Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.

Thesis (M.S.)--University of Akron, 2006. / Title from PDF title page (viewed on Jan. 25, 2007). Includes bibliographical references (p. 62-68).

Nutritional efficiency of deeply frosted and repeatedly defrosted zooplankton has not been totally clarified, and it is often questioned, however, the nutrients composition and effect of such deteriorated feed are missing. The aim of this study was to assess nutritional eddiciency of repeatedly defrosted nauplia Artemis salina, as well as changes in their chemical composition on the basis of the growth, survival and presence of the deformations in early ontogeny of Japanese medaka ( Oryzias latipes). The samples of fresh hatched artemia nauplii served as a control group. The experiment was carried out with samples of live nauplii, permanently frosted at -14°C, defrosted to 4°C and again frosted and defrosted to 25°C and frosted again. The larvae of medaka in the period of one week after shift to the exogenous nutrition were examined. Before the commencement of the experiment the composition of samples in terms of nutrient, amino acids and fatty acid contents was determined. The results proved that Oryzias latipes fed with live artemia not only grew better but also survived more that other fis in other treatments. No deformations were recorded Fish fed frozen food survived better than those fed with live Artemia. It was also found that fish fed live Artemia seems to be the highest however from the amino acid point of view it seems to be more appropriate to freeze it to -14°C, defreeze to 25°C and refreezing to -4°C. as for the fatty acids Artemia adjusted by the permanently freezing to -14°C. The processes of thawing and repeated freezing of artemia nauplii result in leaching of some nutrients but in the thickening of some others.

No description available.

Seasonal variation in zooplanton abundance and diversity in Spring Lake, Florida was studies between 1973 - 1976. This clear, sand bottom lake is considered among the most oligotrophic in central Florida. Sixty rotifer species, sixteen cladoceran species, and seven copepod species were collected during the three year study. Annual mean zooplanton abundances ranged between 70 individuals/l and 80 individuals/l. Rotifers were more abundant than either cladocerans or adult copepods. Rotifers and immature crustaceans comprised nearly 75% of the annual mean zooplankton abundance. There was no significant difference (P < 0.05) between years for the annual mean abundance of zooplankton. The monthly mean abundance of cladocerans and adult copepods was generally less than 5 individuals/l. The greater abundance of rotifers in comparison to other zooplankton was mainly responsible for the variation in the values of the Shannon and Simpson Indices. The monthly mean Shannon Index was usually between 3.0 and 4.0. Seasonal differences in zooplankton abundance were apparently due to water temperature and specific conductivity for the 1974 - 1975 and 1975 - 1976 study years. Shannon diversity was significantly correlated with dissolved oxygen for the 1973 - 1974 and 1974 - 1975 study years.

No description available.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 126-138). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 172-174). Also available on the World Wide Web.

No description available.

Unprecedented rates of anthropogenic environmental change have resulted in dramatic decreases in biodiversity worldwide. In order to persist during changes in both the abiotic and biotic environment resulting from anthropogenic stressors such as climate change and habitat degradation, populations must be able to respond or face extirpation. Predicted population-level responses to environmental change include i) range shifts as individuals disperse into more suitable regions, ii) phenotypic plasticity allowing for shifts in the mean phenotype of the population or iii) microevolution resulting from a genetic change within the population. The goal of this thesis is to assess how species within a community respond to a dramatic change in the environment. This study used the sediment record of a Subarctic pond to investigate the impacts of a rapid increase in salinity on two species of the crustacean zooplankton Daphnia. One species, Daphnia tenebrosa, was unable to persist in the high salinity conditions and is believed to have been extirpated from the system. The other species, Daphnia magna, was tolerant of the new environmental conditions and was present throughout the sediment record. To investigate the changes in life history of D. magna, resting eggs from the sediment were hatched to compare iso-female lines from pre- and post-disturbance time periods. No differences were observed between the clone lines, suggesting that phenotypic plasticity allowed D. magna to persist despite the rapidly changing environmental conditions, and that microevolution in salinity tolerance may not have occurred in this population. This study suggests that, in environments with moderate levels of post environmental change, pre-existing phenotypic plasticity may play a greater role than microevolution in species response to environmental changes. However, not all species from a community display the same response to environmental changes, as seen in this study with the extirpation of D. tenebrosa. To better understand how communities will be affected by future environmental change, further investigations need to be made on what factors influence species response. Identifying species response may allow conservation efforts to focus on species that are unlikely to adapt to environmental change, and are most at risk. / Thesis (Master, Biology) -- Queen's University, 2013-09-29 21:54:34.881