◽  
Data Sets ◽  
Shelf Edge ◽  
Mesozooplankton Biomass ◽  
Celtic Sea ◽  
First Time ◽  
Vertical Scales ◽  
The Vertical Distribution

Zooplankton biomass varies on temporal, horizontal and vertical scales. However, data sets which incorporate all these dimensions at high resolution are very rare. Two devices which measure all these aspects have recently been simultaneously deployed in the Celtic Sea, the continuous plankton recorder (CPR) and the Longhurst–Hardy plankton recorder (LHPR). This demonstrates that integrated biomass derived from the LHPR are not significantly different from those derived using the CPR. Values have, therefore, been combined for the first time to describe the vertical distribution of mesozooplankton biomass at the Celtic Sea shelf edge through an annual cycle. This suggests that the surface biomass peak is broader at the shelf break than in the open ocean and in the autumn the main biomass peak may be below the depth sampled by the CPR.

Microcrystal Morphology

2021 ◽  
pp. 63-89
Author(s):  
David Rickard
Keyword(s):  
Bimodal Distribution ◽  
Frequency Distributions ◽  
Crystal Shapes ◽  
Size Frequency ◽  
Additional Process ◽  
The Common ◽  
Log Normal ◽  
Random Packings

Framboids are constituted by microcrystals with approximately log-normal size-frequency distributions, and 95% of framboidal microcrystals are between 0.1 and 3.1 μ‎m. Nanocrystals are not generally observed in framboids. Packing efficiencies vary between close-packings in which the microcrystals occupy up to 74% of the framboid volume and random packings with a 56% volume of microcrystals. The ratios between framboid diameter and microcrystal size show a clear bimodal distribution which reflects the populations of close-packed ordered framboids and randomly organized framboids. Framboids may contain up to 500,000 microcrystals. The average numbers of microcrystals in both disordered and ordered framboids are similar, which suggests that the organization of microcrystals is the result of an additional process. Minerals that do not commonly produce equant crystals forms are unlikely to display the framboidal texture. Framboid microcrystals are essentially limited to isometric minerals like pyrite which produce equant crystals. Pyrite displays the greatest variety of crystal shapes among the common minerals. This means that pyrite is able to approximate forbidden fivefold symmetries such as the pentagonal dodecahedron, but with asymmetric pentagonal faces, and the icosahedron, again with different-sized triangular faces, as a combination of the octahedron and pyritohedron.

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