Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 55-61).

Greatly condensed portion of Thesis--University of Michigan. / Reprinted from Transactions of the American Microscopical Society, vol. LXIV, no. 1, January, 1945. Literature cited: p. 18-20.

Abstract of Thesis (Ph. D.)--Uppsala University, 1983. / Includes bibliographical references (p. 20-23).

Inaug.-Diss.-Münster. / Vita.

Thesis--University of Wisconsin -- La Crosse, 1972. / Date on title page: 1970. Includes bibliographical references (leaves 24-26).

The food of a common freshwater deposit-feeding amphipod Hyalella ctzteca (Saussure) and the effect of its feeding on energy transfer within the sediments of Marion Lake were examined. By use of C¹⁴ labelling techniques and chemical analyses of food and faeces, Hyalella was shown to digest algal and bacterial cells from ingested sediment particles at a rate sufficient to supply energy necessary for observed growth, respiration and egg production. Non-living sediment organic substances (cellulose and lignin-like materials) were not assimilated. Changes in oxygen concentration over undisturbed sediment cores incubated under light and dark conditions and with antibiotic additions were used to provide an in situ measure of epibenthic algal production and community and bacterial respiration. Seasonal and spatial differences in sediment microflora production potentially available for consumption by Hyalella were positively correlated with amphipod growth, distribution and the onset of egg production. In laboratory experiments amphipods selected sediments with the highest concentrations of microflora and growth was proportional to the abundance of this food source. Numbers of Hyalella were varied in undisturbed sediment cores to evaluate the effect on microflora production. After 43 hr incubation, algal production stimulated at natural amphipod densities and declined, with higher numbers. Lacterial respiration was stimulated at densities four times those observed in Marion Lake and this also decreased with crowding. Total microflora production and amphipod energy requirements were compared to calculate that at natural densities during the summer Hyalella would consume less than 10% of the daily production. The remaining microflora production may be consumed by numerous other deposit-feeding species in the benthic community. Physical leaching and heterotrophic organisms lowered the organic content of faeces in the dark, while autotrophic organisms and dissolved organic compounds released by amphipods added organic matter to faecal pellets. Thus, while Hyalella's browsing activities may reduce the biomass of sediment microflora, it concurrently aided recolonization of faecal material and sediment particles and thus appears to stimulate production of its own food supply. Additional data are presented which compare the respiration of different benthic communities. The similarity of the rates of oxygen exchange, after correction for temperature difference, suggests that processes affecting oxygen availability are important in determining the overall rate of energy transfer within many benthic communities. / Science, Faculty of / Zoology, Department of / Graduate

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

Thesis (Ph. D.)--Biology, Georgia Institute of Technology, 2006. / Mark E. Hay, Committee Chair ; Julia Kubanek, Committee Member ; Joseph Montoya, Committee Member ; J. Todd Streelman, Committee Member ; David M. Lodge, Committee Member. Includes bibliographical references.

The studies on the Vaal River and its tributaries presented here, were carried out for a variety of reasons. Prominent among them were several of immediate practical importance, such as the need to know the pollution status of waters which ultimately form the major supply for the Witwatersrand urban and industrial complex, and the need for background data on a stretch of the river which was to be insecticided to control a Simulium pest. However the results of such work can often be used for wider purposes. In this thesis they are used to examine the major factors thought to govern the distribution and abundance of the invertebrate Metazoa in the river. Introduction, p. 2-3.

Aspects of the biology of the calanoid copepod Pseudodiaptomus hessei are described, with particular reference to its vertical migratory behaviour. The present investigations were carried out largely by means of Nansen-type plankton nets, but several new pieces of apparatus were developed and. are described herein. The daytime vertical distribution of P. hessei varies according to developmental stage and depth of water. In shallow areas of the lake the entire population is benthic or in very close association with the lake bed. In the deepest part of the lake (40m) the naupliar and early (i.e. C I - C III) copepodite stages are essentially pelagic, but the adult and late (i.e. C IV - C V) copepodite stages are predominantly benthic and may be quiescent or infaunal. During the hours of darkness, the calanoids are distributed through the water column. The nauplii are consistently abundant in the surface waters but the distribution of the other stages is not regular. The distribution can be related to lunar intensity in many cases, with the post-naupliar stages frequently occurring deeper in the water column on bright moonlight nights and in the surface waters on overcast moolnless nights. The dusk ascent and dawn descent of the calenoids is clearly related to changes in light penetration in most individuals. The movements of a fraction of the adults occur in the apparent absence of adequate light cues. This behaviour is shown more extensively by the adult females. An endogenous activity rhythm has been shown in the species under laboratory conditions and it is suggested that this may play a part in the migratory movements. A basic examination of the feeding methods, feeding appendages and food sources of adult and late copepodite stages has been made. Changes in feeding intensity through twenty-four have been examined in the field and under laboratory conditions. Using as an index of feeding intensity, the proportion of animals with food in their guts, it has been shown that a pronounced diel difference occurs in adult calanoids in the lake. Feeding is almost entirely restricted to the nocturnal presence of the calanoids in the water coloumn. This difference exists in the pre-adult copepodite stages, but is not nearly as striking. The absence of feeding during daylight is not readily accounted for in terms of food availability and it is attributed to the quiescent or possible infaunal existence of the adults. A periodicity in egg hatching has been shown Naupliar release from the parental egg sac is predominantly a nocturnal phenomenon in the hot and cool seasons. It is suggested that this may be important in attaining a favourable vertical distritution for the nauplii, and may be important in the distribution of the species. A preliminary acccunt of the seasonal cycle and population dynamics of P. hessei is given, based on data collected over two years at a single station. Seasonal changes in calanoid abundance are intermediate between those recorded in truly tropical areas and in temperate latitudes. Potential food sources show relatively little change. The vertical migration of P. hessei is considered in relation to its apparent ecological significance and comparisons are drawn with observations made on the same species or other pseudodiaptomids in estuaries and lagoons elsewhere.