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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.
341

The effect of a marine reserve on the abundance and size of coral reef fishes in Barbados, West Indies /

Rakitin, Ana January 1994 (has links)
This study used trapping and visual census surveys to assess whether a marine reserve in Barbados effectively protected coral reef fish stocks and whether there was evidence of emigration from the reserve. Fish abundance and sizes were higher in the reserve than in surrounding non-reserve areas. Relative differences in abundance and size between reserve and non-reserve of different taxa were positively correlated to vulnerability to traps (the most common fishing method) but not to mobility of fish. Gradients of abundance across the reserve boundaries (decreasing abundance with distance from the reserve center) were apparent for total abundance but not for individual taxa. These patterns suggest that the reserve does protect fish stocks and that emigration is of minor importance.
342

Sequence Stratigraphic Architecture Of Mut Basin Along Ramp To Reefal Margin Transition And Its Diagenetic Imprint

Derman, Hasan Armasan 01 January 2004 (has links) (PDF)
The whole Mediterranean was a site of carbonate deposition during Miocene. Unlike other Miocene basins in the Mediteranean, the importance of Mut Basin lies in its tectonically undisturbed nature that provides excellent exposures to study sequence stratigraphic architecture and carbonate sedimentology. Opening of Mut Basin began during Oligocene / carbonate deposition started during Early Miocene. The pre-Miocene rocks are characterized by (from bottom to top), 1. ophiolites and Mesozoic limestones, 2. Eocene lacustrine limestones, 3. Burdigalian fluvial sandstones and conglomerates. The carbonate deposition began in Miocene, settling on the preexisting topography. Carbonates have been deposited in a ramp setting, where several sequences formed. The ramp was partly subaerially exposed during Early Miocene due to relative sea level fall / however, no significant lowstand deposits were developed. The subsequent sea level rise caused transgressive deposits to overlie this ramp sequence. The patch reefs on this ramp exhibit a keep-up type depositional setting. As the transgression continued, the basin topography controlled the type of depositional setting. Hence, a transition from ramp to reefal margin type setting occurred. In landward direction the topographically low areas became back reef lagoonal part of this reefal margin. A mature reefal environment formed during highstand times, which is characterized by a rich coral fauna / algal flora in the basinward side. Some of the patch reefs of the ramp transformed into pinnacle reefs. Diagenetic alterations are mostly related to duration and degree of sea level fall, and therefore related to sequence boundaries. The Miocene carbonates in the study area consist of six sequences which may be used for correlation with other Miocene carbonates of the Mediterranean region.
343

Meteoric Diagenesis of Plio-Pleistocene Reef Terraces in the Southern Dominican Republic

Hernawati, Yulaika 09 December 2011 (has links)
Four prograding reef terraces (6, 15, 30, and 50 m) have been repetitively exposed to marine and freshwater alteration during the Pliocene and Pleistocene periods. Prolonged freshwater alterations have resulted in many diagenetic overprints that obscure early diagenetic products. This study investigates the sequence of the diagenetic processes and products in the terrace deposits using five long cores and 14 short cores taken from these different reef terraces. The lithologic changes in the cores were documented for reconstruction of the original depositional frameworks prior to embarking on a diagenetic study. Both textural and geochemical changes were examined within all four different terraces in order to characterized the diagenetic history. The textural changes observed in the cores and thin sections, provided preliminary evidence of the diagenetic environment. Through the use of X-ray diffractometry, stable isotopes (C and O), and trace element data, the interpretation of the diagenetic environment can be constrained. The reef terraces were deposited as as shallowing upward units following a down-stepping carbonate sequence. The lithology of the cores is dominated by reefal facies, which consist of the back reef, reef crest, front, and fore reef facies. The exposure surfaces, observed at various depths, constrained the interpretation of early diagenetic environments (met. vadose and phreatic). Three major diagenetic environments can be characterized from the cores, these are meteoric vadose, meteoric phreatic, and dolomitizaton. These diagenetis environments produced different geochemical signatures, which can be quantified through analysis of the stable isotopes and trace elements incorporated into the cements. The different reef terraces represent different duration of exposure, with the higher terraces having been exposed longer than the lower ones. This study enables the documentation and comparison of the processes and products of the meteoric diagenesis that occurred within these different terraces. In addition, this study also constrain the early dolomitization observed in sigmoidal reef deposits. In order to further quantify the process of early dolomitization, mineralogy, isotopes C and O, trace elements, and the Sr-isotopes were examined as well.
344

Wave-forced porewater mixing and nutrient flux in a coral reef framework

Haberstroh, Paul R January 1994 (has links)
Thesis (Ph.D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 235-249). / Microfiche. / xx, 249 leaves, bound ill., maps 29 cm
345

The effects of sedimentation on Indo-Pacific reef corals

Hodgson, Gregor January 1989 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1989. / Includes bibliographical references. / Microfiche. / xxi, 338 leaves, bound ill. 29 cm
346

Zonation of Reef Corals off the Kona Coast of Hawaii

Dollar, Stephen J. 05 1900 (has links)
Analysis of the pattern of zonation of reef corals off the Kona coast of Hawaii revealed the existence of four clearly defined zones. This pattern was confirmed at three sites where corals were counted using a series of 45 meter long transects running parallel to shore from depths of 3 to 40 meters. Clustering analysis dendrographs, spatial changes in illumination and rates of water movement, as well as growth and survival of coral transplants also confirmed the zonation pattern. Each of the four zones is characterized by a dominant coral species, substratum type, depth, and range of physical conditions. Each zone also appears to be in a different stage of community succession due to the frequency of large scale environmental disturbances from winter storm waves. The shallowest zone begins at the base of the shoreline cliff, ranges in depth from 2.5 to 8 meters, and has a bottom cover consisting mainly of irregularly shaped basaltic boulders; Pocillopora meandrina dominates coral cover in this zone. This species appears to be the first to colonize new substrata and persists in large numbers only in the near-shore boulder zone where mechanical stress from wave action is great enough to restrict the growth forms of more competitive species. Due to this high wave stress, the P. meandrina bolder zone appears to be in an early successional stage with low coral cover and dominance and relatively hiqh species diversity. Moving into deeper water the Porites lobata reef building zone ranges in depth from 6 to 14 meters and is characterized by a gently sloping solid basalt and limestone bottom. Porites lobata dominates coral cover by growing in massive lobed and encrusting colonies. While succession seems to be in an advanced stage, monopolization of available space does not appear to be complete enough to exclude a variety of less competitive species, resulting in relatively high species diversities. The third zone occurs on the reef slope and ranges in depth from 14 to 30 meters. Solid substrata is scarce and succession may be a late stage due to domination of bottom cover by thickets of Porites compressa. Most of the other species that persist in this zone avoid competitive interactions by growing above the level of P. compressa. Storm wave stress is most devastating to corals in this zone, and breakage of living colonies seems to increase diversity by reducing P. compressa dominance. Transport of living coral fragments appears to extend zonal boundaries and create new colonies. Extensive "rubble channels" occur in this zone, and these channels may get progressively larger due to churning of rubble fragments with each successive storm. The Porites lobata rubble zone occurs below the deep border of the P. compressa thickets and extends to approximately 50 meters, the depth at which coraIs cease to appear. Substrata consists mostly of fine sand and a variety of small encrusting corals are found growing on scattered rubble fragments. Specialized species with narrow physiological tolerances limited to this zone also increase species diversity. While maximum size of corals may be reduced in this zone due to low light intensity, lack of solid substrata probably determines the lower depth limit of coral occurance. Sand and rubble that is carried downslope during storms cause this zone to be physically unstable and succession appears to be constantly interrupted at early stages. This is in contrast to other deep reef areas, such as off Maui and the Red Sea, where substrata is solid to the depth limit of coral growth. These communities appear to be highly stable and diverse, and in late or climax stages. The depauperate nature of Hawaiian coral fauna is probably due to fairly rigorous environmental conditions in combination with difficulties in larval transport from coral evolutionary centers in the western Pacific. However, reef areas off Kona are relatively rich for Hawaii due to complete protection from tradewind generated seas, partial protection from long period north swells, and the steep nearshore slopes that extend below wavebase. / Typescript. Bibliography: leaves 173-181.
347

The ecology of patch reef fishes in a subtropical Pacific atoll: recruitment variability, community structure and effects of fishing predators

Schroeder, Robert E 05 1900 (has links)
The ecology of patch reef fishes was studied to quantify the main factors that affect the natural variability of the fish community and to determine the effects produced on the community by experimental removal of predators. Initially, a year-long baseline description was completed of the physical, biological and ecological characteristics of 8 pristine patch reefs at Midway lagoon. For over 3 subsequent years, piscivorous predators were spearfished at least monthly, often for days at a time, on 4 of the 8 reefs. Fish populations were visually censused throughout the experiment. In all seasons and years of the project, daily recruitment rate of postlarval fishes to natural patch reefs was compared to that measured on standardized, artificial reefs of various sizes and degrees of inter-reef isolation. Finally, all baseline measurements were replicated and complete collections were made of all fishes, to validate the visual census method. Visual censusing was found to be of adequate precision and accuracy for most resident, non-cryptic species (highest for small patch reefs). Fishes could be assigned to size classes underwater by visual estimate with high accuracy. Rotenone collections were highly effective in quantifying many species commonly missed or underestimated in visual censuses. Only a few species composed the bulk of all recruits, while most species were rare or not seen at all. Variation between species was related to life history strategies or behavioral requirements. High temporal variability was found at the following scales: 1) Annuallywhere variability increased with the magnitude of recruitment, and different species recruited heavily in different years, suggesting that species specific factors in the plankton are more important than general oceanographic conditions; 2) Seasonally- pulsing strongly in summer, and occasionally late fall, when favorable environmental conditions may maximize growth and survival; and 3) Daily- with 1 or 2 strong peaks (each only a few days long) over a period of several weeks of low, variable recruitment. Small-scale spatial variability between replicate attractors (standardized artificial reefs) and between attractor types (coral and wire) were both high for a few species recruiting abundantly, although most recruits are probably substrate generalists. Rigorous visual fish censuses can adequately document moderate- to long-term temporal variation in the abundances of recently recruited juveniles on patch reefs (i.e., based on similar temporal patterns assessed by daily attractors). Daily total recruitment rate increased, although at diminishing densities, with (attractor) reef size, and with degree of inter-reef isolation. Abundances of recently recruited fish censused on neighboring, natural patch reefs (much larger than attractors) increased with reef size. The effect of isolation on these natural reefs was confounded by the stronger effect of reef size. These results suggest that if optimum size and spacing of reefs is provided, either by proper design of artificial reefs or selection of marine reserves, managers may enhance fish recruitment and ultimately improve local fisheries: Of the 135 fishes censused on the patch reefs studied, only 6 species together accounted for 70% of the total number of all fish, mainly due to heavy seasonal recruitment pulses. Strong seasonal and annual variability in recruitment was responsible for most of the temporal variation in fish abundance. The structure of patch reef fish communities at Midway was characterized by high unpredictability (e.g., great seasonal and/or annual variability in recruitment by common species, recruitment limitation for most species, and a high turnover rate detected by frequent sampling). Some predictions of the theory of island biogeography were also met by these fish communities (e.g., species richness correlated strongly with patch reef area, volume and relief). and total fish abundance. Some populations also exhibited a degree of long-term stability. Species diversity [H'] was similar among different size reefs. The experimental fishing on piscivores produced a catch composed mainly of lizardfish, due largely to immigration following the removal of other, competitively superior, highly resident piscivores. Scorpionfish and moray eels were also dominant predators. The expected decreases in catch-per-unit-effort were not realized, except for a quantitatively insignificant family (hawkfish). Conversely, the catch of the highly migratory lizardfish actually increased as fishing progressed. Changes in the catch composition for other piscivores related mainly to major changes in reef size or to patterns of large, inter-year recruitment fluctuations. Census data confirmed the major trends indicted by catch results. Sharks and jacks were attracted to the experimental reefs by spearfishing; the study was unable to determine whether their piscivorous effect was different between reef treatments. Patch reef fish communities at Midway were relatively resilient to long-term, intense fishing pressure on piscivores. However, enhanced survival of a large, annual, summer recruitment pulse of a common cardinalfish, synchronized with a temporary but significant reduction of lizardfish (the most prevalent piscivore) by fishing, suggested that an effect of predation on reef fish populations is experimentally detectable and considerable. However, temporal and spatial variability in recruitment, and reef size differences and changes in size were the primary factors responsible for the observed temporal patterns in fish abundance. COlnmunity analysis involves numerous confounding effects and requires the most careful interpretation for valid conclusions. / xvi, 321 leaves, bound : ill. ; 29 cm.
348

Conflict at the border : competition between algal turfs and Porites lobata / Competition between algal turfs and Porites lobata

Preskitt, Linda B January 2006 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 89-96). / ix, 96 leaves, bound ill. 29 cm
349

Anthropogenic stress, bioerosion, and farming damselfish : potential interactions and effects on coral reefs in American Samoa

McTee, Sarah A January 2007 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 55-60). / vi, 60 leaves, bound ill., map 29 cm
350

Relatedness, host specificity and richness of the genus Ceratomyxa (Myxozoa: Myxosporea) in teleost fishes

Nicole Gunter Unknown Date (has links)
The genus Ceratomyxa Thélohan, 1892 is one of the largest myxozoan genera, the species of which almost always infect the gall bladder of marine teleosts. Although there are over 180 species known globally, prior to this study only three had been described from Australia. This study explores the systematics, host specificity and species richness of Ceratomyxa species from a diverse range of Queensland marine fishes. The first part of this thesis deals with the issues associated with spore based taxonomy and incorporates the first molecular studies to investigate host specificity and radiation in three common families of Great Barrier Reef (GBR) fishes. Twenty-two new species were described in these chapters, and although they were superficially similar in morphology all were genetically distinct. A focus on Ceratomyxa spp. infecting labrid, pomacentrid and serranid fish revealed tight host specificity of parasite species, confirmed the presence of multiple parasite species in a single host and revealed that no parasite radiation had occurred that could be associated with co-evolution with host families. Exploration of intra- and inter-specific variation by sequencing of multiple replicates from host/parasite combinations allowed interpretation of species boundaries within the system. Ten additional species described in Chapter 5 supported the findings from the labrid, pomacentrid and serranid studies but broadened the host range studied. In total 32 Ceratomyxa species were described from Queensland fishes increasing the number of described species in the genus by 15%. This study also reports on undescribed species collected from a further 70 host species and broadens the known host range to seven families of fishes. A checklist of bivalvulidans from marine teleosts in Australia is compiled of described and undescribed species and highlights the abundance of Ceratomyxa relative to other gall bladder dwelling myxosporeans. A phylogeny of the Ceratomyxa based on SSU rDNA analyses explored the taxonomic integrity of the genus. In general, the morphological diagnostic characters that divide the Myxozoa into genera are not well supported by molecular phylogenetic analyses. The relationship between 42 Ceratomyxa spp. and 36 other marine myxosporeans was examined using Bayesian inference, maximum likelihood and maximum parsimony. Results indicate Ceratomyxa is one of the most cohesive lineages within the Myxozoa and that the freshwater fish parasite, C. shasta, does not represent an independent lineage as suggested in previous studies. The strict host specificity of Ceratomyxa species prompted the investigation of species richness on the GBR. Species accumulation curves were used to explore species richness by using Choa2 and Jackknife1 estimators. The estimates suggested Ceratomyxa is almost as rich as their teleost hosts and that 1,600 species could be present on the GBR and as many as 15,000 species may exist globally. As an unexpected result, Ceratomyxa may be the richest metazoan genus in the sea. In light of what the study revealed, a revision of a second genus within the family Ceratomyxidae, Leptotheca, is presented. The boundaries between Ceratomyxa and Leptotheca were unclear. The diagnostic characters that separate these genera (length to thickness ratios) were found to be plastic and the type species of Leptotheca ultimately fitted the diagnosis for Ceratomyxa. To eliminate confusion between these genera and also between Sphaerospora and Leptotheca, the genus Leptotheca was considered invalid, with all species appropriately assigned to other genera based on morphological and biological characters and supported by genetic evidence.

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