Submitted by Alberto Vieira (martins_vieira@ibest.com.br) on 2018-01-31T00:18:00Z No. of bitstreams: 1 414933.pdf: 15896634 bytes, checksum: 6e86128ee7096bec949c9b616f290355 (MD5) / Made available in DSpace on 2018-01-31T00:18:00Z (GMT). No. of bitstreams: 1 414933.pdf: 15896634 bytes, checksum: 6e86128ee7096bec949c9b616f290355 (MD5) Previous issue date: 2000 / CAPES / Animais clonais crescem por acréscimo de unidades funcionais (zoóides) as quais formam a colônia. A abordagem modular consiste em descrever a forma das colônias do ponto de vista do arranjo e tamanho dos módulos. A abordagem modular foi usada aqui para quantificar variações na forma de crescimento do coral Montastraea cavernosa a partir da mensuração do arranjo e áreas dos pólipos na face interna do tecido colonial. Foram coletadas 46 amostras no Parcel das Paredes (BA) e João Pessoa (PB). Os resultados mostraram que área dos pólipos é parcialmente explicada por fatores ligados ao espaçamento entre eles. Estes fatores variam com a forma da colônia e com a faixa de tamanho de pólipos considerada. Foi proposto um modelo conceitual hipotético para a relação entre a forma de crescimento colonial, o tamanho e a organização dos pólipos. São discutidas possíveis razões evolutivas para o modelo proposto e implicações deste para estudos morfométricos da espécie. / Clonal animals grow through addition of functional units (zooids), whose assemblage constitutes a colony. The modular approach consists in describing colony form from the arrangement and size of modules. The modular approach was used here to access variations in growth forms of the coral Montastraea cavernosa using the arrangement and the size of polyps in the inner face of the colonial of 46 samples collected in Parcel das Paredes (BA) and João Pessoa (PB). Results showed that area of the polyps is partially explained by factors related to the spacing among them. These factors vary with the form of the colony and with the range of polyp sizes being analyzed. A hypothetical conceptual model for the relationship among colonial growth forms, polyp sizes and organization is proposed. Possible evolutionary reasons for such a model are discussed as well as possible implications to morphometric studies of this species.

Part I: Coral reefs are essential to coastal economies, protecting coastlines from storms, and harboring high biodiversity. However, reefs are declining due to local anthropogenic stressors and ocean warming. Sedimentation, a local stressor, aggravates the impacts of warming on corals and hinders their survival and growth. Therefore, it is important to investigate whether sedimentation and temperature have a synergistic effect on vulnerable coral species, especially during earlier stages of development. To quantify these effects, survival and growth of newly settled Acropora cervicornis corals were measured at two temperatures (29 and 31°C, representing current and predicted for 2050 Summer temperatures) and three sediment concentrations (30, 60 and 120 mg.cm-2, representing a range from natural sedimentation to dredging conditions). The intent of this study was to mix multiple genotypes to test temperature and sedimentation among genotypic unique individuals. However, only 20% of colonies spawned, and spawning was asynchronous by genotype. Therefore, individuals were produced from self-fertilization. The overall high mortality seen in this study suggests that self-fertilization in A. cervicornis does not produce viable juveniles. Although temperature did not have a significant effect on the survival of self-fertilized juveniles, sediment concentration did. The lowest sediment concentration led to the highest juvenile survival in both ambient and heated conditions. The growth of A. cervicornis selfed individuals was not significantly affected by temperature or sedimentation. These results suggest that reducing sedimentation in dredging and coastal construction areas around coral reefs facilitates the survival of Acropora cervicornis juveniles and may help to ensure their persistence in the future. Because self-fertilized larvae were used, these results need to be interpreted with caution, and this research needs to be repeated with outcrossed A. cervicornis. What is clear is that genotypic diversity is needed for A. cervicornis population growth and resilience. Part II: Chimeras occur when two or more genetically unique individuals of the same species fuse together. The presence of chimerism can aid in the survival and evolution of organisms. This study investigated whether the prevalence of chimerism differs between coral species of different reproduction modes and growth rates. To fulfill this goal, the surface area of egg and/or larvae of three coral species, Montastraea cavernosa, Acropora cervicornis, and Porites astreoides, were measured and compared with the respective surface areas of the newly settled juveniles. This comparison suggested that M. cavernosa displayed a greater tendency to form chimeras than A. cervicornis and P. astreoides. Observations during embryogenesis confirmed this prediction. Montastraea cavernosa is a slow grower and has the smallest eggs of all three study species. Chimerism during embryogenesis may increase this species’ tendency to start the sessile stage at a slightly bigger size and thus increases its competitive abilities for reef space. In contrast, A. cervicornis is a broadcast spawner, fast grower and has a relatively larger egg size, possibly explaining the reduced chimeric tendency during embryogenesis. It is possible that P. astreoides formed chimeras during embryogenesis within the polyp, but they did not form them in the swimming planulae stage. The lack of chimerism during P. astreoides planulae development may be attributed to its brooding reproductive mode, directly releasing large competent larvae that have large initial sizes at settlement. Therefore, the ability to form chimeras in an early developmental stage might provide an ecological advantage to M. cavernosa that contributes to its abundance in Broward County: the greater size at settlement caused by chimerism during embryogenesis may provide this species a competitive advantage for reef space.

Coral reefs are one of the most economically important ecosystems on the planet. Despite their great contribution to the world economy, anthropogenic influence via carbon dioxide emissions is leading to unprecedented changes with concerns about subsequent negative impacts on reefs. Surface ocean pH has dropped 0.1 units in the past century; in spite of this rapid shift in oceanic chemistry, it is unclear if individual species or life stages of Caribbean stony corals will be more sensitive to ocean acidification (OA). Examined is the relationship between CO2-induced seawater acidification, net calcification, photosynthesis, and respiration in three model Caribbean coral species: Orbicella faveolata, Montastraea cavernosa, and Dichocoenia stokesi, under near ambient (465 ± 5.52 ppm), and high (1451 ± 6.51 ppm) CO2 conditions. A species specific response was observed for net calcification; D. stokesi and M. cavernosa displayed a significant reduction in CaCO3 secreted under OA conditions, while O. faveolata fragments showed no significant difference. At the cellular level, transmission electron micrographs verified that all species and treatments were actively calcifying. Skeletal crystals nucleated by O. faveolata in the high CO2 treatments were statistically longer relative to controls. These results suggest that the addition of CO2 may shift the overall energy budget, causing a modification of skeletal aragonite crystal structures, rather than inhibiting skeletal crystal formation. Consequential to this energy shift, Orbicella faveolata belongs in the category of Scleractinian corals that exhibit a lower sensitivity to ocean acidification.

Scleractinian corals are the ‘engineers’ of tropical coral reef ecosystems. Their three-dimensional structure provides habitat for thousands of fish and invertebrate species. The persistence of corals is threatened by climate change. In this study I investigated if corals may be able to increase tolerance to ocean warming through developmental acclimation, i.e. if corals that experience warmer temperatures during embryonic and larval development are better able to cope with higher temperatures later in life. Larvae of the broadcast spawning coral Montastraea cavernosa were raised at ambient (29°C) and future projected ocean warming temperatures (+2°C, 31°C). After larval settlement, coral juveniles from each treatment were split and reared for two months at either current or +2°C conditions. Larvae reared at the warmer temperature had lower survival and displayed a smaller size at settlement. Juveniles that were in the warmer conditions had faster growth rates. Individuals raised during larval and juvenile stages at 31°C had faster growth rates than individuals only in the elevated temperature treatment after settlement, thus indicating that developmental acclimation may have occurred. However, the highest mortality also occurred in this treatment, therefore the growth results could also be explained by positive selection of the most thermally tolerant individuals. My results suggest that acclimation and/or directed selection may help corals withstand future rises in ocean temperature.