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1
Hill, Ross. "Coral bleaching : photosynthetic impacts on symbiotic dinoflagellates /." Electronic version, 2008. http://hdl.handle.net/2100/526.
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University of Technology, Sydney. Faculty of Science.Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. This involves the expulsion of the symbiotic dinoflagellate algae, known as zooxanthellae, from the coral host. Coral bleaching is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. This thesis examined a number of sites within the light reactions of photosynthesis and evaluated the efficiency of photoprotective heat dissipating pathways. Upon expulsion, the capacity for long-term survivorship of expelled zooxanthellae in the water column was also assessed. A reduction in photosystem II (PSII) photochemical efficiency during exposure to elevated temperature and high light (bleaching conditions) was found to be highly dependent upon the increase in abundance of QB non-reducing PSII centres (inactive PSII centres), indicating damage to the site of the secondary electron acceptor, QB, resulting in a limited capacity for its reduction. Therefore, this reduced the rate of the reoxidation of the primary electron acceptor, QA-. Fast induction curve (FIC) analysis of the rise from minimum fluorescence to maximum fluorescence revealed a lower amplitude in the J step along this curve, which was consistent with a reduction in the rate of QA reoxidation. This photoinhibition of PSII was found to occur once the effectiveness of excess energy dissipation through energy-dependent quenching and state-transition quenching was exceeded, suggesting that these mechanisms were incapable of preventing photodamage. Antenna size heterogeneity showed little change under bleaching conditions with a significant increase in PSIIbeta only apparent in one species of coral. The thermostability of the oxygen evolving complex (OEC) and thylakoid membrane were found to increase during exposure to bleaching conditions and exceeded bleaching thresholds of corals. This rapid rise in temperature-dependent thermostability also occurred over seasons, where variation in ocean temperatures was matched by gradual shifts in OEC and thylakoid membrane thermotolerance. Variation in thermostability between species was not found to be linked to zooxanthellae genotype, and instead was related to the bleaching susceptibility of the host. Despite this capacity for resilience to bleaching conditions, the PSII reaction centres did not exhibit such a mechanism for rapid acclimatisation. Corals can only be as tolerant to bleaching conditions as their most sensitive component allows. The formation of nonfunctional PSII centres is therefore suggested to be involved in the initial photochemical damage to zooxanthellae which leads to a bleaching response. Zooxanthellae were found to be expelled irrespective of OEC function and thylakoid membrane integrity, as these sites of the photosynthetic apparatus were still intact when cells were collected from the water column. Although zooxanthellae were photosynthetically competent and morphologically intact upon expulsion, their longevity in the water column was dependent on the time of expulsion following the onset of bleaching and the ambient water temperatures. The survivorship of these zooxanthellae was restricted to a maximum of 5 days in the water column which suggests that unless expelled zooxanthellae inhabit other environs of coral reefs which may be more favourable for survival, their capacity for persistence in the environment is extremely limited. Chlorophyll a fluorescence measurements are a common tool for investigating photosynthetic impacts to in hospite zooxanthellae of corals. Pathways causing dark-reduction of the plastoquinone pool are shown to be active in corals and affect measurements which require dark-adaptation. Pre-exposure to far-red light was found to be an effective procedure to oxidise the inter-system electron transport chain and ensure determination of the true maximum quantum yield of PSII and accurate FICs. It is concluded that the trigger for coral bleaching lies in the photosynthetic apparatus of zooxanthellae and evidence is presented in support of this impact site not being the OEC or thylakoid membrane.
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Savage, Anne Margaret. "Genetic diversity and photosynthetic characteristics of zooxanthellae (Symbiodinium)." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369298.
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Toyoshima, Junko. "Cell migration of zooxanthellae in the coral Montipora capitata." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7050.
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Squire, Louise R. "Natural variations in the zooxanthellae of temperate symbiotic Anthozoa." Thesis, Bangor University, 2000. https://research.bangor.ac.uk/portal/en/theses/natural-variations-in-the-zooxanthellae-of-temperate-symbiotic-anthozoa(a6342fd8-ff91-441e-85db-8b5b1c59167e).html.
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Few previous studies of zooxanthellae have considered temperate Anthozoan symbioses. The present study investigates how the characteristics of zooxanthellae symbiotic with temperate Anthozoa vary in response to natural variations in environmental parameters. Variations in the number (density), division rate, size and ultrastructure of zooxanthellae from the temperate anemones Anemonia viridis (Forskal) and Anthopleura ballii (Cocks) were examined in response to season, water depth and artificial irradiance (A. viridis in aquaria). In addition, variations in chlorophyll concentrations were considered in intertidal and laboratorymaintained A. viridis. Zooxanthellae from both intertidal and shallow subtidal A. viridis showed variations which correlated with seasonal variations in environmental parameters. Zooxanthella density in intertidal A. viridis showed an inverse relationship with temperature, daylength and sunshine. Higher zooxanthella density was observed in A. viridis from a shallow, subtidal habitat during February 1998 (2.06 ± 0.11 x 108 cells g"' wet weight) than during July 1998 (1.01 ± 0.09 x 108 cells g'' wet weight; T= 7.67, p< 0.001). Stereological analysis of transmission electron micrographs showed that zooxanthellae in intertidal A. viridis had significantly higher chloroplast volume fraction during February (32.1 ± 1.5 %) than July (21.8 ± 2.1 %; T= 4.07, p<0.05). The proportion of chlorophyll a per zooxanthella was significantly higher in December than all other months except January (ANOVA, F= 5.62 p<0.05). The zooxanthellae of A. viridis may thus photoadapt to low winter irradiances by increasing zooxanthellae density, chloroplast volume and the proportion of chlorophyll a per cell. By contrast, zooxanthellae from A. viridis maintained in artificial irradiances in the laboratory of 4 µmol m=2 s' and 20 pmol m2 s' showed no variation in density or ultrastructure, due either to the low irradiances used or a lack of variation in other physical parameters compared to the field. A. ballii zooxanthella density responded to both depth and season and was lower at 6m during summer than at 6m during winter and at 18 m during both summer and winter. Chloroplast volume fractions in A. ballii was not affected by depth during winter, nor by season at 18 in. Starch and lipid stores in zooxanthellae from both A. viridis and A. ballii responded to seasonal fluctuations. Lipid was present in zooxanthellae during summer (intertidal A. viridis, volume fraction 19.8 ± 3.4 %) and absent during winter, and starch volume was significantly higher from zooxanthellae in A. ballii at 6 in in winter (14.3 ± 4.2 %) than 18 min winter (4.7 ± 1.6 %) or summer (4.7 ± 1.1 %; ANOVA, F= 6.04 p< 0.05). It is concluded that the zooxanthellae of the temperate anemones A. viridis and A. ballfi show variations in zooxanthellae characteristics which correspond to variations in dayto-day weather, season and water depth.
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Wang, Jih-Terng. "Nutritional interactions between the alga Symbiodinium and sea anemone Aiptasia pulchella." Thesis, University of York, 1998. http://etheses.whiterose.ac.uk/9750/.
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Jokiel, Paul L. "The Photobiology of the Reef Coral Pocillopora damicornis and Symbiotic Zooxanthellae." Thesis, University of Hawai'i, Honolulu, 1985. http://hdl.handle.net/10125/15318.
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Statement of purpose:
The scope of this dissertation was restricted to
exemplary studies on the effects of spectrum, intensity
and modulation (as described above) of the photic
environment of the common reef coral Pocillopora damicornis and its symbiotic dinoflagellate algae.
Various aspects of its biology were investigated. In some
cases direct comparison was wade with othar species to
emphasize similarities or differences. The central
hypothesis of this dissertation can be stated as follows:
Subtle changes in the spectrum, intensity and modulation
of the natural photic environment can produce a profound
effect on growth, reproduction, primary production and
general metabolism of the reef corals.Typescript. Thesis (Ph.D.)--University of Hawaii, 1985. Bibliography: leaves 201-221.
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Burghardt, Ingo. "Biology, diversity and evolution of 'solarpowered' Nudibranchia (Mollusca: Gastropoda) and their symbiosis with Zooxanthellae." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983779732.
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Hancock, Harmony Alise. "One Step Closer to Non-Invasive: Quantifying Coral Zooxanthellae Pigment Concentrations Using Bio-Optics." NSUWorks, 2012. http://nsuworks.nova.edu/occ_stuetd/189.
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Due to the invasive nature of quantification techniques, baseline pigment data for coral-dwelling zooxanthellae are not known. In an attempt to develop a model for non-invasive estimation of zooxanthellae pigment concentrations from corals, field samples were taken from Porites rus and P. lutea in Apra Harbor, Guam. In-situ reflectance spectra (R400-R800) from 22 coral colonies were collected. “Coral truthing” was accomplished by extracting corresponding tissue core samples. Subsequent analysis to quantify the concentrations of 6 zooxanthellae pigments (µg cm-2) was performed using HPLC. Trials of multiple linear regressions were attempted (EJ Hochberg) and found inappropriate, despite previous success. The multivariate calibration technique partial least squares regression (PLS-R) is an excellent tool in the case of co-linear variables. Thus, PLS-R was attempted for chlorophyll c2 and peridinin after demonstration of co-linearity. This may be an appropriate approach for development of bio-optical models to estimate zooxanthellae pigment concentrations. Further, the dinoflagellate diagnostic pigment peridinin may be of great value for reef-scale remote sensing of changes in coral status in the future.
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Venn, Alexander Ashley. "Coral bleaching : the significance of the molecular diversity and photoprotective pigments of zooxanthellae (Symbiodinium)." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423605.
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Denis, Vianney. "Capacités et modalités d’adaptation de deux espèces de coraux zooxanthellés aux perturbations climatiques et anthropiques (île de la Réunion, Sud-Ouest de l’océan Indien)." Electronic Thesis or Diss., La Réunion, 2010. https://tel.archives-ouvertes.fr/tel-04058955.
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Les communautés coralliennes récifales vont subir de profonds changements dans les prochaines décennies. Les potentiels d‟acclimatation et d‟adaptation à des changements environnementaux sont comparés entre deux espèces de coraux Scléractiniaires zooxanthellés dominantes des récifs coralliens réunionnais : le stratège K Porites lutea et le stratège r Acropora muricata. Différents traits des holobiontes (survie, croissance, régénération, biomasse des tissus, contenu en protéines, composition lipidique) et de leurs zooxanthelles (identité génétique, paramètres photosynthétiques) sont caractérisés in situ sur deux à quatre sites des platiers récifaux peu profonds, distants au plus de 11 km. Leurs conditions environnementales offrent une large gamme de variation de température, d‟éclairement, d‟hydrodynamisme et de teneurs en éléments nutritifs. P. lutea, associée à des zooxanthelles thermotolérantes Symbiodinium C15, présente un fort potentiel d‟acclimatation. Après transplantation dans un environnement nouveau, P. lutea ajuste rapidement sa croissance et son contenu en protéines, sans présenter de mortalité. En revanche, A. muricata, associée à des zooxanthelles thermosensibles C2/C3, ne présente pas de telles capacités d‟acclimatation et montre une mortalité élevée. Toutes les caractéristiques d‟A. muricata (excepté sa biomasse de tissus) ainsi que les paramètres photosynthétiques et la biomasse de tissus de P. lutea sont marqués par une « empreinte » du site originel. Cette plasticité phénotypique limitée suggère une différenciation génétique à petite échelle. Chez A. muricata, elle se traduit par une tolérance accrue aux fortes températures dans l‟environnement le plus variable. A. muricata montre également des capacités régénératrices supérieures à celles de P. lutea. Chez cette dernière, la régénération est corrélée à l‟éclairement et la température, via leur contrôle des performances photosynthétiques des zooxanthelles symbiotiques. Une alternance saisonnière autotrophie/hétérotrophie est décelée chez A. muricata dans le site le plus exposé au milieu océanique. La plasticité phénotypique de P. lutea, espèce longévive, lui permet de s‟acclimater à des conditions environnementales changeantes. Les capacités de rétablissement d‟A. muricata couplées à une capacité d‟adaptation locale permettraient aussi à cette espèce opportuniste de survivre aux modifications du milieu attendues dans le cadre du changement global, dans des limites restant à définir pour ces deux ScléractiniairesReef coral communities will undergo major changes in the next decades. The potentials of acclimatization and adaptation to environmental changes are compared between two zooxanthellate scleractinian corals dominant on Reunion coral reefs: the K-strategist Porites lutea and the r-strategist Acropora muricata. Different traits of the holobionts (survival, growth, regeneration, tissue biomass, protein content, lipid composition) and their zooxanthellae (genetic identity, photosynthetic parameters) are characterized in situ in two to four shallow reef flat sites, less than 11 km apart. Their environmental conditions offer a wide range of temperature, light, hydrodynamism and nutrient levels. P. lutea which is associated to the thermotolerant zooxanthellae Symbiodinium C15 has a high potential for acclimatization. After transplantation to a new environment, P. lutea quickly adjusts its growth and protein content, without suffering any mortality. In contrast, A. muricata, which is combined with the thermosensitive zooxanthellae C2/C3, does not display such a capacity for acclimatization and showed a high mortality. All the characteristics (except tissue biomass) of A. muricata and photosynthetic parameters, as well as tissue biomass of P. lutea, are marked by an "imprint" of the original site. This limited phenotypic plasticity suggests a genetic differentiation at small-scale. In A. muricata, it results in an increased tolerance to high temperatures in the most fluctuating environment. A. muricata also shows greater regenerative capacities than P. lutea. In the latter species, regeneration is correlated to solar radiation and temperature, through their control of the photosynthetic performance of symbiotic zooxanthellae. A seasonal change in autotrophy vs heterotrophy is detected in A. muricata at the site where exposition to oceanic environment is the highest. The phenotypic plasticity of P. lutea, a long-lived species, allows it to acclimatize to changing environmental conditions. Recovery capacities of A. muricata, in relation to its adaptive capacity to local conditions, would also allow this opportunistic species to live through the environmental changes that are expected in the context of global change, but within limits yet to be defined for these two scleractinian species
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Krämer, Wiebke [Verfasser], Kai [Akademischer Betreuer] Bischof, and Claudio [Akademischer Betreuer] Richter. "Photoecophysiology of symbiotic zooxanthellae of hermatypic corals / Wiebke Krämer. Gutachter: Kai Bischof ; Claudio Richter. Betreuer: Kai Bischof." Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1071992791/34.
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Rosset, Sabrina Laura. "Plasticity & adaptations of the coral-zooxanthellae symbiosis : responses to nutrient availability & insight into inherent thermal tolerance." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/402319/.
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Sustaining an environment which conveys a high resilience to reef corals is critical in order to mitigate the immediate threat of climate change to reef ecosystems. The nutrient environment plays a significant role in sustaining the stability of the coral-zooxanthellae symbiosis, making anthropogenic nutrient pollution as well as the climate change driven nutrient impoverishment of oceanic waters pressing threats to coral reef persistence. Yet, many aspects of coral nutrient biology remain poorly understood, impeding science driven management strategies. This thesis aimed to advance our knowledge on how different nutrient environments affect the functioning of the coral-algal symbiosis by teasing apart the interacting effects of two principal nutrient sources (dissolved inorganic nutrient uptake and heterotrophic feeding), as well as of the two essential nutrients, nitrogen and phosphorus, both in dissolved inorganic and particulate organic forms. This was achieved through long-term exposure (up to 1.5 years) of the Euphyllia paradivisa-clade C1 Symbiodinium association to replete (+N+P), limited (-N-P), or imbalanced (+N-P/-N+P) dissolved inorganic nutrient availabilities in combination with targeted host feeding with balanced or nitrogen enriched prey items. Thereby, this work stood apart from past investigations by yielding definitive phenotypes representative of different nutrient availabilities. Moreover, the importance of food quality when considering the benefit of heterotrophy to reef corals had previously been overlooked. Findings suggest that heterotrophy provides a greater benefit to the coral host than to the symbiont and is unable to compensate for diminished dissolved inorganic nutrient availability, demonstrating a significantly greater dependence of the symbiosis to the latter nutrient source. A balanced N/P ratio, both in dissolved inorganic and particulate organic form, was shown to be essential for the stability of the symbiosis and for the nutritional benefit provided by heterotrophy. Particularly nitrogen enrichment resulted in severe nutrient stress and compromised thermal stress resilience, implying a vital reliance on a continued supply of phosphorus and emphasising the necessity of managing nitrogen pollution and monitoring N/P ratios. Zooxanthellae ultrastructural biomarkers established in this thesis (cell size, lipid body, starch granule and uric acid crystal accumulation, accumulation body fragmentation) hold potential for the aid in the identification of, and discrimination between different forms of nutrient stress in reef corals. Yet, ultimately corals need to adapt to warmer oceans. Diverse Symbiodinium genotypes convey varied thermal tolerance to their coral host. Yet, the mechanisms underpinning their thermal sensitivity remain largely elusive. The second aim of this thesis was to examine the role played by the algal membrane composition. The intact polar lipid biochemistry of a thermally-sensitive (clade C) and -tolerant (clade D) type were characterised by HPLC-ESI tandem mass spectrometry. Distinctions in chloroplast membrane composition could be related to differential inherent thermal tolerance. Moreover, vast differences in the lipid biochemistry of extraplastidic membranes were identified, exemplifying unprecedented metabolic differences among Symbiodinium clades. Biochemical markers of a thermally tolerant phenotype (MGDG/DGDG ratio, glycolipid saturation) could advance our understanding and projections of the potential of reef corals to acclimate and adapt to future climate change scenarios.
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Lien, Yi-Tiang. "Molecular phylogenetic and ecological analyses of algal endosymbionts (zooxanthellae) in the scleractinian corals in the temperate region of Japan." Kyoto University, 2013. http://hdl.handle.net/2433/175072.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第17643号
農博第2005号
新制||農||1012(附属図書館)
学位論文||H25||N4764(農学部図書室)
30409
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 山下 洋, 教授 左子 芳彦, 教授 朝倉 彰
学位規則第4条第1項該当
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Foster, Kristi A. "Effects of Reduced Light and Elevated Temperature on the Zooxanthellae Concentrations and Diameters, Pigment Concentrations, and Colony Color of Montastrea cavernosa." NSUWorks, 2005. http://nsuworks.nova.edu/occ_stuetd/275.
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This study measured certain biological characteristics (zooxanthellae concentrations and diameters, pigment concentrations, and colony color) of Montastrea cavernosa from the outer reef (16.8 - 26.5 m) in Broward County, FL in response to reduced light and elevated temperature stresses. The low light treatment simulated a lowering of light in the summertime (possibly associated with a turbidity increase from an event such as a hurricane, ship grounding, or dredging). The high temperature treatment was set at the maximum expected anomaly (3°C above the average summer maximum) to simulate the effect of warmer than normal seawater. The combination treatment tested for synergistic effects. Zooxanthellae concentrations and cell sizes were measured microscopically. Photosynthetic pigment (chlorophyll a, chlorophyll c, peridinin, diadinoxanthin, and β-carotene) concentrations were measured by high performance liquid chromatography. Significant decreases were found in zooxanthellae and pigment concentrations due to the elevated temperature treatments. No significant changes in zooxanthellae and pigment concentrations were observed due to the low light conditions or due to interactions from the combined stresses. Zooxanthellae cell sizes-did not change significantly, regardless of treatment.
Coral color change, "bleaching", was measured by a novel RGB color analysis method. Significant decreases were found in coral color due to the elevated temperature treatments. No significant changes were observed due to the low light conditions or due to interactions from the combined stresses. These results agreed with those for zooxanthellae and pigment concentrations, indicating that RGB color analysis was an acceptable, non-destructive method to quantify coral bleaching. RGB color analysis has benefits over qualitative visual observations that include (i) the reproducibility of color values despite differences in color perception and changes in ambient lighting and (ii) comparisons of color change within variable-colored coral species (e.g. Montastrea cavernosa) and between two or more species of different colors (e.g. Acropora cervicornis and Siderastrea radians).
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Bonalume, Clauber. "Utilizaçao de tecnicas fotometricas para estudo do branqueamento e da quantidade de algas simbiontes em colonias coralinas." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250453.
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Orientador: Ines JoekesDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
Made available in DSpace on 2018-08-09T00:07:10Z (GMT). No. of bitstreams: 1 Bonalume_Clauber_M.pdf: 1295510 bytes, checksum: 20c20d40e0b0a19af56f06a1076fb4cb (MD5) Previous issue date: 2006
Resumo: Corais marinhos do mundo inteiro estão ameaçados pelas alterações climáticas que vêm acontecendo nas duas últimas décadas. O aquecimento da superfície terrestre associado à intensificação do fenômeno El Niño têm causado prejuízos à saúde dos corais marinhos com intensidade, extensão e escala temporal sem precedentes. Quando expostos a situações de estresse ambiental, corais podem sofrer branqueamento, perdendo suas algas simbiontes, as zooxantelas, e morrer se não as recuperarem. Desta forma, métodos de avaliação da saúde dos corais tornam-se necessários. Dois métodos fotométricos foram desenvolvidos neste trabalho. No primeiro, utilizou-se a técnica de reflectância difusa para estudo do histórico de branqueamento de fatias de núcleos de esqueletos coralinos através da análise da cor do núcleo na direção do crescimento do coral. Esse método mostrou-se sensível à variação de cor ao longo da amostra e foi capaz de evidenciar o histórico conhecido de branqueamento de 2 entre 3 amostras analisadas. O método é promissor para o estudo de esqueletos, mas depende sensivelmente do tratamento prévio das amostras. No segundo, fotografaram-se amostras de Mussismilia híspida em seu ambiente natural na Laje de Santos. Foram colhidas amostras dos corais fotografados e foi determinada a densidade de zooxantelas em cada amostra. Utilizando o software MatLab e uma rotina específica de análise multivariada, estabeleceu-se uma correlação entre aspectos da imagem digital e a densidade de zooxantelas. A correlação obtida é boa, com erros menores que 35 % na estimativa da densidade de zooxantelas a partir das imagens digitais. O método é bastante promissor e tem a vantagem de ser não destrutivo.
Abstract: In the last two decades marine corals around the world have been threatened by weather global changes. Coral health is declining at unprecedented intensity, extension and temporal scale, by world surface heating associated with the strengthening of the El Niño Southern Oscillation. When exposed to environmental stresses coral can bleach, loosing their symbiotic algae, the zooxanthellae, and die if they are permanently lost. The development of methods capable to assess coral health is necessary. Two photometric methods were developed. In the first one, difuse reflectance spectrophotomety was used to analize the bleaching history of slices of coral skeletons by color analysis along the growing direction of the colony. The method showed apropriate sensibility for measuring color changes along the samples and was able to disclose the bleaching history in two of the three samples studied. However, results depend strongly on the previous treatment of the skeleton samples. In the second method, samples of Mussismilia híspida coral colonies were photographed in their natural habitat in the Laje de Santos marine conservation park. Small samples of the photographed coral were taken and the density of zooxanthellae in each sample was measured. Using the MatLab sofware and a specific algorithm for multivariated image analisys (MIA), a correlation between features of the images and the density of zooxanthellae was established. The correlation obtained is fairly good, with less than 35 % error in the estimation of zooxanthellae density from the digital images. The method is quite promissing and has the advantage of being nondestructive.
Mestrado
Físico-Química
Mestre em Química
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Zamani, Neviaty Putri. "Effects of environmental stress on cell division and other cellular parameters of zooxanthellae in the tropical symbiotic anemone Heteractis malu, Haddon and Shackleton." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294899.
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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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Ribeiro, Filipa Fonseca. "Optimization of heterotrophic feeding of the soft coral Sarcophyton cf. glaucum." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/16072.
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Mestrado em Ecologia AplicadaHeterotrophic feeding has an important role in the processes of growth and reproduction of mixotrophic corals. The soft coral Sarcophyton cf. glaucum is a good candidate for aquaculture due to its economic interest for the marine aquarium trade and for the bioprospection of marine natural products. The lack of information on heterotrophic feeding of this species with preserved microalgae conducted to development of this work. The present study aimed to evaluate the effect of the conservation processes of microalgae in its suitability as heterotrophic feeding for the mixotrophic coral S. cf. glaucum. Additionally, we aimed to identify the most suitable freeze-dried microalgae species and cell density to be employed in the culture of this mixotrophic coral species. Two experiments were performed: in the first experiment the microalgae Nannochloropsis oculata was supplied to coral fragments in three different preservation forms (live paste, frozen and freeze-dried) at the concentration of 106 cell mL-1; in the second experiment three different microalgae species (Nannochloropsis oculata, Isochrysis galbana and Phaeodactylum tricornutum) were tested in two different amounts: 7.33 mg L-1 (corresponding to the concentration of 106 cell mL-1 of Nannochloropsis oculata) and 3.66 mg L-1. Growth rate, survival, organic weight and photobiology of coral fragments, as well as water quality in culture tanks, were evaluated in both experiments. Preserved forms of microalgae did not demonstrated differences in growth rate, organic weight and survival rate of coral fragments, but affected water quality. Freeze-dried microalgae seems to be a good feed supply for coral aquaculture, as it has the best results and it has the higher shell-life time and the lower associated costs. Between the species evaluated in second experiment, Isochrysis galbana promoted higher specific growth rate and higher percentage of organic weight in the coral fragments; additionally the culture tanks supplied with this microalgae species also presented a better water quality in the end of the experiment.
A alimentação heterotrófica desempenha um papel importante nos processos de crescimento e reprodução dos corais mixotróficos. O coral mole Sarcophyton cf. glaucum é uma espécie com potencial para a aquacultura, devido ao seu interesse económico no comércio de organismos ornamentais e na bioprospecção de produtos naturais marinhos. A insuficiente informação sobre a alimentação heterotrófica desta espécie conduziu ao desenvolvimento deste estudo, que teve como objetivo avaliar o efeito dos processos de conservação de microalgas na sua adequabilidade como alimento heterotrófico para o coral mixotrófico S. cf. glaucum. Adicionalmente, pretendeu-se identificar qual a espécie de microalga mais adequada, assim como a quantidade mais apropriada a aplicar no cultivo desta espécie. Realizaram-se duas experiências: na primeira experiência, a microalga Nannochloropsis oculata foi fornecida como alimento a fragmentos de coral em três formas de preservação distintas (pasta de alga viva, alga congelada e alga liofilizada) na dosagem de 106 cell mL-1; na segunda experiência, foram testadas três espécies de microalga liofilizada (Nannochloropsis oculata, Isochrysis galbana e Phaeodactylum tricornutum) em duas dosagens diferentes: 7.33 mg L-1 (correspondente à concentração de 106 cell mL-1 de N. oculata) e 3.66 mg L-1. Em ambas as experiências foram avaliados os seguintes parâmetros: taxa de crescimento dos fragmentos de coral, sobrevivência, peso orgânico, fotobiologia e qualidade da água. Os resultados não mostraram diferenças na taxa de crescimento e peso orgânico, entre os fragmentos de coral alimentados com as três formas de preservação de microalga, no entanto, foram observadas diferenças na qualidade da água. A microalga liofilizada evidencia ser uma boa alternativa como alimento heterotrófico para a aquacultura de corais, uma vez que apresenta os melhores resultados nos parâmetros analisados, tem um tempo de prateleira maior e poucos custos associados ao seu armazenamento. Entre as espécies avaliadas na segunda experiência, a microalga I. galbana foi a que promoveu uma taxa de crescimento mais elevada e uma maior percentagem de peso orgânico nos fragmentos de coral. Adicionalmente, os tanques em que se forneceu I. galbana como alimento heterotrófico apresentaram um maior equilíbrio na qualidade de água de cultivo.
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West, Elizabeth Jane. "The Influence of Zooxanthellate and Non-zooxanthellate Jellyfish on Nutrient Cycling and Trophodynamics." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366387.
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The appearance and disappearance of large numbers of medusae is a common characteristic of jellyfish populations. Blooms of jellyfish can attain very large biomasses that cover wide areas and can be short-lived, after which time the population may crash rapidly. The sheer biomass of jellyfish during bloom periods and the ‘boom and bust’ population dynamics are likely to have considerable impacts on the surrounding ecosystem. Some species of jellyfish contain symbiotic dinoflagellates called zooxanthellae. Zooxanthellae are able to assimilate nutrients from the surrounding water and transfer photosynthetic products to the host jellyfish. Zooxanthellate jellyfish are likely to acquire and recycle nutrients very differently to non-zooxanthellate species, and are therefore likely to have contrasting influences on nutrient cycling and trophodynamics. However, there are large gaps in our understanding of these processes. This thesis directly compares the role of zooxanthellate and non-zooxanthellate jellyfish on nutrient cycles and trophodynamics, by investigating these processes in zooxanthellate jellyfish, Cassiopea sp. and Phyllorhiza punctata, and the non-zooxanthellate jellyfish, Catostylus mosaicus. An important step in understanding the influence of jellyfish on ecosystem processes is to determine how nutrients are cycled within individual medusae. To do this, the exchanges of nutrients with the surrounding water were compared between zooxanthellate and non-zooxanthellate jellyfish. Experiments were done to compare the net exchanges (uptake and excretion) of organic and inorganic nitrogen and phosphorus with the surrounding water. Changes in nutrient concentrations were measured in tubs housing zooxanthellate Cassiopea sp., non-zooxanthellate C. mosaicus, and water control (no jellyfish). Experiments were repeated during the day, when photosynthesis and respiration could occur, and at night when only respiration could occur. Organic nutrients were found to comprise 25 - 43 % of the total excretion by non-zooxanthellate jellyfish. Organic nutrient excretion by blooms (506 t km-2) of non-zooxanthellate jellyfish were estimated to potentially support 62 – 120 mg C m-2 of bacterial production per day. In addition, excretion of inorganic nutrients by blooms of non-zooxanthellate jellyfish were estimated to potentially support 201- 423 mg C m-2 of primary production per day. In contrast, zooxanthellate jellyfish excreted minimal amounts of inorganic and organic nutrients or took them up from the water column. Therefore, nutrients assimilated by zooxanthellate jellyfish are likely to be retained and temporarily stored in the biomass of the population. The assimilation and retention of nitrogen were compared between zooxanthellate and non-zooxanthellate jellyfish. To do this, firstly, the assimilation and retention of nitrogen were directly compared between Cassiopea sp. and C. mosaicus. Jellyfish were labelled with isotopic nitrogen (15N) from two different sources, 15N-labelled Artemia prey and dissolved ammonium (15NH4+). The incorporation and retention of 15N was measured in the jellyfish tissues over nine days. Secondly, experiments were done to measure the influence of the availability of prey and concentrations of nutrients on the retention of nitrogen by Cassiopea sp. To do this, Cassiopea sp. were labelled with 15NH4+ and then placed in pools that had different combinations of high and low nutrient concentrations and high and low feeding regimes. The retention of 15N was measured in jellyfish over 37 days. Respiration and excretion rates were also measured for animals at the end of the experiment. Cassiopea sp. was found to assimilate nitrogen from both NH4+ and prey, and recycle this nitrogen internally. In contrast, C. mosaicus only assimilated nitrogen from prey and quickly excreted this nitrogen to the external environment, resulting in a short retention time. Cassiopea sp. retained nitrogen more than five times longer than C. mosaicus. Further, the nitrogen retention time of Cassiopea sp. was influenced by the availability of prey and dissolved nutrients, with the availability of prey having the greatest effect. Specifically, medusae exposed to low feeding retained nitrogen twice as long as medusae exposed to high feeding, which suggests that ingestion of prey by the host jellyfish is an important source of nitrogen in Cassiopea sp. Further, daily rates of photosynthesis and respiration suggest that photosynthesis by the zooxanthellae can potentially supply all of the carbon required for respiration and growth of the entire medusa. Jellyfish populations can hold considerable proportions of carbon and nutrients in an ecosystem and when a population crashes, jellyfish may sink to the benthos and decompose. An experiment was done that measured the changes in sediment oxygen demand as well as inorganic and organic nutrients during the decomposition of dead jellyfish, C. mosaicus. Fluxes were measured in tubs housing dead jellyfish over nine days as the jellyfish tissue decomposed. The decomposition of C. mosaicus resulted in a rapid leaching of organic nutrients from the dead tissues. Following this, microbial mineralisation dominated, which consumed oxygen and released dissolved inorganic nutrients. Although this release of nutrients may serve as a trophic link to pelagic primary producers, it may also lead to environmental problems associated with low oxygen concentrations depending on the size of the bloom and the degree of mixing in the system. Lastly, the influence of zooxanthellate and non-zooxanthellate jellyfish on plankton communities was compared. An in situ mesocosm experiment was done to compare the influence of C. mosaicus (non-zooxanthellate) and P. punctata (zooxanthellate). Changes in primary production and plankton assemblages were measured in mesocosms containing C. mosaicus, P. punctata, a combination of these species and compared to controls over six days. Catostylus mosaicus was found to increase chlorophyll a and productivity in the water column due to the large amount of nutrients excreted, causing a bottom-up influence on primary producers. This was in contrast to P. punctata, which were found to have little influence on chlorophyll a and production. This study provided direct experimental evidence that unlike C. mosaicus, P. punctata does not enhance primary production due to the minimal excretion of nutrients. Both P. punctata and C. mosaicus also had a large top-down predation pressure on zooplankton communities, causing significant declines in most species. This was with the exception of bivalve veligers, which were not consumed by either species, and gastropod veligers, which were not consumed by P. punctata. The major findings of this research have been integrated into a conceptual model that compares the influence of zooxanthellate and non-zooxanthellate jellyfish on nutrient cycles and trophodynamics. This model has been discussed in context to existing literature and recommendations have been made for future research. Overall this research found that zooxanthellate and non-zooxanthellate jellyfish assimilate, retain and release nutrients very differently and therefore have contrasting impacts on the nutrient cycling and trophodynamics of their surrounding ecosystem.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Airi, Valentina <1979>. "Reproduction of Mediterranean zooxanthellate and azooxanthellate scleractinian corals along environmental gradients." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6425/1/PhDThesis_Airi.pdf.
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Despite extensive studies focus mainly on sexual reproductive characteristics in tropical scleractinian species, there is limited knowledge on temperate regions. The Mediterranean is a biodiversity hotspot under intense pressure from anthropogenic impacts. Climatic models further predict that the Mediterranean basin will be one of the most impacted regions by the ongoing warming trend. This makes it a potential model of more global patterns to occur in the world’s marine biota, and a natural focus of interest for research on climate. The present research contributed to increase data on reproductive modes and sexuality of temperate scleractinian corals, highlighting their developmental plasticity, showing different forms of propagation and different responses to environmental change. For the first time, sexuality and reproductive mode in Caryophyllia inornata were determined. An unusual embryogenesis without a clear seasonal pattern was observed, suggesting the possibility of an asexual origin. Sexual reproduction of Astroides calycularis was governed by annual changes in seawater temperature, as observed for other Mediterranean dendrophylliids. Defining the reproductive biology of these species is the starting point for studying their potential response to variations of environmental parameters, on a global climate change context. The results on the influence of temperature on reproductive output of the zooxanthellate (symbiosis with unicellular algae) Balanophyllia europaea and the non-zooxanthellate Leptopsammia pruvoti suggest that the latter may be quite tolerant to temperature increase, since the zooxanthellate species resulted less efficient at warm temperatures. A possible explanation could be related to their different trophic system. In B. europaea thermal tolerance is primarily governed by the symbiotic algae, making it more sensitive to temperature changes. On the contrary, the absence of symbionts in L. pruvoti might make it more resistant to temperature. In a progressively warming Mediterranean, the efficiency on scleractinian reproduction could be influenced in different ways, reflecting their extraordinary adaptability.
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Airi, Valentina <1979>. "Reproduction of Mediterranean zooxanthellate and azooxanthellate scleractinian corals along environmental gradients." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6425/.
Full textAbstract:
Despite extensive studies focus mainly on sexual reproductive characteristics in tropical scleractinian species, there is limited knowledge on temperate regions. The Mediterranean is a biodiversity hotspot under intense pressure from anthropogenic impacts. Climatic models further predict that the Mediterranean basin will be one of the most impacted regions by the ongoing warming trend. This makes it a potential model of more global patterns to occur in the world’s marine biota, and a natural focus of interest for research on climate. The present research contributed to increase data on reproductive modes and sexuality of temperate scleractinian corals, highlighting their developmental plasticity, showing different forms of propagation and different responses to environmental change. For the first time, sexuality and reproductive mode in Caryophyllia inornata were determined. An unusual embryogenesis without a clear seasonal pattern was observed, suggesting the possibility of an asexual origin. Sexual reproduction of Astroides calycularis was governed by annual changes in seawater temperature, as observed for other Mediterranean dendrophylliids. Defining the reproductive biology of these species is the starting point for studying their potential response to variations of environmental parameters, on a global climate change context. The results on the influence of temperature on reproductive output of the zooxanthellate (symbiosis with unicellular algae) Balanophyllia europaea and the non-zooxanthellate Leptopsammia pruvoti suggest that the latter may be quite tolerant to temperature increase, since the zooxanthellate species resulted less efficient at warm temperatures. A possible explanation could be related to their different trophic system. In B. europaea thermal tolerance is primarily governed by the symbiotic algae, making it more sensitive to temperature changes. On the contrary, the absence of symbionts in L. pruvoti might make it more resistant to temperature. In a progressively warming Mediterranean, the efficiency on scleractinian reproduction could be influenced in different ways, reflecting their extraordinary adaptability.
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Brambilla, Viviana. "Inferred calcification rate of a temperate non-zooxanthellate caryophylliid coral along a wide latitudinal gradient." Master's thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/8208.
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Mestrado em Gestão e Conservação de Recursos Naturais - Instituto Superior de Agronomia / Universidade de ÉvoraCorrelations between environmental parameters (sea surface temperature and solar radiation) and growth parameters (bulk skeletal density, linear extension rate and net calcification rate) of the solitary non-zooxanthellate Caryophyllia inornata, were investigated along an 8° latitudinal gradient on the western Italian coasts. Net calcification rate correlated positively both with bulk skeletal density and linear extension rate, showing that C. inornata allocates calcification resources evenly in thickening the skeleton and increasing linear growth. None of the three growth parameters correlated with any of the two environmental parameters, showing a different trend compared to most studies on zooxanthellate corals. However, the results are in agreement with the only previous analysis of an asymbiotic coral, Leptopsammia pruvoti studied along the same latitudinal gradient. These results support the idea that non-zooxanthellate corals could be more tolerant to temperature increases than symbiotic corals, at least for the few species whose all three growth components have been investigated so far, which are both from the Mediterranean Sea
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Kitano, Yuko. "Molecular phylogeny of the genus Goniopora and taxonomic revision of the family Poritidae (Cnidaria: Scleractinia)." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188513.
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Djeghri, Nicolas. "Variability and plasticity of the nutrition of zooxanthellate jellyfishes : insights from experimental and field studies Review of the diversity, traits, and ecology of zooxanthellate jellyfishes, in Marine Biology 166, October 2019 δ13C, δ15N, and C:N ratios as nutrition indicators of zooxanthellate jellyfishes: insights from an experimental approach, in Journal of Experimental Marine Biology and Ecology 522, January 2020." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0061.
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Alors que la majorité des méduses sont des hétérotrophes strictes, certaines vivent en photosymbiose avec des Dinophyceae autotrophes (« zooxanthelles »). Ces méduses à zooxanthelles, en tant qu’holobiontes, sont mixotrophes, dérivant leur nutrition à la fois de la prédation et de la photosynthèse. Toutefois, l’importance relative de l’autotrophie et de l’hétérotrophie dans la nutrition peuvent varier en fonction de l’ontogénie, de la phylogénie, ou de l’écologie. De telles variations ont d’importantes conséquences pour la dynamique des populations de ces organismes. Il est donc important de pouvoir caractériser la variabilité et la plasticité de la nutrition des méduses à zooxanthelles pour comprendre leur écologie. Au cours de cette thèse, la nutrition des méduses à zooxanthelles a été étudiée par le biais d’expériences de laboratoire et d’observations de terrain. Une première expérience a permis de confirmer des résultats précédents suggérant que la nutrition autotrophe est de faible importance pour les polypes des méduses à zooxanthelles. Une seconde expérience a mis en évidence comment les compositions isotopiques et élémentaires des méduses à zooxanthelles peuvent être utilisées pour étudier leur nutrition. Ces résultats sont ensuite confrontés aux observations de terrain : la nutrition de la méduse à zooxanthelles Mastigias papua a été étudiée dans son environnement naturel (Palaos) via l’étude de leur compositions isotopiques, élémentaires, mais aussi en acides gras. Ces résultats de terrain démontrent l’importante plasticité de la nutrition de Mastigias papua, pouvant aller de la pure hétérotrophie, une autotrophie dominante. L’existence d’une telle plasticité dans la nutrition des méduses à zooxanthelles aide à comprendre certains aspects centraux de leur écologie, tels que leur tendance à former moins de blooms que les méduses sans zooxanthelles, ou leurs réactions aux évènements de blanchissement induit par la températureWhereas most jellyfishes are strictly heterotrophic organisms, some of them undergo a photosymbiosis with autotrophic Dinophyceae (“zooxanthellae”). These zooxanthellate jellyfishes, as holobionts, are mixotrophic deriving nutrition from both predation and photosynthesis. However, the relative importance of autotrophic and heterotrophic nutrition can vary as a function of ontogeny, phylogeny and ecology. Such variations of nutrition have important consequences for the population dynamics of these organisms. It is therefore central to characterize the variability and the plasticity of the nutrition of zooxanthellate jellyfishes to understand their ecology. In this thesis, the nutrition of zooxanthellate jellyfishes was investigated using laboratory experimental systems and field studies. A first experiment allowed to confirm previous findings that autotrophic nutrition is of small importance for the polyp of zooxanthellate jellyfishes. A second experiment assessed how elemental and isotopic compositions of zooxanthellate jellyfishes could be used to study their nutrition. The findings of this experiment are then confronted with results from the field: The nutrition of zooxanthellate Mastigias papua medusae was studied in their natural environments (Palau) through the use of isotopic, elemental but also fatty acids compositions. These field results demonstrate the wide plasticity of the nutrition of Mastigias papua ranging from pure heterotrophy to dominant autotrophy.The existence of such a wide plasticity in the nutrition of zooxanthellate jellyfishes helps to understand some crucial aspect of their ecology such as their generally low ability to bloom relative to non-zooxanthellate jellyfishes, or their reactions to temperature-induced bleaching
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Gibbons, Christopher Lynton. "Carbon flux in the temperate zooxanthellate sea anemone Anthopleura aureoradiata : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Master of Science in Marine Biology /." ResearchArchive@Victoria e-Thesis, 2008. http://hdl.handle.net/10063/869.
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Serrano, i. Gras Eduard. "Demographics and population ecology of the range-expanding zooxanthellate coral Oculina patagonica in the Mediterranean Sea." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/482138.
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Shallow-water rocky ecosystems in temperate areas are dominated by macroalgae, whilst zooxanthellate corals are extremely rare. In an era of global change, sea warming plays a crucial role in the widespread phase shifts from coral- to algal-dominance in tropical coral reef ecosystems, and in the poleward spread and increase in abundance of some tropical and subtropical zooxanthellate corals into algal-dominated temperate areas. In the Mediterranean Sea, the zooxanthellate coral Oculina patagonica (Scleractinia, Oculinidae) is experiencing a range-expanding process, providing a good case study to examine how zooxanthellate corals can affect the structure of temperate ecosystems.
In this PhD Thesis, different field studies were performed along the Iberian coast in the western Mediterranean to examine the demographics and population ecology of O. patagonica and contribute understanding the interaction among the main intrinsic and extrinsic factors in modulating the species’ dynamics. First, we document that O. patagonica is experiencing an invasive behavior that challenges the current conceptual framework of shallow-water rocky ecosystems, by providing evidence that the species is able to: i) form encrusting bioconstructions and drive a phase shift from macroalgal- to coral-dominated states, and ii) experience an invasive behavior at both population outbreak and geographical distribution range levels. Second, over a ~4-yr field experiment we document that a severe and recurrent pattern of partial mortality on O. patagonica colonies occurs under low seawater temperature (ST) conditions during winter, which appears to play a crucial role in constraining the growth dynamics of the species at the high-latitude area in the north-eastern Iberian coast. Third, we document the spatial variation in the demographics of O. patagonica (occurrence, density, cover, colony partial mortality and size-structure) by examining 314 locations along ~1300 km Iberian coast that provides a detailed baseline quantitative dataset. We found that the colony size-structure of coral populations in natural locations were unimodal and positively skewed, indicative of non-stable and growing populations. However, the species’ demographics showed a marked ‘abundant-center’ pattern that is not only related to the time of establishment but also to the relevant role of differences in coral population growth that correlate with key environmental variables.
Finally, we layered our broad spatial scale observations on the demographics of O. patagonica, together with our and previous empirical and experimental studies on the interaction between biological traits and key environmental factors modulating coral performance, to identify the potential causes of the geographic range structure and invasion behavior of this species within the Iberian coast. The success of O. patagonica colonies and populations on natural locations appear to be generally constrained by low ST and light conditions, with thresholds that limit coral growth of mean annual photosynthetic active radiation at 3 m depth <30 mol photons m-2 d-1, mean ST <19ºC, percentile 10th-ST <14ºC and percentile 90th-ST <25ºC, but without severe high-ST periods (percentile 90th-ST >27ºC). In addition, the high availability of open space for O. patagonica to colonize, and the positive effects of sand scouring and sea urchin herbivory on coral population growth, indicate that open space availability is a crucial factor enhancing the proliferation of the species within the Iberian coast. We also found that artificial reefs foster the population growth and the expansion of the distributional range of this coral species. The broad spread of O. patagonica across the Mediterranean Sea, and its invasive behavior at both distributional range shift and population outbreak levels, able to drive phase shifts from macroalgae to coral dominance in natural and artificial reefs, is consistent with the ongoing process of zooxanthellate coral-mediated tropicalization of shallow-water rocky ecosystems documented in other subtropical and temperate areas under current global change.
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Renegar, Dorothy-Ellen A. "Effect of Nutrient Enrichment and Elevated CO2 Partial Pressure on Growth Rate of the Zooxanthellate Coral Acropora cervicornis." NSUWorks, 2003. http://nsuworks.nova.edu/occ_stuetd/289.
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Trends of increasing coastal eutrophication and atmospheric pCO2 require investigation to predict the combined effects on coral and reef condition and growth. Increases in nutrient concentrations have been observed over the past several decades in a number of reef systems, and it has been predicted that this will adversely affect coral growth rates. The species targeted by this research, Acropora cervicornis, is among the most important reef-builders in the Caribbean and has suffered widespread mortality in southern Florida. Approximately 192 branch tips were harvested from two local populations of A. cervicornis and maintained in the laboratory, where the growth rate was measured before, during, and after exposure to elevated levels of nitrate (N) (5 µM and 10 µM), phosphate (P) (2 µM and 4 µM), and/or pCO2 (CO2) (~700-800 µatm). During the control period, there was no significant difference in growth rate between the treatments, with a mean growth rate of 4.84 mg d-1. During Period 2, the first enrichment period, the largest decrease in growth rate was caused by the combined NPCO2 treatment (mean growth rate of 0.51 mg d-1). The least effect on growth rate was caused by the N treatment (mean growth rate of 4.39 mg d-1). During Period 3, the second enrichment period, the lowest growth rate was again found in the NPCO2 treatment tanks (mean growth rate of 0.03 mg d-1). The highest growth rate among the treatments was in the N treatment tanks (mean growth rate of 1.90 mg d-1), however there was no significant difference between the growth rates of the N, P, NP, CO2, NCO2, and PCO2 treated corals during this period. The mean growth rates in the Control tanks were 7.59 and 7.32 mg d-1 during Periods 2 and 3, respectively. During Period 4, the recovery period, the lowest growth rates were found in the combined NCO2 and PCO2 treatment tanks (mean growth rates of 1.00 and 1.02 mg d-1, respectively). The highest growth rate among the treatments was again observed in the N treatment tanks (mean growth rate of 2.75 mg d-1). The mean growth rate in the Control tanks was 7.40 mg d-1 during this period. The results of this study demonstrate that increased levels of nitrate, phosphate, and pCO2 cause statistically significant decreases in the growth rate of A. cervicornis. The effects of nitrate and phosphate appear to be concentration dependent, and the effect of pCO2 is greater than that of nutrification. Therefore, continued eutrophication and projected pCO2 increases can be expected to have negative impacts on the survival and reef building potential of this species.
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Zuccaro, Destefani Ilaria. "Reproductive output of the solitary zooxanthellate coral Balanophyllia europaea (Scleractinia, Dendrophylliidae) along a natural pH gradient at Panarea Island." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20402/.
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Approximately a quarter of the anthropogenic carbon dioxide (CO2) emissions to the atmosphere are absorbed by the ocean. This ocean uptake of CO2 causes a progressive decrease of seawater pH and carbonate ion concentration, also known as ocean acidification and shifts in seawater carbonate chemistry. Ocean acidification will have many negative consequences for marine calcifying organisms, including corals. This thesis examines the short-term potential effects of ocean acidification on reproductive output of the solitary and zooxanthellate coral Balanophyllia europaea, transplanted along a natural pH gradient generated by an underwater volcanic crater near Panarea Island (Sicily, Italy). Cyto-histometric analyses reveal that oocyte and spermary abundance (#/100 mm3), oocyte and spermary gonadal index (%), fertility (#/100 mm3), embryonal index (%) and embryo diameter (μm) of Gonadal development and Maturity period of B. europaea was unaffected by increasing acidification, even under an extreme pH value. Only oocyte and spermary diameter of both reproductive periods varied among sites but without a clear trend. Thus, reproduction of B. europaea seems to be tolerant to decreasing pH, while the azooxanthellate corals, L. pruvoti and A. calycularis, transplanted along the same natural gradient, were negatively affected by increasing acidification. This different result could be explained by the different trophic strategy of B. europaea, as the symbiosis with zooxanthellae could provide additional energy to dedicate in reproduction.
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REYNAUD, VAGANAY STEPHANIE. "Controle environnemental de la physiologie et de la composition isotopique du squelette des scleractiniaires a zooxanthelles : approche experimentale." Nice, 2000. http://www.theses.fr/2000NICE5406.
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Le squelette des scleractiniaires a zooxanthelles (coraux) constitue une base de donnees sur les parametres environnementaux potentiellement importante. Leur utilisation est de plus en plus frequente dans la reconstitution des paleoenvironnements des zones tropicales, pour lesquelles peu de sources d'informations sont actuellement disponibles. L'utilisation de coraux cultives en aquarium permet de controler tres precisement tous les parametres environnementaux et de n'en faire varier qu'un seul a la fois. Une technique experimentale permettant la culture de coraux (stylophora pistillata, acropora sp. Et montipora verrucosa) en conditions controlees a ete mise au point avec succes. Cette methode permet d'echantillonner avec une grande precision le squelette et les tissus neoformes. Cette technique a ete utilisee afin de determiner des relations entre certains parametres environnementaux et les isotopes stables du squelette (et des tissus). Ainsi, une diminution du 1 8o s q l a ete mise en evidence lorsque la temperature ou la salinite de l'eau augmentait. Le 1 8o s q l semblait aussi affecte par la photosynthese : le 1 8o s q l augmentait lorsque la photosynthese etait stimulee. En revanche, le 1 3c s q l semblait plutot influence par la calcification : une stimulation de ce parametre entrainait une augmentation du 1 3c s q l. Une relation entre la temperature et le 1 3c s q l a ete mise en evidence chez acropora sp. Cette nouvelle approche experimentale ouvre de nombreuses perspectives dans le domaine de la validation des traceurs geochimiques (isotopes stables et elements traces). Les efforts doivent a present porter sur la mise en culture de colonies d'autres genres, notamment porites.
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Gattuso, Jean-Pierre. "Ecomorphologie, métabolisme, croissance et calcification du scléractiniaire à zooxanthelles Stylophora pistillata (Golfe d'Agaba, Mer Rouge) influence de l'éclairement /." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37605301r.
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Magalon, Hélène. "Dispersion du corail Pocillopora meandrina et de ses algues symbiotiques en Polynésie Française." Paris 6, 2005. http://www.theses.fr/2005PA066100.
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AL-MOGHRABI, SALIM. "Metabolisme et transport des nutriments dans un modele d'association symbiotique animal-vegetal : les microcolonies d'un scleractiniaire a zooxanthelles galaxea fascicularis." Nice, 1992. http://www.theses.fr/1992NICE4588.
Full textAbstract:
Galaxea fascicularis (linne, 1758), corail scleractiniaire a zooxanthelles, constitue une espece dominante des recifs frangeants indo-pacifiques. La difficulte d'elevage des coraux a rend leur etude en laboratoire difficile. Afin de contourner cette difficulte, la premiere etape de ce travail a consiste en la mise au point d'une technique originale de culture de polypes isoles dont le squelette est completement recouvert de tissu, les microcolonies. Une fois l'outil biologique mis au point, le but de ce travail a ete l'etude des relations physiologiques entre l'hote animal et son symbionte intracellulaire, la zooxanthelle, du point de vue de l'autotrophie et de l'heterotrophie. En ce qui concerne l'autotrophie, les resultats demontrent clairement que la photosynthese des zooxanthelles in hospite depend de l'adsorption par les tissus animaux du bicarbonate dissous dans l'eau de mer. Pour effectuer le transport de bicarbonate, les cellules animales possedent au moins deux transporteurs ioniques differencies par leur sensibilite au sodium externe. De plus, l'anhydrase carbonique est indispensable pour assurer une photosynthese maximale des zooxanthelles. En ce qui concerne l'heterotrophie, nos resultats demontrent que les microcolonies de galaxea fascicularis sont capables d'absorber les acides amines dissous dans l'eau de mer a des concentrations de l'ordre de la micromole. Deux principaux mecanismes d'absorption de la valine ont ete mis en evidence: une importance absorption diffusionnelle, et une absorption dependante de transporteurs membranaires a haute affinite. Ces transporteurs sont differencies par leur sensibilite au sodium externe, leur activite est regulee par la lumiere et l'etat nutritionnel des microcolonies. L'analyse de la composition en acides gras, utilises comme biomarqueurs, des microcolonies et des zooxanthelles isolees a egalement ete effectuee afin de determiner les sources de nourriture de l'animal. La composition en acides gras des colonies temoin a ete comparee a celles de colonies nourries ou non nourries durant une experimentation de 50 jours
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Marchioretti, Manuel. "Nouvelles données écophysiologiques chez les scléractiniaires à zooxanthelles du genre stylophora(Schweigger,1819) : perspectives d'applications à la restauration des récifs coralliens." Nice, 1999. http://www.theses.fr/1999NICE5271.
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GOIRAN, CLAIRE. "La symbiose entre les scleractiniaires et les dinoflagelles : physiologie des zooxanthelles symbiodinium sp. du corail galaxea fascicularis, hors de l'association symbiotique." Nice, 1994. http://www.theses.fr/1994NICE4800.
Full textAbstract:
L'association symbiotique entre les coraux scleractiniaires et les dinoflagelles (zooxanthelles) est a la base meme de l'existence des recifs coralliens, cependant les mecanismes physiologiques permettant la vie en symbiose de ces organismes sont mal connus. Le present travail a donc ete entrepris afin d'elucider certains de ces mecanismes. Pour cela, les zooxanthelles du scleractiniaire galaxea fascicularis ont ete etudiees hors de l'association symbiotique. Les zooxanthelles ont ete preparees de deux manieres differentes. La premiere, qui est l'isolation a partir des tissus de l'hote, produit des zooxanthelles fraichement isolees ou fiz, la seconde, qui consiste en la culture des dinoflagelles in vitro produit des zooxanthelles de culture ou cz. Lorsque les zooxanthelles sont isolees a partir des tissus de l'hote et transferees en eau de mer, la composition ionique du milieu exterieur change brutalement. En reponse a ce choc ionique, la concentration de sodium intracellulaire des fiz double durant la premiere demi-heure. Rapidement, des mecanismes de regulation se mettent en place, et la concentration de sodium revient a la valeur initiale. Les mecanismes grace auxquels les zooxanthelles absorbent le carbone inorganique utilise pour la photosynthese ont ete etudies. Les resultats semblent montrer que les cz absorbent le bicarbonate. Les fiz, en revanche, utiliseraient le gaz carbonique. Ces resultats mettent en evidence l'adaptation des deux types de zooxanthelles a leur environnement habituel: eau de mer ou cellule animale
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Loomis, Nicholas C. (Nicholas Charles). "Computational imaging and automated identification for aqueous environments." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67589.
Full textAbstract:
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2011."June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 253-293).
Sampling the vast volumes of the ocean requires tools capable of observing from a distance while retaining detail necessary for biology and ecology, ideal for optical methods. Algorithms that work with existing SeaBED AUV imagery are developed, including habitat classification with bag-of-words models and multi-stage boosting for rock sh detection. Methods for extracting images of sh from videos of long-line operations are demonstrated. A prototype digital holographic imaging device is designed and tested for quantitative in situ microscale imaging. Theory to support the device is developed, including particle noise and the effects of motion. A Wigner-domain model provides optimal settings and optical limits for spherical and planar holographic references. Algorithms to extract the information from real-world digital holograms are created. Focus metrics are discussed, including a novel focus detector using local Zernike moments. Two methods for estimating lateral positions of objects in holograms without reconstruction are presented by extending a summation kernel to spherical references and using a local frequency signature from a Riesz transform. A new metric for quickly estimating object depths without reconstruction is proposed and tested. An example application, quantifying oil droplet size distributions in an underwater plume, demonstrates the efficacy of the prototype and algorithms.
by Nicholas C. Loomis.
Ph.D.
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Kneeland, Jessie M. (Jessie Mary). "Lipid biomarkers of coral stress : calibration and exploration." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68888.
Full textAbstract:
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2011.Cataloged from PDF version of thesis.
Includes bibliographical references.
Corals are increasingly threatened by warming sea surface temperatures and other anthropogenic changes. The delicate symbiosis between corals and their algal endosymbionts (zooxanthellae) is easily disrupted by thermal stress, leading to bleaching and eventual mortality. The use of lipid ratios as biomarkers of environmental conditions is well established. Coral biomass contains abundant lipids, and the potential of lipid parameters to diagnose thermal tolerance in zooxanthellae has been previously suggested. In this thesis, I explore the response of specific fatty acids, sterols, and thylakoid membrane lipids to thermal and disease stress in zooxanthellae grown in culture, as well as those isolated from living corals. I present the discovery of a bioactive thylakoid lipid within zooxanthellae cells, and show how this compound is selectively mobilized in thermally stressed cells. I present a plausible mechanism for the breakdown of this compound into products that may cause apoptosis and disrupt the coral-algal symbiosis, eventually causing bleaching. I present two new lipid biomarkers of thermal stress in zooxanthellae, the C18 fatty acid unsaturation ratio, and the fatty acid to sterol ratio. I calibrate the decline of these two parameters to levels of thermal stress comparable to those needed to cause bleaching. I further show that these parameters are sensitive to pathogen stress as well. In several case studies of diseased and thermally stressed corals, I demonstrate that these lipid biomarkers of coral stress may be applied to zooxanthellae isolated from environmental samples. I show that these same compounds are preserved within coral aragonite, which opens up the potential to retrieve lipid-based historical records of coral health from annual layers of coral skeleton. This work demonstrates the value of using lipid biomarkers to assess coral health and better understand the biochemical mechanisms of coral bleaching.
by Jessie Mary Kneeland.
Ph.D.
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Wu, Yu Hui, and 吳鈺慧. "Heat shock proteins of coral and its symbiotic zooxanthellae." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/02241998699746796345.
Full textAbstract:
碩士國立中山大學
海洋資源學系
82
The coral community near a nuclear power plant of southern Taiwan has shown annual summer bleaching phenomenon due to heat stress by synthesizing highly conserved heat shock proteins ( hsp ). However, little is known of the biochemical responses concomitant with thermal bleaching of the coral. Our laboratory found that the coral cell of Acropora grandis and its symbiotic will synthesize 35 kDa protein in natural high seawater temper- ature. They synthesized hsp35 after heat shock, in coral cell this occurred at 29 ℃ while in zooxanthellae at 33 ℃. Hsp63 was also found in coral cell when 35S-methionine was added to label proteins for 2 hours after heat treatment for 1 hour at 35 ℃. Hsp35 sustained at least 13 hours in coral and zooxan- thellae at 35 ℃, and coral was bleached at this time. The coral tended to die and hsp35 disappeared when heat exposure lasted continuously for 22 hours at 35 ℃. This response was the same, even the coral exposured to 35 ℃ for only 3 hours. This indicated that coral is damaged when it temporally expo- sures to high temperature. If heat exposure was at 33 ℃, coral survived for at least 24 hours and hsp35 was not significant. The study shed light on a possibility of using hsp35 as an incicator of thermal bleaching in coral.
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Tseng, Chih-Lin, and 曾智麟. "Variations in zooxanthellae and recovery of bleached colonies in Acropora intermedia." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/00163195368522569620.
Full textAbstract:
碩士國立中山大學
海洋生物研究所
93
The maximum quantum yield (Fv/Fm), zooxanthellae density, chlorophyll a concentration and protein concentration of non-bleached and bleached colonies of the reef coral Acropora intermedia were measured in inlet of The Third Nuclear Power Plant of Nanwan Bay in southern Taiwan. A significant positive correlation was found between Fv/Fm and chlorophyll a concentration per zooxanthellae of non-bleached colonies. The chlorophyll a concentration per zooxanthellae and zooxanthellae density of non-bleached colonies were lowest in summer, and were significantly negative correlated with total radiant heat and seawater temperature, respectively. This suggests that the seasonal variation exist, and they maybe regulated by seasonal fluctuation of radiation and temperature. The Fv/Fm, chlorophyll a concentration per cm-2, chlorophyll a concentration per zooxanthellae, zooxanthellae density and protein were significantly lower than those of the non-bleached colonies in the bleaching events. However, compared to the non-bleached colonies, zooxanthellae density, chlorophyll a concentration per cm-2 and protein of bleached colonies were increased and significantly higher than those of non-bleached colonies, then decreased to similar level. However, Fv/Fm increased to similar level, but chlorophyll a concentration per zooxanthellae remained lower. It suggests that number of zooxanthellae rapidly increased while remained stable chlorophyll a concentration during recovery.
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Yang, Ya-Wen, and 楊雅雯. "Polymorphic symbiosis and phylogenetic analysis of zooxanthellae in the Indo- Pacific scleractinian corals." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/13624362212671261200.
Full textAbstract:
碩士國立中山大學
海洋生物研究所
89
Zooxanthellae are very important for the coral reef ecosystem. The diversity of coral hosts is high in the Indo-Pacific, but the diversity of zooxanthellae has not been broadly investigated. Southern Taiwan and Penghu Islands are coral reef and non-reefal communities, respectively. These localities were chosen as the sampling sites for this study to maximize the opportunity of surveying this region in the Indo-Pacific. Zooxanthellae diversity was investigated in 40 host species including 32 species of Scleractinia, 4 species of Actiniaria, 3 species of Milleporina and 1 species of Helioporacea using polymerase chain reaction (PCR) of the ssrRNA gene and restriction fragment length polymorphism (RFLP) patterns. The phylogenetic relationship of partial and complete sequences of the ssrRNA gene were also analysed. Aiptasia puchella harbors clade B; Oulastrea crispata only harbors clade E; while Acropora palifera and Montipora cactus harbor both clades C and E. Zooxanthellae isolated from all except the above 4 host species are identified as "clade C" sensu Rowan and Powers (1991a). Therefore, the clade C is the dominant type in the Indo-Pacific. Phylogenetic analyses based on partial and complete sequences obtained in this study and also from the GenBank data base demonstrate 4 clades (A, B, C and E) in the genus Symbiodinium. Clade E, classed as D3 RFLP type in previous studies, is a distinct clade differing from A, B and C by RFLP and sequencing data. Clade E has only been found in Scleractinia host species collected in shallow-water habitats in the Pacific. The composition of zooxanthellae clades and ecological pattern of polymorphic symbiosis is not consistent with the irradiance adaptation hypothesis in the Caribbean. A literature survey of zooxanthellae in Scleractinian hosts indicates a significant difference between the Caribbean and the Pacific. The documented biogeography of zooxanthellae clades and the ecological pattern of polymorphic symbiosis are also differ between the Caribbean and the Indo-Pacific.
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Cheng, Ying-Min, and 鄭英敏. "Intracellular Survival Mechanisms of Zooxanthellae in Cnidarian Digestive Cells—The Critical Role of ApRab5 and ApRab7." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/75853266093293634333.
Full textAbstract:
碩士國立中山大學
海洋生物研究所
92
Marine cnidarian-microalgal endosymbiosis is an ecologically important intracellular association. However, its underlying molecular mechanisms are essentially unknown. In light of the critical roles of host phagocytosis in intracellular fates of a variety of microbes, and the Rab small GTPases as key mediators of host-symbiont interaction, we set out to investigate the potential involvement of Aiptasia Rab proteins in the model photosynthetic endosymbiosis between the sea anemone, Aiptasia pulchella and the symbiotic dinoflagellate (commonly called zooxanthellae), Symbiodinium spp. Many Aiptasia Rab homologue-encoding cDNA fragments were first cloned through our degenerate RT-PCR and RACE reactions. Significantly, Aiptasia homologues of Rab5 and Rab7 (ApRab5 and ApRab7), two Rabs known to be critical regulators of phagosome maturation were also identified in the screen. The overall sequence identities of ApRab5 and ApRab7 to those of human Rab5C and Rab7 were very extensive, and EGFP reporter, protein fractionation, and immuno-fluorescence studies all suggested that the similarity of the Aiptasia Rabs to their human counterparts extended to the functional levels. Finally, although the phagosomes enclosing latex beads stained positive for ApRab5 and ApRab7 with kinetics characteristics of normal phagosomal maturation, the phagosomes housing zooxanthellae only stained positive for ApRab5. Furthermore, the association of ApRab5 with and the exclusion of ApRab7 from the zooxanthellae-containing phagosomes could be reversed by the heat-killed or photosynthesis-impaired symbionts. Overall, our present study has identified ApRab5 and ApRab7 as potential key regulators of the Aiptasia-Symbiodinium endosymbiosis
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Jiang, Hie, and 姜海. "The Effects of Different Nitrogenous Sources to the Sea Anemone Aiptasia Pulchella and Its Symbiotic Zooxanthellae." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/16850892768706313993.
Full textAbstract:
碩士國立中山大學
海洋生物學系
85
The aims of this study are to understand the role of algal symbiosis and translocation regulation of symbiotic sea anemone Aiptasia pulchella through different nitrogenous sources. The effects of different nitrogenous treatments on symbiotic interaction were investigated by the carbon and nitrogen stable isotope composition of sea anemone tissue and zooxanthellae. Colonies of the sea anemones were fed with newly hatched Artemia nauplii and/or a fish feed or raised in the culture water with or without enrichment of ammonium every other day. The result shows that there was no significant difference in δ13C of zooxanthellae among treatments, indicating that the carbon source of the zooxanthellae is independent of nitrogenous source and is dependent of photosynthesis. The δ13C and δ15N values of sea anemone tissue and zooxanthellae indicate that the addition of ammonium caused a decrease in translocation of nitrogenous matters and photosynthetic products from zooxanthellae to the host, and more over; the input of ammonium caused a tendency toward heterotrophy for the zooxanthellae.
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Michalek-Wagner, Kirsten. "The chemical ecology of the soft coral-zooxanthellae association and its signficance to the bleaching process." Thesis, 1999. https://researchonline.jcu.edu.au/27503/1/27503-michalek-wagner-1999-thesis.pdf.
Full textAbstract:
Biochemical changes in soft corals (Lobophytum compactum and Sinularia flexibilis) affected by bleaching were investigated, with the ultimate aim of understanding how molecular changes are linked to biological responses observed in the wake of bleaching events.
Annual variation in photo-protective mycosporine-like amino acids (MAAs) in soft coral populations provides the first evidence that MAA tissue concentrations are positively correlated with seasonal cycles in both solar irradiance and sea-surface temperatures. The timing of peak concentrations of MAAs in summer when exposure to solar irradiance and sea temperatures are greatest, and in female colonies prior to spawning, further corroborate their role as photo-protectants. In manipulative bleaching experiments elevated UVR and temperature were found to act synergistically in the bleaching process. However, chemical degradation of MAAs during exposure to elevated temperature is not, as previously assumed, the key to understanding the synergistic interaction. In fact, MAA levels increased in response to simultaneous exposure to high temperature and UVR, in both experimentally and naturally bleached colonies, suggesting increased resource allocation towards photo-protection in corals already experiencing thermal stress.
Soft coral responded to bleaching by increasing the production of terpenoid secondary metabolites, which aid in the prevention of microbial and algal fouling. While changes in secondary metabolites were short-lived, a substantial increase of an anti-microbial agent in S. flexibilis may have contributed to the prevention of fouling by opportunistic bacteria. This suggests that soft corals may alter their secondary metabolite chemistry to prevent fouling by opportunistic bacteria following bleaching. These experimental results were validated through analysis of soft corals affected by the 1998 mass bleaching event, where bleached colonies with high levels of algaecides remained free of fouling, while conspecifics with substantially lower levels were found to be overgrown. This suggests that soft corals are capable of surviving short-term bleaching events and detrimental algal overgrowth that is often associated with bleaching, by regulating their secondary metabolite chemistry to counteract fouling.
Understanding the role of symbiotic zooxanthellae in the production of terpenoid secondary metabolites is integral to evaluating the full impact of bleaching disturbances on the soft coral host. Zooxanthella cross-infection experiments with freshly metamorphosed polyps of Lobophytum compactum demonstrated that control over the production of secondary metabolite lies with the animal host. Moreover, the equivalence of secondary metabolite chemistry in apo-and symbiotic polyps clearly shows that the algal partner is not essential for biosynthesis. Despite no direct algal involvement in terpene production, a strong correlation between polyp growth and investment into terpenes suggests that, via their contribution to coral nutrition through primary metabolism, zooxanthellae have the capacity to indirectly influence secondary metabolism. The implications for bleached soft corals are that while the host, with or without energetic contributions from the algal symbiont controls the production of ecologically important terpenes, energy reserves may be insufficient to maintain the production of ecologically significant concentrations.
Severe experimental bleaching was found to have long-term sub-lethal impacts on soft corals, reducing overall reproductive output of Lobophytum compactum for at least two spawning seasons. Polyp fecundity and mean egg diameters were inversely correlated with the degree of bleaching, with complete failure of fertilisation in heavily bleached colonies in the first year and significantly reduced fecundity in the second year after the bleaching event. Although bleached corals recovered their zooxanthellae within 4 months, protein, lipid, MAA and carotenoid concentrations were reduced for at least eight months in adult tissues. The reductions were amplified when they were passed on to gametes, with the greatest reductions occurring in lipid and protein concentrations. Although reductions in MAAs were relatively smaller when passed on to gametes, even minor proportional reductions have significant implications for larval survival, given that MAA levels are approximately three times higher in eggs than in maternal tissues. By the second spawning season (20 months after experimental bleaching) the biochemical compositions of both adult tissues and their gametes were indistinguishable from those of control (unbleached) corals.
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Burghardt, Ingo [Verfasser]. "Biology, diversity and evolution of 'solarpowered' Nudibranchia (Mollusca: Gastropoda) and their symbiosis with Zooxanthellae / vorgelegt von Ingo Burghardt." 2006. http://d-nb.info/983779732/34.
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LEE, JIN-JIE, and 李進傑. "The Effect of pH and Culture Medium on the Growth of Symbiotic Zooxanthellae Isolated from Taiwan Common Cnidarian." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9vy9jt.
Full textAbstract:
碩士國立高雄海洋科技大學
水產養殖研究所
106
The cnidarians form the amazing coral reef ecosystem mutually with zooxanthellae, its foundation was based on the intracellular symbiosis. By endosymbiosis, zooxanthellae were capable of living in cnidarian host gastrodermal endoderm cells with large numbers. Traditionally, the pH of symbiosomal lumen was thought to be 6-7. However, a recently report by utilizing pH indicators indicated that the pH of symbiosomal lumen in coral cells is below 4, revealing that the regulatory mechanism of symbiosome acidification should be clarified. Therefore, this study hypothesized that the pH of symbiosomal lumen in different cnidarian were different. Through culturing the fresh-isolated zooxanthellae with the different medium, the most suitable pH range of different zooxanthellae were evaluated. In this study, a total of eight of cnidarians species, and one test bivalves. The current results indicate that the zooxanthellae from Aiptasia pulchella, Bolocera mcmurrichi, Fungiidae spp. and Sinularia polydactyla, which were can growth at 6.2 and 8.6. The immunofluorescence showed that V-ATPase D was not abundantly distributed on the symbiosomal membrane of coral cells, suggesting symbiosomes were not acidic vesicles. Keyword：Cnidarians、Symbiosome、Zooxanthellae、pH
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Song, Po-Ching, and 宋柏青. "Study on the iron-harvesting pathway of host-harbored zooxanthellae and the high temperature induces Symbiodinium iron-deficiency genes expression during Aiptasia-Symbiodinium endosymbiosis." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98501562492808508766.
Full textAbstract:
博士國立中山大學
海洋科學系研究所
104
Coral bleaching is the consequence of disruption of the mutualistic Cnidaria-dinoflagellate association. Elevated seawater temperatures have been proposed as the most likely cause of coral bleaching whose severity is enhanced by a limitation in the bioavailability of iron. Iron is required by numerous organisms including the zooxanthellae residing inside the symbiosome of cnidarian cells. However, the knowledge of how symbiotic zooxanthellae obtain iron from the host cells and how elevated water temperature affects the association is very limited. Since cellular iron acquisition is known to be mediated through transferrin receptor-mediated endocytosis, a vesicular trafficking pathway specifically regulated by Rab4 and Rab5, we set out to examine the roles of these key proteins in the iron acquisition by the symbiotic Symbiodinium. Thus, we hypothesized that the iron recruitments into symbiotic zooxanthellae-housed symbiosomes may be dependent on rab4/rab5-mediated fusion with vesicles containing iron-bound transferrins and will be retarded under elevated temperature. In this study, we cloned a novel monolobal transferrin (ApTF) gene from the tropical sea anemone Aiptasia pulchella and confirmed that the association of ApTF with A. pulchella Rab4 (ApRab4) or A. pulchella Rab5 (ApRab5) vesicles is inhibited by elevated temperature through immunofluorescence analysis. We confirmed the iron-deficient phenomenon by demonstrating the induced overexpression of iron-deficiency-responsive genes, flavodoxin and high-affinity iron permease 1, and reduced intracellular iron concentration in zooxanthellae under desferrioxamine B (iron chelator) and high temperature treatment. In conclusion, our data are consistent with algal iron deficiency being a contributing factor for the thermal stress-induced bleaching of symbiotic cnidarians.
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Boutilier, Ryan Michael. "Aspects of Nitrogen Metabolism in Symbiotic Cnidarians." Thesis, 2012. http://hdl.handle.net/10214/3874.
Full textAbstract:
The pathway of seawater ammonium assimilation and influence of light on amino acid synthesis remain unresolved in cnidarian symbioses. Labeled ammonium (10 μM 15NH4Cl) in seawater was used to trace the pathway of the incorporation into amino acids in host tissue, Zoanthus sp., and zooxanthellae, Symbiodinium microadriaticum. Freshly isolated zooxanthellae were exposed to 20 μM 15NH4Cl with coral homogenate to evaluate the role of host factors on amino acid synthesis. High performance liquid chromatography and mass spectrometry was used to measure percent labeling and concentrations of amino acids. In zooxanthellae, ammonium was assimilated into glutamine likely via glutamine synthetase and into glutamate via glutamine 2-oxoglutarate amidotransferase. Interrupting photosynthesis with DCMU did not inhibit glutamine and tryptophan synthesis however reduced the 15N-enrichment of glutamate, aspartate, and ornithine in zooxanthellae, as well as arginine, ornithine, and lysine in host tissue. Coral homogenate had little effect on the 15N-enrichment of glutamine, aspartate, and alanine in freshly isolated zooxanthellae. Evidence is presented to support the uptake of ammonium ions and data shows that glutamine and not glutamate is translocated to the coral host.
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Buxton, LJ. "Assessing the photosynthetic impact of inorganic carbon in symbiotic dinoflagellates in culture and in coral host complexes." Thesis, 2008. http://hdl.handle.net/10453/29532.
Full textAbstract:
University of Technology, Sydney. Institute for Water and Environmental Resource Management.Increased atmospheric carbon dioxide concentrations are causing warming of the Earth's atmosphere and having significant effects on the chemistry of the oceans. Disruption to seawater biochemistry is causing associated pH change known as ocean acidification and increased concentrations of dissolved inorganic carbon. Coral reefs are already at risk from increased seawater temperatures; however the impact of ocean acidification will be in addition to that of temperature change alone. The major objectives of this thesis were to provide insight into the effects of temperature, dissolved inorganic carbon concentration and seawater pH on the photosynthesis of the symbiotic algae Symbiodinium sp. both in vitro and in hospite. While it has been speculated that increased carbon dioxide may stimulate primary production, results presented here for short-term incubations show that Symbiodinium sp. photosynthesis is saturated at present concentrations (2 mM). However, photosynthesis in hospite can become significantly limited if DIC falls below 2 mM. This highlights the significant role of host inorganic carbon transport mechanisms for the maintenance in a healthy symbiosis. Symbiodinium sp. in culture however, show significant photosynthetic plasticity over a range of inorganic carbon concentrations (0.1 - 10 mM), and exhibit no photosynthetic inhibition at inorganic carbon concentrations well below ambient levels (0.4 - 2 mM). This suggests that Symbiodinium sp. have well developed carbon concentrating mechanisms and may be able to adapt to changes in inorganic carbon availability, whereas the same algae in hospite requires a higher DIC supply. Exposure to elevated temperature is known to cause photosynthetic inhibition in the coral symbiont Symbiodinium sp. Models of photophysiologcial thermal damage in corals can be generally divided into two broad groups; those that take place at the site of the light reactions and those that occur in the Calvin cycle. Results presented here have identified species- and cladal-specific heterogeneity in thermal inhibition of the dark reactions in the whole corals Stylophora pistillata and Pocillopora damicornis, and amongst Symbiodinium clades A, Band Cl. Furthermore, these patterns are not consistent when observed in vivo and in vitro. pH-drift experiments of Symbiodinium sp. grown in culture have identified significant cladal-specific pH ranges of clades A, B and subclade C1. Results show that Symbiodinium sp. are well adapted for living in rapidly changing pH and dissolved inorganic carbon environments. However, when measured in hospite in the C !- harbouring corals S. pistillata and P. damicornis, photosynthesis became significantly inhibited at pH 7.2 and 7.8 over short-term incubations. Furthermore, the thermal history of corals measured in the field had a significant effect on pH-susceptibility between summer and winter seasons. Results revealed an synergistic affect of elevated temperature and low pH on photosynthesis. The disparity between results observed in vivo and in vitro suggest that the cnidarian host may be considered the more vulnerable partner to changes in pH leading to photosynthetic inhibition and symbiotic dysfunction.
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Schwarz, Jodi A. "Cellular and molecular aspects of cnidarian-algal associations." Thesis, 2002. http://hdl.handle.net/1957/32492.
Full textAbstract:
Intracellular symbioses between cnidarians and dinoflagellates from the
genus Symbiodinium are widespread throughout the marine environment. These
associations are ecologically significant, especially in tropical waters where
symbiotic interactions between corals and Symbiodinium culminate in the
formation of limestone reefs. This thesis focuses on cellular and molecular aspects
of the symbiosis, specifically the initiation of the symbiosis and characterization of
a host gene, sym32, that is believed to function in the symbiosis. Sym32 was
originally identified as a differentially expressed protein in symbiotic vs.
aposymbiotic individuals of the sea anemone, Anthopleura elegantissima. Based
on its deduced amino acid sequence, sym32 belongs to a family of cell adhesion
proteins that play roles in cell recognition in a diverse array of organisms.
Chapter 2 examines the process by which a new cnidarian host acquires its
first symbionts. Larvae of the scleractinian coral Fungia scutaria, which are
initially aposymbiotic, acquired symbionts while feeding. Symbionts that entered
the larval gastric cavity with food were subsequently taken into host gastrodermal
cells by phagocytosis. Chapter 3 describes immunolocalization of sym32 in A.
elegantissima tentacles. In aposymbiotic tentacles, sym32 was localized to vesicles
within the host gastrodermal cells. Symbiotic tentacles lacked sym32-containing
vesicles. Instead, sym32 was present among the membranes that enclose the
symbionts within host cells. Western blots of proteins from Symbiodinium revealed
a 45/48kD doublet that cross-reacts with anti-sym32 antiserum. This suggests that
homologous proteins are expressed in both host (32kD) and symbiont (45/48 kD).
Chapter 4 describes the effects of environmental factors on expression of host
sym32. Aposymbiotic and symbiotic anemones maintained in continual darkness
for 3 weeks experienced a dramatic decline in sym32 protein levels, relative to
anemones maintained on a 12:12 h light:dark cycle. This suggests that light plays a
major role in regulating sym32. Exposure of anemones to elevated temperatures
for 2 days in the dark caused a mild bleaching response (expulsion of symbionts
from the host), but did not affect the levels of sym32 protein. Chapter 5 examines
the role of sym32 during the infection process, using antibody interference
techniques. F. scutaria larvae and symbionts incubated in sym32 antiserum during
the infection process experienced a decline in infection rates. Further, symbionts
that were incorporated into host gastroderm appeared to be degenerating in
antiserum treatments, but appeared to be healthy in preimmune controls.Graduation date: 2003
49
SHUN, WEI-QIAN, and 孫維謙. "Preparation of DNA from scleractinian coral and zooxanthella and used for DNA hybridization." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/53034627866790383600.
Full text
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Lin, Mei-Fang, and 林梅芳. "Mitochondrial genomic comparison provides evolutionary insights into relationships between azooxanthellate and zooxanthellate scleractinians (Cnidaria; Anthozoa)." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/41292717488916208395.
Full textAbstract:
碩士國立臺灣大學
海洋研究所
96
Because only a few studies of azooxanthellate scleractinians exist and results of 16S rDNA analyses of coral phylogeny are ambiguous, a mitochondrial genomics study can provide further understanding of scleractinian evolution. Both Euphyllia ancora and Polycyathus sp. which contain zooxanthellae belong to the suborder Caryophylliina and were previously separated into the robust subclade with family-level debates. The genera, Fungiacyathus and Madrepora, have also been the subject of taxonomic debate after radioimmunoassay and mitochondrial sequence analyses. Four mitochondrial (mt) genomes, two from azooxanthallate corals, Fungiacyathus stephanus and Madrepora oculata, and two from zooxanthellate corals, Euphyllia ancora and Polycyathus sp., were sequenced in this study. Three major features were discovered in the azooxanthellate mt genomes. First, gene rearrangement of cytochrome oxidase subunit II (COII) and cytochrome oxidase subunit III (COIII) and a poly (T) variation in the nad4 protein-coding gene were found in the mt genome of M. oculata. These characters are discussed in the Scleractinia for the first time. Second, F. stephanus presented a loose genome (19,381 bp) with a group I intron in the cox1 gene. In contrast, the zooxanthellate coral, Polycyathus sp., had the most compact mt genome (15,356 bp) among all the scleractinians known to date. Euphyllia ancora presented an extremely long cox1 gene. Phylogenetic analyses also showed unique information of these four mt genomes in the evolutionary trees, and M. oculata formed a single lineage with robust clade corals, supporting the result of rearrangement of the COII and COIII genes. Fungiacyathus stephanus grouped with the Poritidae. The cox1 group I intron occurs in the Fungiacyathus-Poritidae lineage. The high sequence similarity of cox1 intron nucleotides between Fungicyathus and the Poritidae indicates that azooxanthellate and zooxanthellate corals have the same origin of cox1 group I intron. The two Caryophylliina corals, Polycyathus and Euphyllia, were respectively grouped with the robust and complex clades. This suggests that Caryophylliina corals are not monophyletic. In conclusion, based on a mitogenomic approach, this study provides some insights into the phylogenetic relationships and evolution of mitochondrial genomes among these taxonomically ambiguous taxa.