The Standing Crop of Net Plankton in Lakes

1953 ◽  
Vol 10 (5) ◽  
pp. 224-237 ◽  
Author(s):  
D. S. Rawson
Keyword(s):  
Standing Crop ◽  
Seasonal Fluctuation ◽  
Western Canada ◽  
Inverse Relation ◽  
Secondary Effects ◽  
Eutrophic Lakes ◽  
Trophic Condition ◽  
The Past

Plankton sampling has been a part of the program in a number of investigations of lakes in western Canada during the past 20 years. The techniques chosen for this work are discussed and criticized. The resulting data on average standing crop of net plankton are summarized and considered in relation to the kinds of lakes represented. The standing crop in 20 lakes shows an inverse relation to mean depth which is interpreted as indicating that, in most of these lakes, the trophic condition is greatly influenced by morphometry. Deviations from this relation appear to be explained by the secondary effects of climate and edaphic situation.The difference in quantity between the standing crops of net plankton in oligotrophic and eutrophic lakes is not large, and, of course, these lake types intergrade. This lack of sharp differentiation is further obscured by rapid and extensive seasonal fluctuation in amounts of plankton and by the difficulties inherent in present methods of sampling. These circumstances render measurements of standing crop difficult and of only moderate utility in suggesting the trophic type or the possible productivity of a lake.

scholarly journals Control and remediation methods for eutrophic lakes in the past 30 years

2020 ◽  
Vol 81 (6) ◽  
pp. 1099-1113 ◽  
Author(s):  
Yuan Zhang ◽  
Pingping Luo ◽  
Shuangfeng Zhao ◽  
Shuxin Kang ◽  
Pengbo Wang ◽  
...  
Keyword(s):  
New Technologies ◽  
Management Strategies ◽  
Cyanobacterial Blooms ◽  
Small Scale ◽  
Short Term ◽  
Eutrophic Lakes ◽  
Lake Ecosystems ◽  
The Past ◽  
Incomplete Removal

Abstract Accelerated eutrophication, which is harmful and difficult to repair, is one of the most obvious and pervasive water pollution problems in the world. In the past three decades, the management of eutrophication has undergone a transformation from simple directed algal killing, reducing endogenous nutrient concentration to multiple technologies for the restoration of lake ecosystems. This article describes the development and revolution of three remediation methods in application, namely physical, chemical, and biological methods, and it outlines their possible improvements and future directions. Physical and chemical methods have obvious and quick effects to purify water in the short term and are more suitable for small-scale lakes. However, these two methods cannot fundamentally solve the eutrophic water phenomenon due to costly and incomplete removal results. Without a sound treatment system, the chemical method easily produces secondary pollution and residues and is usually used for emergency situations. The biological method is cost-effective and sustainable, but needs a long-term period. A combination of these three management techniques can be used to synthesize short-term and long-term management strategies that control current cyanobacterial blooms and restore the ecosystem. In addition, the development and application of new technologies, such as big data and machine learning, are promising approaches.

THE EFFECT OF SAY STINKBUG FEEDING ON WHEAT

1945 ◽  
Vol 77 (11) ◽  
pp. 200-200 ◽  
Author(s):  
L. A. Jacobson
Keyword(s):  
Western Canada ◽  
Severe Damage ◽  
The Past ◽  
Seed Crops ◽  
Chlorochroa Sayi ◽  
New Pest

Say stinkbug, Chlorochroa sayi Stal, is a comparatively new pest of wheat and other seed crops in Western Canada. In the past ten years it frequently has caused severe damage to wheat in many localized areas.

Late Holocene fluctuations of Stoppani Glacier, southernmost Patagonia

2020 ◽  
Vol 95 ◽  
pp. 56-64 ◽  
Author(s):  
Brian Menounos ◽  
Lyssa Maurer ◽  
John J. Clague ◽  
Gerald Osborn
Keyword(s):  
Pacific Northwest ◽  
Late Holocene ◽  
Response Times ◽  
Western Canada ◽  
Lateral Moraine ◽  
The Past ◽  
Significant Difference ◽  
Glacial Expansion ◽  
Age Range ◽  
The U.S

AbstractSome lateral moraines contain a rich record of Holocene glacial expansion. Previous workers have used such evidence to document glacial fluctuations in western Canada, Alaska, and the U.S. Pacific Northwest, but similar studies in Patagonia are uncommon. Here we report on the late Holocene behavior of Stoppani Glacier, a 75 km2 glacier sourced in the Cordillera Darwin, southernmost Patagonia. Based on radiocarbon-dated wood and organic material contained in the glacier's northeast lateral moraine, we infer that Stoppani Glacier advanced shortly before 3.8–3.6, at 3.2–2.8, 2.3–2.1, and 0.3–0.2, and possibly sometime before 1.4–1.3 and 0.8–0.7 cal ka BP. These advances culminated at 0.3–0.2 cal ka BP, when the glacier constructed a prominent end moraine, marking its greatest extent of the past 4000 years. Although the timing of several of the advances overlap with the age range of glacial expansion recognized elsewhere in Patagonia, some do not. Asynchronous behavior observed in the glacial record may arise from the type of evidence (e.g., lateral stratigraphy vs. end moraine) used to document glacial fluctuations or variations in climate or glacial response times. A significant difference between the Stoppani record and some other Patagonian records is that the former indicates general expansion of ice over the last 4000 years, whereas the latter indicate a net decrease in extent over that period.

Zooplankton Community Structure in Hardwater Hypertrophic Lakes of Alberta

1993 ◽  
Vol 27 (7-8) ◽  
pp. 353-361 ◽  
Author(s):  
B. Pinel-Alloul
Keyword(s):  
Phosphorus Content ◽  
Size Structure ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Western Canada ◽  
Zooplankton Abundance ◽  
Lime Treatment ◽  
Eutrophic Lakes ◽  
Size Spectra ◽  
Zooplankton Community Structure

Excessive concentrations of phosphorus are a common feature of hardwater eutrophic lakes in western Canada. Preliminary experimental lime treatment showed that this approach had a great potential to reduce phosphorus content and algal biomass. Therefore, two pairs of experimental and reference lakes were selected for a whole lake lime treatment and monitored for a full year prior to manipulation. This study presents the composition and size structure of the Zooplankton community of the lakes before treatment in order to assess the natural summer and inter-lake variations. Before lime treatment, seasonal means of total Zooplankton abundance and biomass ranged from 17 ± 8 to 127 ± 84 ind. L−1 and from 4 ± 2 to 138 ± 236 mg m−3, respectively. The two experimental lakes (Halftnoon and Lofty) were the richest in Zooplankton while the references lakes (Crooked and Jenkins) were the poorest. A total of 30 Zooplankton species (17 rotifers, 2 calanoids, 4 cyclopoids and 7 cladocerans) were recorded as well as 3 chaoborid species. The composition and size structure of Zooplankton varied between lakes and dates. Rotifers accounted for the majority of Zooplankton abundances (59-91%) while Cladocera (78-99%) or Copepoda (74%) in Crooked lake formed most of the Zooplankton biomass. Summer variations of the Zooplankton groups were described along with changes in size spectra. The temporal variation and the inter-lake differences in Zooplankton structure were discussed in relation to trophy, fish and invertebrate predation, and cyanophyte interactions.

scholarly journals “Jean Barman — Vernacular Historian”

2017 ◽  
Vol 27 (2) ◽  
pp. 136-146
Author(s):  
Heather Devine
Keyword(s):  
Pacific Northwest ◽  
Mixed Race ◽  
Indigenous Studies ◽  
Western Canada ◽  
French Canadians ◽  
Historical Sources ◽  
The Past ◽  
The Pacific ◽  
Personal Experiences ◽  
Vernacular History

Over the past year, several excellent new publications focused on the histories of mixed-race French-Canadian communities in western Canada and the Pacific Northwest. Of these books, Jean Barman’s French Canadians, Furs and Indigenous Women in the Making of the Pacific Northwest merits special attention, because the author has successfully sought out, and integrated, vernacular voices as historical sources. And for this reason, Jean Barman is sometimes referred to as a “vernacular,” or grassroots historian. What is vernacular history? Is this genre a product of methodology or of one’s worldview? And can a vernacular approach to history help scholars navigate the increasingly politicised environment of indigenous studies? The author reflects on these questions, by sharing some of her personal experiences with Jean Barman that illustrate the complexity of the issues surrounding indigenous historical practice today.

Le Passé a-t-il de l'avenir devant lui? Bilan du théâtre francophone de l'Ouest canadien

1996 ◽  
Vol 21 (3) ◽  
pp. 208-218
Author(s):  
Ingrid Joubert
Keyword(s):  
Nineteenth Century ◽  
Human Rights ◽  
Minority Groups ◽  
Western Canada ◽  
The Past ◽  
French Speaking ◽  
History Of ◽  
Indian Relations ◽  
Anglo Indian

For the French speaking minorities of Manitoba, the struggle against oppression has often meshed with battles for justice and human rights waged by other Canadian minority groups. Over the past two decades, plays by English and French speaking playwrights have echoed theatrical themes of the nineteenth century by centring on the plight of the Métisse. Being of Amer-Indian and Franco-Canadian descent, the history of the Métisse offers a fascinating perspective on Anglo-French and Anglo-Indian relations. In many of the plays, much attention is paid to the legendary story of Louis Riel, a Métisse chief who led the fight against British expansion into Western Canada and who was executed by the Crown for the murder of Thomas Scott, a British officer. With Riel as an emblem, anglophone and francophone playwrights have forged new outlooks on the historical struggle for control of Western Canada. Furthermore, while investigating the past playwrights have uncovered ways in which conflicting interpretations of history throw light upon present-day Canadian cultural complexities.

Biology of Bracon cephi (Gahan) (Hymenoptera: Braconidae), An Important Native Parasite of the Wheat Stem Sawfly, Cephus cinctus Nort. (Hymenoptera: Cephidae), in Western Canada

1953 ◽  
Vol 85 (3) ◽  
pp. 103-107 ◽  
Author(s):  
W. A. Nelson ◽  
C. W. Farstad
Keyword(s):  
Western Canada ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
The Past ◽  
Native Parasite ◽  
Prairie Provinces

During the past 25 years the wheat stem sawfly, Cephus cinctus Nort., has become one of the most destructive pests of wheat in the Prairie Provinces. Annual losses in the wheat-growing area of Saskatchewan have been estimated as high as 17 million bushels (King and McDonald, 1944). There are, however, several native parasites of this pest, and of these Bracon cephi (Gahan) [Microbracon cephi Gahan] is the most important. In some areas this parasite has been very effective in reducing severe sawfly infestations.

Climatic and hydrologic variability during the past millennium in the eastern Rocky Mountains and northern Great Plains of western Canada

2008 ◽  
Vol 70 (2) ◽  
pp. 188-197 ◽  
Author(s):  
Thomas W.D. Edwards ◽  
S. Jean Birks ◽  
Brian H. Luckman ◽  
Glen M. MacDonald
Keyword(s):  
Great Plains ◽  
Rocky Mountains ◽  
Ice Age ◽  
Northern Great Plains ◽  
Western Canada ◽  
Medieval Climate Anomaly ◽  
Air Masses ◽  
The Past ◽  
Hydrologic Variability ◽  
Atmospheric Relative Humidity

AbstractModelling of tree-ring δ13C and δ18O data from the Columbia Icefield area in the eastern Rocky Mountains of western Canada provides fuller understanding of climatic and hydrologic variability over the past 1000 yr in this region, based on reconstruction of changes in growth season atmospheric relative humidity (RHgrs), winter temperature (Twin) and the precipitation δ18O–Twin relation. The Little Ice Age (~ AD 1530s–1890s) is marked by low RHgrs and Twin and a δ18O–Twin relation offset from that of the present, reflecting enhanced meridional circulation and persistent influence of Arctic air masses. Independent proxy hydrologic evidence suggests that snowmelt sustained relatively abundant streamflow at this time in rivers draining the eastern Rockies. In contrast, the early millennium was marked by higher RHgrs and Twin and a δ18O–Twin relation like that of the 20th century, consistent with pervasive influence of Pacific air masses because of strong zonal circulation. Especially mild conditions prevailed during the “Medieval Climate Anomaly” ~ AD 1100–1250, corresponding with evidence for reduced discharge in rivers draining the eastern Rockies and extensive hydrological drought in neighbouring western USA.

Understanding Communities

2017 ◽  
Author(s):  
Stacy C. Kozakavich
Keyword(s):  
Built Environment ◽  
Intentional Communities ◽  
Western Canada ◽  
Field Of Study ◽  
The Past ◽  
Unified Field ◽  
History Of ◽  
History Of Scholarship

This chapter outlines patterns in the history of scholarship on intentional communities, beginning with journalists and social observers contemporary with the groups as well as voices from within communities themselves. The interplay between seemingly dispassionate evaluations, critical excoriations, and glowing endorsements from a multitude of scholars over the past several decades has created not a unified field of study but a multidisciplinary niche accommodating historians, anthropologists, economists, sociologists, and others. Archaeology's strengths in accessing evidence at three scales; landscape, the built environment, and artifacts, are presented and demonstrated in the case study of the ca. 1899–1920 Doukhobor village of Kirilovka in western Canada.

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