More than twenty years ago, over twenty species of the rock-dwelling cichlid species (Mbuna) were translocated from the northern Lake Malawi, where they are endemic, to Thumbi West Island, Lake Malawi National Park, in the southern part of Lake Malawi. Among these species, Cynotilapia afra, Pseudotropheus callainos and Pseudotropheus tropheops 'red cheek' are strongly territorial, and have increased substantially in number and are widely distributed, particularly in the three to seven metre depth band of the rocky habitats at the Island of Thumbi West. It is feared that the increase in population density of translocated species (hereafter referred to as introduced species) may be at the expense of ecologically equivalent native species which could be eliminated. In this thesis the following key hypotheses have been tested: (i) that the introduced species having originated from a region of Lake Malawi which is generally poor in nutrients and introduced in an area which is richer in nutrients, would cope better than the native species during periods of nutrient scarcity which occur frequently, often seasonally in oligotrophic lakes, such as Lake Malawi; (ii) that the introduced species are fitter than their ecologically equivalent native species in the acquisition of territorial space in which they breed, feed and seek shelter, and (iii) that introduced and native species coexist by utilizing different microhabitats. Results show that: 1. the introduced species, P. callainos and P. tropheops 'red cheek' may have responded positively to enhanced nutrient availability, as they were found to have better condition factors and fecundity indices at Thumbi West Island than at sites of their origin, in the northern lake Malawi. Cynotilapia afra, P. callainos and P. tropheops 'red cheek' also maximise their life-span fecundity by starting to reproduce at relatively smaller size than the native species with which they overlap in microhabitat requirements. Similarly, their breeding peaks precede the breeding peaks of the native species with which they overlap in microhabitat requirements. Consequently, due to priority residence effects, the offspring of introduced species may have a competitive edge in the use of essential resources, e.g., refuge over the offspring of the native species whose peak-recruitment occurs later in the year. 2. There is an overlap between the introduced and native species in their microhabitat requirements. Consequently, interference competition between them for territorial sites occurs. The choice of optimal territory sites is constrained by the fact that females preferentially mate with males that defend significantly smaller holes, or crevices among the rocks, probably as a means of minimizing egg predation during spawning. 3. The population of territorial males of introduced species seems to grow exponentially, depending on the availability of suitable microhabitats, and an equilibrium between them and males of the native species may be reached. Competition for optimal territory sites seems to intensify, once the carrying capacity in a particular area has been reached, and it is at this stage that some territorial males of the introduced and native species with similar microhabitat requirements, e.g., C. afra and P. zebra, or P. tropheops 'red cheek' and its sibling native species, P. tropheops 'orange chest' displace each other. However, it seems unlikely that any of the native species which were compared with the introduced species would be driven to extinction because: (a) there is a considerable interspecific territory turn-over between the introduced and native species that overlap in microhabitat requirements. (b) Even in situations where some of the native species occur in microhabitats that are not of their preference, they occupy patches of suitable sites and are capable of breeding. (c) It has been suggested that since introduced and native species breed throughout the year and are polygamous and have intraspecifically shared paternity, they are capable of fertilizing many gravid females of their own species. Therefore, the population of native species may not be detrimentally limited by the presence of introduced species. (d) The introduced and native Mbuna species that prefer small rocks coexist in the same microhabitats, partly by feeding at different sites with different intensity and they also feed at different heights in the water column. 4. The following studies have been recommended before any management intervention, such as culling is adopted: (i). interaction between the introduced and native species in the shallow and deep rocky habitats; (ii) space utilization and survivorship of juveniles of the introduced and native species; (iii) laboratory studies to confirm the role of different nutrient regimes on the fecundity of Mbuna; (iv) the possibility of hybridization between the introduced and native species; (v) monitoring of population growth and distribution of the introduced species around Thumbi West Island should continue in order to detect their long-term effects on the native species.

An understanding of the level of both genetic and morphological diversity within a taxon and how that diversity is structured within and across habitats is important when determining the conservation value of that taxon and for successful habitat management programs to be developed. Atlin Lake is a large lake in northern British Columbia and is one of the largest lakes that contain relatively unperturbed populations of lake trout (Salvelinus namaycush). As the top aquatic predator, lake trout in Atlin Lake are a key component of the lake’s fish community and are important for local fisheries. I assayed lake trout from Atlin Lake and other western lake trout populations at eight microsatellite DNA loci and for body morphology to determine: (i) the level of genetic variation present, (ii) the level of substructure that occurs in Atlin Lake, and (iii) whether there was a relationship between the genetic and morphological variation present. STRUCTURE analysis identified five subpopulations within Atlin Lake. Morphological analysis was used to differentiate between the samples collected throughout Atlin Lake. Cluster analysis of size corrected data separated the fish into two groups making Atlin Lake the smallest lake identified to date to possess more than one morphotype. Genetic and morphological groupings were found not to be correlated with each other. Finally, I was interested in whether each of the genetic subpopulations contributed equally to the local fisheries catches. A mixed stock analysis of samples collected from the commercial fishery and recreational anglers indicated that all of the genetic subpopulations contribute to the fishery along with lake trout subpopulations in the interconnecting Tagish Lake; suggesting that no one subpopulation is being depleted by the fisheries. Continued genetic monitoring, however, is necessary to see if the trends in fishery contribution are temporally stable. Future studies should focus on understanding the source of the morphological variation and maintenance of genetic substructure. / Science, Faculty of / Zoology, Department of / Graduate

The annual testicular cycle of a teleost the lake chub (Couesius plumbeus) from a north temperate latitude (51°N) has been studied by histological and histochemical methods with a planimetric evaluation of the different spermatogenetic stages. The annual cycle is divided into five different stages and the cyclical testicular changes have been correlated with changing environmental conditions. Lobule boundary cells, considered to be homologue of the Leydig cells of higher vertebrates, have been identified, and the changes in their secretory activity have been reported. Temperature is the major environmental factor controlling the testicular cycle. The pituitary gland, through its gonadotropin(s), mediates between environmental changes and developments in the testes. Higher temperatures (16°-22°C) promote spermiogenesis and spermiation, whereas low temperatures (5°-12°C) are more conducive to gonial proliferation and the initial phase of spermatogenesis. Hypophysectomy affects the mitotic ability of the spermatogonia, completely blocks their transformation into spermatocytes and suppresses the secretory activity of the lobule boundary cells. Replacement therapy with fish gonadotropin and mammalian LH restores spermatogenesis to a large extent and maximum response is elicited with whole fish pituitary extract. It is proposed that the fish pituitary gonadotropin is similar to mammalian LH and in this species mammalian FSH is physiologically inactive in the restoration of testicular activity. Since whole fish pituitary produces a maximum response it is suggested that factors such as TSH and STH have a probable synergistic role in the testicular maturation in Couesius plumbeus. Evidence is presented that a weak endogenous rhythm of activity is partly responsible for the timing of various testicular changes. / Science, Faculty of / Zoology, Department of / Graduate

[No abstract available] / Science, Faculty of / Zoology, Department of / Graduate

The population energetics of two species of amphipods was studied at several depths in Marion Lake, BC. Hyalella azteca was abundant at a depth of 1.0 m, (mean summer standing crop, 1952 animals/m2 but became rare (75 animals/m2 at depths greater than 2.5 m. Growth rates, res- piration rates, and hence energy flow were decreased by the lower ambient temperatures of deeper water, On an annual basis, a mean standing crop of 1.1 Kcal/m2 of Hyalella assimilated 18.1 Kcal/m2 respired 14.1 Kcal/m2 and used 4.0 Kcal/m2 in production of growth, molts and eggs, Approximately 3/4 of the annual energy flow was completed between June and October, The ecological efficiency of Hyalella populations was 10, the net production efficiency, 22%, and the net population growth efficiency, 12%-13%, The mean summer density of Crangonyx remained constant with depth (about 249 animals/m2). Annual energy flow and production were not appreciably affected by lower temperatures in deeper water. On an annual basis, a mean standing crop of 0.7 Kcal/m2 assimilated 7.7 Kcal/m2 respired 6.3 Kcal/m2 and used 1.4 Kcal/m2 in production Crangonyx energy flow was fairly constant throughout the year. The ecological efficiency of Crangonyx was 8%, the net production efficiency, 17%-19%, and the population growth efficiency, 14%-15%. Annually, Hyalella populations assimilated only twice as much and produced about 3 times as much energy as did Crangonyx populations, but during the summer, Hyalella energy flow was 4 times that of Crangonyx. A synthesis of existing data on poikilotherm energetics suggests that life history phenomena are important in determining the relationship between annual population respiration and production. Also, annual production and assimilation were found to be closely related to the mean standing crop of various organisms. / Science, Faculty of / Zoology, Department of / Graduate

Manitouwadge, a copper-zinc-silver mining camp, lies 150 miles east of Port Arthur, Ontario, and 25 miles north of Lake Superior. A series of volcanics and sediments, now metamorphosed and migmatized to hornblende schists, quartz feldspar gneisses, and granite gneiss, underlies the Manitouwadge area. These have been folded into an overturned syncline which strikes east-west and plunges gently to the northeast. Three sets of faults are known with at least four periods of movement. The latest of these has offset the mineral deposits and some of the north striking diabase dykes. The two important deposits lie on the south limb of the syncline near the contact between granite and quartz feldspar gneiss. The Willroy property is adjacent to, and immediately west of, the Geco mine. The gneisses on the Willroy property exhibit a complete gradation from quartzite to iron rich hornblende gneiss, and are thought to be sediments that have been metamorphosed to a grade indicated by the amphibolite facies. Detailed mapping and drill hole correlation indicates the presence of several small folds in the east striking formations. All the sulphide deposits occur within individual formations where they are folded. The folds appear to be related to the major deformation, as are numerous pegmatite dykes which cut across the gneisses. The ore occurs in three tabular sulphide replacement bodies, with a strike parallel to that of the enclosing formations. These orebodies plunge to the east at 45 degrees, parallel to the plunge of the folds. The ore consists of pyrite, pyrrhotite, chalcopyrite, sphalerite, galena and tetrahedrite. Silver is present, and is apparently contained in the sulphide minerals. Although precise structural controls are not known, the sulphide deposits of the area all occur adjacent to small folds. Further work in the area might well be concentrated on outlining and prospecting similar structures. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The major rock units within the area investigated are the Permian Chilliwack Group, the Upper Lower Jurassic - lower Middle Jurassic Cultus Formation, and the Upper Jurassic Lower Cretaceous Vedder Mountain Sediments. The Chilliwack rocks examined consist of four limestone units, a thick volcanic sequence, a conglomerate and argillites. The Cultus rocks consist of argillite, shale, graywacke and clastic limestone, The Vedder Mountain Sediments are graywackes, argillites and conglomerates. A tabular body of igneous rock and a schistose cherty rock are included in the sequence. The regional strike is to the north-east. Most of the rocks in the area are strongly fractured. The Cultus Formation is folded into a series of overturned isoclinal folds with axial planes striking north east and dipping south east. The strongly folded Chilliwack rocks are thrust over the Cultus rocks from the south and south east. The relationship of the Vedder Mountain sediments to the other major rock units is unknown. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The problem which this thesis seeks to answer is why the Shuswap region of British Columbia, centrally located in the southern part of the province between Kamloops and Revelstoke, endowed with so many natural advantages of climate and scenery, of location on early water routes and later arterial railway and highways, has remained relatively unimportant in the economy of the province. In the process of finding answers to this problem a systematic study has been made, first of the topography and the natural resources of the area, then of the experiences of those who first sought to open up the region, and finally of the development of mining, agriculture, lumbering and the tourist trade. From the analysis of the growth, or sometimes of the decline, of these industries, much information has been obtained as to the deficiencies of the area in natural resources, the handicaps imposed by the Shuswap region's distance from major markets, and the problems encountered by the inhabitants in utilizing some of the resources. Basically, the area lacks rich natural resources - there is little mineralization; the areas of arable land are limited and are scattered in pockets through the region; the timber resources are not as extensive as at first appears, vast stands of mature timber having been burned over since' settlement came into the area, and much of the remaining timber having a high incidence of disease. Both lumbering and agriculture have been handicapped by high transportation costs because of the remoteness of the area from major markets. The recent vastly increased number of tourists and summer residents in the Shuswap area (much of it due to the completion of the Trans- Canada Highway through Rogers Pass) is responsible for a recent upswing in the region's economy and augurs well for the future. The conclusion is finally reached that the tourist trade is the sole activity which offers real prospect of future development. The Shuswap country's lovely scenery, hundreds of miles of lakeshore, and fine climate have proved to be its major natural resource. The main difficulty encountered in working on this thesis has been finding the necessary data. A certain amount of information is available in printed government documents - in gazettes, sessional papers, annual reports, memoirs and reports of royal commissions. Newspapers, both early and more recent, have proved helpful, as have a few books and some theses. The resources of the University Library, the Provincial Archives, the Vancouver Public Library's Northwest Room and the Kamloops Museum were used. But much vital information was still missing. To make good the deficiencies in the printed materials, many old-timers around Shuswap Lake were interviewed and, in a number of cases, their conversations were tape recorded. These talks were most helpful in securing a general picture of the process of settlement and the history of various industrial and land settlement schemes. Extensive correspondence was carried on with various individuals, government departments and companies, asking for specific information. Much time was spent in personally interviewing key civil servants in such sections as the Legal Surveys Division, the Water Resources Service and the British Columbia Forest Service of the Department of Lands and Forests in Victoria. Thanks to these contacts, permission was obtained to dig deep into files at least fifty years old or, where the files had been destroyed, to use the microfilm copies that had been made for departmental use. Finally, a reasonably balanced and full picture of the growth of the area began to emerge. / Arts, Faculty of / History, Department of / Graduate

No abstract included. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Most paleoflood reconstructions come from the arid dry climate of southwestern USA with very few studies being conducted in temperate climates. The study’s main objective is to determine if oxbow lakes can be used to reconstruct past flood events in temperate regions, such as the Désert River in southwestern Québec, Canada. Sediment cores were extracted and analyzed for magnetic susceptibility, loss-on-ignition and grain-size. These analyses are used to decipher evidence of flood signatures within the cores. Results show a strong relationship between past flood events and known climate variability on multi-decadal to centennial timescales. A higher frequency of floods was observed during the Little Ice Age (LIA; 1450-1850 AD) and the Dark Ages Cold Period (DACP; 300-800 AD) as compared to the Medieval Warm Period (MWP; 900-1200 AD). This study supports previous work on paleoflood hydrology using oxbow lakes as a proxy and its relationship to past hydroclimatic changes. These types of studies contribute to a better understanding of past hydroclimatic changes on regional scales that can be used to better predict future floods under a changing climate.