Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Edward C. Theriot and Judith C. Lang. Vita. Includes bibliographical references.

Uma das espécies de coral pétreo zooxantelado com mais ampla distribuição no litoral brasileiro é Madracis decactis Lyman, 1859. M. decactis forma colônias incrustantes nodulares que podem atingir até 30 cm de diâmetro. O estudo da gametogênese foi realizado através de coletas bimensais na Baía de Ilha Grande, RJ durante 21 meses (agosto/2004-maio/2006), totalizando 10 coletas (12 colônias/coleta) (Licença IBAMA no. 201/2004). Foram realizados cortes histológicos de 7 µm, e de 10 até 16 pólipos por colônia foram analisados, totalizando mais de 1800 pólipos. A análise dos pólipos indicou que M. decactis é hermafrodita, com gametas localizados no mesmo lóculo gástrico, porém em mesentérios diferentes. A gametogênese durou cerca de sete meses. A ovogênese iniciou-se ao redor de outubro, enquanto que a espermatogênese teve inicio no final de fevereiro, ambas terminando em sincronia no final do mês de maio. O exame dos pólipos férteis indicou a presença dos estágios I, II e III de desenvolvimento para a ovogênese e dos estágios I, II, III e IV para a espermatogênese. Não foram encontrados embriões ou plânulas nos cortes histológicos, indicando talvez que estes estágios permaneçam pouco tempo no interior do pólipo. O pico da atividade reprodutiva ocorre entre os meses de fevereiro e abril com todas as colônias férteis contendo ovócitos principalmente no estágio III de maturação. A provável época de liberação de plânulas ocorre entre os meses de abril e maio, sob influencia das condições ambientais como a temperatura da água do mar, a irradiação solar e a pluviosidade. O presente trabalho forneceu informações básicas a respeito da biologia reprodutiva de Madracis decactis presente em Ilha Grande, sendo uma contribuição para outros estudos mais específicos na área de manejo e conservação de ambientes marinhos. / One of the most wide distributed coral species along the Brazilian cost is Madracis decactis Lyman, 1859. M. decactis growths as nodular incrusting colonies that can reach up to 30 cm in diameter. In order to study the gametogenesis cycle, bimonthly collections were done at Ilha Grande Bay, Rio de Janeiro, during 21 months (August/2004- May/2006), totaling 10 collections (12 colonies/collection) (License no. 201/2004). Histological sections of 7 µm thick were done to analyze 10 to 16 polyps per colony (more than 1800 polyps in total). The analysis indicated that M. decactis is hermaphroditic, with male and female gametes developing at the same gastric loculi, but in different mesenteries. The gametogenesis lasted about 7 months, the oogenesis starts at October , while spermtogenesis starts at the end of February, both reaching the maturity in synchrony at the end of May. The exam of fertile polyps indicated the presence of stages I, II and III for oogenesis and I, II, III and IV for spermatogenesis. No embryo or planula were observed in the histological sections, indicating that maybe these stages stay for a short period inside the polyp cavity. The peak of reproductive activity was between February and April when all the polyps were fertile containing manly stage III oocytes. The releasing of planulae may happen between April and May, under the influence of environmental conditions as sea water temperature, solar insolation and rainy season. The present study has provided basic information about the reproductive biology of Madracis decactis from Ilha Grande Bay, and it may be a contribution to further studies about management and conservation of marine environments.

Coral reefs are some of the most diverse ecosystems in the world and provide economic value as well as biodiversity stability. Yet, these ecosystems are threatened from human degradation and climate change. Phylogenetic reconstructions can help identify which species have a potential to undergo greater amounts of change in the near future and also aids in determining evolutionary distinctiveness, which are critical components of conservation management. However, traditional Scleractinia morphological characters have been shown to have limited taxonomic use. Therefore, this study attempts to discover soft tissue characters to produce more robust phylogenies. Eight coral species from the Indo-Pacific families Merulinidae and Lobophylliidae were mail ordered and prepared for histological analysis under light microscopy. A character matrix was analyzed and the results were compared to phylogenies based on skeletal and molecular data. A total of seven MPTs of length 35, C.I. 0.60 and R.I. 0.58 were found. In addition, a detailed description of the histology is included. The topology of MPTs was inconsistent, but several were broadly similar to previous phylogenies based on molecular and skeletal data. Still, using only a small number of characters, the results do promise that histological characters in conjunction with skeletal characters could better delineate species and their evolutionary history. Future results could aid in making conservation decisions based on improved phylogenies.

Reef-building corals (Order: Scleractinia) are undergoing rapid taxonomic revision after molecular systematics disputed the relationships at all taxonomic levels within traditional classification. New morphological characters are being used to produce evolutionary relationships supported by molecular phylogenetics. While these characters are providing more congruent taxonomic relationships, their variation has not been fully explored. Additionally, phenotypic plasticity (changes in morphology resulting from environmental factors influencing the expressed phenotype despite a shared genotype) is prevalent amongst Scleractinia. In order to better understand the nature of these characters and explore their variation, I created a series of aquaria-based experiments designed to test the stability of these new morphological characters in response to differing environmental conditions. Light intensity and temperature were chosen as the environmental factors varied in these experiments on the basis of being a known trigger for environmentally-driven plasticity and their importance in calcification rate. In addition to aquaria-based phenotypic plasticity experiments I also examined a group (Family: Euphylliidae) within Scleractinia that had been divided by molecular phylogeny into two disparate groups. My research focused on morphological features viewed at magnifications observable by scanning electron microscopy (SEM) called micromorphology. Although variation in the skeletal micromorphology is observable, the new morphological characters that are used in taxonomy display only small amounts of variation caused by changing environmental conditions and were found to be stable for use in taxonomic studies. Additionally, I found a few micromorphological features distinguishing the two groups previously assigned to Euphylliidae including the shape of the septal margins and the fine-scale skeletal texture.

Thesis (M. Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 117-126).

This study investigates effects of eutrophication on settlement, abundance, mortality and community structure of soleractinian corals on fringing reefs on the west coast of Barbados, W.I. Juvenile abundance was lower, but juvenile size larger, on eutrophic than less eutrophic reefs. The lower abundance results at least in part from a higher juvenile mortality on eutrophic reefs. Algae were more abundant and grazers (Diadema antillarum and herbivorous fish) less abundant on eutrophic reefs. Juvenile community structure on all reefs, and adult community structure on eutrophic reefs, was dominated by type 1 corals (high recruitment, high natural mortality). Type 2 corals (low recruitment, low natural mortality) were common in adult communities on less eutrophic reefs. Settlement of coral recruits on artificial substrates was lower on more eutrophic reefs.

No description available.

Generations of hard corals have built the complex reef ecosystems that harbour a huge diversity of sea-life in the world’s shallow tropical oceans. These undergo both sexual and clonal reproduction, and may contain signatures in their genomes which help to decipher the riddles of past population dynamics and evolutionary history. Two species of coral, Acropora austera and Platygyra daedalea, were collected from sites along the east African coastline from Kenya in the north to Maputaland, South Africa in the south, and from the Chagos Archipelago. Sequences of two different DNA regions were tested, in a preliminary study, for their potential ability to elucidate connectivity and differentiation among these coral populations. These were the nuclear ribosomal ITS region of P. daedalea populations, and a previously-unused marker, the carbonic anhydrase 3/550 nuclear intron of A. austera. These molecular markers indicated high levels of connectivity amongst populations in a preliminary study based on limited sample sizes and a subset of populations. It was decided to further explore the variability of the carbonic anhydrase 3/550 intron, which showed evidence of subdivision and structuring within Mozambique populations relative to South African populations, in a study in which both the sample size per site and the number and range of sampled sites were increased. ITS sequences, although highly variable, revealed no population differentiation in P. daedalea; STR markers were used in subsequent studies of population differentiation in this species. Populations of both A. austera and P. daedalea showed signs of high connectivity along the region of the coastline sampled in this study. However, there appeared to be a disjunction in ecological connectivity between reefs in Maputaland, South Africa and those in southern Mozambique, between Durban and Maputo where the Agulhas Current originates. This was reinforced in A. austera populations which displayed a region of genetic discontinuity between Inhaca Island and Maputaland reefs of the central reef complex, in the region of Rabbit Rock. Northern reef complexes also harboured unique haplotypes in contrast to southern reefs which shared all haplotypes with those in the north, an indication that northern reefs have seeded the southern (Maputaland) reefs. P. daedalea populations appeared evolutionarily panmictic over scales relevant to this study. Evidence for fine-scale structure indicated that populations were separated from one another over ecologically relevant time-scales. These populations were defined by both their habitats and their sampling location. There was a possibility that the Platygyra species complex included cryptic species that were not distinguishable from P. daedalea. However, the disjunction in the connectivity between northern and southern population groups was also evident in the population structure of P. daedalea. There was a net immigration of propagules of both P. daedalea and A. austera into populations north of the disjunction between groups, where the prevailing current regime is dictated by the Mozambique Channel eddies. In contrast populations to the south of the disjunction (the southern population group) which are subject to the swiftly flowing Agulhas Current, showed a net emigration of propagules from Maputaland reefs. These emigrants were likely to be lost to inhospitable habitat south of the marginal Maputaland region. Although there was evidence for migration of both Platygyra and Acropora propagules between the Bazaruto Archipelago reefs and certain Maputaland reefs, genetic exchange between Mozambique and Maputaland reefs appeared to be limited and may have occurred primarily at evolutionary rather than demographic levels. Managers may need to treat the regional Maputaland reefs as separate stocks and manage them accordingly, as the relative isolation of these corals in the central and southern reef complexes in Maputaland, South Africa, means that they are at risk to losing species to evolutionary extinction. It is also important that reef health in northern Mozambique and Tanzania is maintained as, despite evidence of a break in demographic connectivity, between reefs in these regions and those in Maputaland, there was evidence to suggest that reefs were connected at evolutionary scales, thus maintaining levels of genetic diversity on southern African reefs. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.

Goals of this investigation were: 1) Differentiate between the effects of turbidity and sedimentation on corals. 2) Differentiate the effects of carbonate and terrigenous sediments on coral growth and metabolism. 3) Develop a predictive model relating increased sediment loading to the photosynthetic rate, growth and survival of corals. 4) Evaluate the validity of the widely cited "10 mg cut-off point" and determine the levels of turbidity and sedimentation that are tolerated by corals. Earlier studies suggest that coral reefs decline when sediment loading levels exceed a sediment trapping rate of 10 mg cm-2 d-1 or a turbidity of 10 mg I-1. An integrated experimental design linked field and laboratory experiments. In the field, corals were transplanted to sites with varying levels of sedimentation. Turbidity, as linked to reduced light availability, had a significant affect on coral growth and metabolism in laboratory experiments but not coral growth or survival in field experiments. Turbidity in the field was highly variable and influenced greatly by wind velocity and rainfall. Terrigenous (or land-derived) sediments influenced light extinction more than carbonate (reef-derived) sediments. In laboratory experiments turbidity was more important than sediment trapping rate in affecting the photosynthetic ability and growth rates of corals. The predictive model stated that the lower the light level (as caused by increased turbidity) the lower the photosynthetic production of corals. The model was supported by results of laboratory experiments where conditions were precisely controlled and monitored. Under field conditions, the predictive model did not hold due to extreme natural variability in sediment loading and variation in a wide range of other environmental factors encountered at the experimental sites. Corals tolerated turbidity exceeding 120 mg I-1 and sediment trapping rates in excess of 11 mg cm2 d-1. Sediment loading is correlated with other environmental factors such as nutrient loading and reduced salinity. Composition of sediment varies widely between different locations. The "10 mg cutoff may prove to be useful in setting limits to vigorous coral reef development, although individual corals or coral assemblages may be able to survive and grow at levels exceeding this value. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. Includes bibliographical references (leaves 235-264).

Thesis (Ph.D.) - James Cook University, 2004. / Typescript (photocopy). Appendices : leaves 141-146. Bibliography : leaves 147-169. Also available in an electronic version via the Internet.