A simplified autoradiographic method for estimating species-specific phytoplankton production rates in mixed natural communities was evaluated in the laboratory and employed in the field. Laboratory experiments were designed to test the reliability and variability of the simplified method. Assays of ¹⁴C uptake by liquid scintillation spectrometry were used to evaluate assays by autoradiographic silver grain counts. Linear relationships between the two assays were found for varying activities within a species. With corrections for radiation geometry and self-absorption, a linear relationship was obtained for species from 400 to 50,000 μm³ in cell volume. The coefficient of variation for microscopic grain counting at densities from 10 to 70 grains per 100 μm² was 4% of the mean. Counts of replicate autoradiographs from individual incubations yielded coefficients of variation of 7 and 14% for grain densities of 11 and 30 per 100 μm², respectively. The frequency distribution of grains deposited over different cells of a species with varying photosynthetic activities is indicative of the physiological state of the alga. Samples from five depths at one station in Yaquina Bay, Oregon were incubated in situ with ¹⁴C, daily from 2 April to 7 May 1974. Phytoplankton biomass during the spring bloom reached 7106 μm³ cell volume l⁻¹ and integral production reached 172 mgC m⁻² hr⁻¹. Total community carbon uptake increased with biomass during the study but species-specific uptake decreased as ambient nitrate + nitrite levels decreased. Species-specific production rates were estimated for 22 consecutive days: 16 April to 7 May 1974. Three taxa, Chaetoceros debilis Cleve, Thalassiosira decipiens (Grun.) Jorg., and unidentified flagellates were responsible for over 65% of the community biomass and over 85% of the primary production after 20 April 1974, Carbon-specific uptake rates were calculated for 20 species. Maximum carbon-specific uptake rates (expressed as the percent of the estimated cell carbon content assimilated per hour) for six abundant diatom species ranged from 111 to 158%, but average activity over the study period for 20 species was much lower. Carbon-specific uptake rates (% cell C hr⁻¹) averaged over all samples for the three dominant taxa were: Chaetoceros debilis, 22%; Thalassiosira decipiens, 21%; and flagellates, 54%. Flagellates were always two to three times more productive than the dominant diatoms on a carbon specific basis. Photosynthesis:biomass ratios (P/B) of the three dominant taxa decreased proportionately during the study The percent of total biomass and percent of total carbon uptake contributed by the three dominant taxa were proportional over the period studied. Average daily carbon-specific uptake rates demonstrate that Thalassiosira decipiens succeeded Chaetoceros debilis due to a change in their relative production rates. / Graduation date: 1977

Sediment was fertilized with f/2 algal growth medium in situ and in the laboratory daily for one week. Sampling strategy incorporated two intertidal heights and two sites. Experiments were done in August and January. No significant changes in chlorophyll a or diatom community structure were observed after ten days of growth in either the field or the laboratory experiments. Laboratory experiments also showed slightly increased gross primary production (p<.10) and increased oxygen uptake (p<.01) associated with nutrient enrichment. Unlike planktonic diatoms, sediment-associated diatoms in Yaquina Bay show no nutrient limitation. Thus other factors probably control diatom growth in these sediments such as light intensity, photoperiod, intertidal height, sediment stability and organic content, and animal consumption. / Graduation date: 1982

Graduation date: 1976

Graduation date: 1967

This study aims to investigate the spatial and temporal distribution of siphonophores in relation to water temperature, salinity, concentration of chlorophyll a and the abundance of copepods in Tapeng Bay and Kaoping coastal waters from June 1999 to July 2001. In Tapeng Bay, 20 species of siphonophores belonging to 9 genus and 3 families were identified with the mean abundance of 11¡Ó33 ind./100m3. The 5 most dominant siphonophore species in Tapeng Bay were Lensia subtiloides, Chelophyes appendiculata, Lensia subtilis, Bassia bassensis, and Lensia campanella, comprising 85% of the numerical total siphonophores. The siphonophores were mainly found at north station and scarce or even absent at St. N and St. S. Seasonal distribution of siphonophores was inconsistent, but generally had higher abundance in fall and winter. In Kaoping coastal waters, 34 species of siphonophores belonging to 16 genus and 5 families were identified, with the mean abundance of 648¡Ó636 ind./100m3. Seasonal change in numerical abundance of siphonophores was obvious, with higher in spring and autumn. The 5 most dominant species were C. appendiculata, L. subtiloides, Chelophyes contorta, Sulculeolaria chuni and B. bassensis, and comprised 77% of the total counted of siphonophores. The species number, species diversity, and the mean abundance of siphonophores in Kaoping coastal waters were higher than that in Tapeng Bay. The siphonophores found in the present study mostly belong to the widespread oceanic species and widespread coastal species. The distributions of siphonophore were not significantly (p>0.05) correlated to temperature, salinity, concentration of chlorophyll a and the abundance of copepods, except Abylopsis tetragona and Diphyes dispar, that exhibited significant negative correlation with temperature (p<0.01) and chlorophyll a (p<0.01), respectively.

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The vital rates of beluga, Delphinapterus leucas, harvested in northern Quebec are within the range reported by previous studies in Alaska and the Canadian and Soviet Arctic. Small sample size and inadequate estimates of survivorship rates prevent meaningful calculation of population growth rate. The pattern of changes in vital rates over the life cycle of beluga and analysis of errors associated with stage classification indicate that the demographic information in a 6 x 6 age-grouped Lefkovitch matrix is similar to that in a 38 x 38 age class Leslie matrix. A 3 stage, length-based model composed of newborns, juveniles and adults contains less demographic information than the larger matrices, but is superior to a juvenile/adult classification scheme. The 3 stage model applied to length frequency data from aerial photographic censuses should provide an alternate method of demographic analysis when harvests are small or absent. Colour is a poor criterion for stage classification. / Sensitivity analysis of fecundity and survivorship indicates that survival of gray animals (older juveniles and early breeders) has the most influence on population growth rate. Changes in fecundity have little effect on growth rate. The high sensitivity of population growth rate to juvenile and early adult survival demonstrates that these estimates should be improved if more precise knowledge of beluga demography is required for management purposes. / The age-length data used to evaluate errors associated with stage classification indicate that belugas in Hudson Bay are smaller than those elsewhere, but not to the large degree previously reported. Beluga in estuaries are represented by all size classes. Examination of the integumentary heat loss show beluga and narwhal, Monodon monoceros, to be equally insulated, but only belugas frequent warmer estuarine waters.

No description available.

There are few areas in Canada which have not at one time or another during the past few decades, been drawn to the attention of the public by the movement into them of people and industry as the result of some local characteristic. At the turn of the century it was the wheat fields of the West and the gold discoveries of northern British Columbia and the Yukon. In recent years it has been the iron ore deposits of northern Quebec, the development of extensive mineral finds in the Great Slave Lake area and the valuable oil discoveries of the Prairie regions. Through the medium of the newspaper, motion picture and radio, the average Canadian citizen today has a reasonable geographic knowledge of much of the country and the associated cultural development. However, there are still areas in Canada about which public knowledge is very meagre, regions which due to geographical remoteness or the lack of physical attributes are overshadowed by the commanding interest held by the more spectacular areas. One of these little known areas is the Hudson Bay Lowland, a region that has a history predating the greater part of Canada yet is comparatively unknown to most of the country's population.

No description available.