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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Diversity and production of phytoplankton in the offshore Mississippi River plume and coastal environments [electronic resource] / by Boris Wawrik.

Wawrik, Boris. January 2003 (has links)
Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 329 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: River discharge leads to extensive phytoplankton blooms often observed in ocean color satellite images to extend far into the open ocean as high chlorophyll plumes. We investigated diversity, distribution and ecology of phytoplankton populations in the Mississippi River plume, both spatially and in the water column using molecular tools. A method was developed for the quantification of diatom/pelagophyte rbcL (large subunit of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase) mRNA using quantitative PCR and applied to cultures and in the plume. The vertical structure of phytoplankton species in the Mississippi River plume was described by flow cytometry, pigments, rbcL mRNA and rbcL cDNA libraries. High productivity in the plume was associated with a large population of Synechococcus and elevated levels of cellular form IA rbcL mRNA. / ABSTRACT: rbcL cDNA libraries indicated two vertically separated clades of Prochlorococcus (high-light and low-light adapted) in addition to a diverse group of prymnesiophytes and a microdiverse clade of prasinophytes, which may have dominated the SCM (Subsurface Chlorophyll Maximum). In situ sampling and satellite image analysis were used to estimate that the plume accounted for 41% and 13% of all surface water column ix productivity in the oligotrophic Gulf of Mexico, while covering less than 3% of its area. Coastally the plume is dominated by diatoms, which are replaced by a bloom of Synechococcus as the plume moves offshore. Diatoms as indicated by pigments and rbcL clone libraries again dominated the offshore, least productive plume. 15N uptake measurements indicated that rapid recycling of ammonium despite higher levels of nitrate primarily drives production in the offshore plume. / ABSTRACT: rbcL mRNA levels and photosynthetic capacity displayed strong diel patters in three out of four time series sampled during the GRIST (Geochemical Rate/mRNA Integrated Study). In addition it was demonstrated that transcriptional regulation of the global nitrogen regulatory protein NtcA in Synechococcus WH7803 may involve a small cis-encoded anti-sense mRNA. Methods for the generation of large insert BAC (Bacterial Artificial Chromosome) from cultures and the environment were refined. Partial sequencing and genomic comparison of an ntcA containing BAC clone obtained from Synechococcus WH7803 indicated that ntcA is not part of a larger nitrogen assimilation operon in cyanobacteria. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.
2

Diversity and Production of Phytoplankton in the Offshore Mississippi River Plume and Coastal Environments

Wawrik, Boris 25 September 2003 (has links)
River discharge leads to extensive phytoplankton blooms often observed in ocean color satellite images to extend far into the open ocean as high chlorophyll plumes. We investigated diversity, distribution and ecology of phytoplankton populations in the Mississippi River plume, both spatially and in the water column using molecular tools. A method was developed for the quantification of diatom/pelagophyte rbcL (large subunit of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase) mRNA using quantitative PCR and applied to cultures and in the plume. The vertical structure of phytoplankton species in the Mississippi River plume was described by flow cytometry, pigments, rbcL mRNA and rbcL cDNA libraries. High productivity in the plume was associated with a large population of Synechococcus and elevated levels of cellular form IA rbcL mRNA. rbcL cDNA libraries indicated two vertically separated clades of Prochlorococcus (high-light and low-light adapted) in addition to a diverse group of prymnesiophytes and a microdiverse clade of prasinophytes, which may have dominated the SCM (Subsurface Chlorophyll Maximum). In situ sampling and satellite image analysis were used to estimate that the plume accounted for 41% and 13% of all surface water column ix productivity in the oligotrophic Gulf of Mexico, while covering less than 3% of its area. Coastally the plume is dominated by diatoms, which are replaced by a bloom of Synechococcus as the plume moves offshore. Diatoms as indicated by pigments and rbcL clone libraries again dominated the offshore, least productive plume. 15N uptake measurements indicated that rapid recycling of ammonium despite higher levels of nitrate primarily drives production in the offshore plume. rbcL mRNA levels and photosynthetic capacity displayed strong diel patters in three out of four time series sampled during the GRIST (Geochemical Rate/mRNA Integrated Study). In addition it was demonstrated that transcriptional regulation of the global nitrogen regulatory protein NtcA in Synechococcus WH7803 may involve a small cis-encoded anti-sense mRNA. Methods for the generation of large insert BAC (Bacterial Artificial Chromosome) from cultures and the environment were refined. Partial sequencing and genomic comparison of an ntcA containing BAC clone obtained from Synechococcus WH7803 indicated that ntcA is not part of a larger nitrogen assimilation operon in cyanobacteria.
3

Spåren i bäcken : En undersökning om kvarnlämningar i Forshälla socken, Inlands Fräkne härad Bohuslän / Traces in the stream : An investigation on watermill remains in Forshälla parish, Inlands Fräkne härad Bohuslän

Mattsson, Eva January 2023 (has links)
Syftet med denna uppsats är att undersöka vad som skiljer de lämningar åt från kvarnverksamhet som inte finns i  Fornsök från de som är registrerade som kulturlämning. Historiskt kartmaterial har studerats för att försöka få en uppfattning om det är så att de inte platsar i ramen för en forn- kulturlämning, dvs tillkommen efter år 1850 och om det är därför de inte finns i registret. Alla lämningarna  från kvarnar i Forshälla socken går att återfinna på kartor före år 1850. Uppsatsen önskar också öka uppmärksamheten på denna typ av lämningar i skog och mark så att de erhåller ett starkare skydd när skogen ska avverkas. En analys har gjorts gällande var och en av lämningarna och miljön runt dessa och om de riskerar att skadas vid en avverkning av skogen. / The purpose of this essay is to investigate what distinguishes the remains from mill activities that are not found in Fornsök from those that are registered as cultural remains. Historical map material has been studied to try to get an idea of whether it is the case that they do not fit within the framework of an ancient cultural relic, i.e., added after the year 1850 and if that is why they are not in the register. All the remains from water mills in Forshälla parish can be found on maps before the year 1850. The essay also wishes to increase attention to this type of remains in forest and land so they can receive stronger protection when the forest is cut down. An analysis has been made of each of the remains and the environment around them and whether they are at risk of damage when the forest is harvested.

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