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1
Zomparelli, Alessandro. "Emergent Reefs." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3622/.
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Edwards, David Charles. "Cement reefs." Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390320.
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Bollati, Elena. "Fluorescence on coral reefs." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/424758/.
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Coral reefs are highly biodiverse ecosystems and provide vital resources for the human population. Due to increasing pressure by climate change and local stressors, these ecosystems currently face a global crisis. The development of tools to monitor how coral reefs respond to environmental change is a key aspect of the conservation of their biodiversity and resources. A number of reef organisms produce fluorescent molecules, including photosynthetic pigments and green fluorescent protein (GFP)-like pigments found in Anthozoa. These pigments are responsive to environmental conditions and can be optically monitored in vivo, making them a promising tool to investigate organism- and community-level processes on coral reefs. In this thesis, the fundamental principles and technological developments necessary for the application of fluorescence as a biomarker are explored. First, the mechanisms regulating coral fluorescence are considered for two functionally and biochemically distinct groups of GFP-like proteins. In mesophotic and depth-generalist symbiotic corals, incomplete light-driven maturation of the red GFP-like protein pool is shown to determine the spectrum of fluorescence emission. A role of this mechanism in adaptation to the reduced mesophotic light spectrum is discussed. In corals from shallow water environments, enhancement of internal light fluxes due to reduced absorption by symbiont pigments during bleaching is shown to induce expression of GFPlike proteins. High-level expression of these pigments in bleached tissue is shown to promote recovery of the symbiotic algae complement after a stress event. Second, a novel approach to fluorescence imaging for coral reef surveys is presented. The method enables automatic classification of reef benthic organisms based on the intensity of fluorescent signal in different excitation and emission bands. These findings demonstrate the potential of fluorescence as an in vivo marker for physiological and ecological studies of coral reef organisms, contributing to ongoing efforts to monitor and preserve the health of these ecosystems.
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Miller, Dianna Rose Szedlmayer Stephen T. "A comparison of fish and epibenthic assemblages on artificial reefs with and without copper-based anti-fouling paint." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Fisheries_and_Allied_Aquacultures/Thesis/Miller_Dianna_26.pdf.
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Gherardi, Douglas Francisco Marcolino. "Recent carbonate sedimentation on the coralline algal Atol das Rocas : equatorial South Atlantic, Brazil." Thesis, Royal Holloway, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339213.
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Harwell, Heather D. "Landscape aspects of oyster reefs : fragmentation and habitat utilization /." Electronic version (PDF), 2004. http://dl.uncw.edu/etd/2004/harwellh/heatherharwell.pdf.
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Noren, Hunter KG. "Can Twilight Reefs Usher In A New Dawn For Depauperate Shallow Coral Reefs?" Thesis, NSUWorks, 2016. https://nsuworks.nova.edu/occ_stuetd/421.
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As shallow reefs continue to decline, scientists are searching for the key to their persistence; as it turns out, they may just need to look deeper. Below many shallow tropical reefs, there exist healthy and more stable mesophotic coral reef communities. The ability of these reefs to act as a refuge for declining shallow populations has garnered significant interest among the scientific community; however, the reproductive and larval aspects necessary for this to occur are unknown. This study assesses the ability of deep reefs to act as a reproductive refuge for shallow counterparts by examining gametic compatibility, viability and larval settlement preferences. Gametes from Orbicella franksi inhabiting the shallow (14-20m) and the upper mesophotic (27-32m) were introduced in a series of inter- and intra-depth crosses and found to be compatible. Larval settlement experiments found no natal depth preference, with deep larvae significantly preferring to settle on shallow conditioned substrate. Our findings support the plausibility of healthy mesophotic reefs acting as a refuge for depauperate shallow populations by (1) providing gametes to mix with limited shallow gametes resulting in increased fertilization and (2) providing larvae that recruit and repopulate shallow reefs. This is the first study to comprehensively evaluate the Deep Reef Refugia Hypothesis from a reproductive and larval settlement standpoint. Our results suggest a close coupling between shallow and mesophotic reefs through gamete and larval export and illustrate the current and future importance of these mesophotic reefs.
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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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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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Bries, Jill M. "THE IMPACT OF HURRICANE LENNY ON CORAL REEFS AND ITS RELEVANCE TO PLEISTOCENCE REEF COMMNUNITIES: CURACAO, NETHERLANDS ANTILLES." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990629881.
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Gustavo, Hinestrosa. "Shelf-edge reefs of the Great Barrier Reef: A time-capsule from the last glaciation." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12726.
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A detailed investigation of the internal and external architecture of the shelf-edge reefs (SERs) of the Great Barrier Reef (GBR), Australia is presented here, constituting the most comprehensive seismic stratigraphy study of these drowned reefs. In two sites of the central GBR, seismic reflectors and facies were identified, ground-truthed against core and downhole data from the Integrated Ocean Drilling Program, Expedition 325. Marked depositional differences between the two sites were found and linked to local and regional physiographic and environmental contrasts. A sequential stratigraphy framework was established for these sites, which exhibit a complete depositional sequence dominated by transgressive reefs, bounded by two flooding surfaces. The postglacial flooding of the GBR shelf was also simulated. The measured parameters suggest a strong influence of the local antecedent substrate and of the interplay of regional physiographic variations and sea level change in the development of the SERs. Supported in these new interpretations, local and regional SERs CaCO3 accumulation were estimated. It was found that the Pleistocene SERs of the GBR are equivalent to ca. 20 % of the GBR's Holocene reef mass. Both the magnitude and the timing of the shelf-edge reef accumulation suggest that the drowned reefs in the GBR (and globally) had the potential to influence postglacial climate change. In addition, forward stratigraphic simulations were run on models based on this dataset, which suggest that the ensemble of conditions for reef growth deteriorated as the transgression advanced, resulting in shelf-edge reef demise. The role of the basement substrate was significant, but limited. All together, the multidisciplinary reconstructions in this study represent a useful framework to constrain the development of these under-studied formations, which according to the findings had a significant role in shaping the Quaternary GBR and, possibly, in postglacial climate change.
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Arena, Paul T. "The Structure Of Fish Assemblages On Vessel-Reefs And Adjacent Natural Reefs In Southeast Florida." NSUWorks, 2005. http://nsuworks.nova.edu/occ_stuetd/89.
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Derelict vessels are commonly deployed as artificial reefs in theUnited States, mainly for recreational fishers and divers.Broward County,Floridaalone has more than 70 vessel-reefs located in its coastal waters. Despite their popularity, few studies have rigorously examined fish assemblages on these structures and compared them to natural reefs. Resource managers need information about fish assemblages on vessel-reefs and natural reefs to better understand the dynamics of local fish populations, understanding which can then effect more informed management decisions.
The nearshore environment ofBroward County,Floridaconsists of three reef terraces, each separated by sand substrate, running parallel to the coastline in sequentially deeper water. All vessel-reefs in this study were located in 19 to 21 m of water, on the sand flat, which separates the middle and offshore reef terraces. SCUBA diving was used to perform a non-destructive point-count method to visually assess the fish assemblages at both artificial and natural reef sites.
A total of 279 point-counts were performed to characterize the fish assemblages on six vessel-reefs and neighboring natural reefs offshore of Broward County, Florida over 25 months in two intervals (March 2000 to March 2001 and March 2002 to February 2003). This study tested the hypotheses of no difference in fish assemblages between vessel- and natural reefs and also of no difference in fish assemblages between individual vessel-reefs.
In a second study, initial fish colonization on a newly deployed vessel-reef, the Ebinizer II, a 25.5m merchant marine vessel, was studied from May 2002 – February 2004. The ship was scuttled in May 2002 off Broward County, Florida and was censused 13 times during the study period. Adjacent natural reefs and the McAllister, a nearby, 30m vessel-reef deployed in June 1998, were also censused during the same period. This study tested the hypothesis that vessel-reefs simply attract fish from surrounding areas rather than increase fish production. If this was the case, initial fish colonization of the vessel-reef would be primarily composed of adult fishes.
In general, vessel-reefs had significantly greater mean abundance, species richness, and biomass than nearby natural reefs (p < 0.05, Mixed model ANOVA). Vessel-reef fish assemblages were found to be unique when compared to the nearby natural reefs (SIMPER, MDS, ANOSIM) and the trophic structure differed strikingly between the two reef types. Planktivores dominated on vessel-reefs where these fishes may be utilizing food resources and habitat characteristics not accessible from or found at natural reefs. These results support recent research which suggests artificial reefs that provide unique habitat characteristics not found at local natural reefs may develop a distinct fish assemblage. Additionally, observations of recruitment and growth of particular species (e.g., Lutjanus buccanella, Haemulon aurolineatum, Chromis scotti), which was not observed at nearby natural reefs provides evidence for species-specific production at vessel-reef sites.
The initial colonization of the Ebinizer II did reveal attraction of transient piscivores from the family Carangidae, as well as attraction of adult herbivores. However, juvenile fishes dominated (63% of total fish abundance) during the first two sample periods and data from subsequent censuses provided some evidence for continued growth and survival of these recruits. The results also reveal some economically important fish species (i.e. lutjanids and carangids) seem to prefer vessel-reefs, as there was a greater abundance of these species on vessel-reefs than surrounding natural reef areas. Vessel-reef locations are public knowledge and many of these sites are popular fishing spots. The concentration of these valuable species on vessel-reefs should concern local resource managers as these fishes may be exposed to considerable amounts of fishing pressure.
Fish assemblages at natural reef sites within artificial reef permit areas were compared to those found in areas with no artificial reefs nearby (> 1.9 km) to further elucidate the potential effects of attraction. Mean fish abundance, mean fish biomass and mean species richness were greater at natural reefs neighboring vessel-reefs (< 1.9 km away), but were not significantly different from natural reefs with no artificial structures nearby. This suggests vessel-reefs are not simply attracting fish away from neighboring natural reefs. As a whole, the results of my studies demonstrate the importance of species-specific analyses when trying to determine the extent to which attraction and/or production may be occurring at a specific artificial reef.
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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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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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Pearce, Bryony. "The ecology of Sabellaria spinulosa reefs." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/10098.
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Reef habitats built by the tubiculous polychaete Sabellaria spinulosa have been identified as a habitat with significant conservation importance, based on their historic decline across Europe and the assumption that, like many other biogenic reef systems, S. spinulosa reefs enhance biodiversity. Despite the high conservation status of this habitat very little work has been undertaken to explore the role that S. spinulosa reefs play in marine ecosystems, or their sensitivity to anthropogenic disturbance. Observations of the reproductive ecology and population dynamics of the reef building organism indicate that S. spinulosa exhibit life-history traits typically associated with r-strategists, indicating that this species is likely to have the ability to recover quickly following most anthropogenic disturbance events. A series of surveys on S. spinulosa reefs identified at the Thanet Offshore Wind Farm site, where the extent of the reef habitat was found to have increased between the pre-construction and post construction survey despite extensive cable laying and turbine installation, corroborates these findings. Detailed investigations into the macrofauna associated with S. spinulosa reefs in the eastern English Channel revealed that S. spinulosa reefs support macrofaunal communities that are comparable to those associated with adjacent muddy sandy gravel and gravelly muddy sand in terms of species composition, taxonomic breadth and beta-diversity. A consistent enhancement in species richness, abundance and biomass was identified in samples collected from S. spinulosa reefs when compared with adjacent sedimentary deposits, as well as a corresponding reduction in the equitability of species, indicating that some macrofauna are able to exist in higher densities within this habitat. The increase in macrofaunal biomass associated with S. spinulosa reefs was found to influence the diet of demersal fish species, with some species feeding on the reef organism itself while others feed on species found in high densities on the reefs. The high abundance of juvenile flatfish associated with this habitat also suggests that S. spinulosa reefs may provide an important nursery habitat.
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Goldsmith, Ian Robert. "Cementation in modern and ancient reefs." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6748/.
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Lokrantz, Jerker. "Exploring the resilience in coral reefs /." Stockholm : Department of systems ecology, Stockholm university, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26659.
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Webster, Jody Michael. "The response of coral reefs to sea level change: evidence from the Ryukyu Islands and the Great Barrier Reef." Thesis, The University of Sydney, 1999. https://hdl.handle.net/2123/28076.
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This thesis defines the response in two time frames, of individual reefs and coral reef ecosystems to sea-level change, through the bio-geological analysis of such reefs, on both active and passive margins. The raised Holocene reefs at Kikai-jima, Japan (Central Ryukyu Islands, ie. active margin) were examined for horizontal and vertical variation in exposed sections, and in drill core to determine the biological response of reefs to sea level fall. Holocene palaeoclimatic signals from a massive fossil coral at Kikai-jima were also investigated and their implications for reef growth and palaeoceanography discussed. Finally, two high-resolution cores from the Northern Great Barrier Reef (ie. passive margin) were examined to determine the biological response of reefs to repeated sea-level rise and fall over the last ~3 50 ky.
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Scheffers, Sander R. [Verfasser]. "Benthic-Pelagic Coupling in Coral Reefs: Interaction between Framework Cavities and Reef Water / Sander R Scheffers." Aachen : Shaker, 2005. http://d-nb.info/1186577347/34.
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Haas, Andreas. "Coral reefs in a time of change." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-116066.
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Hurley, Tania Dianne. "Sediment-algal interactions on intertidal rocky reefs." Thesis, University of Canterbury. Biological Science, 2009. http://hdl.handle.net/10092/3197.
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Macroalgae are a dominant feature of many rocky intertidal habitats worldwide. An understanding of the processes affecting their growth and survival, especially at early life history stages, is therefore important to an understanding of the structure of rocky intertidal communities. This thesis examines the role that the sediment environment has on habitat-dominating fucoid algae and intertidal community structure. Measurements of sediment flux showed considerable spatial and seasonal variation, while the benthic sediment environment remained relatively stable. Experimental disturbances over 13 months, showed two distinct effects. First, direct effects of sedimentation favoured ephemeral algae and also those with tough thalli. Secondary to this was an alteration of species interactions due to the shifts in community composition. The effect sedimentation has on habitat dominating fucoid algae was also examined with laboratory experiments and outplants of cultured algae. The presence of sediment had a negative effect on the ability of Cystophora torulosa and Hormosira banksii zygotes to attach to the substratum, with even sparse coverings of sediment preventing at least 37% of zygotes attaching to the substratum, and almost a complete recruitment failure with dense coverings of both sand and silt. Sediment and disturbance of turfing communities also influenced early post-settlement survival especially of C. torulosa. Manipulations of the sediment load, nutrient levels and grazer abundance showed the resilience of rocky intertidal communities to the predicted increase in nutrient leaves in coastal waters due to increases anthropogenic intrusion. Most research into the effects of sedimentation have been observational studies and much of the experimental work has been carried out subtidally. My experiments have extended research into the intertidal zone, finding that if sedimentation increases as predicted there will be a consequential loss of habitat dominating fucoid algae and its replacement with sediment tolerant species
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Forsythe, G. T. W. "Construction and ecology of icehouse algal reefs." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599129.
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Tropical reefs, constructed during the late Palaeozoic icehouse climate, suffered high amplitude, high frequency sea level changes (Gondwanan glaciation). Rare three-dimensional outcrops of Virgilian (Pennsylvanian) and Wolfcampian (Early Permian) reefs occur in the Hueco Mountains, Texas. The reefs form part of a highly cyclical carbonate platform succession that suffered repeated emergence. The reefs are dominated by platy 'phylloid algae', these algae may belong to either Rhodophyta or Chlorophyta. The erect, recumbent or cyathiform genus Eugonophyllum is interpreted as belonging to the green algal family Halimedaceae. Eugonophyllum is the dominant reef building alga in the area studied. The prostrate phylloid alga Archaeolithophyllum is interpreted as belonging to the red algal family Corallinaceae. Archaeolithophyllum does not occur in the reefs, but forms extensive biostromes. The dominant constructional mechanism for reef formation has previously been regarded as sediment baffling and trapping, mainly by erect phylloid algae. Analysis of reef ecology clearly shows that these algae were in fact capable of forming a framework, to which considerable stability was added by secondary encrusting organisms such as the problematica Tubiphytes (or Shamovella) and Archaeolithoporella. Complex, multiple encrustations (both in-vivo and post-mortem) of these organisms were a fundamental element of reef construction. The effect of diagenesis on the phylloid algae and Tubiphytes are illustrated. Tubiphytes were found to be commonly altered on the ultrastructural scale, inferred to be by dissolution and reprecipitation, but with some preservation of microstructural features such as laminae.
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Manoukian, Sarine. "Impacts of Artificial Reefs on Surrounding Ecosystems." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3223.
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Artificial reefs are becoming a popular biological and management component in shallow water environments characterized by soft seabed, representing both important marine habitats and tools to manage coastal fisheries and resources. An artificial reef in the marine environment acts as an open system with exchange of material and energy, altering the physical and biological characteristics of the surrounding area. Reef stability will depend on the balance of scour, settlement, and burial resulting from ocean conditions over time. Because of the unstable nature of sediments, they require a detailed and systematic investigation.
Acoustic systems like high-frequency multibeam sonar are efficient tools in monitoring the environmental evolution around artificial reefs, whereas water turbidity can limit visual dive and ROV inspections. A high-frequency multibeam echo sounder offers the potential of detecting fine-scale distribution of reef units, providing an unprecedented level of resolution, coverage, and spatial definition. How do artificial reefs change over time in relation to the coastal processes? How accurately does multibeam technology map different typologies of artificial modules of known size and shape? How do artificial reefs affect fish school behavior? What are the limitations of multibeam technology for investigating fish school distribution as well as spatial and temporal changes? This study addresses the above questions and presents results of a new approach for artificial reef seafloor mapping over time, based upon an integrated analysis of multibeam swath bathymetry data and geoscientific information (backscatter data analysis, SCUBA observations, physical oceanographic data, and previous findings on the geology and sedimentation processes, integrated with unpublished data) from Senigallia artificial reef, northwestern Adriatic Sea (Italy) and St. Petersburg Beach Reef, west-central Florida continental shelf. A new approach for observation of fish aggregations associated with Senigallia reef based on the analysis of multibeam backscatter data in the water column is also explored.
The settlement of the reefs and any terrain change are investigated over time providing a useful description of the local hydrodynamics and geological processes. All the artificial structures (made up by water-based concrete for Senigallia reef and mainly steel for St. Petersburg Beach reef) are identified and those showing substantial horizontal and/or vertical movements are analyzed in detail. Most artificial modules of Senigallia reef are not intact and scour signatures are well depicted around them, indicating reversals of the local current. This is due to both the wind pattern and to the quite close arrangement of the reef units that tend to deflect the bottom flow. As regards to the St. Petersburg Beach reef, all the man-made steel units are still in their upright position. Only a large barge shows a gradual collapse of its south side, and presents well-developed scouring at its east-northeast side, indicating dominant bottom flow from west-southwest to east-northeast. While an overall seafloor depth shallowing of about 0.30 m from down-current deposits was observed for Senigallia reef, an overall deepening of about 0.08 m due to scour was observed at the St. Petersburg Beach reef.
Based on the backscatter data interpretation, surficial sediments are coarser in the vicinities of both artificial reefs than corresponding surrounding sediments. Scouring reveals this coarser layer underneath the prevalent mud sediment at Senigallia reef, and the predominant silt sediment at St. Petersburg Beach reef. In the ten years of Senigalia reef study, large-scale variations between clay and silt appear to be directly linked to large flood events that have occurred just prior to the change.
As regards the water column investigation, acoustic backscatter from fish aggregations gives detailed information on their morphology and spatial distribution. In addition, relative fish biomass estimates can be extrapolated. Results suggest that most of the fish aggregations are generally associated with the artificial modules showing a tendency for mid- and bottom-water depth distribution than for the surface waters.
This study contributes to understanding the changes in artificial reefs over time in relation to coastal processes. Moreover, the preliminary results concerning the water column backscatter data represents progress in fisheries acoustics research as a result of three-dimensional acoustics. They demonstrate the benefits of multibeam sonar as a tool to investigate and quantify size distribution and geometry of fish aggregations associated with shallow marine habitats.
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Hill, Jon. "Modelling of reefs and shallow marine carbonates." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/2610.
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Carbonate sediments are often highly heterogeneous due to the numerous factors that control deposition. Understanding the processes and controls that are responsible for such complexity has, however, proved problematic. In addition, several of these processes are non-linear, so that depositional stratigraphies may consequently form complicated, perhaps even chaotic, geometries. Forward modelling can help us to understand the interactions between the various processes involved. Here a new three-dimensional forward model of carbonate production and deposition is presented, Carbonate GPM, which is specifically designed to test the interactions between the three main carbonate production controls: light intensity, wave power and carbonate supersaturation, the latter of which is unique to this model. The model also includes transport processes specific to the reef sediment only. The effect of supersaturation and reef transport is demonstrated by comparing the output of three, otherwise, identical runs. From these simulations the need to accurately model the flow of water around a reef system and to correctly take into the account the binding nature of reefal sediments can be seen. Analysis of the stratigraphy generated by changing the antecedent topography by 1m in one locality over a 50km square platform suggest that it may be impossible to predict in detail the stratigraphy of carbonate deposits due to its sensitivity to initial conditions or controlling parameters. This reinforces the conclusions reached using previous process models. However, unlike previous models, our model does not explicitly include nonlinear biological interactions as a control. Instead it shows that similar sensitive behaviour may originate from physicochemical processes alone. External factors, such as sea-level changes, will also influence the complex stratigraphy generated by the model. The effect of several different relative sea-level curves was assessed, each corresponding to a combination of three different hierarchies of sea-level oscillations. Large-scale external processes dominate internal processes, dampening their effect on stratigraphy. However, small-scale, high frequency external processes coupled with autocyclic processes do not show any discernable stratigraphic differences from autocyclcic processes alone. The model also produces an exponential cycle thickness distributions that are similar to those found in ancient deposits.
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Paredes, Gustavo Adolfo. "Degradation and recovery of Caribbean coral reefs." Diss., [La Jolla, Calif.] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3356249.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Harris, Daniel. "Physical processes and morphodynamics of coral reefs." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10435.
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Coral reefs are valuable ecosystems due to their ability to support many diverse biological and geological assemblages. They are also of social and economic significance with the Great Barrier Reef (GBR) an important national symbol for Australia and a UNESCO world heritage site. Ecological studies have observed a decline in coral reef health in many parts of the world over the last few decades, due to human pressures (both local and global) in addition to natural variations of the environmental setting. However, the spatial and temporal resolution of most ecological assessments is inevitably limited, particularly on the scales of decadal to millennial coral reef change. Geological studies on the other hand accurately assess coral reef evolution over thousands of years but struggle with small scale changes in geomorphology and biological assemblages. Studies with a geomorphic and morphodynamic focus are required in order to bridge the gap between the ecological and geological understanding of coral reef evolution and provide information regarding the decadal to millennial change in reef geomorphology and carbonate production. In spite of this, physical process studies on coral reefs are few, particularly when compared to siliciclastic settings (such as estuaries and beaches) with a limited understanding of the mechanisms initiating geomorphic change in coral reef systems. The physical processes (waves and currents) acting on a coral reef windward platform and back-reef sand apron were assessed, along with morphological surveys and sedimentologic and chronostratigaphic reconstruction of sand apron evolution. Dating of dead patch-reefs buried by sand apron accretion was conducted in order to examine long-term sand apron evolution. Sampling and dating of fossil micro-atolls was also conducted in order to establish potential sea level history for the southern GBR. The sand apron geomorphology was shown to have channel formations as well as shallower areas which were associated with buried patch reefs. These features affected current flow on the sand apron with channels directing current off the sand apron, mainly during ebb tides (ebb dominated), into the lagoon or towards the reef crest and the shallow areas which were dominated by lagoonward directed flow across the sand apron (flood dominated). This is similar to the processes in siliciclastic environments, such as estuaries, and indicates that morphodynamic relationships between current flow and geomorphology occur in coral reef environments. In spite of this, average current flow did not exceed the required velocity to entrain sediment; sediment entrainment was only caused by short term peaks in current due to waves. These results showed that sediment entrainment under modal low-energy conditions does occur in back-reef environments; albeit on a small scale (only 3.5% of all recorded waves could entrain sediment). Most entrainment occurred at higher tidal stages (when depth over the reef platform (hd > 1 m) when potential mobility PM of sediment could be up to 40%. Spatial variation in PM and significant wave height (Hs) were found to extend beyond cross-reef attenuation of wave height and energy. The attenuation of Hs across the sand apron could be reasonably described based on the changes in offshore wave height, depth over the reef platform, and cross-reef distance from the reef rim (Xd). However, these variables could not explain along-reef trends within the data. To assess the along-reef variation in wave characteristics an additional distance value was introduced (Xpd) which combined the cross-reef distance to the reef rim (Xd) and the along-reef distance from the initial point of wave refraction on the reef rim (Xp). Spatial changes in wave height, PM wave velocity and grain size correlated with changes in Xpd. An empirical model was developed which could calculate wave height based on a few basic inputs of offshore wave weight, offshore wave direction, Xd and Xp. This model can be used in windward reef environments to not only assess the spatial variation in wave characteristics but also potential areas of sediment mobility and trends in sediment grain size. Radiocarbon ages and elevations of the fossil micro-atolls show that relative sea level was between 1-1.3 m higher than present between 3800-2200 cal. yr. BP. This data set is the first direct constraint through fixed biological indicators on sea level during the Holocene highstand in the southern GBR. These dates suggest that the Holocene sea level for the southern GBR follows a similar trend to current sea level curves for the east Australian coastline where the Holocene highstand was between 7000-2000 cal. yr. BP before falling to its present level. Rapid sand apron development occurred between 6000-2000 cal. yr. BP with most of the sand apron established during this period. Little or no sand apron development has occurred in the last 2000 years. This correlates with the micro-atoll data in this thesis and the sea level fall observed in previous studies at approximately 2000 cal. yr. BP. The fall in sea level caused an ecological shift on the reef platforms from live coral to algal dominated turning off the majority of carbonate production. It is likely that this led to a hiatus in sand apron development that has persisted for 2000 years. A conceptual model was developed that describes the non-linear lagoonal infill and sand apron development during the Holocene due to variations in sea level. In this model, rapid development of both reef platforms and back-reef sedimentary formations initially occurred during catch-up reef growth phase or when the windward margins reached sea level. This highly productive state may persist if sea level remains consistent and allows for productive live coral growth on reef platforms. A fall in sea level strands live coral on the reef platforms, leading to a turn-off of carbonate production and sediment input resulting in a reduction in the rate of lagoon infill. This conceptual framework has significant consequences for traditional reef growth models which generally show linear trajectories of reef evolution and also for assessments of coral reef response under future climate change predicted variations in sea level.
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Metallo, Amber C. "A Comparison of Macroinfaunal Community Structure between Artificial Concrete Boulder Reefs and Adjacent Natural Reefs in Broward County, Florida." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/395.
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Relatively little is known about either the biological (i.e., predation) or physical (i.e., current, sedimentation) effects that artificial reefs may have on surrounding benthic infaunal communities. Following deployment of artificial reefs (concrete boulders) between the first and second reefs off Fort Lauderdale, Florida, on 30 October 2009, sediment cores were taken at 4 distances along three replicate 10-m transects on 13 and 26 September 2013, and 24 and 25 May 2014 at each of four artificial reef sites and four of their adjacent natural reef sites using SCUBA. Infauna (>0.5mm) were extracted from the sediment and identified to the lowest possible taxonomic level. Statistical analysis (PRIMER, PERMANOVA, SIMPER) focused on four main variables: type of reef, year, site, and distance. Type of reef, year, and site was significantly different between samples, while distance did not affect density. There is a clear separation of communities between the artificial and natural reefs. From 2013 to 2014, a slight shift occurred between communities suggesting the artificial reef community composition became slightly more similar to the natural reef. All four artifical reef sites were more taxonomically distinct at the phylum and class level then the natural reef, which had higher diversity, higher species richness and more low-density taxa. This two year study provides insight on infauna communities four and five years out from deployment, but follow up monitoring in 3-5 years could shed light on whether these patterns of shift to more similar assemblages between reefs will continue as the artificial reef matures. Environmental data collection including longer time-series datasets, longer transects, and physical and geological data could provide more knowledge of how the artificial reef infaunal communities are changing over time.
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Siciliano, Daria. "Latitudinal limits to coral reef accretion : testing the Darwin point hypothesis at Kure Atoll, Northwestern Hawaiian Islands, using new evidence from high resolution remote sensing and in situ data /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.
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Fonseca, Carolyn E. "The value of Fijian coral reefs by nonusers." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29691.
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Thesis (Ph.D)--Public Policy, Georgia Institute of Technology, 2010.Committee Chair: Noonan, Douglas S.; Committee Co-Chair: Norton, Bryan; Committee Member: Bowman, Kirk; Committee Member: Fox, Mary F. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Kennedy, Emma Victoria. "Climate change impacts on Caribbean coral reefs : reef accretion and scope for acclimation through symbiont genetic diversity." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13142.
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Caribbean coral reefs are in crisis. Degradation of living coral and fish assemblages has accelerated during the past half century, with a suite of anthropogenic drivers –from local fishing pressure to unprecedented global scale climate change– implicated. Accompanying these losses is the physical disintegration of the three-dimensional calcium carbonate reef structure. Flattening of reefs, synonymous with loss of ecosystem function and provision of services, is caused by an imbalance in the carbonate budget: a trade-off between carbonate production and consolidation by calcifying organisms (principally coral-algal symbioses) and framework breakdown by bioeroding organisms and storms. This thesis focuses on expanding our understanding of two functionally critical issues that strongly influence Caribbean coral reef community composition and dynamics, and which look likely to have a key bearing on the future state of reefs in the region: coral photosynthetic endosymbionts, and carbonate budgets. The former exert an important role in the production of the coral carbonate framework, whilst the latter reflect the dynamics of reef carbonate production and erosion. In the first part of the thesis, existing information on rates of carbonate production and erosion on Caribbean reefs is utilised to construct a detailed theoretical carbonate budget model. The model is used to chart historic changes in Caribbean carbonate budgets, tracking reef flattening across time and identifying key ecological drivers of these changes. This “eco-geomorphic” model is then coupled with state-of-the-art climate and ecological models, to project reef processes to the end of the century, asking the question ‘at what point will Caribbean reefs shift to net erosional regimes?’. The models are also used to explore the efficacy of local management and climate mitigation in altering the negative trajectory of reefs under projected warming and ocean acidification. In the second part of the thesis, 632 corals from across the wider Caribbean are screened, to construct the largest recorded baseline of symbiont biogeography for the region’s key remaining reef framework builder, Montastraea annularis. Spatial patterns of symbiont diversity are explored in terms of environmental, geographic and genetic factors, contributing to the growing body of work currently in the early stages of cataloguing symbiont diversity and its ecological significance. Although carbonate budget models forecast a bleak outlook for the Caribbean, detection of widespread low-level prevalence of thermally-tolerant endosymbionts in M. annularis provides a weak ‘nugget of hope’ for potential coral acclimation. Combined local management and aggressive mitigative action on carbon emissions are pre-requisites for maintenance of functioning reefs into the next century. Coral reef conservation efforts can be improved if we fully appreciate the contributions of all reef components –not just the enigmatic ones– to healthy reef functioning.
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Patranella, Allison. "Artificial Reefs as Juvenile Fish Habitats in Marinas." NSUWorks, 2016. http://nsuworks.nova.edu/occ_stuetd/423.
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Coastal infrastructure has replaced many vital fish nursery habitats with structures designed without fully mitigating for the loss of the natural ecosystems. This thesis details research focused on the use of small, inexpensive, artificial reef modules as replacement juvenile fish habitat within marinas. My research hypothesis was that the placement of small, structurally complex artificial reef modules would increase fish abundance and species richness relative to unmodified marina seawalls. Non-destructive visual surveys of fishes were completed monthly for 14 months for 12 artificial reef sites and 12 control (unmodified) sites within the Nova Southeastern University Guy Harvey Oceanographic Center (NSU-GHOC) marina. Divers recorded species, abundance, and size class (0-2 cm, >2-5 cm, >5-10 cm, >10-20 cm, >20-30 cm, >30-50 cm, >50 cm) for all sites. Data was statistically analyzed using analysis of variance (ANOVA) and post-hoc Student Newman-Keuls (SNK) tests to explore differences in mean abundance, mean species richness, and mean abundance and species richness by size class and month. Total mean fish abundance and mean species richness (all months and sizes combined) were both significantly higher at artificial reef sites than at control sites. Artificial reef sites were consistently higher in total abundance and species richness when analyzed by month. Analysis of mean abundance by size class found the >2-5 cm, >5-10 cm, >10-20 cm and >20-30 cm classes were significantly higher for artificial reef sites. Species richness analysis by size class found classes >2-5 cm, >5-10 cm, >10-20 cm, and >20-30 cm were significantly higher at artificial reef sites. Fishes from the grunt (Haemulidae) and snapper (Lutjanidae) families contributed the most to the total abundance for both types of sites. These results support my hypothesis and have important implications for mitigating ecological impact to coastal fish nursery areas with the use of artificial structure.
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Epstein, Nimrod. "Coral reefs aspects of management, conservation and restoration /." Amsterdam : Amsterdam : Universiteit van Amsterdam ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/62020.
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Wirt, Katherine. "Potential Habitat of Acropora spp. on Florida Reefs." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3411.
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Elkhorn and Staghorn corals (Acropora palmata, A. cervicornis) were listed as threatened species under the Endangered Species Act (ESA) in 2005. The threatened status of these species is unprecedented given the vital role they historically played as major constructors of western Atlantic and Caribbean coral reefs. The goal of my study was to evaluate the current extent of habitat of the two species using a database of reported in situ observations. From these observations, potential habitat maps were produced based on benthic substrata and depth parameters throughout the Florida reef tract using GIS software. Locations of 99% of A. palmata observations and 84% of A. cervicornis observations coincided with previously mapped reef or hardbottom habitat. These results indicate that potential habitat for A. palmata is currently well defined and that potential habitat for A. cervicornis is more variable than that for A. palmata.
This study provides a starting point in the creation of a revised critical habitat delineation for Acropora spp. in Florida. Using the mapped reef and hardbottom classifications throughout the Florida reef tract, probable habitat maps were generated using buffers that incorporated 95% and 99% of reported observations of colonies of Acropora spp. One of the most important differences between the previously generated critical habitat map and the new probable habitat map is observed in the southeast Florida region, where probable habitat extends further north than critical habitat and, thus, encompasses additional habitat for A. cervicornis and potentially A. palmata.
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Rose, Craig. "Modelling and measuring the habitat of artificial reefs." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417518.
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Hart, Sean Fraser. "Palaeoecology of Lower Cambrian and Lower Ordovician reefs." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361669.
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Al-Bouraee, Yassir. "Numerical modelling of the flow about artificial reefs." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2325.
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Artificial reefs have been serving the world in many fields, such as protecting beach erosion, enhancing recreational fishing, surfing and fostering biotic diversity, for many years. One major use for an artificial reef is to deploy it effectively to attract and aggregate fishes and marine life organisms for commercial and scientific purposes. The global hydrodynamic conditions in the vicinity of an artificial reef dictate its structural design (reef stability etc) and the nature of its large scale environmental impact (sediment transport and erosion etc), as well as its operational characteristics. On the West Coast of Scotland an artificial reef was deployed under the direction of Dunstaffnage Marine Laboratory in 2001. It was designed by the fishing industry to promote the economic potential of reef-based fisheries such as the European Lobster (Homarus gammarus (L.)). The size of the reef site equates to about 50 football pitches. There are forty two artificial reefs, comprising two different types of reef module, and 25,000 tons of concrete blocks have been used to create each one of them. However, the investigation of global hydrodynamics requires solving the tidal flow in Loch Linnhe. A numerical model has been adopted to solve the 2D shallow water equations using a Finite Volume Godunov-type scheme. The scheme has the ability to deal with complicated topography such as Loch Linnhe. The initial and boundary conditions of the two-dimensional numerical model were imposed using tidal records obtained from the UK Hydrographical Office for the inlet and outlet of the Loch. A tidal field measurement was carried out using ADCP (Acoustic Doppler Current Profiler) instruments for the purposes of input to the model as well as its validation. These instruments were positioned on location near a group of artificial reefs to gather tidal wave elevations and currents profiles. The results of a two-dimensional numerical model were compared with the data given by the ADCP instruments and tides gauges station in the Loch. A good agreement was observed between the numerical model and data measurement taken from ADCP. The result of the two-dimensional numerical model indicates the ability of the model to represent the complex tidal conditions in the region convincingly. The local hydrodynamic conditions dictate flow separation and the production of turbulence generating eddies and vortices over a range of scales. This, in turn, determines the water quality characteristics, such as the oxygen content, and settlement patterns over the reef and regions favourable, or otherwise, to fish activity (predation, evasion, congregation etc). For these reasons, a reliable procedure for determining the hydrodynamics of local and global of flows about artificial reefs is an essential prerequisite to their satisfactory design. The ADCP instruments were placed in three locations over a complete spring-neap tides cycle around a selected reef to investigate the three-dimensional hydrodynamics affecting it. The RNG k-e turbulent model based on Fluent CFD (ANAYSIS 13) was matched to the global flows output from the shallow water flow model and used to simulate the hydrodynamic forces and flow fields with different flow velocity profiles of the tidal currents. The tidal current dynamics profile over a complete daily spring tidal cycle was investigated to identify the flow regimes on the reef. The results of the numerical model were compared with the data gained from the ADCP beside the chosen artificial reef.
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Sherman, Robin L. "Studies on the Roles of Reef Design and Site Selection in Juvenile Fish Recruitment to Small Artificial Reefs." NSUWorks, 2000. http://nsuworks.nova.edu/occ_stuetd/73.
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Although there is a long history of artificial reef use, little statistically verifiable experimentation has been done examining questions about artificial reef functionality. In a series of four studies using small artificial reefs as models, I examined the effects of manipulation of: refuge size, resident fishes, complexity, attractants, and site selection on fish recruitment and fish assemblage formation.
Each study was conducted over 18 to 24 months by divers on SCUBA doing visual censuses monthly with the exception of one study which was censused quarterly. During all censuses, fishes within 1m of the reef were identified to species, individuals were counted, and all fishes were assigned to one of five size classes (0-2, 2-5, 5-10, 10-20, and 20+ cm total length). Mean total lengths were used to calculate biomass using published length-weight relationships.
Using Rinker reef modules, a multilevel reef design with high internal complexity, deployed on sand substrate at 21m depth, I examined the effects of resident fishes on fish recruitment and overall fish assemblage formation, and secondarily, compared the results of my study to those of a similar study done at a different depth (7m), nearby. There were significant differences in recruit abundance (fishes <5 cm TL), total fish abundance, and species richness between treatments at the deep site as well as differences between the deep and shallow sites. Results of my study indicate that reef fish recruitment in Broward County water is likely not resource limited but may be driven by larval limitation or post-settlement predation. This finding, however, may be site specific. Comparison with the other study indicates differences between sites in fish abundance, juvenile abundance, species richness, and species composition.
Using Reef Ball™ artificial reef modules, hemisphere shaped reefs with a large central void space and 18 side holes, I examined differences in recruitment and fish assemblage formation on identical reefs at different depths (21m and 7m), approximately 1.5km apart. There were significant differences between sites for species richness, fish abundance (all species combined, >5 cm TL), juvenile abundance (fishes <5cm TL), and biomass. Results indicate greater juvenile (fishes <5cm TL) abundance at the shallow site but greater overall fish abundance and greater species richness deep. These results suggest important site dependent differences in both juvenile recruitment and overall fish assemblage formation.
Swiss Cheese reefs, concrete cubes with 12 tunnels of varying sizes through them, were used to examine the effects of refuge size and complexity on recruitment and assemblage formation. Significant differences were found between treatments for large fish abundance (>20cm TL), total fish abundance, and species richness. Results of this study support the importance of refuge size in both recruitment and overall fish assemblage formation, with more fishes of all size classes on large refuge reefs than small. However, there was no statistical support for a role for complexity (two refuge sizes) versus single refuge size in fish assemblage formation.
Using Reef Ball™ artificial reefs I examined the effect of floating a single, 10m, poly-propylene line suspended over the reef module. In this case, there was no significant effect of using this type of attractant. The second part of the study examined the effect of complexity versus void space on recruitment and assemblage formation by adding concrete blocks to the internal void space in the Reef Balls. In this study there was significantly greater fish abundance, juvenile abundance, and species richness on the modules with concrete blocks. These result support a clear-cut role for internal complexity in fish recruitment and overall assemblage formation.
Overall, results of this multi-part study provide important new information about the effects of various design and functional attributes of artificial reefs. In particular, the importance of complexity in design, and site selection, on recruitment and assemblage formation was further clarified.
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Wallace, Amy. "Dynamics of Stony Coral Assemblages on Patch Reefs of the Upper Florida Reef Tract, Including Biscayne National Park." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3400.
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The patch reefs located in Biscayne National Park (BNP) are some of the most northern reefs of the Florida reef system. The focus of my study is seven patch reefs that were first surveyed annually between 1977 and 1981, revealing 8% - 28% cover by scleractinian corals. An assessment of BNP patch reefs completed in 2000 reported that coral cover had decreased to approximately 0.4% - 10%. The once dominant species in the Florida reef tract, Acropora palmata and A. cervicornis, have rapidly declined over time and were not found in any transects during the 2000 survey.
This study is a re-assessment of the BNP patch reefs surveyed in 1977-1981. In addition, one patch reef from BNP and three in upper keys region of the Florida Keys National Marine Sanctuary (FKNMS) have been included (a total of 11 patch reefs, all with historical data available). This study found 2% - 13% coral cover at these 11 reefs using a photographic survey (Point Count) and 4% - 21% coral cover using Atlantic and Gulf Rapid Reef Assessment (AGRRA) survey methods. These results are relatively similar to results reported for the same patch reefs in the 1990s and in 2002, indicating that the major changes occurred earlier with the extreme decline in Acropora spp. Montastraea annularis complex cover has also declined substantially at the BNP sites from 5.4% in 1977-81 to 1.3% in 2009.
Although the number of species recoded on the seven resurveyed BNP patch reefs was only 23, compared with 28 recorded in the 1977-81 study, all species are still present in the region surveyed, indicating no actual loss of over all species richness.
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Widman, Elizabeth. "Trait similarity vs species similarity in coral reef ecology : test of improved monitoring methods using Southwest Madagascar reefs." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/57082/.
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Trait-based approaches are emerging in various fields of ecology, and are here developed for coral reefs. ‘Traits’ means biological characteristics of each species; thus closely related species may have different traits and distantly related species may share common traits. This promotes understanding of a system better than using species alone. Chapter One summarizes existing methods, mostly from plant ecology, explores their utility for corals, and an extensive review then extracts candidate Scleractinian traits (Chapter Two). A dataset of 26 key traits from 231 species from Southwest Madagascar was then collected using 68 reefs of several typologies along several natural and ‘use’ gradients (Chapter Three). This used over 7,000 photo-quadrats on reefs spanning over 200 km (Chapter Four). Trait-based approaches require species-level identification. However, where species are difficult to distinguish, a species-replacement methodology facilitated translation of species to trait-combinations (Chapter Four). Inter-specific trait similarity between the 231 corals and their 26 traits is examined (Chapter Five). In total, 13 groups of corals with highly similar trait-combinations were identified, in which species are functionally equivalent and which therefore can be considered as functionally interchangeable parts in the ecosystem. However, because one quarter of species had unique trait combinations, a functional group approach to surveying reefs may not adequately describe existing trait diversity. Therefore a methodological alternative to using functional groups alone was developed. A trait-based similarity coefficient (Tsim) was developed to take into account both species and trait combination similarities between reefs (Chapter Six). A R-based package that calculates and visualizes Tsim is provided. Tsim’s characteristics were compared to species-based coefficients (Renkonen similarity). Tsim identifies functionally similar reefs missed using species identity alone (Chapters Six and Seven), and can be used to determine reefs that have highly similar trait combinations while being very dissimilar in terms of species.
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Bries, Jill M. "The impact of hurricane Lenny on coral reefs and its relevance to pleistocene reef communities Curacao, Netherlands Antilles /." Cincinnati, Ohio : University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin990629881.
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Bartlett, Lucy. "Dynamics and Survival of Coral and Octocoral Juveniles following Disturbance on Patch Reefs of the Florida Reef Tract." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5342.
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Over the past several decades, rapid decline in adult stony-coral (comprising the Orders Scleractinia and Anthomedusae, specifically Family Milleporidae) cover has occurred concurrent with an increase in adult octocoral (Octocorallia/gorgonian) cover along the Florida Reef Tract. In January 2010, the Florida Keys experienced extremely cold air and water temperatures, below the lethal threshold for many reef organisms including corals. Very high stony-coral mortality occurred on some patch reefs. The newly-available space created by this disturbance event provided the opportunity for recruitment and settlement of new coral larvae and other reef organisms.
The goal of this study was to examine post-disturbance recruitment and survival of juvenile stony corals and octocorals on patch reefs in the Middle and Upper Florida Reef Tract. Permanent quadrats were established at eight patch-reef sites. Stony-coral and octocoral juveniles, visible to the naked eye and having a maximum 4 cm diameter for stony corals or 4 cm height for octocorals, were identified, measured, and photographed to track each colony through spring and fall for two years. Juvenile densities increased significantly over that time; octocoral density increased with higher significance (p
Opportunistic and/or hardy organisms are re-populating patch-reef sites, whereas slower growing, massive stony-coral species are declining. When a reef environment is plagued with chronic stressors, such as terrestrial runoff, overfishing, high temperature fluctuations and turbidity, the succession process may be inhibited following acute disturbances such as cold-water events. Patch reefs of the Florida Reef Tract now appear to be caught in a perpetually disturbed state, which supports opportunistic and hardy taxa and inhibits recovery of slower-growing climax taxa that dominated until the past few decades.
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Edinger, Evan Nathaniel. "Effects of land-based pollution on Indonesian coral reefs : biodiversity, growth rates, bioerosion, and applications to the fossil record /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ42843.pdf.
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Lee, Hing-kong Edwin. "Methods to assess fisheries enhancement by the deployment of artificial reefs (a case study at Hoi Ha Wan, Hong Kong) /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22264048.
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Gustafson, Steven K. "Assessment of Image Analysis as a Measure of Scleractinian Coral Growth." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3768.
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Image analysis was used to measure basal areas of selected colonies of Montastraea annularis and Porites astreoides, following the colonies over a three-year period from 2002 to 2004. Existing digital images of permanently-marked quadrats in the Caye Caulker Marine Reserve, Belize, were selected based on image quality and availability of images of selected quadrats for all three years. Annual growth rates were calculated from the basal-area measurements. Mean growth rates (radial skeletal extension) for M. annularis and P. astreoides were 0.02 cm yr-1 and -0.20 cm yr-1, respectively. Basal area measurements demonstrated a large degree of variability. Increases were approximately balanced by declines giving the impression of stasis. By removing negative values and correcting by 25% to allow for comparison with vertical growth rates, mean values increased to ~0.5 cm yr-1 for M. annularis and ~0.8 cm yr-1 for P. astreoides.
Basal area as a growth measure was compared to methods used in earlier studies. A new growth index based on basal area and perimeter was proposed and modeled. This growth index can be useful for reporting growth measured from basal areas and comparable other methods. The index also measures negative growth, or mortality, which conventional methods cannot do.
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McCarthy, Daniel Anthony. "Life history patterns and the role of disturbance in intertidal and subtidal populations of the polychaete Phragmatopoma lapidosa lapidosa in the sub tropical western Atlantic." Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251828.
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Macdonald, Iain Andrew. "Reef growth and framework preservation in a turbid lagoon environment, Discovery Bay, North Jamaica." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288141.
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Slingsby, Shauna N. "Patterns of association and interactions between juvenile corals and macroalgae in the Caribbean /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/slingsbys/shaunaslingsby.pdf.
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Dechnik, Belinda. "Evolution of the Great Barrier Reef over the last 130 ka; a multifaceted approach, integrating palaeo ecological, palaeo environmental and chronological data from cores." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15488.
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Over the last few decades there has been a significant decline in the health and diversity of modern reefs globally. High resolution millennial scale records of coral reef response to environmental per- turbations are needed to determine if this decline is the result of recent anthropogenic activity, or represents part of a natural longer-term geological cycle. Hence, a range of multi-proxy palaeode- positional indicators (coralgal assemblages, sedimentary facies and associated biota) were integrated with chronologic data, to provide a greater understanding of the geologic and ecologic factors which controlled reef development during the Holocene and Last Interglacial (LIG). This constitutes the most comprehensive regional chronologic and ecologic investigation of mid-outer platform reefs, in the Great Barrier Reef (GBR) over the past 130 ka. Fifteen pre-existing long cores (< 40 m) and thirty-four new short cores (< 2 m) were examined, providing greater constraints on coral reef response, tolerance and thresholds to major palaeoenvironmental changes, on millennial timescales within glacial and interglacial cycles, over the past 130 ka. Using quantitative surveys of key modern coral reef biota (coral, coralline algae, vermetid gastropods) at a GBR representative study site (One Tree Reef), in combination with similar coralgal assemblages from elsewhere in the Indo- Paci c, palaeodepositional constraints on analogous fossil coralgal assemblages were determined for both Holocene and LIG reefs. Using these assemblages in conjunction with sedimentary facies, 85 new U/Th and 21 new 14C-AMS ages and a re-analysis of all existing radiocarbon data (n = 266), the palaeoenvironmental conditions and subsequent biologic and geologic response of reefs to repeated transgressive and highstand events, between the last two interglacial's (i.e Holocene and LIG) was determined. Using a qualitative re-investigation of fteen cores from the Southern GBR a distinct delay of 0.7-2 ka was observed between substrate fooding and fi rst colonisation of reef communities (8.3 0.04 to 7.6 0.03 ka), providing robust new constraints for the Holocene 'turn-on' in the Southern GBR. Higher input of ne siliciclastic material from regional sources, exposure to hydrodynamic forces and colonisation in deeper waters were identi ed as the main factors impeding initial reef growth. Distinct shallowing upwards sequences, previously masked by more simpli ed sedimentary facies classi cations (ie. branching, massive etc) were also identi ed, in response to initial inimical conditions and re- duced accommodation space following the stablisation of sea level, approximately 7 ka. Furthermore, these results show that the development of reefs analysed in this study satisfy only some of the key elements and predictions used to de ne a reefs nal evolutionary state (juvenile, mature or senile), with size and shape of the antecedent substrate having a greater e ect than substrate depth alone. The response of mid-outer platform reefs to the Holocene stillstand including; the timing of when they rst approached sea level and the direction, rate and continuity of reef flat accretion was also investigated, using closely spaced reef core transects at Heron and One Tree Reefs and including a meta-analysis of all available previously drilled reef flats (n=27) across the GBR from 14 to 25 S. Results from Heron and One Tree showed the reef flats fi rst approached present mean sea level (pmsl) 6 ka where growth was then dominated by lateral accretion. Hydrodynamic energy was identi ed as the main driver of accretional direction across all reef flats analysed, based on normalized wave fetch scenarios and typical wind patterns, with exposed reefs accreting primarily lagoon-ward and protected reefs accreting seawards, contrary to the traditional growth model in the GBR. Lateral accretion rates varied from 86.3 m/ka - 42.4 m/ka on the exposed One Tree windward reef and 68.35 m/ka - 15.7 m/ka on the protected leeward Heron reef, suggesting that wind/wave energy is not a dominant control on lateral accretion rates. A distinct hiatus in reef flat growth from 3.6 ka 0.1 to 1.6 0.2 ka was also observed from all available mid-outer reef flat ages, with the exception of the central GBR. Increased upwelling, turbidity and cyclone activity, in response to increased SST's, precipitation and ENSO variability, were ruled out as possible mechanisms of reef turn o . A relative fall ( 0.5 m) in sea-level at 4-3.5 ka was the most likely explanation for why reef flats in the northern and southern regions turned o during this period. Greater hydro-isostatic adjustment of the cen- tral GBR and long term subsidence from the Halifax basin, provided greater vertical accommodation space for the mid-outer platform reefs of the central GBR, allowing these reefs to continue to accrete vertically despite a relative fall in sea level 4-3.5 ka. Thus, these results not only provide important information about possible reef flat hiatuses in response to natural environmental change, but also provide insights into the stability of relative sea level along the east Australian margin following the Holocene post-highstand fall. Thirty-nine new mass spectrometry ages in conjunction with palaeoecological and sedimentologi- cal data from seven LIG platform reefs across the northern, central and southern GBR, are reported. These results provide the rst closed system ages (128.7 0.7-126.1 0.8) for the pre-Holocene reef, con rming growth during the LIG. Combined with our new open-system model ages, we are now able to constrain the interval of signi cant LIG reef growth in the southern GBR to between 128.7 0.7 and 120.9 0.6 ka. Using the chronological, sedimentologic and coralgal assemblage data in the context of newly derived glacial-isostatic adjusted (GIA) sea level models, a new conceptual model for the LIG reef development of the GBR is proposed. Three main growth phases were de ned, including a possible near drowning event at 129 ka. Moreover, this study provides the rst, GIA-corrected relative sea level predictions for the GBR during the LIG, suggesting a peak relative sea level of 6 to 11 m above pmsl. Lastly the high resolution coralgal assemblage information developed in this thesis provides the rst detailed regional comparison of reef response, from the northern to the southern GBR, over longer term (>10 ka) geological timescales. Results suggest that the palaeoenvironments during the initial turn-on phases of the two interglacial intervals (Holocene and LIG) were signi - cantly di erent. However, similar composition of ultimate shallow-water coralgal assemblages and slow reef aggradation rates following stabilisation of sea level, suggest both the LIG and Holocene reefs developed in a similar way as they approached mean sea level. These results further suggest that if rapid sea level rise were to occur in the future, similar to that at the onset of the LIG and in combination with other environmental stresses (e.g. warmer SST, increased turbidity, ocean acidi - cation, increased bleaching, excess nutrient runo ), the GBR may experience a near drowning event analogous to that experienced during the LIG.
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Shinohara, Aya. "Competition Among Juvenile Acropora on Shallow Reefs, Okinawa, Japan." NSUWorks, 2004. http://nsuworks.nova.edu/occ_stuetd/273.
Full textAbstract:
The processes structuring coral communities involve many factors including recruitment dynamics, competitive interactions, and acute and chronic disturbances. The shallow reef at Sunabe (Okinawa, Ryukyu Islands, Japan) was dominated by a dense cover of mainly Acropora spp. until the bleaching event in 1998, when most colonies died. Subsequent monitoring of the community showed that the number of juvenile colonies was high in 2000 and competition among these colonies may affect community dynamics. The aim of this study was to determine the possibility of predicting community change and recovery, using short-term observation data of size-specific mortality and growth rates of coral recruits. Predictions were made using a demographic model based on a Leslie-matrix approach with data collected on the shallow reefs of Sunabe in 2000. This existing data showed a tendency of high mortality of competing colonies, but with no significant difference among species. Over the period of 2000-2004 percent cover of Acropora sp. increased from 16% to 22% however the number of colonies decreased (from 6.5 per quadrat to 2.5 per quadrat). The prediction of size fraction derived from the matrix population model and the observed size fraction based on the 2004 data showed some agreement; however the model predicted a high number of colonies in the largest size class. There were no adult colonies in 2000. A known bleaching event in 2002, causing mortality of reproducing adult colonies (high mortality and low growth rates) is most probably the reason for the disagreement between is the matrix model-based prediction and the observed community structure. Therefore, it is suggested that one more size class is add to the model, representing reproducing colonies. It is also suggested that further improvement of the model is needed for disturbances (such as bleaching, typhoon, and mass predation events). Despite these suggested improvements, the model presented here shows that it is possible to use simple community data taken over the course of 1 year to predict short-term community size class dynamics and population growth on juvenile Acropora spp. dominated reefs. Thus, such investigations have practical value for the management of coral resources.
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Mörk, Erik. "Macroalgal community dynamics on coral reefs : Implications for management." Doctoral thesis, Stockholms universitet, Systemekologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-48281.
Full textAbstract:
Although rather inconspicuous on healthy coral reefs, macroalgae form the basis of coral food webs. Today, macroalgae are generally increasing and many reefs undergo transitions from coral to macroalgal dominance resulting from e.g. enhanced nutrient loading or increased fishing. This thesis aims to investigate the relative importance of top-down and bottom-up regulation, and different herbivore types, on macroalgal distribution, fecundity and community composition on coral reefs. Papers I and II indicate that macroalgal abundance in a coral reef system is largely governed by top-down regulation through grazing by herbivores, while bottom-up regulation through enhanced nutrient availability rather influence algal species composition. Paper II also shows that these regulating effects are not as evident in an area with relatively strong water motion, suggesting that impacts of anthropogenic disturbance may be site-specific. Paper III shows that herbivory is an important factor influencing macroalgal growth and subsequent reproduction. Furthermore, Paper IV and V conclude that efficiency in removing macroalgal biomass is dependent on the type of dominant herbivore, where sea urchins seem to be more effective than fish. Paper IV indicates a seasonal variation in macroalgal biomass and distribution in a small geographic scale but with relatively high temporal resolution. Paper V on the other hand shows these same effects, but with a focus on geographic variation, including a large part of the East African region, as well as between year temporal variations in Kenya. Together, results from the two latter studies indicate that herbivory by fish may not be able to prevent a macroalgal bloom in a degraded system where substrate availability for algal colonization is high, but that it may still facilitate coral recovery over time. Thus, a large algal biomass may not necessarily indicate a reef beyond the possibility of recovery.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted. Paper 4: Manuscript. Paper 5: Manuscript.