Phytoplankton, Nutrients, and Primary Production in Fertilized and Natural Lakes at Saqvaqjuac, N.W.T.

1989 ◽  
Vol 46 (1) ◽  
pp. 90-107 ◽  
Author(s):  
Harold E. Welch ◽  
John A. Legauit ◽  
Hedy J. Kling
Keyword(s):  
Primary Production ◽  
Light Flux ◽  
Phytoplankton Production ◽  
Small Lakes ◽  
Experimental Lakes Area ◽  
Natural Lakes ◽  
Northwestern Ontario ◽  
North Temperate Lakes ◽  
P Addition ◽  
Very High

Whole-lake phosphorus (P) and nitrogen (N) addition experiments at Saqvaqjuac, N.W.T. (63°N in the central Canadian arctic), showed that the lakes were P limited but required both P and N for increased production. Photosynthetic response to 0.1 g P and 1.0 g N∙m−2∙yr−1 was immediate (15→30 g C∙m−2∙yr−1), with simultaneous increases in protozoa, while oligotrophic chrysophyte assemblages gave way to volvocalean greens. Cyanophytes were not important during P-only or P and N additions or in oligotrophic lakes, but formed permanent blooms in several naturally mesotrophic lakes near sea level. Retention of P was naturally low, but high during P addition. Silicon (Si) retention was always very high. Chlorophyll: P ratios were similar to those of subarctic and north-temperate lakes. Saturation light intensity (Ik) tracked surface light flux with a 2- to 3-wk delay, averaging 15 E∙m−2∙s−1 in winter and peaking at 140 E∙m−2∙s−1 in July. Comparison of our data with those for lakes in the Experimental Lakes Area (northwestern Ontario, 50°N) and Char Lake (75°N) shows that with increasing latitude, in small lakes, (a) phytoplankton production decreases, (b) phytoplankton production per unit light decreases less sharply, and (c) the proportion of primary production occurring beneath ice cover increases.

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.

Emergence of Chironomidae (Diptera) in Fertilized and Natural Lakes at Saqvaqjuac, N.W.T.

1988 ◽  
Vol 45 (4) ◽  
pp. 731-737 ◽  
Author(s):  
Harold E. Welch ◽  
John K. Jorgenson ◽  
Martin F. Curtis
Keyword(s):  
Primary Production ◽  
Phytoplankton Production ◽  
Experimental Lakes Area ◽  
Natural Lakes ◽  
Before And After ◽  
Mean Size ◽  
Apparent Reason ◽  
Total Primary Production ◽  
Latitudinal Range ◽  
Lake Fertilization

Chironomid emergence was quantified in four small lakes at Saqvaqjuac, N.W.T. (63°39′N), before and after lake fertilization. Emerging biomass responded immediately to increased phytoplankton production, reaching equilibrium the following year. Emergence from the reference lake was extremely variable, for no apparent reason. The emergence – phytoplankton production relationships found by Davies for the Experimental Lakes Area (~49°N) were generally valid for Saqvaqjuac lakes and Char Lake (74°42′), except that (1) biomass was better correlated than numbers because of increased mean size with increasing latitude and (2) total primary production was a better predictor than phytoplankton production alone because benthic photosynthesis increases with increasing latitude. Chironomid production seems to be a predictable function of total primary production throughout the latitudinal range of the small Canadian lakes examined.

Comparison of Phosphorus Turnover Times in Northern Manitoba Reservoirs with Lakes of the Experimental Lakes Area

1984 ◽  
Vol 41 (4) ◽  
pp. 605-612 ◽  
Author(s):  
Dolores Planas ◽  
R. E. Hecky
Keyword(s):  
Large Range ◽  
Turnover Time ◽  
Unit Weight ◽  
Experimental Lakes Area ◽  
P Deficiency ◽  
Natural Lakes ◽  
Northwestern Ontario ◽  
North Temperate Lakes ◽  
Phosphorus Turnover ◽  
Independent Indicator

The turnover time, τ, of [32P]PO4 was measured during July and September in a natural lake and two lakes in northern Manitoba that were undergoing impoundment in 1976. The τ values were 10–1000 times longer than those observed in the epilimnia and hypolimnia of two lakes being experimentally enriched in northwestern Ontario (Experimental Lakes Area) in the same summer. Algal populations in the Experimental Lakes Area exhibited short τ values over a large range of temperature and light values, which exceeded the ranges of temperatures and light intensities measured in northern Manitoba. In northern Manitoba the shortest τ values occurred in July when an independent indicator of sestonic P deficiency, the particulate alkaline phosphatase activity per unit weight ATP, measured moderate to severe P deficiency. In September in northern Manitoba, τ values were at least 10 times greater than in July and were among the highest reported in the literature. The 2-yr-old Notigi Reservoir had the highest τ values in both July and September, and it deviated strongly from the expected chlorophyll–phosphorus relation for north temperate lakes. These new reservoirs in northern Manitoba are not P limited and even the natural lakes may be only moderately P limited.

Methyl mercury in aquatic insects from an experimental reservoir

1998 ◽  
Vol 55 (9) ◽  
pp. 2036-2047 ◽  
Author(s):  
B D Hall ◽  
D M Rosenberg ◽  
A P Wiens
Keyword(s):  
Aquatic Insects ◽  
Methyl Mercury ◽  
Fold Increase ◽  
Fish Tissue ◽  
Functional Feeding Groups ◽  
Experimental Lakes Area ◽  
Major Pathway ◽  
Natural Lakes ◽  
Northwestern Ontario ◽  
Before And After

Our objective was to study the effects of experimental flooding of a small wetland lake on the methyl mercury (MeHg) concentrations in aquatic insects and to compare MeHg concentrations in insects with those in water and fish from the same system. Insects were collected from the shorelines of the experimental reservoir before and after flooding, an undisturbed wetland lake, and an oligotrophic lake, all in the Experimental Lakes Area in northwestern Ontario. Samples were identified to the lowest possible taxon and categorized into functional feeding groups (FFGs; predators or collector/shredders). The insects were analyzed for MeHg and total Hg using clean techniques. Contamination was not a problem because levels of MeHg in insects were much higher than background concentrations. Odonata, Corixidae, Gerridae, Gyrinidae, and Phryganeidae/Polycentropodidae exhibited increases in MeHg concentrations in response to flooding. When data were grouped into FFGs, increases were observed in predators. There were insufficient numbers of collector/shredders collected to make a definitive conclusion on MeHg increases. Predators exhibited an approximately threefold increase in MeHg concentrations after flooding compared with a 20-fold increase in water concentrations and a four- to five-fold increase in fish concentrations. Trends in MeHg concentrations in aquatic insects from reservoirs and natural lakes in Finland and northern Québec were similar to ours. Evidence of an increase in MeHg concentrations in the lower food web helps explain increases in MeHg concentrations in fish from reservoirs because food is the major pathway of MeHg uptake in fish tissue.

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.

Chemical Factors Involved in the Control of Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario

1971 ◽  
Vol 28 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Mitsuru Sakamoto
Keyword(s):  
Inorganic Carbon ◽  
Phytoplankton Production ◽  
Carbon Uptake ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Photosynthetic Carbon ◽  
General Order ◽  
Chemical Factors

In short-term experiments (6 hr–3 days) the general order of decreasing importance of nutrients added individually to samples of lake water and contained phytoplankton was inorganic carbon, Fe, P, and N. The comparable order for long-term experiments (8–20 days) was P, Fe, N; or P, N, Fe. No relation was found between concentrations of chlorophyll and inorganic carbon in the lakes. The addition of iron and trace elements in chelated form and chelators (HEDTA, NTA) alone, increased photosynthetic carbon uptake. The deficiency of iron was mostly due to a lack of iron in a readily assimilable form.

Production of Epilithiphyton in Two Lakes of the Experimental Lakes Area, Northwestern Ontario

1973 ◽  
Vol 30 (10) ◽  
pp. 1511-1524 ◽  
Author(s):  
D. W. Schindler ◽  
V. E. Frost ◽  
R. V. Schmidt
Keyword(s):  
Liquid Scintillation ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Seasonal Effects ◽  
Algal Flora ◽  
Experimental Lakes Area ◽  
New Techniques ◽  
Natural Lakes ◽  
Northwestern Ontario

Two new techniques for measuring photosynthesis by benthic algal flora in waters low in dissolved inorganic carbon are described. The first uses gas chromatography to measure changes in DIC in incubation chambers directly. The second is a variation of the usual 14C procedure, in which disappearance of 14C from the water is measured by liquid scintillation instead of uptake of 14C by the algae. This procedure is simpler than measuring the uptake of 14C, because digestion and/or combustion of samples is not necessary. Results are compared with the commonly employed 14C uptake and O2 release techniques.Tests showed that heterogeneity of substrate was the major source of variation in in situ results, being large enough to make interpretation of seasonal effects and other causal factors extremely difficult.Annual production by epilithiphyton in two natural lakes in the Experimental Lakes Area (ELA) was 5.19 g C and 5.18 g C/m2 of substrate annually for lakes 239 and 240, respectively. These are the lowest values recorded for freshwater lakes at temperate latitudes.Because DIC and O2 concentrations could be measured simultaneously, it was possible to calculate photosynthetic quotients on several dates. These were extremely high, averaging 2.6 for the summer of 1971.

Relationship of Crayfish (Orconectes virilis) Growth to Population Abundance and System Productivity in Small Oligotrophic Lakes in the Experimental Lakes Area, Northwestern Ontario

1985 ◽  
Vol 42 (6) ◽  
pp. 1096-1102 ◽  
Author(s):  
R. L. France
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Maximum Size ◽  
Reproductive Capacity ◽  
Phytoplankton Production ◽  
Orconectes Virilis ◽  
Experimental Lakes Area ◽  
System Productivity ◽  
Frequency Distributions ◽  
Northwestern Ontario

Crayfish growth in four lakes in the Experimental Lakes Area (ELA) was examined by analysis of size-frequency distributions, molt increment data, and calculation of instantaneous growth and mean size at onset of sexual maturity. Orconectes virilis growth rates at ELA are only 27–38% of those reported for other areas. Growth varied both among study lakes and between years. Higher temperatures and a longer growing season during 1980 increased growth an average of 12% over that of the preceding year. Crayfish growth and maximum size in four to six lakes were significantly correlated with phytoplankton production and chlorophyll a concentration. Growth regulated both the number of age 1 animals attaining sexual maturity and the per capita egg production, and was also directly related to the proportion of mature females that were fertilized. I believe population regulation is mediated through alterations in reproductive capacity that is correlated with system productivity.

Eutrophication of Lake 227, Experimental Lakes Area, Northwestern Ontario, by Addition of Phosphate and Nitrate

1971 ◽  
Vol 28 (11) ◽  
pp. 1763-1782 ◽  
Author(s):  
D. W. Schindler ◽  
F. A. J. Armstrong ◽  
S. K. Holmgren ◽  
G. J. Brunskill
Keyword(s):  
Standing Crop ◽  
Dominant Species ◽  
Inorganic Nitrogen ◽  
Late Summer ◽  
Phytoplankton Production ◽  
Experimental Lakes Area ◽  
Algal Production ◽  
Ph Values ◽  
Northwestern Ontario ◽  
Nitrogen Concentrations

Addition of 0.34 g P as Na2HPO4 and 5.04 g N as NaNO3 per square meter to a small unproductive Canadian Shield lake over a period of 17 weeks caused a severalfold increase in phytoplankton standing crop, and a change in dominant species from Chrysophyceae to Chlorophyta. Reactive phosphate concentrations remained at undetectable levels in the epilimnion after fertilization, and inorganic nitrogen concentrations remained low. Most of the added phosphorus and nitrogen was rapidly taken up by phytoplankton and sedimented with the seston.Although concentrations of total CO2 decreased to less than 20 μmoles/liter and pH values increased to greater than 9 in late summer, a high standing crop of phytoplankton was maintained. No marked increase in the rate of phytoplankton production was noticed Experiments in polyethylene containers suspended in the lake during this period of low total CO2 indicated that carbon was not limiting to algal production, except possibly at algal standing crops in excess of 100 μg/liter chlorophyll a, and that phosphorus was the primary limiting nutrient.Sodium added with the nutrients remained in the epilimnion until fall overturn, indicating that very little of it was utilized by phytoplankton.

Sign in / Sign up

Export Citation Format

Share Document