A quantitative study of bacteria and nitrogenous compounds of Barren River in Warren County, Kentucky, was undertaken to determine the relation between the number of bacteria and the amount of nitrate nitrogen found.

Graduation date: 1968

Natural populations of phytoplankton from Yaquina Bay, Oregon, were incubated in large polyethelene bags in- situ, with and without the natural assemblage of zooplankton. Samples were taken daily for two weeks in April, 1974. The biomass of phytoplankton in the bag without grazers reached values two to three times the biomass of phytoplankton in the bag with grazers. Sixty-eight to 93% of the cells in the bag without zooplankton were Thalassiosira fluviatilis, while the major species in the bag with zooplankton were T. fluviatilis, T. decipiens and Chaetoceros debilis, no one of which ever accounted for more than 40% of the cells. Nitrate-nitrite became depleted two days earlier in the bag without grazers and urea and ammonia values were higher in the bag with the grazers. Primary productivity, per unit cell volume, was higher in the grazed bag following nutrient depletion, suggesting some productivity enhancement by grazers. Physiological parameters indicate that the cells in the bag with zooplankton were richer in carbon, nitrogen and chlorophyll a, a higher percentage of the chlorophyll was degraded to phaeophytin and carbon to nitrogen ratios were lower. Data obtained from the bag with zooplankton were similar in range to data from the bay. The results support the contention that zooplankton can have a large effect on phytoplankton in terms of biomass, species composition, productivity and physiological state. / Graduation date: 1975

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

No description available.

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Ability to regenerate is found in many groups of metazoans but the majority of research is focused on adults from just a few taxa, such as planarians and hydra (Agata and Inoue, 2012; Bely et al., 2014). Increasing the diversity of study organisms and life stages can reveal new and interesting aspects of regeneration mechanisms. This study focuses on regeneration of the nemertean pilidium larva. The planktotrophic pilidium of Maculaura alaskensis provides a unique model in which to observe several components of the regeneration process. Here I have documented a timeline for regeneration and have begun to evaluate the cells responsible for regenerative success. This study has revealed the interplay between regeneration and degeneration, a tradeoff between larval and juvenile structures, as well as the important relationship between global versus local signaling in proliferation and differentiation responses.

The intertidal ecology of approximately seventy miles of coast, along the southwest shores of Vancouver Island from Port Renfrew to Victoria, was studied during the period from May 1957 until July 1958. This coast is a transition area between the open ocean at Port Renfrew and more sheltered waters east of Victoria, which are much freshened by the influx of the Fraser River. Attention was concentrated on the more conspicuous forms, mostly on those algae of the order Laminariales which do not occur in the more sheltered localities. Observations were made at twenty-six stations spaced along this coast. In collecting specimens, particular attention was given to those algae where identification is difficult or doubtful. These collections were made to complement the direct observations on those entities which could readily be identified in the field. The presence or absence of the entities studied was noted at each station. The distribution of some of the very conspicuous forms was determined along most of the coast between the stations. Any distinct upper or lower limits in the intertidal organisms at a station were recorded. Limited observations were made at fourteen other points, where these were needed to elucidate questions raised by the earlier data. Conditions of the physical environment, particularly of salinity, sea temperature, and tidal rhythms, were monitored at each of the stations wherever possible. Most of the twenty-six stations were occupied at least once each summer. Some of the more centrally located ones were visited at various times throughout the year in order to observe seasonal changes in the organisms and environmental conditions studied. When two or more measurements of the same upper or lower limit of an organism were made at different times, these replicates were used to calculate error in the technique used in finding the levels of these limits. The open coast forms penetrate varying distances along the coast into Juan de Fuca Strait in an easterly direction. Evidence is presented that different factors in the physical environment may be limiting for the geographical distribution of different organisms. Thirty-six vertical limits of the organisms studied are discussed. These are all the limits which were measured at nine or more stations throughout the area studied. The heights of each limit were plotted against the headland to headland distance between stations. Each limit was approximated by a line of least squares. The validity of this approach is discussed. The limits studied were grouped as follows: 1. Limits which are very variable throughout the area studied. 2. Limits which are more variable on the coast west of Sooke, than east of it. 3. Only slightly variable limits which have a definite slope downward from Port Renfrew to Victoria. 4. Only slightly variable limits which have no definite slope between Port Renfrew and Victoria. Various combinations of factors are suggested as explanations for these various types of limits. These factors include surf, light, desiccation, and nutrients, together with adult size and longevity of the organism. The theory of critical tidal factors is criticised. Species of the order Laminariales in this area which are as yet of questionable taxonomic status, are found in the following genera: Hedophyllum, Alaria, Costaria, Cymathere, and Laminaria. Of these, Hedophyllum and Alaria were studied in some detail. Hedophyllum was cultured from zoospores obtained from the sporophyte, through gametophyte stages, to what was presumably a young sporophyte of the same entity. The young sporophytes were not grown to stage where positive identification of secondary morphological characteristics was possible. The alternation of generations observed conformed to the pattern known for the other members of the Laminariales. Hedophyllum subsessile (Areschoug) Setchell, one of the two species of Hedophyllum reported from British Columbia, is reduced to synonomy under the other, H. sessile (C. Agardh) Setchell. A transitory stage in the development of H. sessile in its second season corresponds closely to the herbarium material on which Setchell appears to have based his description of H, subsessile. Variations in the bullation of the lamina of H. sessile are largely the result of environment, probably of exposure to, or shelter from, sunshine. Although the species of Alaria (A. marginata Postels and Ruprecht, A. nana Schrader, A. tenuifolia Setchell, and A. valida Kjellraan and Setchell) reported from British Columbia are very variable, they may usually be distinguished by the morphological characters of those sporophylls which are in a mature and fertile condition. These four species are therefore regarded as taxonomically valid in this study. / Science, Faculty of / Botany, Department of / Graduate

The primary purpose of this study was to deal with the taxonomy of the sand-dwelling dinoflagellates occurring in the North East Pacific Ocean. A preliminary examination of the community and the major ecological parameters affecting these organisms (exposure, grain size, temperature and salinity) was also undertaken. Although the study was mainly confined to those species inhabiting the inter-tidal zones of five marine beaches in British Columbia, some subtidal work was done. The conclusions are based on the analysis of approximately 120 samples from 15 field trips over a one year period. Forty-one species were recorded of which 12 could not be identified and may warrant being described as new species. In general, the number of both species and individual cells increased from winter to spring and summer with maximum comentrations between March and September. Out of the environmental parameters measured, grain size (which is primarily determined by tides and currents) is probably the most important factor in determining the distributions of these organisms in the summer months. / Science, Faculty of / Botany, Department of / Graduate

A biogeographic analysis of the seaweed flora of the area from Lüderitz to Cape Agulhas was undertaken. Biogeographic patterns were reviewed across 15 geographic regions. A TWINSPAN analysis showed a clear division of the area into two separate species communities. These two communities are the Benguela province, and the western overlap region between the Benguela and Agulhas provinces. The western overlap region was found to be the most diverse. Diversity was shown to decrease with a decrease in latitude. Patterns in endemism among the brown seaweeds follow this trend. In contrast to this, red and green endemics increase with a decrease in latitude. Shore distribution patterns were reviewed, and demonstrated an increase in diversity with a progression down the shore. Among the red seaweeds, this increase, with greater depth was considerable. Species distribution patterns in both shore and shore pool zones were found to follow the same pattern, except for a drop in species in the subtidal fringe pools, which this study concluded was a meaningless concept. These results have been reviewed in relation to present conservation areas along this shore, and future recommendations were made for location of sites for the conservation of seaweed. These were the formation of reserves between Lüderitz and Port Nolloth, between Yzerfontein and Melkbosstrand, and from Scarborough to Cape Hangklip. In some of these areas existing reserves need to make policy adjustments while in others reserves need to be established for the conservation of both diversity and uniqueness of seaweed species.