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1
Ceh, Janja. "Coral-associated microbial communities in reef-building corals of Ningaloo Reef Western Australia." Thesis, Ceh, Janja (2011) Coral-associated microbial communities in reef-building corals of Ningaloo Reef Western Australia. PhD thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/8480/.
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Coral reefs are at risk and human-induced environmental stressors in synergism with microorganisms have been shown to be the key players for their deterioration. Little is known about the dynamics of coral-microbial associations through different life stages of the coral holobiont and virtually nothing is known about coral-microbial partners in Western Australian coral reef systems. This project intended to investigate the presence, diversity, community structure and role of coral-associated microbes in Ningaloo Reef spawning and brooding corals. Different coral life stages were assessed.
To determine ‘normal ranges’ of coral-associated microbes, three coral species (Acropora tenuis, Pocillopora damicornis and Favites abdita) were tagged and examined over a period of one year, with sampling deployed every three months. One coral species was additionally sampled on Rottnest Island, 1200km south of Ningaloo Reef, to provide comparisons between coral-associated microbes in different geographical areas. The community structure of the coral-associated microorganisms was analysed by phylogenetic analysis of 16S rRNA gene clone libraries. Principal component analysis (PCA) revealed that samples grouped according to time and not species, indicating that coral-microbial associations may be a result of environmental drivers such as oceanographic characteristics, benthic community structure and temperature. Tissue samples from Rottnest Island corals revealed similarities in bacteria to the samples at Ningaloo Reef. This study highlights that coral-associated microbial communities are highly diverse; however, the complex interactions that determine the stability of these associations are not necessarily dependant on coral host specificity.
Reproduction plays a crucial role in the survival of species, therefore, data was acquired from three adult coral colonies, Acropora tenuis (broadcast spawner), Pocillopora damicornis (brooder) and Tubastrea faulkneri (ahermatypic), before and after coral mass spawning to determine if and through which drivers coral microbial communities changed through this event. A contemporary 454 sequencing approach was implemented and results revealed distinct bacterial shifts through coral mass spawning for all corals, independently of reproductive activity. Clear changes in bacterial assemblages were also detected for brooders after planulation. This infers that coral-associated microbial communities change through a coral mass spawning event and are likely driven by environmental factors and the respective bacterial community in the seawater, as well as by actual coral reproduction. Differences in coral-microbial communities reflected different life styles between brooding and spawning corals. Most α-Proteobacteria increased in abundance after spawning as well as after planulation, suggesting that specific bacteria are involved in coral reproduction irrespective of reproductive strategies; particularly bacteria affiliated with the Roseobacter clade followed this pattern.
The assessment of seawater collected from the broadcast spawning coral A. tenuis and P. damicornis after spawning and planulation, respectively revealed that adult corals, irrespective of their reproductive strategy release bacteria with their offspring which likely increases the fitness in the following processes involved in settlement and survival. Species affiliated with the genera Roseobacter and Alteromonas appear to play important roles in coral reproduction and early life history in corals.
Isolates from P. damicornis planulae were mainly affiliated with the genera Vibrio and Alteromonas and were found to be similar to bacteria released by the mother colony during planulation.
Finally the establishment of coral-microbial partnerships in coral larval stages and the potential role of these symbiotic relationships were studied. The early onset of bacterial associations in brooding and broadcast spawning corals was visualized, exploring bacterial presence and their location in the coral organism, determining when and how bacteria enter coral tissues and their cycling of nutrients towards the coral-symbiotic algal partners. Nano-scale Second Ion Mass Spectrometry (SIMS) was applied to detect, image and map the uptake and translocation of 15N from bacteria into coral larvae on a sub-cellular level. The study also combined Fluorescent In Situ Hybridisation (FISH) to co-localize the labelled substrate with bacteria and Transmission Electron Microscopy (TEM) to allow for ultra-structural resolution images to provide high resolution images. This study for the first time demonstrated the beneficial role of specific bacteria in translocating nitrogen into the coral holobiont, which is particularly important in the nutrient-poor environments corals live in.
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Graham, Nicholas. "Effects of coral bleaching on coral reef fish assemblages." Thesis, University of Newcastle Upon Tyne, 2008. http://hdl.handle.net/10443/128.
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Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of climate warming to the loss of live coral cover has been well documented, the associated effects on fish have not. Such information is important as coral reef fish assemblages provide critical contributions to ecosystem function and services. This thesis assesses the medium to long term impacts of coral loss on fish assemblages in the western Indian Ocean. Feeding observations of corallivorous butterflyfish demonstrates that considerable feeding plasticity occurs among habitat types, but strong relationships exist between degree of specialisation and declines in abundance following coral loss. Furthermore, obligate corallivores are lost fairly rapidly following decline in coral cover, whereas facultative corallivores are sustained until the structure of the dead coral begins to erode. Surveys of benthic and fish assemblages in Mauritius spanning 11 years highlight small changes in both benthos and fish through time, but strong spatial trends associated with dredging and inter-specific competition. In Seychelles, although there was little change in biomass of fishery target species above size of first capture, size spectra analysis of the entire assemblage revealed a loss of smaller individuals (<30cm) and an increase in the larger individuals (>45cm). This represents a lag effect where fishery production cannot be assured for the long term. A targeted before (mid-1990s) – after (2005) sampling program of coral reef benthos and fish assemblages in 7 countries across the Indian Ocean demonstrated changes in size structure, diversity and trophic composition of the reef fish community have followed coral declines in both fished and protected areas. The thesis highlights the pivotal role that loss of reef structural complexity plays in the effects of bleaching on fish assemblages and that coral reef management needs to radically adapt to address climate change issues.
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Wormald, Clare Louise. "Effects of density and habitat structure on growth and survival of harvested coral reef fishes /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3277014.
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Andras, Tiffany D. "Seaweed allelopathy against coral: surface distribution of seaweed secondary metabolites by imaging mass sepctrometry." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44797.
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Coral reefs are in global decline, with seaweeds increasing as corals decrease. Though seaweeds have been shown to inhibit coral growth, recruitment, and survivorship, the mechanism of these interactions is poorly known. Here we use field experiments to show that contact with four common seaweeds induces bleaching on natural colonies of Porites rus. Controls in contact with inert, plastic mimics of seaweeds did not bleach, suggesting treatment effects resulted from allelopathy rather than shading, abrasion, or physical contact. Bioassay-guided fractionation of the hydrophobic extract from the red alga Phacelocarpus neurymenioides revealed a previously characterized antibacterial metabolite, Neurymenolide A, as the main allelopathic agent. For allelopathy of lipid soluble metabolites to be effective, the metabolites would need to be deployed on algal surfaces where they could transfer to corals on contact. We used desorption electrospray ionization mass spectrometry (DESI-MS) to visualize and quantify Neurymenolide A on the surface of P. neurymenioides and found the metabolite on all surfaces analyzed. The highest concentrations of Neurymenolide A were on basal portions of blades where the plant is most likely to contact other benthic competitors.
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Santora, Karen A. "Abundance and diversity of culturable bacteria from healthy and suspect white plague type II-infected corals in the Flower Garden Banks National Marine Sanctuary." Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3074.
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Thesis (M.S.)--George Mason University, 2008.Vita: p. 103. Thesis director: Robert B. Jonas. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science and Policy. Title from PDF t.p. (viewed July 3, 2008). Includes bibliographical references (p. 96-102). Also issued in print.
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Matthews, Elizabeth. "Community-based and collaborative management of coral reefs and coastal resources in Palau /." View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3284827.
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Uyarra, Maria Calvo. "Managing Tourism for Coral Reef Conservation." Thesis, University of East Anglia, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514338.
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Mason, Benjamin M. "The importance of detritus and microenvironment nutrient enrichment to the growth of coral reef macroalgae, Halimeda and Dictyota /." Electronic version (PDF), 2004. http://dl.uncw.edu/etd/2004/masonb/benjaminmason.html.
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Barreto, Felipe S. "Assortative mating as a barrier to gene flow in a coral reef fish species flock /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/barretof/felipebarreto.pdf.
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Geange, Shane Wallace. "An evaluation of prior residency and habitat effects on the persistence of settling reef fishes : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Marine Biology /." ResearchArchive@Victoria e-Thesis, 2010. http://hdl.handle.net/10063/1169.
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Billinghurst, Zoe. "Genetic variation within the coral Symbiodinium symbiosis of Bermudian reef corals." Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286055.
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Scales, Helen Joanna. "Exploitation of coral reef fishes for the Live Reef Fish Trade." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615075.
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Hardt, Marah Justine. "Human impacts on Caribbean coral reef ecosystems." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3255619.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed May 10, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Hedley, John D. "Spectral unmixing in coral reef remote sensing." Thesis, University of Exeter, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407280.
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Reverter, Miriam. "Host-parasite interactions of coral reef fish." Thesis, Paris, EPHE, 2016. http://www.theses.fr/2016EPHE3060/document.
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Les parasites sont une partie très importante des écosystèmes, néanmoins, dans certains cas tels que l’aquaculture ils causent des épidémies. Dans cette thèse j’ai étudié les interactions hôte-parasite chez les poissons coralliens, dans les milieux naturels et les milieux aquacoles. J’ai étudié l’arrangement des communautés de 13 espèces de monogènes de 34 espèces de poissons papillon dans l’Indo-Pacifique. Les résultats montrent qu’il existe un patron de distribution stable des espèces, ce qui, combiné avec les résultats de l’étude biogéographique, suggère que la spécificité parasitaire observée a pu se développer tout au long des épisodes biogéographiques passés. Notamment, seule une espèce, Chaetodon lunulatus, n’est jamais parasitée. J’ai étudié le mucus des poissons qui est décrit comme la première ligne de défense contre des agressions externes, pour analyser quels facteurs de C. lunulatus pourraient être reliés à l’absence des parasites. Le microbiome et le métabolome du mucus branchial des poissons papillons montrent une grande diversité. C. lunulatus présente une plus grande abondance de Fusobactéries qui est corrélée avec une surexpression de peptides pouvant dériver de la β-hémoglobine. La purification, la synthèse et l’évaluation des activités antiparasitaires des peptides sont en cours au laboratoire. J’ai aussi étudié l’utilisation des plantes médicinales comme alternative à des traitements chimiques dans l’aquaculture. J’ai testé l’activité antibactérienne et immunostimulatrice de plusieurs plantes et algues polynésiennes. L’algue rouge Asparagopsis taxiformis montre de fortes activités antibactériennes sur Vibrio harveyi et Tenacibaculum maritimum et induit une augmentation de l’expression de deux gènes liés à l’immunité chez Platax orbicularisFish parasites are an important part of ecosystems, however, in certain cases such as in aquaculture they can cause severe disease outbreaks. In this thesis I have studied host-parasite interactions in coral reef fishes, both in the natural and culture environments. I have studied the distribution of 13 dactylogyrid species from 34 butterflyfishes in the Indo West-Pacific. Composition of dactylogyrid communities was host specific and together with the biogeography results, where a turnover in the main Haliotrema species was observed, suggest that parasite specificity might result from host-parasite coevolution derived from past biogeographical episodes. Only one butterflyfish species, Chaetodon lunulatus, was never found parasitized by gill monogeneans. I have studied the butterflyfish mucus, which is the first barrier against pathogens, to investigate the C. lunulatus factors that might be related to the monogenean absence. Butterflyfish gill microbiome and metabolome revealed a high diversity. C. lunulatus presented a significantly higher abundance of Fusobacteria which was correlated to a higher expression of potentially derived β-hemoglobin peptides. Synthesis and evaluation of the peptide antiparasitic activities are being performed in the laboratory. I have also studied the use of medicinal plants as an alternative to chemotherapy in fish aquaculture. I investigated the antibacterial and immunostimulant activities of several local Polynesian plants and algae, and I found that Asparagopsis taxiformis displayed a potent antibacterial activity against Vibrio harveyi and Tenacibaculum maritmum and increased expression of two immune-related genes in Platax orbicularis
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Walsh, Sheila Marie. "Linking coral reef health and human welfare." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3369722.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed September 17, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Sun, Yanan. "Biodiversity and phylogeny of coral-associated polychaetes." HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1278.
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Waltho, Nigel. "The appearance of stochastic control in fish communities on coral reefs : a hierarchical approach to system organization /." *McMaster only, 1997.
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Savaro, Jennifer. "Connectivity of Reef Fishes Between Mangroves and Coral Reefs in Broward County, Florida." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/378.
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Many marine fishes use the mangrove ecosystem for foraging, protection, spawning, and as a nursery habitat. To develop a better understanding of energy flow between the coastal mangrove and coral reef ecosystems, the ontogentic migration and trophic connectivity of reef fishes were examined through the use of carbon (C), nitrogen (N), and oxygen (O) stable isotope ratios. Juvenile and adult gray snapper Lutjanus griseus, lane snapper L. synagris, bluestriped grunt Haemulon sciurus, French grunt H. flavolineatum, sailor’s choice H. parra, yellowfin mojarra Gerres cinereus, and great barracuda Sphyraena barracuda were collected from both mangrove and coral reef sites located near Port Everglades, Broward County, Florida. All species were analyzed for δ13C and δ15N of muscle tissues and δ 18O and δ 13C of otoliths to evaluate ontogenetic migrations, foraging, and occupation within both the mangrove and reef sites. The δ13C and δ15N in muscle tissue were more depleted in juvenile fish from the mangroves than their adult forms caught on the adjacent reef. The δ18O and δ13C otolith data were significantly different between species, age class, and habitat, with lower δ18O values for juvenile fish caught in the mangroves. A general trend of increasing δ13C in otoliths corresponded to increasing total length, also suggesting juvenile movements from mangrove to nearshore reefs with age. Overall, the findings of this study further confirm that several commercially and recreationally important reef-associated fishes utilize mangrove ecosystems during juvenile life stages.
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East, Holly Kate. "The evolution of Maldivian coral reef rim islands." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30860.
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The first detailed investigation of Maldivian rim island development and reef-to-island connectivity is presented. Study sites were selected on windward and leeward rim aspects of Huvadhu Atoll, and analyses were undertaken at a millennial, contemporary and near-future temporal scales. At millennial temporal scales, contrasting models of island development were presented for the windward and leeward sites. Marked between-site differences were found in the timings of island initiation (2,800-2,000 cal. yr. B.P. and 4,200-3,600 cal. yr. B.P. at the windward and leeward sites respectively). Hence, sea-level does not represent the sole control upon island formation. The period of island initiation and heightened mobility occurred during the mid-Holocene sea-level highstand. Future sea-level rise may thus reactivate the process regime responsible for reef island initiation, potentially inducing further island building and/or heightened island mobilisation. Contemporary analyses highlighted the homogeneity of the sediment reservoir across marine, beach and island sediments. Specifically, sand-grade coral was dominant across all samples within both sites (>50%). The most likely source of sand-grade coral is excavator parrotfish, which was consistent with ecological survey-based estimates of sediment production (excavator parrotfish accounted for 72.8% and 68.2% of sediment production at the windward and leeward sites). The highest sediment production rates were found within the lagoonward environments (59.4% and 75.4% at the windward and leeward sites), which is consistent with the more recent lateral lagoonward mode of island building. With regard to near-future analyses, the apparent recent areal expansion of seagrass beds demonstrated the capacity of ecological changes to cause shifts in sediment production budgets (contributing an additional ~243 tonnes yr-1 of sediment on the leeward rim platform). In addition, significant increases in benthic sediment mobility were found at both study sites under sea-level rise scenarios. Increases in mobility were markedly larger in magnitude at the leeward site than at the windward site. A challenge for the adaptive capacity of atoll nations is thus to acknowledge this atoll-scale diversity in future management strategies.
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Nicholls, Thaddeus Allen. "Decadal-Scale Changes on Coral Reefs in Quintana Roo, Mexico." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/238.
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In 1988 data on coral reef community composition were collected from two areas, Akumal and Chemuyil, Quintana Roo, Mexico, ranging from 5-35m depth. These areas were revisited in 2005 and data were collected by the same methods and at the same depths as in 1988. Data from 1988 and 2005 were compared to determine if the coral reefs had undergone significant changes, and what specific changes had occurred. Chi-square analysis determined that community composition data collected in 1988 are significantly different from data collected in 2005 at all sites and depths within the categories of corals, gorgonians, sponges, and macroalgae. Mann-Whitney U analyses were performed on abundance data for coral, gorgonians, sponges, macroalgae, crustose coralline algae, erect coralline algae/calcareous algae, filamentous/multi-species turf algae, and non-living substrate. Results from the Mann-Whitney U analysis varied between sites; however significant trends of increasing macroalgae, crustose coralline algae and filamentous/multi-species turf, and declining non-living substrate were observed at almost all sites. H' biodiversity indices J' evenness values and species number (S) were calculated for all sites over the two time periods, with no discernable trends observed. Increases in crustose coralline algae and filamentous/multi-species turf algae suggest that eutrophication and overfishing may be responsible for the trends observed on the reefs at Akumal and Chemuyil. Anecdotal accounts also suggest that eutrophication from septic water flowing through the highly porous karst limestone of the Yucatan Peninsula may be the largest malefactor causing the observed changes. The increase in filamentous/multi-species turf algae exhibited by the data suggests that eutrophication is predominantly responsible for the alternate states of the reefs. Furthermore, evidences indicative of other forms of stress on the reefs, such as bleaching, scraped or broken coral heads, disease, and sedimentation, were rarely observed.
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Lamb-Wozniak, Kathryn Amanda. "Nitrogen Cycling on Coral Reefs: A Stable Isotopic Investigation of Nutrient Dynamics within the Florida Keys Coral Reef Tract." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/23.
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This dissertation serves as a comprehensive, natural-abundance analysis of the present-day spatial and temporal dynamics and trophic linkages of nitrogen from within the Florida Keys National Marine Sanctuary (FKNMS). This work was accomplished by documenting the delta 15 N of particulate organic matter (POM), several genera of aquatic vegetation and herbivorous fish, as well as dissolved water column nitrogen. Seasonal and spatial variations in delta 15 N were assessed, trophic level variations among reef constituents were quantified, and relative contributions of both natural and anthropogenic nitrogen into the reef tract were determined. The measured mean delta 15 N of POM (3.64 per mil), aquatic vegetation (Dictyota = 2.39 per mil; Thalassia = 1.91 per mil; Rhizophora mangle = 1.46 per mil; Halimeda = 1.62 per mil; sponges = 4.13 per mil; turf algae = 2.67 per mil), herbivorous fish (4.92 to 8.47 per mil), as well as the delta 15 N and delta 18 O of nitrate (4.40 and 20.36 per mil, respectively) suggest that the primary nutrient sources directly impacting the reef are from natural sources, principally nitrogen fixation, and not anthropogenic wastes. Clear trophic linkages, without evidence of disturbances from anthropogenic wastes, are apparent in this study; herbivorous fishes show distinct 3 to 4 per mil enrichments over their food source. The presence of anthropogenic wastes was detected in the delta 15 N and delta 18 O of nitrate from Key Largo canal waters (10.09 per mil), however, sewage derived nutrients did not exist in any measurable or detectable amount outside the canals. Additionally, an assessment of the total yearly nitrogen contributions to the FKNMS was conducted, demonstrating that nitrogen fixation was the largest contributor of nitrogen to the ecosystem, delivering approximately 43 percent of all nitrogen. Anthropogenic wastes, however, contributed only about 8 percent to the total nitrogen budget, far less than biotic (non-human) wastes (13 percent), upwelling (10 percent), and gyre waters from the Gulf of Mexico (9 percent). For the first time, a long term, spatially diverse investigation has presented a more complete depiction of delta 15 N composition of various reef components found in the FKNMS, critical and imperative for accurately assessing nutrient pressures on coral reefs. As such, the data presented in this study do not support the theory that continuous anthropogenic nutrient loading from nearshore populations is the sole cause of reef decline in the FKNMS.
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Daniels, Camille A. "Coral reef assessment an index utilizing sediment constituents /." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001180.
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Sathe, Melissa P. "Factors Influencing Southeast Florida Coral Reef Community Composition." NSUWorks, 2008. http://nsuworks.nova.edu/occ_stuetd/241.
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This study analyzed data collected during the Broward County beach renourishment project yearly monitoring site visits. Twenty four sample sites throughout the county were established to monitor the coral reef community during beach renourishment efforts sponsored by Broward County and the Florida Department of Environmental Protection. Data collected during each site visit included stony coral cover, density, and colony size. Octocoral and sponge density were also collected. A sediment bottle trap was deployed at each site in order to record the sedimentation rates and grain sizes. These traps were collected and analyzed approximately every 60 days. This project used data collected from the year 2000 until 2004. During this time there were no beach renourishment construction activities therefore sedimentation can be assumed to be natural. The sample sites occur on unique habitat categories. These are: colonized pavement-shallow, ridge-shallow, linear inner, middle, and outer reef. It was previously unclear what was driving the composition of the coral reef communities at these sites. Using available information, this project’s objective is to examine whether or not the southeast Florida coral reef community varies temporally (2000-2004) and spatially (by habitat category). Additionally, this project seeks to examine whether sedimentation rate, grain size and/or depth, have any influence on the coral reef community data obtained at these sites.
Changes in the southeast Florida reef system over time (2000-2004) were examined using univariate statistics. Multivariate statistical analyses were used to determine differences by habitat category. The reef communities on the ridge-shallow were statistically different than the reef communities on the linear middle and outer reefs. Sedimentation also varied in this study. The ridge-shallow had the highest sedimentation rates and grain sizes. Some stony coral species exhibited correlations with sedimentation rate, grain size, and depth. Stephanocoenia intersepta in particular showed more cover and higher densities in area where sedimentation rates were low, sediment grain sizes were smaller and depths were deeper. The following paper examines southeast Florida community patterns and how these factors may influence them.
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Nugues, Maggy. "Effects of multiple stresses on coral reef communities." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341771.
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Hagman, Derek Kristian. "Reproductive dynamics of coral reef biota at the Flower Gardens /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008347.
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Afifi, Mansur. "Socio-economic and ecological impacts of coral reef management in Indonesia." Göttingen : Cuvillier, 2003. http://catalog.hathitrust.org/api/volumes/oclc/55018162.html.
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Duce, Stephanie Jane. "The form, function and evolution of coral reef spurs and grooves." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16729.
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The fore reef spur and groove (SaG) zone is an important, but poorly understood, zone of coral reefs. Spurs (parallel ridges of carbonate material), are separated by grooves (regularly spaced channels) to form a distinct finger-like pattern around the margins of coral reefs. Few studies have collected quantitative data in SaG systems and many questions remain about their formation and evolution. This thesis aims to describe the eco-morphodynamics of SaGs by establishing the interactions and feedbacks between their geomorphology (form), hydrodynamics (function) and reef growth (evolution) across multiple spatial and temporal scales at reefs in the Indo-Pacific. This constitutes the most extensive and comprehensive study of SaG features to date. A remote sensing analysis of SaG morphometrics at 17 reefs in the southern Great Barrier Reef (GBR), Australia, revealed exposure to wave energy was the most important factor influencing SaG morphology with fore reef slope playing a secondary role. Four statistically distinct classes of SaG were also identified and described. In-situ hydrodynamic data from SaG zones at One Tree Reef, in the GBR and Moorea in French Polynesia showed that the fore reef SaG zone is a remarkably effective breakwater, dissipating up to 86% of wave energy. Currents in the zone were complex and variable. A unique suite of 38 cores from SaG zones at One Tree and Heron Reefs (in the southern GBR) and Moorea were combined with existing reef platform cores to identify three potential modes of fore reef and reef flat evolution. These modes were matched to the remote sensing defined classes, suggesting that remotely sensed data can provide insight into SaG evolution and potentially upscale the findings of in-situ hydrodynamic and reef growth studies. While further research is required, by studying multiple sites on multiple reefs this study provides globally applicable insights into SaG eco-morphodynamics across a broad spectrum of environmental conditions.
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Humphries, Austin Turner. "Fishing for resilience : herbivore and algal dynamics on coral reefs in Kenya." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013147.
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Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
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McCorry, Denise. "Hong Kong's scleractinian coral communities : status, threats and proposals for management /." Thesis, Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25155131.
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Robison, Jennifer D. "The photophysiology of symbiotic dinoflagellates (Symbiodinium) under varying light and thermal conditions and the implications for coral bleaching." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 8.14 Mb., 97 p, 2006. http://proquest.umi.com/pqdlink?did=1163244091&Fmt=7&clientId=8331&RQT=309&VName=PQD.
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Monty, Jamie A. ""Coral of Opportunity" Survivorship, Growth, and Use with "Coral Nurseries" and "Integrated Stakeholder Involvement" in Coral Reef Restoration." NSUWorks, 2006. http://nsuworks.nova.edu/occ_stuetd/269.
Full textAbstract:
Coral reef degradation from ship groundings and construction activities is unfortunately becoming an increasingly common occurrence worldwide, especially in densely populated regions like southeast Florida, U.S.A., where each year there are a number of coral reef injury events that require mitigation and/or restoration. These activities generally begin with the rescue and reattachment (triage) of scleractinian corals dislodged during the injury event. Because dislodged colony mortality is typically high, colonies may die during legal enforcement action delays. Additionally, natural reef recovery in southeast Florida is typically slow; therefore, transplantation of additional (donor) scleractinian corals into an injured area has been used to restore natural species richness, percent cover, and density, which can accelerate reef recovery. Donor colonies available for transplantation have been grown in situ, grown in laboratories, and taken from uninjured reef areas. An alternative source of donor coral colonies for transplantation is “corals of opportunity,” which I define as scleractinian corals that have been detached from the reef through natural processes or unknown events. My thesis was part of a project, the Coral Nursery Project, initiated in 2001 in Broward County, Florida, U.S.A. that was developed to collect these dislodged colonies and transplant them to a coral nursery. Coral nurseries are interim locations that function as storage sites for corals of opportunity where they can be cached, stabilized, and allowed to grow until needed as donor colonies for future restoration activities. My thesis utilized a partnership between a local university, county government, and a volunteer dive group. Two hundred fifty-three corals of opportunity were located, collected, and transported to coral nurseries. Corals of opportunity were tagged, transplanted to the coral nurseries, and monitored quarterly for survivorship and growth from date of transplantation to February 2004. Survival of corals of opportunity transplanted to coral nurseries was found to be statistically similar to that of control corals naturally attached to reef, and significantly greater than that of control corals of opportunity left unattached. Growth rates of control corals naturally attached to reef were similar to that of corals of opportunity transplanted to coral nurseries. Results provide resource managers with information on the utility of using corals of opportunity as a source of transplant donor colonies, on coral species- and colony size-specific transplantation success, and on transplanted colony survival and growth. I discuss the value of using coral nurseries as cache sites for corals of opportunity to be used in future coral reef restoration activities, and provide recommendations for coral nursery characteristics for optimum coral survival, developing community-based restoration projects, and fostering participatory management. However, the ultimate goal of the Coral Nursery Project is to use these rescued corals of opportunity from this nursery as a source of donor coral transplants in future coral reef restoration activities. Stabilized and healthy transplanted corals of opportunity from this coral nursery will provide a living resource for coral transplantation during coral reef restoration projects. Corals of opportunity, coral nurseries, and integrated stakeholder involvement may become important tools in creating proactive coral reef management programs.
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Arnold, Suzanne N. "Running the Gauntlet to Coral Recruitment through a Sequence of Local Multiscale Processes." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/ArnoldSN2007.pdf.
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Zampa, Greta. "Possible effects of gold mining on coral reef health." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17426/.
Full textAbstract:
Indonesia, being the core of the Coral Triangle, is supposed to hosts the most healthy and diverse coral reefs on the Planet Earth. However, the combination of global and local stressors has led to a decline in coral reef communities around the world. Anthropic activities of particular interest in North Sulawesi are industrial and artisanal gold mining (ASGMs). Industrial mining activities generally used the alkaline cyanidation method while ASGMs still employ mercury amalgamation to extract gold from ores. The extraction and processing of gold produces mine tailings that contain heavy metals, which may be dispersed in the catchment basin due to rain and flooding events and could alter the natural defences of the corals and favour the onset of diseases. The objective of this study was to assess the possible impacts of gold mines in North Sulawesi on coral reef health by comparing prevalence of coral diseases and aggressive species interactions between putatively affected and control sites. As putatively impacted sites, coral reefs downstream to four mining sites were selected: one long-time and one recently established ASGM, a modern industrial mine and a new site in preparation.
Among the 21 possible diseases and other signs of compromised health investigated, gastropod corallivory, aggressive overgrowth, skeletal deformations caused by pyrgomatid barnacle and bleaching, were significantly more abundant at some sites affected by mining activities, compared to controls. A significant increasing of coral bleaching appeared as a result of the pollution generated by ASGMs, which release mercury in the aquatic environment. Detected alterations indicate that long term mining activities can affect the health of coral reefs. Mining in the area is expected to increase due to the large availability of resources, but well environment-based policies are needed to ensure that this development does not compromise biodiversity and marine resources.
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Puebla, Oscar. "Molecular ecology and evolution in "Hypoplectrus" coral reef fishes." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95551.
Full textAbstract:
The marine environment presents fewer absolute geographic barriers to gene flow than its terrestrial and freshwater counterparts. In addition, the prevalence of planktonic larval stages in marine taxa provides potential for gene flow across large geographic distances. These observations raise two fundamental questions. How do new species arise in the marine environment? Considering the potential for gene flow in marine systems, it remains unclear to what extent allopatric speciation alone can account for the high levels of diversity observed in the marine realm, whether marine speciation also operates in the presence of gene flow, and if it does under what specific mechanisms. How far do planktonic larvae travel with marine currents? The generally low levels of genetic structure among marine populations suggests extensive dispersal, yet planktonic larvae are notoriously difficult to track owing to their small size and as a consequence the spatial scale of marine dispersal is still largely eluding ecologists. Here, I consider brightly colored coral reef fishes in the genus Hypop/ectrus (Serranidae) as a model system to address these two questions. I demonstrate the potential for ecological speciation with gene flow to operate in this system through the pleiotropic effect of color pattern, which appears to be involved both in mimicry and mate choice. I show that local processes are operating at the Caribbean scale in this system, suggesting dispersal limitation. I test and confirm this hypothesis by reporting genetic isolation by distance in the barred hamlet (Hypop/ectrus puel/a) at spatial scales ranging from 175 to 3,200 km. In order to estimate mean dispersal distance, I complement genetic data with SCUBA surveys of population densities covering 94,000 m2 of reef and provide dispersal estimates ranging between 2 and 14 km for specific dispersal functions notwithstanding the three-week pelagic larval stage of H. puel/a and very low levels of genetic structure aL'environnement marin présente moins de barrières au flux génétique que ses équivalents terrestres et d'eau douce. De plus, les phases planctoniques larvaires prévalences chez les espèces marines peuvent potentiellement maintenir un flux génétique a travers de grandes distances géographiques. Ces observations soulèvent deux questions fondamentales. Comment se développent de nouvelles espèces dans le milieu marin? Considérant le flux génétique potentiellement important, il demeure incertain dans quelle mesure la spéciation allopatrique peut expliquer la grande diversité observée dans le milieu marin, si la speciation opère également en présence de "flux génétique, et si oui par quels mécanismes. Quelle distance parcourent les phases larvaires planctoniques avec les courants marins? La structure génétique généralement faible parmi les populations marines suggère une dispersion extensive, mais les larves planctoniques sont notoirement difficiles a suivre en raison de leur petite taille et par conséquent I’ échelle spatiale de la dispersion marine échappe encore largement aux écologues.lci, je considère les poissons de récifs coralliens brillamment colores du genre HypopJectrus (Serranidae) comme systeme modèle pour aborder ces deux questions. Je démontre comment la speciation écologique avec flux génétique peut opérer dans ce système par I’ effet plëiotropique du patron de coloration, qui semble être impliquée dans le mimétisme ainsi que dans le choix d'un partenaire sexuel. Je montre que des processus locaux opèrent a I’ échelle des Caraïbes dans ce systeme, ce qui suggère une dispersion limitée. Je teste et confirme cette hypothèse en reportant de I’ isolement génétique par la distance chez HypopJectrus puella des échelles spatiales allant de 175 a3,200 km. Afin d'estimer la distance de dispersion moyenne je complémente les données génétiques avec des relèves de densités de population couvrant
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Solandt, Jean-Luc. "Herbivore interactions on an algal dominated Carribean coral reef." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300024.
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Harborne, Alastair R. "The ecology of coral reef communities at seascape scales." Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439125.
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Goodson, Michael Stephen. "Symbiotic algae : molecular diversity in marginal coral reef habitats." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341115.
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Leong, Wai. "Patterns of resource allocation in Caribbean coral reef sponges." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/leongw/waileong.pdf.
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Hou, Shang-Ju, and 侯尚儒. "Coral Reef Patch Mapping." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/78553194759526420403.
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碩士國立交通大學
土木工程系所
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Coral reef is formed by the corals’ growth and accumulation. According to the geography, it can be divided into two parts: the flat and the slope. By its construction, coral reef can be divided into three types: the fringing reef, the barrier reef and the atoll reef. The atoll reef areas on Dongsha Island are what being researched in this study, and this research aims at detecting and drawing the location of reefs around the Dongsha atoll area. The data used in this research includes digital elevation model (DEM) and satellite images. Three 1/5000 drawings had been chosen as the researched area depending on the characteristics of terrain, and their locations are: the middle of the lagoon area, the junction of the lagoon and the reef plat, and the reef plat. Trend surface analysis and object based segmentation are the two reef location-detecting ways that this research uses. The first one can only detect the location of reefs in DEM, while the second can detect both in DEM and the satellite images. The detected results will be compared with the real situation basing on the human observation of DEM and the sketched map of the reefs distribution. According to the different ways and combinations, it proves that object based segmentation in combination of the image of DEM, serves best. Among the five different analyses, the best one is DEM weight of 4 and image weight of 1. The average accuracy of the three areas is above 0.97, and the Kappa coefficient is higher than 0.84.
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Kiene, William Edward. "Biological Destruction on the Great Barrier Reef." Phd thesis, 1988. http://hdl.handle.net/1885/111570.
Full textAbstract:
This thesis is an experimentally based study of the processes of
biological destruction on dead coral substrates on the Great
Barrier Reef. By placing recently killed coral samples in reef
environments it has been possible to compare the impact of
bioerosion processes on hard coral skeletons between different
environments and reefs. The experiments have shown that once a
dead coral substrate becomes available it is subjected to
recruitment by a diverse assemblage of endolithic borers that
excavate the interior of the substrate, while its surface is
eroded by the grazers that are adapted to scraping carbonate
substrates to remove epilithic and endolithic algal growth.
Experiments on Lizard Island reef have identified grazing as the
major destruction agent on coral substrates over the initial 4
years of exposure. Major differences between environments in the
amount of grazing are controlled by the distribution of the
highly mobile herbivorous fish community that is dominated by
scarids and acanthurids. Subtidal reef slopes and lagoon
environments of water depths less than 20 m are subjected to
higher rates of grazing erosion than shallow reef flat
environments. These differences in grazing are a result of tidal
cycles limiting the access of grazing fish to reef flats to high
tides only. The variability of grazing activity by bioeroding
fish is highly complex due to ecological and behavioral factors.
However, over time periods important to the geological
development of reef environments, these factors would be less
important than the major physical features of the reef that
determine scarids and
acanthurids populations between environments.
The Lizard Island experiments indicate that extensive borer
populations require at least 4 years to develop and that
consecutive 2-year sampling periods show significant differences
in the successful recruitment of borers. Early cryptofauna to
colonise dead coral substrates are small fabriciniid polychaetes.
These small polychaetes are followed by larger cirratulids,
spionids, eunicids and sabellines. Sipunculans, bivalve molluscs
and sponges only become important in the experiments after 4
years. This importance of time to the extent of borer excavation
in experimental substrates suggests that reef surfaces will be
extensively bored if they survive the destructive effects of
grazing. Recruitment differences within and between environments
and season will influence the structure of the borer community.
However, the long-term erosional impact of endolithic borers on
reef framework will be closely linked to the rate of surface
destruction by grazers.
The geological impact of the relationship between grazing and
boring is further revealed in experiments in the southern Great
Barrier Reef. These experiments were designed to assess the
differences in grazer and borer communities for 2 years on reefs
that represent adolescent, mature and senile stages of evolution
at sea level. These reefs were Llewellyn, One Tree, and Wreck.
Experimental samples placed in reef slope, flat, and lagoon
environments show that destruction caused by grazing fish is
reduced as lagoon environments are restricted by sedimentary
infill that expands reef flat conditions. In addition, grazing
by gastropods becomes increasingly important in these reef flat
conditions. However, the rates of erosion by these grazing
molluscs in senile environments on the protected surfaces of
substrates are considerably less than the rates of destruction
caused by fish in subtidal adolescent reef environments. With
reduced destruction, accretion by encrusters is important on
substrates. This accretion further protects surfaces, preserving
the volume of the substrate and allowing the establishment of
borer communities. Through the turnover of these borers and the
addition of encrustation, substrates may be preserved, but they
are likely to be converted from original coral to substrates
composed of bored encrustation. Extrapolating the patterns of
the accretion - erosion balance on experiments to the long term
impact on reef surfaces predicts that framework in senile reef
environments will be subjected to many cycles of boring and
encrustation, producing a highly altered reef rock. Dead coral
framework in adolescent environments is subjected to rapid
destruction by grazers such that borer communities may remain in
early successional stages. The conversion of framework to
sediment through this destruction is an important contribution to
the infilling of the lagoons and to the way that growth
frameworks are ultimately incorporated into the foundation of the
reef.
In addition to these experiments in subtidal environments, an
experiment was designed to measure rates of surface destruction
on windward intertidal reef crest surfaces at One Tree Reef.
Using an instrument that measures differences in the elevation of
reef surfaces through time it was possible to establish that
rates of destruction increase toward the reef margin and that the
highest rates recorded approach the rates of construction that
have been estimated by others for the environment. Biological
processes, including grazing, are interpreted to be responsible
for this destruction since longer exposure to subtidal conditions
increases erosion and the activity of grazers and borers. The
intertidal pavement that is submerged for longer periods during
tidal cycles recorded rates of erosion more than twice those
recorded on the supertidal cemented rubble platform. The rates
indicate the magnitude of accretion that has been necessary to
maintain this environment in intertidal conditions.
Overall, the study provides a different view of short-term
biological processes that effect the long-term geological
development of reefs. The changing relationship of grazing,
boring and accretion on frameworks as a reef evolves provides a
geological record that is a potential measure of the physical and
ecological change that has occurred in the past, and is occurring
on reefs today.
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Neely, Karen Lynn. "Influence of Substrate on Coral Reef Fish Communities." Diss., 2008. http://dukespace.lib.duke.edu/dspace/bitstream/10161/820/1/D_Neely_Karen_a_200808.pdf.
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Hall, Vicki R. "Injury and regeneration of common reef-crest corals at Lizard Island, Great Barrier Reef /." 1998. http://eprints.jcu.edu.au/8.
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Pascelli, Sant'Ana Santos Cecília. "Viruses in coral reef sponges." Thesis, 2019. https://researchonline.jcu.edu.au/64965/1/JCU_64965_Pascelli_2019_thesis.pdf.
Full textAbstract:
Cecília Pascelli studied viruses in coral reef sponges, identifying 50 viral morphotypes and over 25 viral families, which correlates with the sponge microbial symbionts. Cecília also showed that coral reef sponge viruses hold several metabolic genes which may provide competitive advantage for the host environmental acclimatisation.
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Hempson, Tessa N. "Coral reef mesopredator trophodynamics in response to reef condition." Thesis, 2017. https://researchonline.jcu.edu.au/53079/19/53079-hempson-2017-thesis.pdf.
Full textAbstract:
Habitat degradation in coral reef ecosystems is occurring at an unprecedented rate and scale around the world. This habitat decline is driven by both intensifying local stressors and the escalating effects of global climate change. Concurrently, the ubiquitous loss of large consumers from ecosystems, known as trophic downgrading, has important ramifications for the function and resilience of both terrestrial and marine ecosystems. Mesopredators represent an important component of coral reef ecosystems, both economically, supporting large reef fisheries, and ecologically, as potentially important drivers of reef trophodynamics. While there has been substantial focus on the effects of habitat degradation on the small-bodied reef fish community, which is closely associated with the reef benthos, relatively little is known about the implications for piscivorous reef mesopredators. These large-bodied, mobile species are less directly reliant on the reef benthos, and likely to experience the strongest effects of habitat degradation mediated via the fish community on which they prey. This thesis addresses this important research gap by focusing on four key implications of habitat degradation for mesopredators and their role in coral reef trophodynamics.
Dietary adaptability is likely to be an important factor in determining the vulnerability of piscivorous mesopredators to changing prey availability associated with habitat degradation. In chapter 2, I use stable isotope analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) to investigate whether coral trout (Plectropomus maculatus), in the Keppel Island group on the southern Great Barrier Reef (GBR), can switch their diet to exploit the altered prey base on degraded reefs. Coral bleaching and sediment-laden flood plumes have driven extensive live coral loss on these reefs. The resulting shift in dominant prey species from pelagic plankton-feeding damselfishes to benthic algal-feeding species, represents a shift in the principal carbon pathways in the food web. The δ¹³C signature in coral trout shifted from a more pelagic to a more benthic signal, reflecting the prey community shift, and demonstrating that trout appear to alter their diets as reefs degrade. Nitrogen signatures also indicated that trout with a more benthic carbon signature were feeding at a lower trophic level, indicating a shorter food chain on degraded reefs. Despite this apparent adaptability, mesopredator populations at this location are in steep decline, driven primarily by reduced total available prey biomass.
Thus, despite dietary flexibility conferring a degree of trophic resilience in the short term, mesopredators are nonetheless vulnerable to the effects of habitat degradation. Due the relative longevity of many mesopredator species, sublethal effects of changing prey resources may be difficult to detect. Chapter 3 investigates whether a common mesopredator species (Cephalopholis argus) in the Seychelles inner island group shows evidence of a loss of condition due to habitat degradation. Following extensive live coral loss during the 1998 mass bleaching event, some reefs have regained high coral cover, while others have experienced a regime shift to an algae-dominated state. Stable isotope analyses demonstrated that C. argus on regime-shifted reefs fed lower down the food chain, on a narrower range of carbon sources, than those on recovering reefs, suggesting a simplification of the food web. Histology of liver tissue showed reduced hepatocyte vacuolation in fish from regime-shifted reefs, and reduced lipid stores in spawning females. Reduced energy reserves can lead to decreased growth rates, fecundity and survivorship, ultimately resulting in long-term population declines.
Long-term effects of regime-shift in coral reef ecosystems can substantially alter the trophic structure of fish communities, yet understanding of how these changes manifest through time is limited. In chapter 4, I use a 20-year dataset documenting changes in the benthic and reef fish communities on the Seychelles inner island reefs, to examine how trophic structure has changed on recovering and regime-shifted reefs following the 1998 mass bleaching event. I demonstrate how reef fish communities become increasingly dissimilar, as the benthic states diverge with time since disturbance. Trophic pyramids of relative biomass on regime-shifted reefs developed a concave structure, with increased herbivore biomass supported by increased algal resources, a loss of mid trophic level specialist species, including corallivores, and biomass in the upper trophic levels maintained by large-bodied generalist species. In contrast, on recovering reefs, after an initial loss of mid trophic level biomass, pyramids developed a bottom-heavy structure, which is commonly predicted in stable ecosystems by the theory of energy transfer efficiency in food webs.
Benthic habitat and associated fish communities can also be altered via climate-driven shifts in coral assemblages. One of the predicted characteristics of novel future coral ecosystems is a loss of thermally sensitive coral taxa and an increasing dominance of taxa with higher thermal tolerance, many of which have low structural complexity. In chapter 5, I used a patch reef experiment at Lizard Island on the northern GBR to investigate the effects of thermally 'vulnerable' and 'tolerant' coral assemblages on the trophodynamics of reef mesopredators and their prey fish communities. Fish communities which established naturally on the low structure 'tolerant' patch reefs had lower diversity, abundance and biomass than 'vulnerable' reefs with higher structural complexity. The introduction of a mesopredator (Cephalopholis boenak) had a greater impact on the prey fish community composition of 'tolerant' reefs than 'vulnerable' reefs, and total lipid content of C. boenak indicated that those introduced to 'tolerant' reefs had lower energy reserves than those on 'vulnerable' reefs, indicating a sub-lethal cost to condition.
My research provides novel insight into the effects of habitat degradation on the trophodynamics of coral reef mesopredators, mediated via the fish community on which they prey. I demonstrate that while certain mesopredator species may be able to adapt their diets to changing prey availability, their trophic niche becomes altered as they feed further down the food chain, and they may experience sub-lethal costs due to reduced energy reserves. This work highlights the importance of improving our understanding of how mesopredators are affected by habitat degradation, particularly with respect to the long-term implications of sub-lethal effects for their populations. Sustainable management of these species into the future will require the explicit recognition of the potential for such costs to mesopredator condition as reefs degrade.
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Kisten, Yanasivan. "The influence of heterotrophy on the resilience of hard coral Pocillopora damicornis to thermal stress and bleaching." Thesis, 2013. http://hdl.handle.net/10413/11212.
Full textAbstract:
Global warming from anthropogenic greenhouse gas emissions causes temperature
increases in aquatic ecosystems. The rise in environmental temperatures places sensitive
organisms under thermal stress. Reef-building corals are a critically important group of
animals that provide many ecosystem services for coral reef ecology and the economy
and are at a high risk of loss from thermal stress. Thermal stress causes corals to lose
their colour, i.e. become bleached, resulting from the loss of symbiont zooxanthellae.
This diminishes the energetic benefits that zooxanthellae provide to corals leading to a
decline in coral health and high mortality rates. However, corals are also predators and
can thus draw nutrients from zooplankton prey to supplement their nutritional
requirements. This study investigated whether heterotrophic feeding can ameliorate the
effects of thermal stress on coral physiology by providing an alternative energy source
to zooxanthellar photosynthesis. Fragmented Pocillopora damicornis coral colonies
were exposed to daily maximum temperatures of up to 31°C while being either starved
or fed. During the experimental period coral nubbins were monitored for changes in
polyp extension, oxygen consumption rate, feeding rate, colour, chlorophyll a content,
zooxanthellae density, antioxidant potentials and DNA integrity during stress and after a
short recovery period. It was found that, as expected, coral polyp extension, oxygen
consumption rate, colour health, chlorophyll a content, zooxanthellae density and DNA
integrity were all adversely affected by thermal stress. This indicted that all these
measurements were viable biomarkers for assessing the negative effects of thermal
stress on coral health. Coral colour, oxygen consumption rate, chlorophyll a content,
lipid content, antioxidant potential and DNA integrity were all significantly improved
by feeding. These results indicate that feeding does play a role in improving overall
coral health and supports the physiological processes in coral tissue during and after
thermal stress. The conclusions from this study also have great significance for coral
reef ecology and management as predictions of reef resilience can be made from
zooplankton ecology and boosting zooplankton availability to corals may be considered
to mitigate the harmful effects of thermal stress and bleaching.M.Sc. University of KwaZulu-Natal, Durban 2013.
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Hubble, Marc. "The ecological significance of body size in tropical wrasses(Pisces : Labridae)." Thesis, 2003. https://researchonline.jcu.edu.au/81/1/01front.pdf.
Full textAbstract:
Among terrestrial organisms, body size exhibits predictable relationships with many characteristics including growth rate, mortality rate, longevity, reproductive traits, abundance, species richness and habitat use. However, the majority of studies
identifying such relationships have looked at a limited range of terrestrial taxa, in particular mammals, birds and beetles. These patterns have received much less attention among marine organisms and consequently their generality is questionable. Factors influencing growth of organisms in terrestrial and marine environments may be
fundamentally different. This variation could result in considerable differences in growth processes among marine and terrestrial organisms and influence constraints on
body size among species in these environments. The principal aim of this study was to identify whether numerous body size-related patterns observed in terrestrial taxa were repeated in a group of coral reef fishes, and assess reasons for differences when
predicted relationships were not detected.
This study employed a multispecific comparative approach to examine life history and ecological correlates of body size in coral reef fishes of the wrasse family (Pisces:
Labridae), a group in which species range in length from 4cm to over 2m. To account for the influence of evolutionary history of species on the patterns observed, a working hypothesis for a wrasse phylogeny was derived for the sampled species. This phylogeny was integrated into the analyses for Chapters 2 and 3 of this thesis.
The study comprised four main data chapters examining relationships between body size and a range of life history traits and other ecological characteristics. In
Chapter 2, the relationships between maximum body size of species and growth rate, mortality rate and longevity were examined among ten species of wrasses which
encompassed a ten-fold size range. Based on current theory it was predicted that there should be a positive relationship between maximum size of species and maximum age and a corresponding negative relationship between maximum species size and mortality rate. Both of these relationships were detected for the wrasses studied here. Conceptual models indicating ways in which differences among body sizes of fish species can arise
were developed and tested. It was found that in some species larger size was simply attained by growing at the same rate as smaller species but for a longer period of time. In other species faster growth enabled the attainment of larger body size but at the cost iiof
shortened life-span. There was limited evidence that by growing faster individuals became larger and less susceptible to predation sooner, resulting in larger body sizes and longer life spans. A further idea was that smaller species are smaller because they have determinate growth and stop growing sooner than larger species. Wrasse species studied here exhibited the range from indeterminate to determinate growth but there was
no apparent relationship between maximum body size of species and growth strategy.
In Chapter 3 covariation between maximum size of species and reproductive characteristics was explored. It was predicted that smaller species should mature and
change sex at a smaller proportion of maximum size and proportionally earlier in life than larger species. They were also expected to have greater reproductive effort than
larger species. Despite this, none of these relationships between maximum species size and reproductive traits were evident. Relationships between maximum size and size at
maturity and sex change were in fact opposite to those expected as smaller species matured and changed sex at a greater proportion of maximum size than larger species.
Similarly, short-lived species matured and changed sex proportionally later in life than long-lived species. In general, body size appeared more important than age in
determining when maturation and sex change occurred both among and within species. Energy invested per reproductive episode was not significantly related to species body size.
In Chapter 4, covariation among body size, growth rate, longevity, reproductive effort and size/age at maturity and size/age at sex change was examined in the wrasse
Halichoeres melanurus. Individuals were sampled at four locations along a latitudinal cline. Consistent with patterns identified to date it was predicted that with an increase in latitude there should be a decrease in growth rate, and an increase in body size and longevity. Initial growth rate was slightly slower at the two higher latitude locations and the maximum body size and maximum age of individuals within populations did tend to increase with an increase in latitude. It was also considered that an increase in latitude should be associated with an increase in the proportion of adult size and age attained
before maturation and sex change, and an increase in reproductive effort. However, there was no consistent relationship between the latitude at which individuals were
sampled and the proportion of maximum size/age attained at maturity or sex change. In addition reproductive effort of individuals did not vary predictably as latitude increased.
Individuals collected at the Palm Islands matured relatively earlier, exhibited greater iiireproductive
effort and changed sex proportionally earlier in life than those collected at Kimbe Bay, Lizard Island and Heron Island.
In Chapter 5, relationships between body size and ecological characteristics including local abundance, species richness, habitat use and depth range, were
investigated among all wrasse species present at a range of locations. Based on patterns identified within both marine and terrestrial taxa it was predicted that the smallest species would not be the most abundant with abundances peaking in species of small to intermediate size. Very large species were expected to have low abundances. This relationship was expressed for the wrasse species examined here. In addition, the body size-species richness distribution of wrasses at a number of locations was log normal, with many species of small to intermediate size and low numbers of very small or very large species. Smaller reef fish species were expected to be associated with a smaller range of microhabitats than larger species, be more habitat specific and have smaller depth ranges than larger species. The small wrasse species examined here were found to use a small, intermediate or large diversity of available microhabitats, whereas the
larger species consistently used a wide diversity of microhabitats. Depth ranges of small species lay on a continuum from very small to very large, whereas larger species consistently had large depth ranges.
Variation between some of the patterns observed in this study and those described in previous studies, demonstrates the need to replicate similar studies in a wide range of organisms inhabiting a wide range of habitats before their generality can be assessed.
Repeating similar studies among species within a large range of reef fish families is crucial to determine the utility of species body size as a predictor of life history
characteristics and other ecological variables in reef fishes.
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Hubble, Marc. "The ecological significance of body size in tropical wrasses (Pisces: Labridae) /." 2003. http://eprints.jcu.edu.au/81.
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Bay, Line K. "The population genetic structure of coral reef fishes on the Great Barrier Reef /." 2005. http://eprints.jcu.edu.au/14.
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Morais, Araujo Renato. "The productivity of coral reef fishes." Thesis, 2020. https://researchonline.jcu.edu.au/65115/1/JCU_65115_Morais-Araujo_2020_thesis.pdf.
Full textAbstract:
Renato Morais developed a method to quantify the productivity of coral reef fishes. He used this method to evaluate the effects of fishing and climate change on the amount of fish that coral reefs produce. This method can be used to improve assessments of critically important, but increasingly threatened, tropical fisheries that sustain millions of people.