Jack Lake Research Articles

Integration of mineral resource data for Kasmere Lake area, Northwest Manitoba, with emphasis on uranium

Geological and geophysical data digitized by Fabbri (1981)are augmented by eleven lakesediment geochemical variables in a quantitative study of the Kasmere Lake—Whiskey Jack Lake area, NW Manitoba. Each of 33 geological map units (Archean and Aphebian igneous and metamorphic rocks)have a fairly distinct multivariate geochemical and geophysical signal, as shown by discriminant analysis which is able to “recover” the geological map from the geophysical and geochemical data. Autocorrelation analysis of the geochemical variables, after removing a quadratic trend, indicate that copper, nickel, uranium, and cobait have a zone of influence from 15 to 30 km or more, with a marked anisotropy parallel to geological, geophysical, and structural trends which run NE-SW, parallel to the Wollaston fold belt. The observed uranium autocorrelation coefficients are modeled as a two-dimensional exponential function with elliptical contours. A trend-signal-noise model is applied to the lake-sediment uranium using kriging on residuals from the quadratic trend. A map comparing the resulting lake-sediment uranium signal with radiometric uranium/thorium patterns indicates considerable overlap and a generally good prediction of known uranium occurrences. In areas with a strong lake-sediment uranium signal, Aphebian metasediments have a somewhat different multivariate geochemical character from Archean and Hudsonian igneous and metamorphic rocks, suggesting a method of removing areas from the signal underlain by granites that may be economically uninteresting. Logistic and stepwise regression experiments based on a control area which includes most of the presently reported occurrences are used to predict areas favorable for uranium exploration.

Reproductive Behavior of Hybrid Charr (Salvelinus fontinalis × S. namaycush)

Observations of the reproductive behavior of splake (Salvelinus fontinalis × S. namaycush) planted in Jack Lake, Algonquin Park, Ont., indicated that they spawned on rocky shoals from late October to early November. In mid-October, splake approached the spawning locations. By late October females had selected redd sites and dominant males were aggressively defending the sites that had been cleared by the females, against other males. Redd digging was variable in duration and frequency. Depth of water over redds varied between 0.5 and 4 m. No attempts were made to cover the eggs, most of which settled into the crevices between rocks. Males and females used acoustic signals during both aggression and courtship. The male initiated courtship by maintaining his head over the female's tail, then crisscrossing over the tail. Parallel positioning of the two sexes was a prerequisite to release of sex products. Visual and sonic cues appeared to be used in sequencing behavior. Circling functioned as a neutral action to which any other courting behavior could revert. Nest digging ceased after completion of egg deposition. A swim-in-place behavior of the female was a positive indicator of egg deposition. Egg predation by adult splake was observed, but it appeared to offer no serious threat to natural reproduction. Laboratory observations of splake reproductive behavior in aquaria did not indicate any behavioral obstacles to successful natural reproduction. Courtship behavior and egg deposition in the artificial spawning beds was followed by normal development and emergence of fry.Key words: splake, reproductive behavior, Ontario, visual and acoustic signaling

Significance of algal extracellular products to bacteria in lakes and in cultures

In simulated diurnal experiments withChlorella pyrenoidosa andPseudomonas fluorescens, bacterial growth was virtually confined to the daylight period and occurred at the expense of glycolate, the predominant extracellular product of the alga. Both glycolate levels and(14)C-DOC excretion rates were much lower in mixed algal-bacterial than in axenicChlorella cultures.This close coupling of bacterial growth to algal photosynthesis and extracellular release was also observed in Jack's Lake, but not in Lake Erie. Experimental enrichment with lake water particulates >30μm suppressed the daytime growth of bacteria in Jack's Lake, but increased it dramatically in Lake Erie. Daylight doubling times for bacteria in lakewater ranged from 2 to 19 days. In mixed culture withChlorella, Pseudomonas had a doubling time of about 2 hours in the light.