Sex-change (or sequential hermaphroditism) is a phenomenon whereby an organism functions first as one sex, and then as the other in the later stage of its life. Sex change is an adaptation that has evolved to allow certain organisms to increase fitness through resource allocation of male and female functions in a single lifespan. Since the timing of sex change in an organism is critical to its reproductive output, the size or age at sex change is expected to be plastic in response to different environmental conditions. Social and environmental conditions usually convey the cues about the relative advantages of functioning as one sex or the other. Identifying the factors that influence the timing at sex change is important to understand the evolution of sex change in the life history. In order to elucidate how to optimize fitness through sex allocation in response to different environment, I studied the timing at sex change of Coralliophila violacea in different approach, including the age of individual, the compositions of social groups and the difference between two types of coral hosts in this thesis. Firstly, I present a method to determine the age of this snail and its age at sex change. The growth striae on the operculum were studied and compared to the age estimated by the Gompertz growth function based on growth data obtained from mark-recapture experiments. There is a significant correlation between the number of striae on the operculum and the age estimated from the Gompertz growth function, and the relationship is 1:1. These results suggest that the number of striae on the operculum can be used as an age index, with each stria representing 1 year of age. The age of sex change of this snail, according to my estimates by both stria number and aperture-length inferences, occurs between 4 and 6 years old. Growth rates of the snails are negatively correlated to size. Furthermore, individuals undergoing sex-change grew faster than males and females. This snail, Coralliophila violacea, forms snail patches on the surface of the massive coral, Porites spp. Secondly, the social factors were analyzed for the timing of this sedentary snail. These factors include the sex ratio, number of male and females, and the size of females in the snail patches, all of which could be important information in determining the timing of sex change. In this study only the size of the largest female could be significantly correlated with the size at sex change in a snail patch. Finally, I survey the distribution, size and reproductive characteristics of the snail, Coralliophila violacea (Lamarck), which inhabits the surface of both the branching coral Porites nigrescens and the massive corals, P. lobata and P. lutea. Based on these results I examined the host effect on (1) population structure and (2) reproductive characteristics, including the size at sex change of symbionts. On branching hosts, most snails were solitary, whereas on massive hosts, most had formed multiple-snail patches. Significantly smaller snails as well as proportionally more females were found on branching than on massive hosts. Furthermore, the fecundity of the females on the branching hosts was significantly lower than that on the massive hosts. The size at sex change (male to female) of the snails was smaller on the branching hosts than on massive hosts. Patch composition differences can partly explain the smaller size at sex change for snails on branching hosts; however, there was also evidence that host morphology had a significant effect on the timing of sex change.

Photosensitive behaviors and circadian rhythms are well documented in reef-building corals and their larvae, yet photoreceptive structures and opsins have not been described in these organisms. Here I provide evidence for red sensitivity in several species of coral larvae. Behavioral experiments with two Caribbean corals, Porites astreoides and Acropora palmata demonstrated that larvae settle and metamorphose at a greater frequency on red substrata than on similar substrata of other colors. Attachment to red substrata was not observed when larvae were maintained in the dark, suggesting that red sensitivity was responsible for the observed behavior. Extracellular recordings confirm photosensitivity and indicate that the peak sensitivity of coral photoreceptors are shifted towards the orange-red region of the visible light spectrum, similar to the spectra (fluorescence and reflectance) of preferred artificial (plastic) and natural (crustose coralline algae) settlement substrata. Using Blast analyses and a PCRbased approach, I have identified, sequenced and cloned two full-length opsin cDNAs from A. palmata larvae. One cDNA (Acropsin 1) encodes an opsin protein that is similar to a vertebrate melanopsin; the second (Acropsin 2) encodes a protein that is most similar to cephalopod rod opsin. I have successfully developed synthetic peptide antibodies against each Acropsin 1 and Acropsin 2. Western blots of adult A. palmata and A. cervicornis protein detect a 37kDa and 40kDa band, corresponding to the predicted molecular weights of Acropsins 1 and 2, respectively. Immunohistochemistry confirms expression of both opsins in A. palmata larvae. Staining of sectioned larvae demonstrates that Acropsin 1 is localized in the larval gastroderm while Acropsin 2 is localized in solitary epithelial cells, scattered throughout the larval ectoderm but with a polarized distribution and higher concentration in the aboral epidermis. This research provides several lines of evidence to support the existence, and demonstrate one potential ecological function, of opsin-based photosensitivity in corals.

The coral-inhabiting snail Coralliophila violacea is a common species in the Indo-Pacific coral reefs and it usually lives on the surface of its host, Porites spp. In this study, field survey on the distribution of C. violacea on poritid corals, Porites spp. among sites were conducted. And the influence of flow rate on the distribution of snails was also examined through a simulation model. The sampling sites were northeastern of Taiwan, Taitung, Penghu, Lutao, Hsiao-liu-chiu and Lanyu. The presence of spatial variability in the relative abundance of C. violacea on porited corals has been observed. The highest percentage of corals with snails was in northeastern Taiwan, i.e. 45% and the lowest ones were in Lutao and Lanyu, i.e. 12%. The distribution of snails among sites were heterogeneous (X2-test of independence; p<0.001). Significant differences of shell length in snails among sites were also found. Among them, the distribution pattern of shell length in snails from Lutao and Lanyu was not normal. Difference in the age-distribution of snails among sites was present. In general, five and six years old snails were most abundant. A lack of snails under two years old had been found in Lutao, Lanyu and Penghu. Based on the simulated downward trajectory of snail larvae, it was indicated that a minimum substratum for larval settlement varied with flow rates and depth of water.

Sexual reproduction in Porites divaricata (Le Sueur, 1820) was studied over a one year period (August, 2012 to August, 2013) in a shallow water (~2m depth) carbonate bank (also described as marginal) habitat at Rodriguez Key, a small island located 1.44 km off the east coast of Key Largo. Porites divaricata is a brooding, gonochoric species with peak reproductive output (planula release) occurring in March and at least a smaller event in May. This species showed an overall female to male sex ratio of 3.5:1. However, during peak reproduction, the sex ratio was 1.2:1. Spawning (sperm release) most likely occurred in late February when 78% of all oocytes and 84% of all spermaries were in stage IV of development. The largest output of stage IV eggs (n=164) occurred at this time, and these oocytes also had the second largest average individual oocyte volume (3.34x10-3 mm3, n = 79) compared to those from other sample dates. The largest average egg volume (3.79x10-3 mm3, n = 8) occurred in May, but with fewer eggs present (n=13). Population surveys showed P. divaricata densities of 7.4 and 17.7 colonies m-² at Site 1 and 2, respectively. Temperature data documented that SSTs were highly variable in the seagrass/coral habitat at site 2 (primary collection site), ranging from 13.1 to 34.9°C, with an average temperature of 25.9°C. Corals at Rodriquez Key are exposed to temperatures much higher (+3.8°C) during the summer and much lower (-8.2°C) in winter compared to corals living at a nearby bank reef (Molasses Reef). This is the first comprehensive reproductive study performed on Porites divaricata and may provide valuable information to the ongoing debate concerning the taxonomic relationships among P. divaricata, P. porites, and P. furcata.

Made available in DSpace on 2015-03-26T13:47:08Z (GMT). No. of bitstreams: 1 texto completo.pdf: 407930 bytes, checksum: 2e2e384d18c87e7272273f070c122bed (MD5) Previous issue date: 2006-09-29 / The necessity to treat different etiologies, magnitudes and localization of bone defects has stimulated the search and development of materials capable to substitute the bone. Autogenous bone graft, although considered ideal because his behavior, in the majority of the situations, presents intrinsic morbidity of attainment, and limitation as for the amount and morphology. The bone s bank allows to provide great part of the current necessities, but it possess related problems with cost, infrastructure necessity and, in human medicine, legal issues. The ideal bone substitute must be osteogenic, biocompatible, capable to provide scaffolds, to propagate other substances, to be easily usable in the clinic and have adjusted ratio cost-benefit. On the other side, in determined applications, it is desirable that some of these characteristics predominate on others, depending on the necessity of the case to treat. This paper has for objective to evaluate the Porites astreoides coral as alternative of bone substitute in the fulfillment of small defects, associate or not to the autogenous bone marrow, and to compare its morphology and composition with normal bone tissue. With this intention there was accomplish a comparative study of the structural and morphologic properties of Porites astreoides coral samples, synthetic hydroxyapatite and bone of young and adult dogs, by x-rays diffraction; and an experimental study, comparing the samples previously, in the repair bone defects in dogs tibia , by radiographic and histology evaluations. / A necessidade de tratar defeitos ósseos de diferentes etiologias, magnitudes e localizações têm estimulado a busca e desenvolvimento de materiais capazes de substituir o osso. O autoenxerto, mesmo sendo considerado o enxerto ideal por seu comportamento, na maioria das situações, apresenta morbidade intrínseca a sua obtenção, e limitação quanto à quantidade e morfologia. Os bancos de ossos permitem resolver grande parte das necessidades atuais, mas possui problemas relacionados a custo, necessidade de infra-estrutura e, em medicina humana, de ordem médico-legal. O substituto ósseo ideal deve ser osteogênico, biocompatível, capaz de proporcionar suporte estrutural e de veicular outras substâncias, facilmente utilizável na clínica e com adequada proporção custo-benefício. Por outro lado, em determinadas aplicações, é desejável que algumas dessas características predominem sobre outras, dependendo da necessidade do caso a tratar. Esta dissertação tem por objetivo avaliar o coral Porites astreoides como alternativa de substituto ósseo no preenchimento de pequenos defeitos, associado ou não à medula óssea autógena, e comparar a sua morfologia e composição com a do tecido ósseo normal. Para tal propósito foi realizado um estudo comparativo das propriedades estruturais e morfológicas de amostras do coral Porites astreoides, hidroxiapatita sintética e de ossos de cães jovens e adultos, por meio da difração de raios-x; e um estudo experimental, comparando as amostras citadas anteriormente, na reparação de falhas ósseas realizadas na tíbia de cães, por meio de avaliações radiográficas e histológicas.

Tsang, Yu Man. / "November 2009." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 268-277). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.iii / Content --- p.vii / List of Tables --- p.ix / List of Figures --- p.xx / Chapter Chapter One --- General Introduction --- p.1 / Introduction --- p.1 / Coral Reefs --- p.1 / Coral-Algal Symbiosis --- p.2 / The Dinoflagellate Symbiodinium --- p.11 / Coral Communities in Hong Kong --- p.18 / Objectives --- p.21 / Study Sites - Tung Ping Chau Marine Park --- p.21 / Coral Species chosen for the Experiment --- p.23 / Platygyra acuta --- p.23 / Porites lutea --- p.23 / Thesis Outline --- p.24 / Chapter Chapter Two --- Temporal variation in photophysiological parameters of Hong Kong corals and their relationship with the environmental factors --- p.28 / Introduction --- p.28 / Methods and Materials --- p.33 / Study Sites --- p.33 / Coral Sampling for zooxanthellae density and chlorophyll concentration analysis --- p.34 / Measurement of changes in the photosynthtic activity of the corals --- p.38 / Environmental Factors --- p.38 / Data analysis --- p.39 / Results --- p.41 / Density of Zooxanthellae --- p.41 / Concentrations of Chlorophyll a and c2 (per zooxanthella) --- p.43 / Concentrations of Chlorophyll a and c2 (per surface area) --- p.46 / Chlorophyll ratio --- p.49 / Effective quantum yield --- p.51 / Photosynthetically active radiation (PAR) --- p.54 / Intra-colony variation for Platygyra acuta --- p.56 / Comparison between Platygyra acuta and Porites lutea --- p.64 / Environmental factors and their correlations with photophysiological parameters in corals --- p.68 / Discussion --- p.73 / Density of zooxanthellae --- p.74 / Concentrations of Chlorophyll a and c2 --- p.80 / Chlorophyll ratio --- p.85 / Effective quantum yield --- p.88 / Intra-colony variation --- p.94 / Between species comparison --- p.98 / Summary --- p.107 / Chapter Chapter Three --- PCR-RFLP Analysis on Symbiodinium in Platygyra acuta --- p.241 / Introduction --- p.241 / Methods and Materials --- p.244 / Sample collection --- p.244 / Molecular phylotyping --- p.245 / Results --- p.247 / Discussion --- p.249 / Summary --- p.257 / Chapter Chapter Four --- Summary and Conclusion --- p.262 / References --- p.268

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 89-96). / ix, 96 leaves, bound ill. 29 cm

Coral reefs constitute some of the most prolific and diverse ecosystems on our planet, but also among the most threatened. This thesis investigates the effects of environmental stressors on corals’ metabolism and symbiont diversity. Paper I shows that the coral Turbinaria mesenterina withstood a single stressor while a combination of two stressors (decreased salinity and increased seawater temperature) lead to decreased metabolism. Increased seawater temperature in combination with two stressors (enhanced nutrients and decreased salinity) lead to rapid mortality of all specimens. Paper II shows that chronic stress in combination with increased seawater temperature affects coral species differently. Porites lutea did not show any difference in response to temperature increase, regardless of environmental disturbance history, while Galaxea fascicularis’ metabolism was negatively affected in chronically disturbed corals but not in corals from less disturbed areas. The main explanation for the difference in response between the two species is different compositions of endosymbionts as found in paper III. P. lutea only harboured the symbiont C15, regardless of environment, whilst D1a dominated the nearshore G. fascicularis and C1 dominated offshore corals. In paper IV there was a clear inshore-offshore pattern of D1a along the whole coast of Vietnam, where D1a dominated inshore. In contrast, the five symbionts belonging to group C displayed a strong latitudinal gradient, with diversity increasing from north to south. The coral host showed higher diversity offshore than inshore. The thesis emphasizes the importance of improving water quality (paper I and II) and protecting marginal areas since tolerant coral hosts and symbionts can be found there (paper III and IV), as well as safeguarding areas with high symbiont diversity (paper IV) to increase the ability of corals to withstand future environmental changes. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

The proximity of coral reefs to coastal urban areas and shipping lanes predisposes corals to petroleum pollution from multiple sources. Previous research has evaluated petroleum toxicity to coral using a variety of methodologies, including monitoring effects of acute and chronic spills, in situ exposures, and ex situ exposures with both adult and larval stage corals. Variability in toxicant, bioassay conditions, species and other methodological disparities among studies prevents comprehensive conclusions regarding the toxicity of hydrocarbons to corals. This research evaluated the 48-hour toxicity of 1-methylnaphthalene to Porites divaricata using a continuous-flow passive dosing system. The range-finding exposure evaluated the dosing protocol and verified the effectiveness of the passive dosing technique at maintaining exposure concentrations. The full-toxicity exposures resulted in a precise estimate of toxic threshold concentrations for use in the target lipid model. The target lipid model promoted comparisons across different species by calculating the critical target lipid body burden of 355.7 µmol/ g lipid for P. divaricata. This indicates a greater resilience to petroleum hydrocarbon exposure compared to other species for which these data are available.