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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.
171

Phytoplankton Responses to Mass Coral Spawning in the Flower Garden Banks, Gulf of Mexico

Horne, Courtney Leigh 2011 May 1900 (has links)
Mass coral spawning represents a nutrient input to coral reef systems that for Pacific reefs has been shown to stimulate pelagic and benthic processes. If phytoplankton in the water column over the reef are able to utilize this annual nutrient input, this could potentially alter phytoplankton biomass and community composition, in what is normally a very oligotrophic system. Sampling was performed at East Flower Garden Bank (EFGB), Gulf of Mexico during May, July, and August 2009. The annual coral spawning event occurred there August 11-14, 2009. Samples were collected morning and evening at three depths and analyzed for nutrients, chlorophyll a, accessory pigments, phytoplankton species composition, and carbon, hydrogen, and nitrogen (CHN). During spawning, only small changes in nutrient concentrations were detected. Dissolved inorganic nitrogen (DIN) peaked on the second day of spawning and N:P ratio was highest on 5/28, likely due to particularly phosphate concentration. Chl a biomass was significantly different between sample dates and the biomass increased steadily throughout the spawning period. The contribution of different phytoplankton classes to total chlorophyll a was determined using known pigment algorithms. Prokaryotes were the dominant class across the entire sampling period with 60-80 percent abundance. Trichodesmium spp. was the dominant genus throughout the study and genus specific changes per sample date were seen. On 8/11 and 8/13 two genera contributed the majority of chl a (Trichodesmium spp. and Ceratium spp.; Cylindrotheca spp. and Trichodesmium spp., respectively). Abundance showed variability during spawning with a peak at 11 cells/ml on 8/12. The high abundance of Trichodesmium spp. could indicate N limitation is alleviated at the Flower Garden Banks (FGB). Current literature on coral spawning is limited to studies performed in the Great Barrier Reef, with assessment areas close to a major shoreline. Genera found at EFGB were similar to those found in other reef systems. It cannot be determined if nutrient input increased diversity, as diversity was high prior to spawning as well. Greater increase in available forms of nitrogen would have likely been found several days post major spawning. The FGB were a unique system to study, as they are coral reefs, but are located 200 km offshore. This study provided a snapshot into phytoplankton dynamics as a result of spawning. Changes across the short time scale were seen in biomass and community composition.
172

Change of benthic communities at Tiaoshi coral reef, southern Taiwan

Wu, Bing-je 27 August 2005 (has links)
Coral community at Tiaoshi in Nanwan Bay, southern Taiwan was originally dominated by branching Acropora corals which formed some monopolized patches. The community had been changed apparently on a local scale (<2 km) since 1994. Several Acropora patches were almost completely replaced by the solitary sea anemone Condylactis sp. after man-made and typhoon disturbances. However, sea anemones were apparently decreased in 2002. To understand the change of the benthic communities, three areas, including Anemone-dominated, Coral-recovery and Acropora-dominated, at depths of 6 to 10 m were selected and monitored by permanent transects from 2003 to 2005. Each site included three replicate patches. At Anemone-dominated area, the mean cover of sea anemone ranged from 24.6 to 15.3% and that of the hard corals was low with 1.4 to 3.9%. At Coral-recovery area, the mean cover of the hard corals was significantly increased from 21.3 to 38.9%, while macroalgae was significantly decreased from 20.7 to 6.1% and sea anemone was low with 1.4 to 3.0%. At Acropora-dominated area, the cover of the hard corals was ranged from 70.0 to 56.6% while macroalgae and anemone was 1.1 - 3.4% and 3.5 - 4.7%, respectively. In general, the results showed that anemone and macroalgae were decreased and corals were recovery. In addition, the diversity index of coral genera at Anemone-dominated area was higher due to coral recruitment in 2004 and 2005. The new recruits were dominated by Montipora stellata.
173

Studies on Secondary Metablites of the Formosan Soft Coral Sinularia gibberosa

Hsieh, Ya-ting 31 July 2006 (has links)
Investigation on the chemical constituents of the Formosan soft coral Sinularia gibberosa, collected by hand using scuba off the coast of Kenting, had led to the isolation of seven new cembranoids , gibberorenes A-G¡]2-8¡^, three new sterols, gibberoketosterol B¡]10¡^, gibberoepoxysterol¡]11¡^, gibberoketosterol C ¡]12¡^ along with two known compounds, (1Z,3E,7E,11S,12S,14S)-11,12-epoxycembra-1,3,7 -trien-14-ol¡]1¡^and gibberoketosterol¡]9¡^. The structures of 1-12 were elucidated on the basis of extensive spectroscopic analysis, including IR, MS, 1D, and 2D NMR. Cytotoxicities of 1-12 against a limited panel of cancer cell lines were also evaluated. Among these metablites, compounds 9 and 11 were found to exhibit moderate cytotoxicity toward MCF-7, A549, MDA-MB-231, and HepG2 tumor cells. The ability of 9 and 10 to inhibit the pro-inflammatory iNOS and COX-2 expression of LPS-stimulated RAW264.7 macrophage cells has been also estimated.
174

The structure and variation of benthic communities in coral reefs of southern Taiwan

Kuo, Chao-yang 16 May 2007 (has links)
Benthic community structure was studied by sample quadrates on transects at depths of 5 to 10 m in four sites, including Wanlitong, Leidashih, Siangjiao Bay, and Longkun, in coral reefs of southern Taiwan from 2003 to 2005. Totally 154 species in 45 genera of hard coral and 45 species in 10 genera of soft coral, representing 67% of known coral species were recorded. Covers of benthic organisms and hard coral growth forms were similar among years, but were significantly different among sites. Mean cover of all corals was high in Siangjiao Bay (56.88%) and Leidashih (65.69%), but hard coral (65.43%) was dominanted in Siangjiao Bay while soft coral (39.00%) was dominanted in Leidashih. Mean cover of all coral and benthic algae was similar in Wanlitong and Longkun. For hard coral growth forms, massive and encrusting corals were dominanted in three of four sites. This may be resulted from the strong wave. Cover of bare substrate was high (21.39%) in Longkun which was the most exposed to wind and wave stress. Foliaceous coral was abundant with the dominated species, Montipora aequituberculata (20.59%) in Siangjiao Bay which was a more protected site. However, foliaceous coral was more susceptibe to typhoon. Coral diversity was higher in Leidashih. This was related to both hard and soft corals were common and no dominant species. Comparing to previous studies, the long term change of coral abundance shows stable and/or increasing trends. It may be related to the dominance of massive and encrusting coral communities in southern Taiwan.
175

Cell migration of zooxanthellae in the coral Montipora capitata /

Toyoshima, Junko. January 2003 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references (leaves 49-58). Also available via World Wide Web.
176

The effects of sea level fluctuations on coral reef fishes : genetic differences between outer reef and lagoon inhabiting wrasses (genus Halichoeres)

Ludt, William Benton 17 February 2012 (has links)
Sea levels fluctuated following glacial cycles during the Pleistocene, reaching approximately 115-130m below current sea levels in the Indian and Pacific Oceans during the last glacial maximum 17,000 years before present. The effects of these sea level fluctuations on population structure have been shown in many near-shore marine taxa, revealing several common patterns. However, the underlying mechanisms behind these observed patterns are largely unknown. Drops in sea level affect the distribution of shallow marine biota, exposing the continental shelf on a global scale, and displacing coral reef habitat to steep slopes where shelf breaks are shallow. In these circumstances, we expect that species inhabiting lagoons should show reduced genetic diversity relative to species inhabiting more stable outer reefs. Here, I tested this expectation on the scale of an entire ocean-basin with four wrasses (genus Halichoeres): H. claudia (N=194, with ocean-wide distribution) and H. ornatissimus (N=346, a Hawaiian endemic) inhabit seaward reef slopes, whereas H. trimaculatus (N=239) and H. margaritaceus (N= 118) inhabit lagoons and shallow habitats throughout the Pacific. Two mitochondrial markers (cytochrome oxidase I and control region) were sequenced to resolve population structure and history of each species. Haplotype and nucleotide diversity were similar among all four species. The outer reef species showed significantly less population structure, consistent with longer pelagic larval durations and a historically stable population. Mismatch distributions and significant negative Fu’s F values indicate Pleistocene population expansion for all species, and (contrary to expectations) reduced genetic diversity in the outer slope species. These data indicate that lagoonal species may persist through the loss of habitat, but are restricted to isolated refugia during lower sea level stands, which may inflate genetic diversity during high sea levels. Outer reef slope species on the other hand have homogeneous and well-connected populations through their entire ranges regardless of sea level fluctuations. These findings contradict the hypothesis that shallow species are less genetically diverse as a consequence of glacial cycles. / text
177

Boring by macro-organisms in the coral Montastrea annularis on Barbados reefs

MacGeachy, James Kirk. January 1975 (has links)
No description available.
178

Reproductive Biology of the Deep-Water Gorgonian Coral Acanella arbuscula from the Northwest Atlantic

Beazley, Lindsay 11 February 2011 (has links)
This thesis examined the reproductive biology of the poorly-known deep-water gorgonian Acanella arbuscula from the Northwest Atlantic. Colonies were collected from The Gully in 2007 and 2010 between 914 and 1860 m depth, and the Flemish Cap in 2009 between 671 and 1264 m. Mean polyp fecundity was relatively high for both females and males, and the large oocyte size suggests that A. arbuscula produces lecithotrophic larvae. This species may have overlapping periodic or seasonal cycles of gametogenesis, and the absence of planulae suggests that A. arbuscula is a broadcast spawner. No spatial variation in the reproductive characteristics of this species was found, suggesting that environmental conditions are similar between the two sites. Female polyp fecundity decreased with increasing depth, which may be due to the high cost of producing oocytes versus sperm. The relatively high mean polyp fecundity, probable lecithotrophic larval development, and broadcast spawning may allow for the wide dispersal and settlement of A. arbuscula across the North Atlantic.
179

Submarine diagenesis of the corals of the Bellairs reef, Barbados

Boucher, Dennis A. January 1977 (has links)
No description available.
180

An ecological study of a reef-associated zooplankton community of Barbados, West Indies /

Boers, Jacobus Johannes January 1988 (has links)
A reef-associated zooplankton community was monitored at weekly intervals for 53 weeks. Samples were collected from quadrats of dense coral cover using emergence net traps. The numerical and biomass fluctuations of 15 taxonomic groups, 7 size classes and 5 feeding groups of the community were determined both temporally and spatially. The community was composed of abundant and diverse taxa (81) with cyclopoid copepods being the most important taxon. Larger-sized fauna (e.g. amphipods, decapods, mysids, etc.) were the second most important abundance and biomass contributors. Size class analysis illustrated a bimodal size distribution spectrum. The well developed second mode of the spectrum was attributed to substratum characteristics which permitted an enhanced macrofaunal/detritivore presence. Although week to week fluctuations of the abundance/biomass data were marked, diversity indices indicated a persistent and resilient community. The nocturnal vertical migrations of the fauna did not show a persistent pattern with the varying phases of 12 sequentially monitored lunar cycles. Substratum heterogeneity was primarily responsible for the spatial distribution pattern of the fauna. Although the data variance suggested stochasticity, time-series procedures determined that cross-correlations between the numerical abundances of taxa, size classes and feeding groups occurred without a lead or lag. Similar analyses identified chlorophyll a as the important environmental variable and also as a leading indicator of particular taxonomic, size and feeding group abundances. It was concluded that reef-associated zooplankton communities are abundant, diverse assemblages structured by periodicities which in combination act to form important links between tropical, inshore benthic and pelagic ecosystems.

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