Late winter – early spring sedimentation off the Great Whale River, southeastern Hudson Bay

1988 ◽  
Vol 25 (6) ◽  
pp. 930-933 ◽  
Author(s):  
B. d'Anglejan ◽  
G. Biksham
Keyword(s):  
Algal Biomass ◽  
Sediment Traps ◽  
Early Spring ◽  
Early Summer ◽  
Late Winter ◽  
Hudson Bay ◽  
Sedimentation Rates ◽  
Summer Period ◽  
The Mean ◽  
Peak Runoff

Sediment traps were used to measure particle-settling fluxes in serial moorings offshore of Great Whale River (Hudson Bay), both under the late winter sea-ice cover and during and after breakup. Before breakup, the settling fluxes ranged between 0.25 and 2 g cm−2 100 a−1, increasing from April to May in response to the progressively larger under-ice algal biomass. Fluxes also increased with depth. During and after breakup, including the early summer period of peak runoff, sedimentation rates increased to values of up to 33 g cm−2100 a−1. These fluxes agree with the mean sedimentation rate determined from 210Pb activities in the underlying sediments.

scholarly journals Changes of Variability in Response to Increasing Greenhouse Gases. Part II: Hydrology

2009 ◽  
Vol 22 (22) ◽  
pp. 6089-6103 ◽  
Author(s):  
Richard T. Wetherald
Keyword(s):  
Soil Moisture ◽  
Greenhouse Gases ◽  
General Circulation ◽  
Circulation Model ◽  
Early Spring ◽  
Precipitation Rate ◽  
Late Winter ◽  
Annual Data ◽  
Geophysical Fluid Dynamics Laboratory ◽  
The Mean

Abstract This paper examines hydrological variability and its changes in two different versions of a coupled ocean–atmosphere general circulation model developed at the National Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics Laboratory and forced with estimates of future increases of greenhouse gas and aerosol concentrations. This paper is the second part, documenting potential changes in variability as greenhouse gases increase. The variance changes are examined using an ensemble of 8 transient integrations for an older model version and 10 transient integrations for a newer model. Monthly and annual data are used to compute the mean and variance changes. Emphasis is placed on computing and analyzing the variance changes for the middle of the twenty-first century and compared with those found in the respective control integrations. The hydrologic cycle intensifies because of the increase of greenhouse gases. In general, precipitation variance increases in most places. This is the case virtually everywhere the mean precipitation rate increases and many places where the precipitation decreases. The precipitation rate variance decreases in the subtropics, where the mean precipitation rate also decreases. The increased precipitation rate and variance, in middle to higher latitudes during late fall, winter, and early spring leads to increased runoff and its variance during that period. On the other hand, the variance changes of soil moisture are more complicated, because soil moisture has both a lower and upper bound that tends to reduce its fluctuations. This is particularly true in middle to higher latitudes during winter and spring, when the soil moisture is close to its saturation value at many locations. Therefore, changes in its variance are limited. Soil moisture variance change is positive during the summer, when the mean soil moisture decreases and is close to the middle of its allowable range. In middle to high northern latitudes, an increase in runoff and its variance during late winter and spring plus the decrease in soil moisture and its variance during summer lend support to the hypothesis stated in other publications that a warmer climate can cause an increasing frequency of both excessive discharge and drier events, depending on season and latitude.

Some Aspects of the Ecology of Lake Macquarie, N.S.W., with Regard to an Alleged Depletion of Fish. V. Chlorophyll Distribution

1959 ◽  
Vol 10 (3) ◽  
pp. 316
Author(s):  
PS Davis
Keyword(s):  
Surface Waters ◽  
Vertical Profile ◽  
Chlorophyll Concentration ◽  
Euphotic Zone ◽  
Early Summer ◽  
Late Winter ◽  
Light Penetration ◽  
Chlorophyll Distribution ◽  
The Mean ◽  
Made In

The chlorophyll a in samples from five stations in Lake Macquarie was determined over the period July 1955 to November 1956. The mean surface value for the four stations within the lake proper was 1.26 mg/m³. The vertical profile at one station was studied and the mean of these profile values was 1.23 mg/m³. Throughout the period of the survey chlorophyll concentrations in the lake varied from 0.1 to 4.0 mg/m³. The lowest values were found in the late winter and early summer (November) and the peaks during spring and autumn. The chlorophyll concentration in the surface waters of Lake Macquarie was shown to be significantly higher than that of the marine water entering the lake, but lower than that of a comparison station in the Hawkesbury River. One series of light penetration measurements made in December 1956 showed that all the water in the lake, and all but one section of Dora Creek, lay within the euphotic zone.

The rumenitis and liver abscess complex and vitamin A status in beef cattle

1970 ◽  
Vol 12 (2) ◽  
pp. 291-298
Author(s):  
A. C. Rowland
Keyword(s):  
Vitamin A ◽  
Late Summer ◽  
Early Spring ◽  
Agglutination Test ◽  
Late Winter ◽  
Liver Lesions ◽  
Seasonal Incidence ◽  
Vitamin A Status ◽  
The Mean ◽  
Intensively Managed

SUMMARYThe seasonal incidence of rumen and liver lesions is recorded in traditional and in intensively managed cattle, together with the vitamin A status of the two groups. Rumen lesions were observed to reach a peak in the late winter and early spring in traditional cattle, at which time the liver vitamin A levels fell to the lowest point; liver lesions reached a peak in the late summer. No specific trend was observable in rumen and liver lesions in the barley beef group. The mean levels of vitamin A were approximately one-third of those shown by the traditionally managed animals.It did not prove possible using the agglutination test to identify the sera of animals showing active hepatic necrobacillosis at the time of slaughter.

Tree lines

1989 ◽  
Vol 324 (1223) ◽  
pp. 233-245 ◽  
Keyword(s):  
Growing Season ◽  
Early Spring ◽  
Summer Temperature ◽  
Northern Europe ◽  
Late Winter ◽  
Controlled Environment ◽  
Cold Climates ◽  
Tree Line ◽  
The Mean ◽  
Boreal Period

Trees do not generally grow in places where the mean temperature of the warmest month is less than about 10 °C. At their limit, trees are often short and crooked, the condition known as krummholz ; and the transition from tall forest to dwarf shrubby vegetation is often abrupt, forming a distinct tree line. Tree lines fluctuate with climatic change. There is compelling evidence to suggest that they shift to higher elevations and higher latitudes in warmer periods. In northern Europe, they were about 200 m higher in the Boreal period when the temperature is believed to have been 2 °C warmer than now. Controlled-environment studies and tree-ring evidence also point to considerable sensitivity of growth at the tree line to fluctuations in the summer temperature. Forest vegetation differs aerodynamically from dwarf vegetation in being aerodynamically rough. Consequently, the temperatures of above-ground tissues are closely coupled to temperatures of the air. In contrast, shorter vegetation experiences tissue temperatures and microclimates that depend substantially on other climatological variables, notably radiation and wind speed. Short vegetation is, on average, warmer than the air; this is the main reason why dwarf shrubs can succeed in cold climates where trees fail to grow and reproduce. Water stress commonly occurs in late winter and early spring when soil water is frozen. The foliage of trees at the tree line displays an inability to restrict water loss, either because the epidermis is damaged by abrasion or because the cuticle does not properly develop in the reduced growing season. Consequently, the longevity of leaves is reduced. Winter damage to trees is also likely as a result of gales and the deposition of ice in the canopy, both of which break branches and may contribute to the generally misshapen form of the crown.

scholarly journals Settling particle fluxes across the continental margin of the Gulf of Lion: the role of dense shelf water cascading

2009 ◽  
Vol 6 (4) ◽  
pp. 7897-7931 ◽  
Author(s):  
C. Pasqual ◽  
A. Sanchez-Vidal ◽  
D. Zúñiga ◽  
A. Calafat ◽  
M. Canals ◽  
...  
Keyword(s):  
Organic Matter ◽  
Calcium Carbonate ◽  
Continental Slope ◽  
Sediment Traps ◽  
Early Spring ◽  
Late Winter ◽  
Shelf Water ◽  
Physical Forcing ◽  
Settling Particles ◽  
Mass Fluxes

Abstract. Settling particles were collected using sediment traps deployed along three transects in the Lacaze-Duthiers and Cap de Creus canyons and the adjacent southern open slope from October 2005 to October 2006. The settling material was analysed to obtain total mass fluxes and main constituent contents (organic matter, opal, calcium carbonate, and siliciclastics). Cascades of dense shelf water from the continental shelf edge to the lower continental slope occurred from January to March 2006. They were traced through strong negative near-bottom temperature anomalies and increased current speeds, and generated two intense pulses of mass fluxes in January and March 2006. This oceanographic phenomenon appeared as the major physical forcing of settling particles at almost all stations, and caused both high seasonal variability in mass fluxes and important qualitative changes in settling material. Fluxes during the dense shelf water cascading (DSWC) event ranged from 90.1 g m−2 d−1 at the 1000 m depth station in the Cap de Creus canyon to 3.2 g m−2 d−1 at the canyon mouth at 1900 m. Fractions of organic matter, opal and calcium carbonate components increased seaward, thus diminishing the siliciclastic fraction. Temporal variability of the major components was larger in the canyon mouth and open slope sites, due to the mixed impact of dense shelf water cascading processes and the pelagic biological production. Results indicate that the cascading event remobilized and homogenized large amounts of material down canyon and southwardly along the continental slope contributing to a better understanding of the internal dynamics of DSWC events. While the late winter/early spring bloom signature was diluted when DSWC occurred, the primary production dynamics were observable at all stations during the rest of the year and highlighted the biological community succession in surface waters.

Reproduction in Sminthopsis-Longicaudata (Marsupialia, Dasyuridae) - Laboratory Observations

1986 ◽  
Vol 13 (1) ◽  
pp. 7 ◽  
Author(s):  
PA Woolley ◽  
A Valente
Keyword(s):  
Endangered Species ◽  
Breeding Season ◽  
Early Summer ◽  
Oestrous Cycle ◽  
Gestation Period ◽  
Late Winter ◽  
Breeding Condition ◽  
Males And Females ◽  
The Mean

Observations on the pattern of reproduction in Sminthopsis longicaudata, at present considered to be an endangered species, are presented. S. longicaudata is polyoestrous and in the laboratory females are in breeding condition from late winter (August) to early summer (December). They enter oestrus up to four times during the breeding season. Two litters were born 17 and 19 days post-mating, but the gestation period may be less than 15 days. The mean length of the oestrous cycle is 34.4 days. Both males and females may be able to breed in more than one season.

scholarly journals A late-winter to early-spring temperature reconstruction for southeastern Norway from 1758 to 2006

2007 ◽  
Vol 46 ◽  
pp. 404-408 ◽  
Author(s):  
Ø. Nordli ◽  
E. Lundstad ◽  
A.E.J. Ogilvie
Keyword(s):  
20Th Century ◽  
19Th Century ◽  
18Th Century ◽  
Temperature Reconstruction ◽  
Early Spring ◽  
Late Winter ◽  
Spring Temperature ◽  
Early 19Th Century ◽  
The Mean ◽  
The 19Th Century

AbstractSystematic temperature observations were not undertaken in Norway until the early 19th century, and even then only sporadically. Climate-proxy data may be used to reconstruct temperatures before this period, but until now there have not been any climate proxies available for late winter. This situation has recently changed, as a diary containing historical ice break-up data from a farm near lake Randsfjord in southeastern Norway has been discovered. These data, together with observations from lake Mjøsa in the same region, make it possible to reconstruct temperature back to 1758. The reconstructed series, combined with instrumental series from the area near the lake, were merged into one composite time series covering the period 1758–2006. The lowest temperatures are seen during the Dalton sunspot minimum in the early 19th century. The 20th century was 1.3˚C warmer than the 19th century, whereas the 19th century was 0.4˚C warmer than the last 43 years of the 18th century. During the period 1758–1850, the mean temperature was 1.4˚C lower than the mean value of the 20th century. The warmth observed in the 1990s and at the start of the 21st century is unprecedented during the whole series.

Seasonal dynamics of Proteocephalus sagittus in the stone loach Barbatula barbatula from the Haná River, Czech Republic

2004 ◽  
Vol 78 (3) ◽  
pp. 225-229 ◽  
Author(s):  
J. Jarkovský ◽  
B. Koubková ◽  
T. Scholz ◽  
M. Prokeš ◽  
V. Baruš
Keyword(s):  
Czech Republic ◽  
Seasonal Cycle ◽  
Early Spring ◽  
Early Summer ◽  
Fish Host ◽  
Late Winter ◽  
Stone Loach ◽  
Barbatula Barbatula ◽  
Infection Parameters ◽  
First Time

AbstractThe seasonal cycle of the cestode Proteocephalus sagittus (Cestoda: Proteocephalidae) was studied for the first time in the stone loach Barbatula barbatula from the Haná River, Czech Republic. A total of 180 loaches were examined monthly from January to December 2001. The parasite occurred in loaches throughout the year but infection parameters differed significantly among seasons, with the highest values of prevalence and abundance from the late winter to the early summer. Parasite recruitment took place in the winter and early spring and the worms sexually matured in the late spring and early summer. In contrast to P. torulosus, the gravid worms of which laid eggs only at the end of the spring/beginning of the summer, gravid worms of P. sagittus were also found, although in low numbers, in the autumn and early winter. The rate of infection of loach with P. sagittus was neither dependent on the sex nor on the size of its fish host.

scholarly journals STUDIES IN THE BLOOD CYTOLOGY OF THE RABBIT

1930 ◽  
Vol 52 (2) ◽  
pp. 167-179
Author(s):  
Louise Pearce ◽  
Albert E. Casey
Keyword(s):  
Peripheral Blood ◽  
General Trend ◽  
Early Summer ◽  
Late Winter ◽  
General Tendency ◽  
Mean Values ◽  
The Mean

Consecutive weekly observations on the lymphocyte and monocyte counts of the peripheral blood were made on 5 groups of normal rabbits, a total of 45 animals, during a period of 20 months from October, 1927 to July, 1929. Individual groups were examined 8 to 35 weeks. The results are analyzed on the basis of the mean group values of each week. In the case of the 4 groups followed 13 to 35 weeks, there was a general tendency for the lymphocyte mean values to become increased; with the group observed 8 weeks, the level of mean values showed little change. The general trend of the monocyte mean values was also in the direction of higher levels but it was less pronounced than that of the lymphocytes. The period of greatest irregularity in the mean values of the lymphocytes was in the late winter and spring months of both years. With the monocytes, periods of fluctuating values occurred in the fall of 1927, the spring and early summer of 1928, and in the late winter, spring, and early summer of 1929. There was a certain degree of parallelism in the case of two groups examined during the same months with respect to the direction and time of occurrence of a change in the level of lymphocyte and monocyte mean values. The general levels of lymphocyte and monocyte mean values in the groups examined during 1927–28 were higher than in the groups of 1928–29. The results based upon the trends of mean group values obtained from consecutive weekly observations showed no evidence of a consistent numerical relationship between lymphocytes and monocytes.

Population dynamics of three species of dasyurid marsupials in arid central Australia: a 10-year study

2001 ◽  
Vol 28 (5) ◽  
pp. 493 ◽  
Author(s):  
Christopher R. Dickman ◽  
Adele S. Haythornthwaite ◽  
Gayle H. McNaught ◽  
Paul S. Mahon ◽  
Bobby Tamayo ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Life Histories ◽  
Arid Zone ◽  
Early Spring ◽  
Early Summer ◽  
Late Winter ◽  
Sand Ridge ◽  
Red Foxes ◽  
Central Australia ◽  
Simpson Desert

This study investigated the population dynamics of three species of dasyurid marsupials in sand ridge habitat of the Simpson Desert, western Queensland, over a 10-year period between March 1990 and December 1999. The lesser hairy-footed dunnart (Sminthopsis youngsoni), was captured most consistently over the period of study, followed by the wongai ningaui (Ningaui ridei), and the mulgara (Dasycercus cristicauda). Rates of recapture were low (4.5–22.2%), probably because individuals of each species are very mobile. All species bred in late winter or early spring when animals were aged at least 8–10 months, and independent juveniles first appeared usually in summer. S. youngsoni reared a second litter in late spring or early summer in 3 of the 10 years studied, when the availability of food was likely to have been high; neither N. ridei nor D. cristicauda were known to attempt a second litter within a season. To explore factors that might influence population dynamics, we compared capture rates of each species with measures of rainfall, temperature, vegetation cover, abundance of predators [feral cats (Felis catus), red foxes (Vulpes vulpes), and goannas (Varanus spp.)], dragons, other dasyurids and indices of food abundance. The abundance of S. youngsoni appeared to depend primarily on the cover of spinifex 7–9 months earlier, that of D. cristicauda was related most strongly to rainfall 7–9 months earlier, while that of N. ridei was related to minimum temperature lagged by 1–3 months. While the dynamics of other arid-zone mammals are driven demonstrably by interactions between rainfall, resource availability and predation, our findings suggest that dasyurids have limited flexibility in their life histories and are influenced more subtly and by factors such as facilitation that are just beginning to become apparent.

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