Thesis (Ph. D.)--York University, 2000. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ56267.

Thesis (Ph. D.)--University of Chicago, Dept. of Ecology and Evolution, August 2000. / Includes bibliographical references. Also available on the Internet.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 185-195).

The effect of the Asian grass carp (Ctenopharyngodon idella Val.) and aquatic vegetation upon the zooplankton in four adjacent experimental ponds (0.139 ha each) was studied for one year. Zooplankton were collected with a newly designed shallow-water sampler. Pond 1 contained no aquatic vegetation. Ponds 2, 3, and 4 contained nine species of rooted aquatic plants. Grass carp were stocked into Pond 2 (65 per ha) and Pond 3 (611 per ha). Physicochemical parameters were similar among the ponds. Eighty-eight zooplankton species were enumerated. The abundance of zooplankton groups (Rotifera, Cladocera, and Copepoda) was not significantly different among the ponds containing grass carp. No significant differences existed between Pond 3 (high grass carp stocking rate) and Pond 4 (no carp) for species diversity (d) and species dominance. The number of species and species diversity (d) was found to be significantly different in Pond 2 (low grass carp stocking rate) when compared to Ponds 3 and 4; those differences probably were not due to the grass carp. Grass carp did not appear to affect the water quality of the ponds. In general, it was concluded that grass carp had little, if any, direct or indirect affect upon the zooplankton. Species commonness was greatest among ponds containing vegetation. Rotifers were the dominant zooplankton group in those ponds. Zooplankton ware moat abundant in the pond without vegetation and were dominated by copepods (notably Tropocyclops prasinus). That pond contained the lowest number of species and had the largest species diversity (d) of the ponds. The annual mean for the Simpson Index (species dominance) was highest in Pond 1. The lack of vegetation may have influenced the abundance and diversity of the zooplankton in Pond 1 compared to the other ponds. Those differences also may have been due to selective predation by mosquitofish (Gambusia affinis); that fish was significantly less abundant in Pond 1.

No description available.

Alterations in the summer zooplankton community that have appeared since Johnson's (1972) study of a Michigan City (site M) transect in southeastern Lake Michigan were investigated. Vertical tows were made at 5, 10, 15, and 18 meters from June through August in 1987 and 1988 in order obtain data that could be compared with that of Johnson (1972).Subsamples analyzed were proportionately larger than those of Johnson (1972), in order to obtain a detailed profile of the species and numbers in the community, and to identify large, predatory zooplankton species that are believed to have been severely impacted by the explosive growth of the alewife population during the 1960's.The most common crustacean species collected were: Diacyclops thomasi, Leptodiaptomus minutus, Leptodiaptomus ashlandi, calanoid and cyclopoid nauplii and copepodids, Daphnia retrocurva, and Bosmina longirostris. The most common rotifer species collected were Keratella c. cochlearis, Keratella crassa, Kellicottia longispina, Conochilus sp., and Polyarthra sp.. Higher numbers of Epischura lacustris adults and copepodids, Leptodora kindti, Mesocyclops edax, Daphnia galeata mendotae, and the rotifers Asplanchna priodonta, Conochilus sp., Keratella crassa, and Ploesoma truncatum were recorded as compared to Johnson's 1972 data. The summer zooplankton community of this transect appears to have been represented in the summers of 1987 and 1988 by a greater number of large crustacean zooplankton species, as opposed to a 1970 community dominated by small microfiltrators and D. thomasi. / Department of Biology

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

The species compositions and densities of the littoral and pelagic zooplankton assemblages in Crater Lake were compared. The littoral and pelagic zooplankton assemblages of most lakes are typically different due to different habitat conditions in the two zones. The littoral zone of Crater Lake lacks many of the habitat characteristics, which distinguish a typical littoral zone from the pelagic zone. In fact, none of the water quality variables measured differed significantly between the littoral zone and epilimnion of the pelagic zone in Crater Lake. The littoral and pelagic zones of Crater Lake were sampled with twelve paired sites in August and again in September of 1995. For the purposes of this study, the littoral zone was defined as lakeward from the shoreline to the 10m depth contour. At each paired site the pelagic assemblage was sampled to a depth of 120m at the 200m depth contour. Despite the almost identical water quality between the pelagic and littoral zones of Crater Lake, lack of vascular macrophytes in the littoral zone, and well-mixed epilimnion, the littoral zooplankton assemblage differed from the pelagic assemblage in both species composition and density. Several ubiquitous zooplankton taxa dominated both the littoral and pelagic zooplankton assemblages, although the density of these taxa as well as the relative abundance of these taxa differed between zones. These ubiquitous species reached their maximum densities in the metalimnion of the pelagic zone at a depth range of 10 to 60 meters below the lake surface and were considered primarily pelagic. A shift in wind direction between sampling periods influenced the distribution of pelagic zooplankton taxa in the littoral zone. Twenty-four taxa were recorded in the littoral zone, and aside from infrequent exceptions, none of these taxa were found in the pelagic zooplankton assemblage. Most of the littoral taxa were primarily adapted to the benthic zone. / Graduation date: 1999

Filter-feeding macrozooplankton were collected from 24 lakes in south-central Ontario to examine relationships between environmental factors and methyl mercury accumulation. Zooplankton methyl mercury levels ranged from 19 to 448 ng$ rm cdot g sp{-1}$ dry weight in the study lakes and were highest in zooplankton from acidic brownwater lakes. Water color and lake water pH were the best predictors of methyl mercury levels in zooplankton explaining 73% of the variation. Methyl mercury concentrations were positively correlated with water color and inversely correlated with lake water pH. Water color explained a greater portion of the overall variance in methyl mercury levels, indicating that the supply of mercury from the drainage basin plays a key role in determining methyl mercury concentrations in the lacustrine biota. Zooplankton methyl mercury levels were well correlated with mercury concentrations in smallmouth bass (Micropterus dolomieui) and largemouth bass (Micropterus salmoides) from 11 of the study lakes showing zooplankton to be good indicators of the relative bioavailability of mercury at the base of the food chain.

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 70-75). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11819