This study deals with the ecology of ciliated protozoa in the benthos of a small (10 hectares), eutrophic loch (OS ref. 808 966). Regular sampling of the benthos and overlying water at three markedly different sites over a two-year period was complemented with laboratory experiments on individual ciliate species. In part 1 of the thesis, variation in the complete ciliate population (temporal and vertical distribution of numbers and biomass) is analysed by single and multiple regression on the other factors recorded (including redox potential, sulphide ion activity, pH, oxygen flux, nematodes, bacteria, chlorophyll a and phaeophytin, sediment density and organic carbon, temperature, daylength and various aspects of water chemistry). Seasonal cycles were recorded for ciliate number, biomass and pattern and extent of depth penetration. The most prominent seasonal characteristic was the accumulation of ciliates at the sediment surface during the summer (up to 83000 cm-2, > 99% being in the top 1 cm of sediment). This has been explained in terms of the summer increase in benthic productivity increasing the available food sources for ciliates at the sediment surface, and upwards migration of the redox potential discontinuity forcing the ciliate population into the oxidised microzone. In the second part, the distribution and abundance of individual species has been described. Species such as Cyclidium glaucoma and Aspidisca costata occurred on almost every sampling occasion. Large species such as Loxodes striatus, Spirostomum teres and Frontonia leucas were more frequent and abundant during the summer. Species with known or suspected tolerance of anoxia and reducing conditions, such as Caenomorpha spp., Mylestoma uncinatum and Epalxella spp., were more common in the sub-surface sediment. Although 91 species were identified during the whole sampling programme, the maximum number distinguished on any one occasion was 25. Computer-assisted association analyses identified groups of similar species and similar occasions. Species-groups composed predominantly of large ciliates were defined for each of the three sites. Occasions were sorted into seasonal groups, the species-groups composed of large ciliates accounting for most of the coincidence with the summer and autumn occasion-groups. The factors controlling seasonal variation are discussed. Part 3 is concerned with the energetics of the complete ciliate population and its constituent size classes. While estimates of production were high, (345 149 and 40 J cm-2 year-1 at the three sites) respiratory energy losses were relatively low (18, 11 and 4 J cm-2 year-1 at the three sites with ciliates accounting for a maximum of 3.5% of total benthic respiration). Seasonal variation was detected in population net production efficiencies (range 63 - 98%), the lower values being more common in the winter, The energetic efficiencies of the ciliate population are considered with reference to data in the literature for higher organisms. The contribution made by ciliates to energy flow through the benthos is discussed.

No description available.

Standard toxicity tests often require high costs for maintaining healthy cultures, so few test species are employed in routine ecotoxicological analysis. An alternative is the "battery of tests" approach involving using rapid toxicity tests for screening. Rapid-screening toxicity tests must display organism sensitivity, similarity in responses to other test organisms, relevancy to many circumstances, and repeatability. Protozoa are ideal candidates for rapid-screening bioassays. They are cosmopolitan, play important roles in ecosystems, and have high reproductive rates. Many protozoa can form a resting stage (cyst) that remains viable during adverse conditions, eliminating the need for maintaining continuous cultures for testing. The main objective of this research was to evaluate the soil ciliate, Colpoda inflata (Stokes), as a bioassay organism in rapid-screening tests by determining its sensitivity to a variety of model compounds. These tests were based on the principle that exposure to a toxic compound would negatively affect population growth. To test for sensitivity, C. inflata was exposed to different levels of dissolved organic carbon in test media for each compound tested. C. inflata was expected to be more sensitive to toxicants in an inorganic medium than in media with high organic carbon content. Data were analyzed by determining the median tolerance limit for inhibition of population growth (IG50) relative to controls. IG50 values of the eight model compounds tested varied considerably. C. inflata growth was not significantly affected by 2,4-D or malathion. C. inflata showed differences in sensitivity between organic and inorganic media for the toxic metals tested and the order of toxicity corresponded to those found in standard tests. A significant difference occurred between the test media and the pesticide PCP, where growth was not inhibited in the organic medium; in the inorganic medium the IG50 was 0.269 mg/L. No significant effect of test media was found for ammonia or SDS. Compared to several published toxicity results, C. inflata proved more sensitive overall than other rapid-screening tests and many standard acute toxicity tests. Results of this study show that this rapid-screening toxicity test is sensitive, repeatable, and provides information similar to traditional standard toxicity tests.

No description available.

Thesis (Ph. D.)--University of Adelaide, Dept. of Animal Sciences, 1994. / Videorecording has title: Effect of antibodies on the motility of rumen ciliates. Includes bibliographical references (leaves 197-259).

Thesis (Ph. D.)--University of Southern California, 1981. / Includes bibliographical references (leaves 228-251).

Conjugation in Stentor coeruleua was investigated using two experimental methods which regularly yielded large numbers of mating pairs. One method involves a particular culture technique, the other requires a mixture of cells from different stocks. Mating pairs appeared in the form of bursts of conjugation, either induced by mixing certain stocks or occurring spontaneously in some stock cultures. Spontaneous bursts, in the majority of cases, occurred during a definite interval in the development of a culture. Morphologically distinct pre-conjugator cells appear immediately before as well as during the initial stages of a burst of conjugation. Mating pairs were formed by the union of two pre-conjugators. Mixing eight stocks in all possible combinations of twos and observing their subsequent response revealed they were separable into two complementary mating types. The majority of mating pairs formed in mixtures of stocks consisted of individuals of different mating types. Evidence is presented which is compatible with the hypothesis that cell to cell contacts between individuals of differing mating type are necessary for the initiation of a mating reaction. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Includes bibliographical references (leaves 197-259). / xv, 261, [9] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. + 1 videocassette (6 min. (VHS) : sd., col. ; 1/2 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1994

Videorecording has title: Effect of antibodies on the motility of rumen ciliates. Bibliography: leaves 197-259. Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates.