Element Concentrations in Chironomids and Their Abundance in the Littoral Zone of Acidified Lakes in Northwestern Ontario

1993 ◽  
Vol 50 (5) ◽  
pp. 953-963 ◽  
Author(s):  
Vincent L. St. Louiss
Keyword(s):  
Emerging Adults ◽  
Littoral Zone ◽  
Poor Quality ◽  
Low Ph ◽  
Experimental Lakes Area ◽  
Acid Lakes ◽  
Northwestern Ontario ◽  
Accumulation Of Metals ◽  
Low Levels ◽  
Reference Lakes

I studied species diversity of the chironomid community, abundance of emerging adults, and accumulation of metals and elements in chironomids in the shallow littoral zone of experimentally acidified and unmanipulated reference lakes at the Experimental Lakes Area in northwestern Ontario. Orthocladiinae were significantly more abundant in acid lakes than in reference lakes, while the Chironominae were less numerous. The lower abundance of Chironominae resulted from fewer chironomids in the Tribe Tanytarsini. Chironomini were more common in acid lakes than in the reference lakes. Biomass of emerging chironomids either increased significantly following acidification or was not different from that of reference lakes. Concentrations of Al, Ca, Mn, and Zn were on average higher in chironomids from a number of the acid lakes than in chironomids from reference lakes. Calcium concentrations in chironomids from the most acid lake were significantly lower, however, suggesting that at low pH levels, Ca may be difficult to sequester. Increased accumulation of certain metals in chironomids, coupled with increased biomass of emerging chironomids as well as low levels of Ca, makes chironomids a potentially abundant but poor-quality food source for organisms that rely on them as prey.

Changes in diatom assemblages since pre-industrial times in 40 reference lakes from the Experimental Lakes Area (northwestern Ontario, Canada)

2011 ◽  
Vol 46 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Mihaela D. Enache ◽  
Andrew M. Paterson ◽  
Brian F. Cumming
Keyword(s):  
Diatom Assemblages ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Reference Lakes

Ecological effects of blooms of filamentous green algae in the littoral zone of an acid lake

1995 ◽  
Vol 52 (10) ◽  
pp. 2264-2275 ◽  
Author(s):  
Michael A. Turner ◽  
Bruce E. Townsend ◽  
Gordon G. C. Robinson ◽  
Brenda J. Hann ◽  
John A. Amaral
Keyword(s):  
Green Algae ◽  
Littoral Zone ◽  
Dissolved Inorganic Carbon ◽  
Ecological Effects ◽  
Experimental Lakes Area ◽  
Filamentous Green Algae ◽  
Northwestern Ontario ◽  
Lake Bottom ◽  
Chemical Cycling ◽  
Physical Features

Ecological effects of blooms of filamentous green algae (FGA) were studied in an experimentally acidified lake (pH 4.5) at the Experimental Lakes Area in northwestern Ontario, Canada. Blooms of FGA influenced the energy balance, chemical cycling, physical features, and biological conditions in the littoral zone. Photosynthetic capacity of the FGA, dominated by Zygogonium, was greater than that of acidified epilithon, the normally dominant littoral algal association, partially offsetting acidification-induced oligotrophication in the littoral zone. Intra- and inter-annual variability of FGA growth was large, however, so that FGA were an unreliable energy source for the littoral food web. Nutrient uptake varied with the degree of FGA growth; e.g., FGA were occasionally the largest phosphorus pool in the epilimnion. Nitrogen dynamics of FGA varied seasonally causing acidification in spring and summer, and alkalinization in fall. The blooms also affected epilimnetic cycling of dissolved inorganic carbon. Peak blooms prevented as much as 90% of the light from reaching the lake bottom. Local depletions of oxygen resulting from FGA decomposition also posed potential risks for animals using the FGA as habitat.

Phytoplankton Community Responses to Nutrient Addition in Lake 226, Experimental Lakes Area, Northwestern Ontario

1987 ◽  
Vol 44 (S1) ◽  
pp. s35-s46 ◽  
Author(s):  
D. L. Findlay ◽  
S. E. M. Kasian
Keyword(s):  
Species Composition ◽  
Water Exchange ◽  
Phytoplankton Community ◽  
Late Summer ◽  
Nitrogen And Phosphorus ◽  
Experimental Lakes Area ◽  
Carbon And Nitrogen ◽  
Northwestern Ontario ◽  
Average Biomass ◽  
Reference Lakes

Inclusion of phosphorus in fertilizer added to one of two basins of a small lake, between which water exchange was greatly reduced by a vinyl sea-curtain, significantly increased epilimnetic phytoplankton biomass, and altered species composition. Over an 8-yr period, the average biomass of phytoplankton in the basin receiving carbon, nitrogen, and phosphorus (in ratios of 10:5:1) increased 4 to 8 times and the biomass in the basin receiving only carbon and nitrogen (in ratios of 10:5) increased 2 to 4 times over non-fertilized years. The basin receiving all three nutrients consistently had blooms in late summer which were dominated by nitrogen fixing species of cyanophytes. In comparison with unfertilized reference lakes, the proportion of phytoplankton in fertilized basins which was available to zooplankton as food was 10 times greater in the basin receiving all three nutrients, and two times greater in the basin receiving only nitrogen and carbon. When fertilization of both basins was stopped, species composition and levels of biomass reverted within a year to the composition and biomass levels of phytoplankton observed in the reference lakes and remained at those levels for 2 further years of study.

Land water linkages: influences of riparian deforestation on lake thermocline depth and possible consequences for cold stenotherms

1997 ◽  
Vol 54 (6) ◽  
pp. 1299-1305 ◽  
Author(s):  
Robert France
Keyword(s):  
Thermal Stratification ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Thermocline Depth ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Riparian Trees ◽  
Tree Removal ◽  
Riparian Tree ◽  
Land Water

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.

Phosphorus Budgets and Stoichiometry during the Open-Water Season in Two Unmanipulated Lakes in the Experimental Lakes Area, Northwestern Ontario

1994 ◽  
Vol 51 (12) ◽  
pp. 2739-2755 ◽  
Author(s):  
P. Campbell
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Open Water ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Phosphorus Budgets ◽  
Mass Balance Approach ◽  
Primary And Secondary Producers ◽  
Column Total

A comparative mass-balance approach is used to describe and quantify phosphorus (P) cycles during the open-water season in two unmanipulated Experimental Lakes Area (ELA) lakes. A bimodal cycle generally prevailed, in which water-column total phosphorus (TP = total dissolved P plus sestonic particulate P) peaked just after ice-out and again late in the summer. Changes in mass of water-column TP were often much larger than corresponding net external inputs. Shifts of P to and from either zooplankton or fish in the water column do not explain the P residuals. Rather, the bottom sediments must have been adding P to the water column. Short-term regeneration of P from the bottom sediments also probably occurs in artificially eutrophied ELA lakes. The mechanism of regeneration is probably biological. Other aspects of P cycling and P stoichiometry are discussed, particularly in relation to nutrient control of population structure and the function of primary and secondary producers.

Decline of Mysis relicta During the Acidification of Lake 223

1983 ◽  
Vol 40 (11) ◽  
pp. 1905-1911 ◽  
Author(s):  
R. W. Nero ◽  
D. W. Schindler
Keyword(s):  
Confidence Limits ◽  
Experimental Lakes Area ◽  
Mysis Relicta ◽  
Ph Values ◽  
Northwestern Ontario ◽  
Population Comparisons ◽  
Acidification Of Lake ◽  
Ph Range ◽  
Shield Lakes ◽  
Direct Toxicity

The population size of Mysis relicta in Lake 223 of the Experimental Lakes Area, northwestern Ontario, decreased from 6 700 000 ± 1 330 000 (± 95% confidence limits) during August of 1978, to 270 000 ± 75 000 during August of 1979, a 96% decrease. Because Mysis, a cold stenotherm, is restricted to the metalimnion and hypolimnion of lakes during summer, the pH range encountered by the population was 5.51 to 6.32 in 1978 and 5.23 to 6.10 in 1979, even though mean pH values in epilimnion waters for the 2 yr were 5.84 and 5.60. A decrease in pH of its habitat from 6.2 to 5.6 during fall overturn in 1979 caused the elimination of the remaining 4% of the population. Comparisons with four control lakes suggested that the decline and disappearance were not normal occurrences in unstressed lakes. Concentrations of Zn, Al, Mn, Fe, Cd, Cu, Ni, and Hg in Lake 223 water were low, and concentrations in Mysis were less than or equal to those in animals from five control lakes, suggesting that the decline in this species was not due to the toxic effects of metals. All size classes were affected, so that direct toxicity of hydrogen ion may be responsible for this abrupt population collapse. These results suggest that Mysis may be a useful early indicator of acidification damage to Precambrian Shield lakes.

Primary Production and Phytoplankton in the Experimental Lakes Area, Northwestern Ontario, and other Low-Carbonate Waters, and a Liquid Scintillation Method for Determining 14C Activity in Photosynthesis

1971 ◽  
Vol 28 (2) ◽  
pp. 189-201 ◽  
Author(s):  
D. W. Schindler ◽  
S. K. Holmgren
Keyword(s):  
Primary Production ◽  
Liquid Scintillation ◽  
Species Abundance ◽  
Euphotic Zone ◽  
Phytoplankton Production ◽  
Phytoplankton Species ◽  
Experimental Lakes Area ◽  
Phytoplankton Species Composition ◽  
Northwestern Ontario ◽  
Filtration Error

A modified 14C method is described for measuring phytoplankton production in low-carbonate waters. The procedure includes the use of the Arthur and Rigler (Limnol. Oceanogr. 12: 121–124, 1967) technique for determining filtration error, liquid scintillation counting for determining the radioactivity of membrane filters and stock 14C solutions, and gas chromatography for measuring total CO2.Primary production, chlorophyll a, and total CO2 were measured for two dates in midsummer from each of several lakes in the Experimental Lakes Area (ELA), ranging from 1 to 1000 ha in area and from 2 to 117 m in maximum depth. Phytoplankton species abundance and biomass were determined for the same dates. Production ranged from 0.02 to 2.12 gC/m3∙day and from 0.179 to 1.103 g C/m2∙day. Chlorophyll ranged from 0.4 to 44 mg/m3 and from 5 to 98 mg/m2 in the euphotic zone. The corresponding ranges for live phytoplankton biomass were 120–5400 mg/m3 and 2100–13,400 mg/m2. Chrysophyceae dominated the phytoplankton of most of the lakes.A system for classifying the lakes in terms of phytoplankton species composition and production–depth curves is developed.

Food Poisoning Potential of Pathogens Inoculated onto Bologna in Sandwiches1

1978 ◽  
Vol 41 (12) ◽  
pp. 953-956 ◽  
Author(s):  
D. C. PARADIS ◽  
M. E. STILES
Keyword(s):  
Food Poisoning ◽  
Food Service ◽  
Low Ph ◽  
Enteropathogenic Escherichia Coli ◽  
Experimental Conditions ◽  
Gram Negative ◽  
Significant Growth ◽  
Bacterial Competition ◽  
Low Levels ◽  
And Storage

Bologna sandwiches inoculated separately with low levels (100 to 1000 per g) of specific pathogens at time of sandwich preparation to simulate conditions that might occur in home or food service preparation, were stored at 4, 21 and 30 C for 0, 4, 8 and 25 h and monitored for growth of pathogens. All pathogens, except Clostridium perfringens, were capable of significant growth after more than 8 h of incubation at 30 C, but not at 4 or 21 C. Significant growth at 21 C only occurred with Staphylococcus aureus after 25 h of incubation. C. perfringens failed to grow on bologna in all sandwiches. All other pathogens, except S. aureus, failed to grow on bologna with low pH (pH <6.1). Growth of S. aureus, was retarded on bologna at pH 5.5, and inhibited at pH 5.1. Only gram negative pathogens (enteropathogenic Escherichia coli and Salmonella typhimurium) were adversely affected by increased bacterial competition. Results indicated that bologna in sandwiches under these experimental conditions would only become a potential vehicle for food poisoning under almost unrealistic conditions of handling and storage.

Iron substitution in aluminosilicate sols synthesized at low pH

Clay Minerals ◽  
1984 ◽  
Vol 19 (1) ◽  
pp. 1-8 ◽  
Author(s):  
M. B. McBride ◽  
V. C. Farmer ◽  
J. D. Russell ◽  
J. M. Tait ◽  
B. A. Goodman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ir Spectroscopy ◽  
Esr Spectroscopy ◽  
Spectroscopic Analysis ◽  
Low Ph ◽  
Transmission Electron ◽  
Low Levels ◽  
Aluminosilicate Mineral ◽  
Tubular Morphology

AbstractThe procedure for synthesizing proto-imogolite (an acid-soluble hydroxy-aluminium orthosilicate complex) and imogolite (a tubular aluminosilicate mineral) was used to produce ferruginous aluminosilicates over a range of Al/Fe ratios to determine whether Fe3+ can be incorporated in the imogolite structure. Analysis of the synthesized products by transmission electron microscopy, electron diffraction, and IR spectroscopy indicated that, while imogolite was formed in the presence of iron, increased Fe3+ in the systems caused the formation of ferrihydrite and poorly-organized aluminosilicates resembling proto-imogolite allophane. Treatment of these materials with Na-citrate/dithionite/bicarbonate dissolved the ferrihydrite and poorly-organized aluminosilicate, and concentrated products with tubular morphology. Analysis of the structural Fe3+ by ESR spectroscopy suggested that little or no Fe3+ was incorporated in the structure of imogolite, although the less crystalline proto-imogolite allophane may have accommodated some structural Fe3+. A separate iron-rich product, identified as ferrihydrite, was formed at low Al/Fe ratios. Mössbauer spectroscopic analysis of 57Fe3+ doped at very low levels into proto-imogolite and imogolite indicated that the sites of substitution were better defined in the latter. At least part of this Fe3+ may have been incorporated in the structure of boehmite, an impurity formed during synthesis.

Population Dynamics of Lake Whitefish (Coregonus clupeaformis) During and After the Fertilization of Lake 226, the Experimental Lakes Area

1987 ◽  
Vol 44 (S1) ◽  
pp. s55-s63 ◽  
Author(s):  
K. H. Mills ◽  
S. M. Chalanchuk
Keyword(s):  
Population Dynamics ◽  
The Other ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Experimental Lakes Area ◽  
Northwestern Ontario

Responses of an unexploited population of lake whitefish (Coregonus clupeaformis) to the fertilization of Lake 226 in the Experimental Lakes Area, northwestern Ontario, are described for the fifth through eighth years of fertilization (1977–80) and for three years after fertilization was terminated (1981–83). A vinyl curtain separated Lake 226 into two basins. One basin (L226NE) received additions of phosphorus, nitrogen, and carbon; the other (L226SW) received nitrogen and carbon. Lake whitefish in L226NE were faster growing, had higher condition (k), were more numerous, had higher survival from age 0 to age 1, had greater biomass, and had greater production than L226SW whitefish from 1977 to 1980. Some of these effects continued in 1981 and 1982 after fertilization was terminated, but only biomass differences remained by 1983.

Sign in / Sign up

Export Citation Format

Share Document