Global ETD Search

1	Studies on the growth and alkaloid production of tissue cultures of Vinca rosea L. 何潔芳, Ho, Kit-fong. January 1980 (has links) published_or_final_version / Botany / Master / Master of Philosophy Callus (Botany) Madagascar periwinkle. Alkaloids. Plant tissue culture.
2	The effect of cattle grazing on the abundance and distribution of selected macroinvertebrates in west Galveston Island salt marshes Martin, Jennifer Lynn 30 September 2004 (has links) The effect of cattle grazing on the abundance and distribution of vegetation, burrowing crabs (Uca rapax, Uca pugnax, and Sesarma cinereum), marsh periwinkles (Littoraria irrorata), horn snails (Cerithidea pliculosa), and salt marsh snails (Melampus bidentatus) was evaluated over four seasons (summer 2000, fall 2000, winter 2001, and spring 2001) in grazed and ungrazed treatments. A Galveston Island salt marsh adjacent to Snake Island Cove was sampled at five elevations, from the water's edge to the high tidal flats. Data were analyzed for statistical differences using a two-way ANOVA in SAS. Cattle grazing may affect the vegetation and macroinvertebrate communities in salt marshes through trampling and herbivory. Vegetation resources available to other herbivores are decreased by the direct consumption of plant material by cattle. Spartina alterniflora and Salicornia virginica heights were significantly greater in ungrazed treatments than grazed for every season in the edge, upper, and middle elevation zones. Total aerial vegetative cover was also reduced significantly in grazed treatments, with the greatest impact in the edge and upper marsh. In the ungrazed treatments, S. alterniflora stem density was significantly greater in edge elevations, while both S. virginica percent cover and stem density in the edge elevation was greater. Burrowing crab populations were greater in the upper marsh and edge habitat of ungrazed treatments, while significantly greater in most of the middle marsh habitats of the grazed treatment. Size of burrowing crabs was generally significantly greater in ungrazed treatments. Cerithidea pliculosa size decreased in grazed treatments, but population had an overall increase in grazed treatments. Littoraria irrorata had very few differences between treatments, although few specimens were found. Melampus bidentatus populations were too small to evaluate thoroughly. Macroinvertebrate populations could be used to assess the overall health of grazed salt marshes. grazing salt marsh Spartina alterniflora Salicornia virginica Salicornia bigelovii Batis maritima Uca rapax Uca pugnax fiddler crabs Sesarma cinereum marsh crab Cerithidea pliculosa horn snail Littoraria irrorata marsh periwinkle Melampus bidentatus salt marsh snail
3	The effect of cattle grazing on the abundance and distribution of selected macroinvertebrates in west Galveston Island salt marshes Martin, Jennifer Lynn 30 September 2004 (has links) The effect of cattle grazing on the abundance and distribution of vegetation, burrowing crabs (Uca rapax, Uca pugnax, and Sesarma cinereum), marsh periwinkles (Littoraria irrorata), horn snails (Cerithidea pliculosa), and salt marsh snails (Melampus bidentatus) was evaluated over four seasons (summer 2000, fall 2000, winter 2001, and spring 2001) in grazed and ungrazed treatments. A Galveston Island salt marsh adjacent to Snake Island Cove was sampled at five elevations, from the water's edge to the high tidal flats. Data were analyzed for statistical differences using a two-way ANOVA in SAS. Cattle grazing may affect the vegetation and macroinvertebrate communities in salt marshes through trampling and herbivory. Vegetation resources available to other herbivores are decreased by the direct consumption of plant material by cattle. Spartina alterniflora and Salicornia virginica heights were significantly greater in ungrazed treatments than grazed for every season in the edge, upper, and middle elevation zones. Total aerial vegetative cover was also reduced significantly in grazed treatments, with the greatest impact in the edge and upper marsh. In the ungrazed treatments, S. alterniflora stem density was significantly greater in edge elevations, while both S. virginica percent cover and stem density in the edge elevation was greater. Burrowing crab populations were greater in the upper marsh and edge habitat of ungrazed treatments, while significantly greater in most of the middle marsh habitats of the grazed treatment. Size of burrowing crabs was generally significantly greater in ungrazed treatments. Cerithidea pliculosa size decreased in grazed treatments, but population had an overall increase in grazed treatments. Littoraria irrorata had very few differences between treatments, although few specimens were found. Melampus bidentatus populations were too small to evaluate thoroughly. Macroinvertebrate populations could be used to assess the overall health of grazed salt marshes. grazing salt marsh Spartina alterniflora Salicornia virginica Salicornia bigelovii Batis maritima Uca rapax Uca pugnax fiddler crabs Sesarma cinereum marsh crab Cerithidea pliculosa horn snail Littoraria irrorata marsh periwinkle Melampus bidentatus salt marsh snail
4	Ocean acidification effects on marine organisms : a study of Littorina littorea and Balanus improvisus Domeij Hilliges, Isak, Stendahl, Cecilia January 2011 (has links) The world’s oceans are becoming more acid in a process called ocean acidification. The pH of the ocean have already decreased by 0.1 units from pre-industrial time until today. Scientists predict that by the year of 2100 the pH will decrease by as much as 0.4 units. This is a big potential problem to many marine species, because they have developed in such a stable environment that has not changed for millions of years. It is difficult to predict how they might be affected by such a decrease in pH during a relatively short time period. Several studies have been made on marine species exposed to decreased pH-levels, the results showed changes in their physiology but it is hard to predict how these changes will affect the organism in a long-term scale and if this might change ecosystem dynamics. Our study measured the activity of Littorina littorea and Balanus improvisus when exposed to lower pH, the results of our study showed an increase in activity for the lower pH (pH 6.0-7.5) when compared to the control (~pH8). The area of ocean acidification is a field that requires further studies to fully understand its effects on the marine ecosystems and the species within it. ocean accidification accidification pH sea marine organism marine littorina littorea balanus improvisus periwinkle barnacle CO2 acid ecosystem activity cirral movement calcium carbonate system buffering low pH havsförsurning försurning pH hav marina organismer marin littorina littorea balanus improvisus havstulpan strandsnäcka CO2 surt ekosystem aktivitet cirrala rörelser buffrande lågt pH

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