The environmental impacts of log storage on water quality and microbiology in Babine Lake, B.C. were studied in experimental enclosures. The enclosure work was a two phase study, with data collected during the summers of 1984 and 1985. The experiments performed in the field season of 1984 involved the addition of mixed lodgepole pine (Pinus contorta) and white spruce (Picea glauca) bark debris, in different amounts, to the enclosures to examine effects on water quality (dissolved oxygen, lignins-tannins, total organic carbon, total inorganic carbon, pH, and alkalinity), bacterial activity (heterotrophy), and phytoplanktonic primary production. The 1985 study attempted to simulate a shallow water log storage facility by adding logs to the enclosures. A comparison was made of differences in water quality (including the above measurements plus chemical oxygen demand, nutrients, volatile fatty acids, and carbohydrates), and sestonic bacterial and phytoplanktonic algal populations (enumeration and biomass calculations) between (i) lodgepole pine and white spruce, and (ii) the number of logs per enclosure. The bark enclosure study resulted in organic enrichment of the enclosure ecosystem. More than 50% of the total organic carbon (TOC) was attributed to leached lignins and tannins. The leachate was capable of modifying microorganism production. Phytoplanktonic algal biomass, measured by chlorophyll ɑ, was completely eliminated at high concentrations of bark. Short term laboratory studies with bark leachate inhibited microbial activity of natural aquatic bacteria, however, from the enclosure experiments, it was apparent that with time a population of microbes would develop to utilize the chemically complex leachate. The presence of utilizable organic material (i.e. wood sugars) and an active microbial community resulted in a significant decrease in the dissolved oxygen levels. The results of the log study found significant decreases in the amount of organic extractives leached from logs compared to the TOC concentration in the bark experiment. For example, the TOC concentrations in the 5 log enclosures were approximately 20 mg/l by the end of the 25 day test period (≤ 10% was lignin and tannin carbon) ; this value was significantly smaller compared to the bark experiments, where the TOC levels in the heavy bark treatment (20 kg) reached ≃ 400 mg/l after 25 days. A comparison between the bark and log experiments (on an equivalent bark dry weight basis) found water quality degradation by bark leachates more severe than log leachates. The log leachate stimulated bacterial production and did not adversely affect phytoplankton biomass. The increase in bacterial production, a direct result of (i) an available carbon source, determined by TOC measurements and the very low concentrations of volatile fatty acids and reduced carbohydrates (rapidly utilized), and (ii) an increase in water temperature caused a decrease in dissolved oxygen levels. The spruce log enclosures for both June and July had higher heterotrophic uptake rates than the pine log enclosures. This indicated a difference in the chemical composition of the spruce and pine log leachates. This chemical difference was detected in the TOC and COD measurements and the microbial uptake kinetics experiment. These measurements found that the pine log leachate was more readily degraded (high affinity, Vmax/Kt) by a heterotrophic population than the spruce leachate, and that this difference could account for the higher dissolved oxygen demand of the pine log enclosures compared to the spruce logs. Detailed chemical analyses of the leachates in the presence of microbial inhibitors may help to delineate this discrepancy between the spruce heterotrophic uptake rates and the chemical and bacterial measurements of the pine log leachates. The enclosure studies indicated that log storage in a shallow, poorly flushed, littoral area of a lake would possibly result in an accumulation of organic components leached from the log and bark debris. The organic enrichment of the aquatic ecosystem would contribute to a potential decrease in dissolved oxygen, thus, negatively affecting fish habitat, but could increase microbial production. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

A computer simulation model was written to mimic the natural movement of salmon fry in Babine Lake, B.C.. Simulated distributions of fry were compared with field observations taken in 3 sampling periods during the summer and fall in 1967, 1968, 1971, and 1972, in order to evaluate the model's validity. Simulated distributions of fry, when random and heavily-biased movements were combined, were in reasonable accord with naturally observed distributions of fry in periods 1 and 2. In period 3 the model successfully produced a distribution similar to that naturally observed when the fry were programmed to undergo only random movement. Factors which might account for the various distributions of fry in different periods include the effects of current and innate behavioral responses of the fry to limnological conditions. In constructing my model, I assumed that fry travelled at speeds observed in the laboratory in still water. The model of fry dispersal in Babine Lake could be improved as more information is collected on the limnology of the lake and on fry behavior. In addition, the model has much generality and the techniques used may be applied to the dispersal of other organisms and to other lakes. / Science, Faculty of / Zoology, Department of / Graduate

A procedure for applying the concepts of Bayesian decision theory to salmon management is presented and illustrated with an application to the Babine system sockeye salmon fishery in British Columbia. The particular decision considered is the recommended escapement to aim for in a given year. The Babine fishery is described and the decision theory concepts are outlined. The procedure involves defining the relationship between the recommended spawning escapement and the number of adults returning in the cycle year in probabilistic terms; defining the utility, that is the relative desirability of various sizes of catch; and computing the total expected utility of both the catch in the current year and the spawning returns associated with alternative values of the recommended escapement. The escapement with the maximum expected utility should be chosen and recommended. / Graduate and Postdoctoral Studies / Graduate

Effects of log storage on water quality, zooplankton and juvenile salmonids were investigated at Babine Lake, British Columbia in a series of enclosure, field and laboratory experiments. Enclosures were stocked with lake zooplankton and treated with lodgepole pine (Pinus Contorta) and white spruce (Picea glauca) logs for two 25 day periods. Oxygen depletion, to levels as low as 2.5 mg/l, and increased lignin and tannin (L-T) concentration (a measure of wood leachate) occurred in log treated enclosures. Zooplankton density significantly decreased with increased log number, but changes in community diversity were not consistent. In field studies at Morrison Arm, Babine Lake, extreme oxygen depletion (<1 mg/l) was observed in localized surface waters within a log storage area. Dye tracer studies within the log bundles implied reduced water movement, which may be involved in oxygen depletion. Local zooplankton abundance was usually lower at log storage sites than nearby undisturbed littoral sites and sockeye fry held in situ for 24 h periods acquired fewer and/or a lower diversity of prey items in log storage areas. Laboratory toxicity studies indicated that spruce bark leachates were more toxic than pine, but lethally toxic bark leachates had higher L-T values than those measured in the Morrison Arm log storage area. In chronic Daphnia bioassays, mortality rates significantly increased and fecundity rates significantly decreased during long term exposure to low concentrations of bark leachates. Results of enclosure experiments, field studies and laboratory bioassays provide evidence that zooplankton are reduced in abundance by conditions which accompany log storage, possibly through chronic toxicity or reduce fecundity. Because fry diet was sensitive to small changes in food abundance, there is potential for reduced survival of sockeye fry exposed to low oxygen concentrations and reduced food levels. / Science, Faculty of / Zoology, Department of / Graduate

A two year study was initiated in 1973 to examine effects of substantial (3.8 fold; from a 1962-66 mean of 39 million to about 150 million in 1973 and 1974) increases in sockeye (Oncorhynchus nerka) Walbaum) fry numbers on zooplankton abundance in Babine Lake. Several lake areas and stationsware sampled for zooplankton bimonthly from May to October during 1973 and 1974 and compared to data gathered between 1958 and 1962 prior to a large scale enhancement program for sockeye stocks. Zooplankton biomass had decreased up to 70% in some areas of the lake during 1973, but only 40% in 1974. Decreases in numbers were also evident. Although seasonal changes in fry diet followed changes in zooplankton species abundance, feeding was selective. The less abundant but larger forms, Daphnia and Heterocope together comprised 70% of the diet during summer, while Cyclops and Diaptomus formed the bulk (87%) of the diet in late fall. Significant decreases in Daphnia and Diaptomus abundance and increases in nauplii-early copepodite abundance had occurred by 1973. The increased 1974 zooplankton abundance relative to 1973 was attributed to decreased mid-summer fry numbers in the lake. Field data suggested low Diaptomus numbers contributed to much higher fry mortality (about double in 1974) compared to 1973. An experimental study of species selectivity by sockeye fry indicated that they selected Cyclops and Diaptomus adults. The larger copepods, Heterocope and Epischura, were rejected by fry encountering zooplankton for the first time. Copepodites and nauplii were rejected, but less so when preferred prey were scarce. Prey activity, in my experiments, could not be used to predict predation vulnerability and hence the species selectivity displayed by the fry. Light and temperature had little effect on Cyclops, Dlaptomus and Heterocope activity. / Science, Faculty of / Zoology, Department of / Graduate