Geochemical Pathways and Biological Uptake of Radium in Small Canadian Shield Lakes

1984 ◽  
Vol 41 (3) ◽  
pp. 459-468 ◽  
Author(s):  
R. H. Hesslein ◽  
E. Slavicek
Keyword(s):  
Lake Trout ◽  
Pimephales Promelas ◽  
Canadian Shield ◽  
Coregonus Clupeaformis ◽  
Experimental Lakes Area ◽  
Biological Uptake ◽  
Single Addition ◽  
Shield Lakes ◽  
Large Adult

The sediment–water interactions and biological uptake of 226Ra are described for four small Canadian Shield lakes at the Experimental Lakes Area, Kenora, Ont. A single addition of 226Ra was made to each lake between 1970 and 1976. Approximately 90% of the added 226Ra initially sorbed to the sediments. Outflow from the lakes showed losses of only 5–11% 226Ra per year. Models are proposed for adsorption and outflow of 226Ra from lakes. Biological uptake and long-term 226Ra concentrations were measured in three species of macrophytes, crayfish, and five species of fish. Bioaccumulation ranged from 1100 to 5000 in macrophytes, 750 in crayfish, from 30 to 80 in large adult lake trout (Salvelinus namaycush), white sucker (Catostomus commersoni), and lake whitefish (Coregonus clupeaformis), and from 230 to 1200 in fathead minnows (Pimephales promelas), pearl dace (Semotilus margarita), and northern redbelly dace (Chrosomus eos). The concept of Ra/Ca ratio in organisms versus water and food is used to explain the differences in bioaccumulation. 226Ra is discriminated against versus calcium by fish but favored by macrophytes and crayfish.

Pelagic distribution of lake trout (Salvelinus namaycush) in small Canadian Shield lakes with respect to temperature, dissolved oxygen, and light

1998 ◽  
Vol 55 (1) ◽  
pp. 170-179 ◽  
Author(s):  
Todd J Sellers ◽  
Brian R Parker ◽  
David W Schindler ◽  
William M Tonn
Keyword(s):  
Light Intensity ◽  
Dissolved Oxygen ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Canadian Shield ◽  
Small Lakes ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Oxygenated Water ◽  
Shield Lakes

The distribution of lake trout (Salvelinus namaycush) with respect to water temperature, dissolved oxygen, and light intensity was surveyed in three small Canadian Shield lakes at the Experimental Lakes Area, northwestern Ontario. Based on hydroacoustic and gillnet surveys, there was considerable variation among lakes in temperatures occupied by lake trout during the summer. During the day, lake trout were concentrated at 4-8°C in Lake 375, broadly distributed from 6 to 15°C in Lake 442, and concentrated in the epilimnion at 19°C in Lake 468. At night, lake trout in all lakes occupied epilimnetic waters at 19-20°C. Lake trout inhabited highly oxygenated water, with 75-90% of fish at >6 mg dissolved oxygen ·L-1 throughout the spring and summer in all three lakes. Light intensity did not affect lake trout distribution in Lake 468 but may have contributed to lake trout daytime descent into cool waters in Lakes 375 and 442. We suggest that previously assumed niche boundaries of lake trout do not adequately describe critical habitat for the species in small lakes, the same lakes that are likely most sensitive to erosion of such habitat.

Long-Term Effects of Diet on the Biology of the Lake Trout and the Fishery in Lake Opeongo, Ontario

1970 ◽  
Vol 27 (1) ◽  
pp. 125-146 ◽  
Author(s):  
N. V. Martin
Keyword(s):  
Lake Trout ◽  
Feeding Activity ◽  
Salvelinus Namaycush ◽  
Point Of View ◽  
Average Weight ◽  
Coregonus Clupeaformis ◽  
Long Term Effects ◽  
Food Content ◽  
Coregonus Artedii

From 1936 to 1965 food content was examined in 17,171 Lake Opeongo lake trout (Salvelinus namaycush). The diet is analysed from the point of view of frequency of occurrence of foods, their weight, feeding activity of trout, size of trout and size of food, and seasonal and annual changes in food habits.In the late 1940's and early 1950's perch, Perca flavescens, largely disappeared from the diet. The lake trout initially turned to lake whitefish, Coregonus clupeaformis, and then to the cisco, Coregonus artedii, introduced into Lake Opeongo in 1948.As a result of these dietary changes lake trout are now heavier and rate of growth has improved. Age and size at maturity is later and there are fewer infertile fish. Egg counts, egg size, and ovary weights are now greater, particularly in the medium-sized lake trout.In the fishery the average weight of individual trout taken has almost doubled. About 25% more of the immature stock is exploited by the recent fishery. The harvest and catchability of lake trout has remained generally constant on a numerical basis but show an improvement on a poundage basis in the more recent years. The possible effects of these changes on the character of the fishery are discussed.

Evaluation of the responsiveness of the crustacean zooplankton community size spectrum to environmental change and an exotic invader in a sample of Canadian Shield lakes

2020 ◽  
Author(s):  
Lauren Emily Barth ◽  
Brian J. Shuter ◽  
W. Gary Sprules ◽  
Charles K. Minns ◽  
James A Rusak
Keyword(s):  
Time Series ◽  
Environmental Change ◽  
Canadian Shield ◽  
Ecosystem Change ◽  
Crustacean Zooplankton ◽  
Size Spectrum ◽  
Zooplankton Size ◽  
Shield Lakes ◽  
Change In Mean

We evaluated the crustacean zooplankton size spectrum as an indicator of lake characteristics and ecosystem change. First, we used time-series from seven Canadian Shield lakes to identify the factors associated with among-lake and among-year variability in the spectrum slope (relative abundance of small and large zooplankton) and centered height (total abundance). Second, we used time-series from an invaded and three control lakes to assess change in mean and variability in slope and height due to a Bythotrephes invasion. We found that the slope and the height reflected among-lake predictors related to morphometry. The slope was responsive to long-term declining lake phosphorus levels, whereas the height reflected both increases in dissolved organic carbon and decreases in ice duration. We detected a significant increase (i.e. flattening) in mean slope and substantial (up to 120%) increases in the CV of height after Bythotrephes invaded Harp Lake. Thus, the zooplankton size spectrum was responsive to long-term environmental change and a strong top-down perturbation can be detected through regular and frequent monitoring programs.

Spatial and environmental correlates of fish community structure in Canadian Shield lakes

2006 ◽  
Vol 63 (12) ◽  
pp. 2780-2792 ◽  
Author(s):  
Andrea Bertolo ◽  
Pierre Magnan
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Castor Canadensis ◽  
Canadian Shield ◽  
Coregonus Clupeaformis ◽  
Fish Community Structure ◽  
Piscivorous Fish ◽  
Environmental Correlates ◽  
Beaver Dam ◽  
Shield Lakes

We used data on fish species biomass from 38 lakes of the Canadian Shield (Québec) to determine the contribution of environmental (lake and watershed morphometry) and spatial (e.g., hydrographic connectivity and geographic coordinates) variables on fish community structure. By using a combination of multivariate analyses, we show that nearly half of the variation in the fish community structure is explained by the independent contributions of spatial and environmental factors. Walleye (Sander vitreus) and lake whitefish (Coregonus clupeaformis) were significantly associated with the absence of beaver (Castor canadensis) dams, whereas northern pike (Esox lucius) was positively correlated with beaver dam presence. Altitude and longitude, but not current patterns in lake connectivity, were the main explanatory spatial variables accounting for the observed pattern in fish community structure. Large piscivorous fish were associated with a reduced richness and biomass of small prey, suggesting that predation is a structuring factor in these lakes. By showing that geographic coordinates and altitude are better descriptors of fish community structure than hydrographic connections, our study suggests that past colonization routes are relatively more important than current ones in structuring fish communities at the landscape level. This interpretation is supported by recently published genetic data.

Long-term stability of cladoceran assemblages in small, shallow, Canadian Shield lakes experiencing marked calcium declines

2015 ◽  
Vol 77 (4) ◽  
pp. 547-561 ◽  
Author(s):  
L. E. Mosscrop ◽  
A. M. Paterson ◽  
A. M. DeSellas ◽  
J. Kurek ◽  
R. Weeber ◽  
...  
Keyword(s):  
Canadian Shield ◽  
Term Stability ◽  
Long Term Stability ◽  
Shield Lakes

Responses of Fish Populations in Lake 223 to 8 Years of Experimental Acidification

1987 ◽  
Vol 44 (S1) ◽  
pp. s114-s125 ◽  
Author(s):  
K. H. Mills ◽  
S. M. Chalanchuk ◽  
L. C. Mohr ◽  
I. J. Davies
Keyword(s):  
Fathead Minnow ◽  
Lake Trout ◽  
Pimephales Promelas ◽  
Salvelinus Namaycush ◽  
Early Years ◽  
White Sucker ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Slimy Sculpin ◽  
Experimental Acidification

Lake 223 in the Experimental Lakes Area, northwestern Ontario, was experimentally acidified with sulfuric acid from 1976 (initial average pH 6.49) to 1981 (average pH 5.02), and then maintained at pH 5.02 to 5.13 from 1981 to 1983. Lake trout (Salvelinus namaycush), white sucker (Catostomus commersoni), fathead minnow (Pimephales promelas), and slimy sculpin (Cottus cognatus) were abundant at the onset of acidification. A decline in the abundance of fathead minnow began in 1979 (pH 5.64), and was followed first by a rapid increase in number of pearl dace (Semotilus margarita) in 1980 (pH 5.59) and then a rapid decrease in 1982 (pH 5.09). The abundance of slimy sculpin decreased rapidly in 1979. Abundances of lake trout and white sucker increased during the early years of acidification, but declined following consecutive recruitment failures starting in 1980 for trout and in 1981 for white suckers. By 1982 recruitment had ceased for all Lake 223 fishes. Survival of lake trout [Formula: see text] age 1 decreased in 1982 and 1983, but no other changes in survival of fish [Formula: see text] age 1 were detected for lake trout or white sucker. By spring 1983 many lake trout were emaciated due to losses of the lake trout food organisms. No changes in growth of lake trout and white suckers occurred during the initial years of acidification, but growth of lake trout slowed in 1982 and growth of white sucker increased in 1979.

Interspecies differences in biochemical, histopathological, and population responses in four wild fish species exposed to ethynylestradiol added to a whole lakeThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1920-1935 ◽  
Author(s):  
V. P. Palace ◽  
R. E. Evans ◽  
K. G. Wautier ◽  
K. H. Mills ◽  
P. J. Blanchfield ◽  
...  
Keyword(s):  
Lake Trout ◽  
Population Decline ◽  
Pimephales Promelas ◽  
Population Level ◽  
Experimental Lakes Area ◽  
Population Responses ◽  
Species Population ◽  
Second Year ◽  
Histopathological Effects ◽  
Histopathological Evidence

Efforts to understand the effects of environmental estrogens on fish have shifted away from biochemical indicators towards population-level impacts. Ethynylestradiol (EE2) was added to a whole lake at environmentally relevant concentrations for 3 consecutive years to examine links between vitellogenin (VTG) induction, histopathological impacts, and population decline in four species of fish. VTG induction and histopathological effects in tissues were most severe in fathead minnow ( Pimephales promelas ) and pearl dace ( Margariscus margarita ). VTG was induced to a similar extent in lake trout ( Salvelinus namaycush ) but less so in white sucker ( Catostomus commersonii ). There were no histopathological effects in tissues of the two latter species. Population decline occurred in fathead minnows in the second year of EE2 additions and there were some indications of population decline in pearl dace during the third year. White suckers were not affected but lake trout declined in year 3. Habitat selection probably altered EE2 exposure and the different effects in each species likely also reflect differing sensitivities. It appears that VTG induction is not sufficient to predict effects of xenoestrogens on fish populations. However, stronger predictions can be made when VTG induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage.

scholarly journals Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen

2014 ◽  
Vol 369 (1656) ◽  
pp. 20130578 ◽  
Author(s):  
Karen A. Kidd ◽  
Michael J. Paterson ◽  
Michael D. Rennie ◽  
Cheryl L. Podemski ◽  
Dave L. Findlay ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Fathead Minnow ◽  
Lake Trout ◽  
Prey Availability ◽  
Pimephales Promelas ◽  
Endocrine Disrupting Chemicals ◽  
Benthic Invertebrate ◽  
Small Scale ◽  
Direct Effects ◽  
Experimental Lakes Area

Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5–6 ng l −1 ), indicating no direct toxic effects. Recruitment of fathead minnow ( Pimephales promelas ) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout ( Salvelinus namaycush ) and male and female white sucker ( Catostomus commersonii ) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus , and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23–42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin ( Cottus cognatus ). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors.

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