Coccolithophores of the Gulf of Mexico and their relationship to water column properties /
The concentration and relative abundance of coccolithophore
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739887791&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The concentration and relative abundance of coccolithophore species in the upper 200 m of the Gulf of Mexico in October 1990 and March 1991 differ markedly. In October the maximum concentration of coccolithophores per liter is about 30,000; in March, about 100,000. The difference is due to Emiliania huxleyi. In October, there is a three-layer system of species distribution. Umbellosphaerairregularis dominates the upper layer of the photic zone, Umbellosphaera tenuis dominates in the middle layer, and Florisphaeraprofunda dominates the lower layer. In March, there is a two-layer system of coccolithophore distribution. Species typical of the October middle layer are in the March upper layer. F. profunda is characteristic of the lower layer. Each layer also has other species associated with the dominant species. U. irregularis is very rare in March, as are other species that were predominantly in the October upper layer. Emiliania huxleyi dominates throughout in March. Physical and chemical properties define the layers occupied by different coccolithophore assemblages. In October, the upper layer corresponds to the mixed layer and top of the thermocline, the middle layer corresponds to a lower gradient in the thermocline, and the lower layer corresponds to the nutricline. In March, the nutricline and thermocline coincide; the upper layer species in March are those that were predominantly middle layers species in October. The species in the lower level are the same in October and March but some of these species also occur in the upper layer in March. A warm-core eddy, sampled during both cruises, was associated with higher coccolithophore concentrations and higher diversity. In October the middle layer was expanded within the eddy. The nutricline was depressed in the eddy and concentrations of lower level species were reduced. Seven of the ten most abundant species in the upper photic zone are also among the ten most abundant in GOM sediment. GOM species associations are similar to those at the same latitudes elsewhere but neither sediment nor water assemblages correspond well to biogeographic zonations in the literature. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | xi, 187 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 142-149. |