Recent trophic changes in Kootenay Lake, British Columbia, as recorded by fossil diatoms

1983 ◽  
Vol 61 (7) ◽  
pp. 1983-1992 ◽  
Author(s):  
G. L. Ennis ◽  
T. G. Northcote ◽  
J. G. Stockner
Keyword(s):  
Drainage Basin ◽  
Sediment Cores ◽  
Phosphate Fertilizer ◽  
Phosphorus Loading ◽  
Diatom Species ◽  
Asterionella Formosa ◽  
Trophic Changes ◽  
Fragilaria Crotonensis ◽  
Kootenay Lake ◽  
Fossil Diatoms

Short sediment cores (ca. 40 cm long) were collected from three locations within Kootenay Lake, B.C., and the occurrence of diatoms within the cores was recorded and analyzed. This analysis of fossil diatoms in the sediments of Kootenay Lake has provided evidence for environmental change as a result of man's activities in the drainage basin. Changes to the trophic status of the lake are related to operation of a phosphate fertilizer plant (beginning in 1953) on the major southern inlet river and to more recent water regulation on both the southern and northern major inlet rivers. Diatom numbers and volumes at the deeper core depths were lowest. Diatom species in the deeper core depths consisted of an assemblage of oligotrophic and eutrophic indicators corresponding to high (but not critically high) phosphorus loading to the lake. Above the 5-cm depth, numbers increased and peaked at the 3-cm depth in samples nearest the south end of the lake. At other locations within the lake, where sedimentation rates were lower, numbers peaked in the top centimetre of sediment. Concomitant with increased phosphorus loading diatom species indicative of oligotrophic conditions such as Cyclotella ocellata declined, while eutrophic indicators including Cyclotella glomerata, Melosira granulata v. angustissima, Stephanodiscus spp., Asterionella formosa, and Fragilaria crotonensis increased. Asterionella formosa and Fragilaria crotonensis showed highest abundances in the top 2 cm of the core. These species, which form a major component of the spring and fall diatom blooms, were responding to both increased nutrients and improved light conditions resulting from decreased freshet turbidity. The Araphidineae/Centrales ratio was not useful in classifying trophic changes in Kootenay Lake since numbers of centric diatoms did not decline with nutrient enrichments (although there was a dominance shift from oligotrophic centrics to eutrophic centrics). Shannon–Wiener diversity values remained high throughout the recent history of the lake.

Climate Variation and the Rise and Fall of an Andean Civilization

1997 ◽  
Vol 47 (2) ◽  
pp. 235-248 ◽  
Author(s):  
Michael W. Binford ◽  
Alan L. Kolata ◽  
Mark Brenner ◽  
John W. Janusek ◽  
Matthew T. Seddon ◽  
...  
Keyword(s):  
Agricultural Production ◽  
Climate Changes ◽  
Drainage Basin ◽  
Sediment Cores ◽  
Agricultural Field ◽  
Lake Levels ◽  
Level Variation ◽  
Spatial And Temporal Patterns ◽  
Lake Titicaca ◽  
Basin Water

Paleolimnological and archaeological records that span 3500 years from Lake Titicaca and the surrounding Bolivian–Peruvian altiplano demonstrate that the emergence of agriculture (ca. 1500 B.C.) and the collapse of the Tiwanaku civilization (ca. A.D. 1100) coincided with periods of abrupt, profound climate change. The timing and magnitude of climate changes are inferred from stratigraphic evidence of lake-level variation recorded in14C-dated lake-sediment cores. Paleo-lake levels provide estimates of drainage basin water balance. Archaeological evidence establishes spatial and temporal patterns of agricultural field use and abandonment. Prior to 1500 B.C., aridity in the altiplano precluded intensive agriculture. During a wetter period from 1500 B.C. to A.D. 1100, the Tiwanaku civilization and its immediate predecessors developed specialized agricultural methods that stimulated population growth and sustained large human settlements. A prolonged drier period (ca. A.D. 1100–1400) caused declining agricultural production, field abandonment, and cultural collapse.

Paleolimnological analyses of cultural eutrophication patterns in British Columbia lakes

2000 ◽  
Vol 78 (7) ◽  
pp. 873-888 ◽  
Author(s):  
Euan D Reavie ◽  
John P Smol ◽  
Ian D Sharpe ◽  
Lisa A Westenhofer ◽  
Anne-Marie Roberts
Keyword(s):  
Water Quality ◽  
British Columbia ◽  
Total Phosphorus ◽  
Human Intervention ◽  
Cultural Eutrophication ◽  
High Productivity ◽  
Planktonic Diatoms ◽  
Stratigraphic Analysis ◽  
Fragilaria Crotonensis ◽  
Fossil Diatoms

Diatom-based paleolimnological approaches were used to determine the effects of cultural impacts on eutrophication histories in four lakes from central British Columbia. Stratigraphic analysis of fossil diatoms in 210Pb-dated cores and inferences of past total phosphorus concentrations using diatom-based models were used to reconstruct the nutrient histories of Takysie, Tchesinkut, Francois, and Tyhee lakes. Diatom microfossils indicate that these lakes are probably naturally productive, but some nutrient enrichment has likely occurred in response to human development (since A.D. 1850), particularly in Tyhee Lake. However, in Tchesinkut and Francois lakes, some reduction in total phosphorus may have occurred in recent decades. Takysie, Tchesinkut, and Francois lakes have been dominated by planktonic diatoms indicative of high productivity (e.g., Stephanodiscus, Asterionella, Fragilaria crotonensis, Aulacoseira). Tyhee Lake has been dominated by benthic Fragilaria species, but Stephanodiscus minutulus has increased in recent decades. These data were pooled with previously published paleolimnological data from British Columbia to summarize cultural eutrophication patterns in this region. Out of 11 British Columbia lakes considered, 10 were productive before human intervention, but 7 eutrophied further as a result of human activities. One lake exhibited no obvious post-1850 change in diatom assemblage, suggesting little human impact on water quality. In three of the lakes, recent improvements in water quality may have occurred in response to recent mitigation efforts.Key words: eutrophication, paleolimnology, British Columbia, diatoms, lakes, mining.

scholarly journals Last-glacial to postglacial climate formation in the continental interior inferred from multi-proxy records of Lake Hovsgol, Mongolia

2010 ◽  
Vol 6 (2) ◽  
pp. 385-420
Author(s):  
K. Minoura ◽  
D. Sugawara ◽  
T. Kawai
Keyword(s):  
Solar Energy ◽  
Drainage Basin ◽  
Sediment Cores ◽  
Vegetation Feedback ◽  
Climate Conditions ◽  
Orbital Parameters ◽  
Proxy Records ◽  
The North ◽  
Abstract Knowledge ◽  
Lake Hovsgol

Abstract. Knowledge of the evolution of arboreal forests is necessary to interpret the cause of climate formation in intracontinental regions. Paleoproxy records of sediment cores from Lake Hovsgol, Mongolia show that watershed conditions have fluctuated widely during the last 30 ka because of changing orbital parameters. Termination of glacial cooling and the subsequent prevalence of deglacial warming were consequences of solar forcing. Arboreal forests exerted an important influence on the atmospheric moisture cycle at high latitudes. Air pressure decreased because of raised humidity from water vapor penetration into inland regions that occurred along with summer monsoons. Data showing utilization of solar energy are necessary for establishing climate conditions. Atmospheric warming under increased insolation caused a shift of the monsoon limit to the north, amplifying the summer moisture supply to the watershed. That amplification engendered the appearance of the maximum vegetation in the Hovsgol drainage basin at the beginning of the Holocene. The retreat of arboreal forests that occurred along with decreased solar energy shrank the humidification-vegetation feedback loop, thereby decreasing the atmospheric humidity. The consequently lowered vapor pressure contributed to the incursion of cool air masses from the north.

scholarly journals Lake Onego development in the late glacial assessed with the use of GIS technologies

2019 ◽  
pp. 83-90 ◽  
Author(s):  
D. A. Subetto ◽  
M. S. Potakhin ◽  
M. B. Zobkov ◽  
A. Yu. Tarasov ◽  
T. S. Shelekhova ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Sediment Cores ◽  
Late Glacial ◽  
Lake Basin ◽  
Lake Area ◽  
Digital Maps ◽  
Digital Elevation ◽  
Spatial Parameters ◽  
Elevation Model ◽  
Maximum Development

The GIS-based reconstructions of Lake Onego development in the Late Glacial (14500–12300 yrs ago) were performed. Reconstructions have been based on the deglaciation model of the Lake Onego depression, digital elevation model of the lake depression, SRTM model of its drainage basin and on the data obtained from the palaeolimnological studies of numerous lake sediment cores. This allowed us to distinguish six main stages of the lake development for which a series of detailed schemes were produced. 1. Formation of the ice-dammed lake as a result of the ice sheet retreating (14.5 cal ka BP). 2. Emerging of the southern and central parts of the lake basin from the ice cover (14.0 cal ka BP). 3. The maximum development of the proglacial lake (13.3 cal ka BP). The lake area in this period was around 33 000 km2. 4. The first regression (13.2 ka BP). 5. The second regression (12.4 ka BP). 6. The third regression (12.3 ka BP), when the area of the lake dropped to 18 000 km2. We created detailed digital maps of the main stages of Lake Onego development during the Late Glacial and calculated the spatial parameters of the lake. The quantitative data obtained in this study would be used in estimation of the volumes of the lake and outflow discharges in the past. Maps are available in electronic form.

Evidence of cultural eutrophication of the Gulf of Gdańsk based on diatom analysis

2019 ◽  
Vol 48 (3) ◽  
pp. 247-261 ◽  
Author(s):  
Jarosław Pędziński ◽  
Małgorzata Witak
Keyword(s):  
Surface Sediments ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Gulf Of Gdańsk ◽  
Cultural Eutrophication ◽  
Organic Matter Concentration ◽  
Nitrogen Loads ◽  
Trophic Changes ◽  
Gulf Of Gdansk ◽  
Matter Concentration

Abstract The objective of this study was to reconstruct the environmental changes in the Gulf of Gdańsk in the last 200 years. Four subbottom sediment cores were analyzed with respect to diatom flora and anthropogenic effects. The so-called “anthropogenic assemblage” – a result of cultural eutrophication – was observed in the surface sediments. Changes in the species composition may have been caused by the increased use of fertilizers, nitrogen loads and increasing organic matter concentration. Three phases (A, B and C) were distinguished based on the floristic spectrum, which clearly indicates trophic changes in the study area.

Sediment Records of Man’s Activities in the Kootenay Lake Drainage Basin

1994 ◽  
Vol 29 (1) ◽  
pp. 103-116
Author(s):  
R.W. Macdonald ◽  
E.C. Carmack ◽  
C.H. Pharo
Keyword(s):  
Sedimentation Rate ◽  
Drainage Basin ◽  
Road Construction ◽  
The North ◽  
Mining History ◽  
Boom And Bust ◽  
History Of ◽  
Lead Zinc ◽  
Lake Drainage ◽  
Kootenay Lake

Abstract Four cores from Kootenay Lake have been dated using 2l0Pb. These cores have also been analyzed for total Pb concentration specifically to compare the sediment record with the known history of lead-zinc mining around the lake. Two sorts of impact on the lake are recorded in the sediments. First, there is obvious contamination by Pb in which concentrations within cores parallel the regional “boom-and-bust” mining history. Second, the sedimentation rate appears to have been affected by damming of the inflowing rivers and probably also by logging and the associated road construction in the watersheds. Spatial variability within the lake sediments is evident: sedimentation rate is highest towards the north and south ends of the lake where river inflow is greatest; contamination by Pb is highest in the middle of the lake close to the major mining activities.

Internal phosphorus loading from bottom sediments of a shallow preliminary reservoir

2008 ◽  
Vol 37 (2) ◽  
Author(s):  
Renata Dondajewska
Keyword(s):  
Bottom Sediments ◽  
Seasonal Variability ◽  
Sediment Cores ◽  
Phosphorus Release ◽  
Ex Situ ◽  
Phosphorus Loading ◽  
Internal Phosphorus Loading

Internal phosphorus loading from bottom sediments of a shallow preliminary reservoirThe aim of the studies done in a shallow preliminary reservoir (western Poland) was to determine the intensity and seasonal variability of phosphorus release from bottom sediments. Ex situ studies were done using intact sediment cores taken in succeeding seasons at 3 research stations. The highest phosphorus loading was observed in spring (May and April), both in 2005 and 2006. The range of loading was between 23.7 and 66.6 mgP m

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