Conselho Nacional de Desenvolvimento Científico e Tecnológico / Alguns recifes de coral da Baía de Todos os Santos passaram a ser dominado pelo zoantídeo Epizoanthus gabrieli em 2003. Fenômeno resultante da degradação dos recife de coral que atinge 20% desses ecossistemas e ameaça outros 35% no mundo. Apesar de sua importância, apenas a mudança na comunidade para o domínio de macroalgas foi suficientemente estudado. Assim, torna-se urgente estudos sobres alterações envolvendo a dominância de outros organismos. Estes fornecem subsídios para produção de modelos funcionais que podem ajudar na tomada de decisão para o manejo destes ecossistemas tanto na prevenção destas alterações quanto na recuperação de suas comunidades. Os objetivos deste trabalho são (i) verificar se este fenômeno constitui uma mudança de fase, a partir da redução da abundância de corais e persistência da alta cobertura de E. gabrieli por pelo menos cinco anos, (ii) avaliar os efeitos da competição entre este zoantídeo e corais adultos e recrutas com experimentos manipulativos e (iii) investigar os efeitos desta dominância na assembleia de peixes recifais. Os resultados confirmaram a existência de uma mudança de fase, sugerindo que a abundância de E. gabrieli aumentou em 2003 ou antes e que até 2007 houve uma redução da cobertura de coral, condição que se mantêm pelo menos até 2013. As três espécies de corais testadas mostram-se muito sensíveis ao contato com E. gabrieli, com necrose em 78% das colônias e ocupação do esqueleto dos corais em 35% dos casos em um período de 118 dias. Além disso, um modelo feito a partir dos dados de proporção de colônias de corais em contato com este zoantídeo e a cobertura de E. gabrieli sugere que quando o zoantídeo atinge 6% de cobertura, 50% das colônias de corais entram em contato com o mesmo. Estes dados são fortes evidências de que a redução da cobertura de coral observada entre 2003 e 2007 foi causada por competição entre estes organismos. Não foi observado efeito negativo no recrutamento do coral em substrato artificial livre em recifes dominados por E. gabrieli, nem nas proximidades das suas colônias. Isso sugere que uma suposta redução da cobertura deste zoantídeo deve ser acompanhada pelo aumento da taxa de recrutamento de corais e que a competição com a inibição do recrutamento não suporta um efeito de histerese. Foi constatado que esta mudança de fase reduz a riqueza de espécies de peixes recifais, apresentando dez espécies a menos que os recifes normais, e que favorecem os invertívoros moveis em detrimento dos carnívoros e invertívoros sésseis. Contudo não se observou diferença na abundância de peixes. / Some coral reefs of Todos os Santos Bay have undergone a drastic change in the benthic community. In 2003, they began to be dominated by the zoanthid Epizoanthus gabrieli. This phenomenon is a consequence of coral reef degradation that now reaches approximately 20% of coral reefs worldwide and and threatens another 35%. The most dramatic consequences of this degradation are the phase shift phenomena which are characterized by reduction of coral abundance and increase of organisms that do not build reefs. Despite their importance, only a phase shift to the domain of macroalgae has been sufficiently studied. Given this situation, it is urgent to create functional models that demonstrate the ecological processes that occur in the installation of alternative states that persist over time. These models provide important information that can help in decision making on management measures both for prevention and recovery of these ecosystems. The aims of this work are (i) to verify if this phenomenon is a phase shift, (i.e. the reduction of the abundance of coral and persistence of high coverage E. gabrieli for more than five years of monitoring), (ii) evaluate the effects of competition between this zoanthid and recruits and adult coral with manipulative experiments and (iii) study the effects of dominance on the fish assemblage. The result confirmed the existence of a phase shift, suggesting that the abundance of E. gabrieli increased in 2003 or before and in 2007 there was a reduction in coral cover, and that this condition remained until at least 2013. The three coral species tested show great sensitivity to contact with E. gabrieli, with necrosis in 78% of the colonies and with overgrow in 35% of cases in a period of 118 days. In addition, a model made from the data of a proportion of coral colonies in contact with this zoanthid and coverage of E. gabrieli suggests that when the zoanthid reaches 6% coverage, 50% of coral colonies come in contact with it. These data are strong evidence that the reduction of coral cover observed between 2003 and 2007 was caused by competition between these organisms. There was no negative effect on the recruitment of coral on artificial substrate free in reefs dominated by E. gabrieli or near their colonies. This suggests that a presumed reduction of coverage of this zoanthid should be accompanied by an increase in coral recruitment rates and the competition by inhibition of recruitment does not support an effect of hysteresis. It was found that this phase shift reduces species richness of reef fishes, by ten species unless reefs normal, and that favor mobile invertivores to the detriment of carnivores and sessile invertivores. However there was no difference in the abundance of fish.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-26T16:06:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Pinheiro_BR_2016_PPGO_UFPE.pdf: 4797187 bytes, checksum: 23d620ab5ad4e454bcb109d992f47da5 (MD5) / Made available in DSpace on 2017-04-26T16:06:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_Pinheiro_BR_2016_PPGO_UFPE.pdf: 4797187 bytes, checksum: 23d620ab5ad4e454bcb109d992f47da5 (MD5) Previous issue date: 2016-08-30 / O aumento da pressão parcial de dióxido de carbono (pCO2) na atmosfera, que passou de uma média de 280ppm antes da revolução industrial para acima de 400ppm nos dias atuais, é um dos principais responsáveis por uma série de mudanças globais. Entre elas, a elevação da temperatura superficial da água do mar (TSM), a elevação do nível do mar, e a acidificação oceânica (AO). Os ambientes recifais têm sido apontados como os mais vulneráveis a estas mudanças. Efeitos da elevação da pCO2 sob ambientes recifais no Atlântico Sul, são escassos e na sua maioria reportam apenas efeitos da elevação da TSM e eventos de branqueamento. O Atol das Rocas é a primeira Reserva Biológica marinha do Brasil e foi escolhido neste estudo por ser um exemplo de recife biogênico, oceânico e praticamente livre de impactos como sobrepesca, poluição, e turismo desordenado. Desta forma, o objetivo do presente estudo foi avaliar os efeitos da elevação da pCO2 atmosférica sob os organismos construtores do atol para estabelecer um ponto de referência para futuras comparações, devido a sua vulnerabilidade a estes processos. A pesquisa foi dividida em três etapas, sendo essas a caracterização, a avaliação do estado e a experimentação dos prováveis efeitos da acidificação nos organismos calcários. Inicialmente são apresentados dados sobre a cobertura bentônica e a sua interação com os parâmetros abióticos (temperatura, salinidade, disponibilidade de nutrientes dissolvidos, pH e alcalinidade total). Foi observada dominância de macro e tufos de algas em locais com maior disponibilidade de nutrientes dissolvidos, indicando que maiores concentrações de nutrientes inorgânicos na água do mar contribuem para a distribuição dos organismos no atol. E, além disso, ambientes com alta frequência de organismos carbonáticos foram associados com uma diminuição da concentração de alcalinidade. Em seguida, dados foram obtidos sobre reprodução, crescimento e distribuição de frequência da população da espécie de coral dominante nas piscinas do atol (Siderastrea stellata). Foi observado um evento de planulação e o crescimento inicial dos pólipos primários, os quais, após 3 meses mostraram uma média de diâmetro de 1,49±0,45 mm, variando entre 0,9 e 2,28 mm e 14,70% de taxa de mortalidade. A média da taxa de extensão anual das colônias adultas foi de 6,8 ± 0,7 mm. ano-1. Colônias com 4,1 a 10 cm de diâmetro também foram frequentes no atol (48,1±14,5%). A população de S. stellata no atol mostra-se com um alto potencial de manutenção e recuperação, embora tenha sido observado uma baixa taxa de recrutamento. Na outra etapa do estudo se fez uma caracterização do sistema carbonato no atol, avaliando a influência do metabolismo dos organismos sob as variações espaço-temporais observadas. Os resultados indicaram uma grande disponibilidade de carbonato dissolvido nas piscinas do atol. Os índices de saturação de aragonita não só suprem as necessidades metabólicas dos organismos, como estão acima dos observados para outros ambientes recifais. Desta forma, é possível que a intensa atividade biológica no atol das rocas possa servir como um tampão adicional para o equilíbrio do pH e mitigar alguns dos efeitos da acidificação oceânica localmente. Por fim, foi realizado um experimento com espécies que ocorrem no atol, o coral scleractíneo Porites astreoides e o zoantídeo Palythoa caribaeorum. Foram avaliadas as respostas fisiológicas (crescimento, respiração, fotossíntese, lipídios totais e clorofila a) desses organismos mediante condições de estresse térmico e acidificação. P. astreoides sofreu influência do aquecimento e da acidificação em todas as taxas metabólicas avaliadas, enquanto o P. caribaeorum teve um menor, ou nenhum impacto no seu metabolismo. / The increase in carbon dioxide partial pressure (pCO2) in the atmosphere, which rose from an average of 280 ppm before pre-industrial times to over 400 ppm today, it is one of the main responsible for a series of global changes. Among them, increasing sea surface temperature (SST), sea level rise and ocean acidification (OA). Coral reefs have been identified as the most vulnerable ecosystem to these changes. Investigations about the effects of elevated anthropogenic pCO2 on coral reef environments in the South Atlantic are scarce and mostly only effects of the increase of SST and bleaching events were reported. Rocas Atoll is the first Marine Biological Reserve in Brazil and was chosen in this study because it is an example of a oceanic biogenic reef, and virtually free from impacts such as overfishing, pollution, and unregulated tourism. Thus, the aim of this study was to evaluate the effects of increased atmospheric pCO2 on the atoll building organisms to establish a benchmark for future comparisons, because of their vulnerability to these processes. Initially are presented data on the benthic cover and its interaction with the abiotic parameters (temperature, salinity, availability of dissolved nutrients, pH and total alkalinity). It was observed a dominance of macro and tuff algae in places with higher availability of dissolved nutrients, indicating that higher concentrations of inorganic nutrients in seawater contribute to the spatial distribution of organisms on the atoll. And besides, environments with high frequency of carbonate organisms were associated with a decrease of alkalinity. Then, data were obtained on reproduction, growth and frequency distribution of the population of the dominant coral species in the atoll pools (Siderastrea stellata). A planulation event was observed and initial growth of primary polyps which, after 3 months showed 1.49 ± 0.45 mm average diameter ranging between 0.9 and 2.28 mm and 14.70% mortality rate. The average annual extension rate of adult colonies was 6.8 ± 0.7 mm. year-1. Colonies with 4.1 to 10 cm diameter were also common in the atoll (48.1 ± 14.5%). The population of S. stellata in the atoll shows a high potential for maintenance and recovery, although it was observed a low recruitment rate. In another stage of the study, a characterization of the carbonate system of the atoll was made, in order to assess the influence of the metabolism of organisms under spatio-temporal variations. The results indicated a large availability of dissolved carbonate in the atoll pools. The aragonite saturation rates not only supply the metabolic demands of the corals, but are above those observed for other coral reef environments. Thus, it is possible that the intense biological activity of the Rocas Atoll can serve as an additional buffer for the pH equilibrium and locally mitigate some of the effects of ocean acidification. Finally, an experiment was conducted with species that occur in the atoll, the scleractinian coral Porites astreoides and the zoanthid Palythoa caribaeorum. The physiological responses of these organisms were evaluated (growth, respiration, photosynthesis, total lipids and chlorophyll a) under conditions of heat stress and acidification. P. astreoides was influenced by warmer temperatures and acidification in all measured metabolic rates while P. caribaeorum showed a minor or no impact on your metabolism.

Herbivorous reef fish are a key functional group for the ecological resilience of coral reefs. Asthey feed on algae, a major resource competitor of coral polyps, they can prevent and reversecoral-macroalgal phase shifts. The resilience of the reefs against such phase shifts is given bythe ability of herbivores to keep the system in a cropped state from filamentous algae or bytheir capacity to feed on macroalgae. Most of the management plans that aim to protect coralreefs have been focusing on the establishment of marine protected areas or no-take areas wherefishing activities are strictly restricted or prohibited. In low-income countries, such managedareas can be difficult to accept from a fisher´s perspective and lack of money also tends to leadto limited surveillance capabilities and lowered compliance. These challenges are important toaddress when managing small-scale fisheries and where fish are considered as both, amarketable commodity and a subsistence good.A perhaps less contentious strategy for fishers is gear-based management, where the use offishing gears that are detrimental to coral reef resilience are restricted and at the same timegears that do not compromise resilience are promoted. This study aims to investigate how ninedifferent fishing gears (i.e. different lines, traps, nets and spears) used in the coral reef fisheriesof Zanzibar (Tanzania) capture herbivorous reef fish that can prevent (preventers) or reverse(reversers) coral-macroalgal phase shifts. Two interesting findings emerged from the study.First, different fishing gears had different impacts on these two functional groups where lines,large traps and seine nets fisheries had most impacts. Second, there were monsoonaldifferences in the catch of preventers and reversers. These findings are discussed in relation toi) similar studies conducted in different reef environments and ii) the feasibility of gear-basedmanagement in Zanzibar.

Coral reef ecosystems are some of the most biologically diverse systems in the world, and provide a number of ecosystem services that humans depend on for their wellbeing. Marine protected areas (MPAs) are a social-ecological intervention that while conserving these ecosystems, also have significant impacts on the communities that depend on them for their wellbeing. Community-based MPAs are growing in popularity with the assumption that by putting communities at the forefront of their planning and management, more participation will occur, ensuring positive social and ecological impacts. This study, through mixed qualitative and quantitative methods, examines two community-based MPAs in coastal Kenya (called tengefus) to understand how each tengefu was incepted, and how resource users perceive the impacts of the tengefu on ecosystem services and human wellbeing. Participation in and donor support for the tengefu were found to influence how resource users perceived impacts. Individuals who were more engaged in the project or held some type of leadership position perceived more positive impacts on ecosystem services and human wellbeing compared to those not involved. In the two cases, tangible benefits (e.g. fisheries spillover and ecotourism) from the marine enclosure itself are too few to benefit the community as a whole. For tengefus to be social successes, more attention should be given to engaging all resource-dependent community members in their planning, implementation and management, and to understanding the multifaceted role of donor funding in supporting these initiatives.

Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The purpose of this study was to evaluate tourism capacity, the effectiveness of the management plan and the visitors’ willingness to pay (WTP) for increased conservation effort in the Buccoo Reef Marine Park (BRMP) in Tobago. Non-market contingent valuation was applied to estimate tourists’ WTP, using the data from a survey of 164 tourists. Local residents and government agencies were consulted to evaluate the management plan and the tourism capacity. Eighty-eight percent of local residents stated that the park was not well managed and that they lacked trust in the park agency. The density of tourists was 67-97% more than socially acceptable crowding norm. The tourists were willing to pay an additional entry fee of US$11.72 per person, which would generate additional revenue for the park management. In conclusion, the BRMP management needs modification in order to increase stakeholders’ trust, reduce tourists crowding intensity, and generate additional user-based revenue.

Genetic variation was examined in bluehead wrasse, Thalassoma bifasciatum, populations along the Florida Keys. Interpretion of mean heterozygosity (H), percent polymorphic loci per population (P), genetic similarity, and F and G statistics demonstrated a clear division of wrasse populations into "northern" and "southern" groups. Correlation and cluster analyses indicated the six reefs can be grouped in a similar fashion based on genetic and environmental data. The conclusion from this analysis of wrasse populations in the Florida Keys is that substantial population subdivision occurs in response to differing selective pressures created by heterogeneous environments.

No description available.

Since the 1980’s, there has been an unprecedented decline in the reef-building Caribbean corals, Acropora cervicornis and A. palmata, which has led to their listing as “threatened” under the U.S Endangered Species Act. Despite this protective status, these Acropora species continue to experience declines primarily attributed to disease, global climate change, and storm damage. Recent evidence suggests the hybrid of these threatened species (A. prolifera) is found at abundances similar to or higher than the parental species at many sites throughout the Caribbean. However, there is still much that is unknown as to how and why hybrids may be increasing in abundance at select sites. In 2007, scientists from NOAA NMFS established 9 permanent transects at three sites in the USVI to quantify fish diversity and coral tissue condition in A. cervicornis thickets. Over the years, they observed that A. prolifera seemed to be increasing in abundance on transects that were once dominated by A. cervicornis. This dataset provided a unique opportunity to investigate whether a shift from a threatened parental species to its hybrid may have occurred. This study has two objectives, (1) to quantify the change in A. cervicornis and A. prolifera percent cover and colony health over a 9-year period, and (2) to compare the genotypic diversity among the three Caribbean acroporids on and near the transects to determine the primary method of propagation, i.e., sexual versus asexual. For this study, I used transect photographs taken in March, July and November 2009, April 2012, and August 2017 to compare intra- and interannual variation in acroporid cover and colony health. Striking losses were observed in A. cervicornis cover between March 2009 and August 2017. At Thatch Cay, A. cervicornis declined from 25.7% to 8.9% between March 2009 and November 2009, but remained stable (10.2%) up to August 2017. Acropora cervicornis cover declined from 13.2% to 0% at Lovango Cay, and from 8.2% to 0% at No-Name Bay. At the one site (No-Name Bay) that A. prolifera was present during the original surveys of the transects, the percent cover remained relatively high and stable over the sample period. At No-Name Bay, A. prolifera percent cover (18.2%) was significantly higher than A. cervicornis (5.4%) by November 2009. It appears that A. prolifera expanded in the habitat left void by the decline in A. cervicornis. The general health of A. cervicornis based on the amount of healthy versus white and pale tissue appeared to decline at all sites between March 2009 and November 2009. To determine if the high percent cover on some transects was derived from asexual propagation or sexual recruitment, 139 tissue samples were collected in 2017 and genotyped using five microsatellite markers. No significant difference in genotypic richness (number of unique genotypes divided by the sample size) was observed among A. cervicornis (0.62), A. prolifera (0.64), and A. palmata (0.68). This suggests that the hybrid colonization is from multiple sexually derived individuals, not just asexual propagation from a rare hybridization event. High genotypic diversity, stable population abundance, and healthier colonies, suggest acroporid hybrids may become the primary habitat building coral of shallow reefs in the U.S. Virgin Islands. Due to considerable differences in morphologies between A. cervicornis and A. prolifera, it is unclear how a shift to the hybrid may affect the organisms that occupy acroporid structure and if the same ecological functions can be fulfilled.

Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references. / To understand how waves and sea level shape sandy shoreline profiles, I use existing energetics-based equations of cross-shore sediment flux to describe shoreface evolution and equilibrium profiles, utilizing linear Airy wave theory instead of shallow-water wave assumptions. By calculating a depth-dependent characteristic diffusivity timescale, I develop a morphodynamic depth of shoreface closure for a given time envelope, with depth increasing as temporal scale increases. To assess which wave events are most important in shaping the shoreface in terms of occurrence and severity, I calculate the characteristic effective wave conditions for both cross-shore and alongshore shoreline evolution. Extreme events are formative in the cross-shore shoreface evolution, while alongshore shoreline evolution scales linearly with the mean wave climate. Bimodal distributions of weighted wave heights are indicative of a site impacted more frequently by tropical storms rather than extra-tropical storms. To understand how offshore wave climate and underlying geometry of a carbonate reef platform shapes evolution of atolls, I simulate the hydrodynamics of a simplified reef flat, using XBeach, a two-dimensional model of infragravity wave propagation. The reef flat self-organizes to a specific width and water depth depending on the offshore wave climate and characteristics of the available sediment. Formation of a sub-aerial landmass, like a motu, can be initiated by a change in offshore wave climate (like a storm), which can create a nucleation site from mobilization and deposition of coarse sediment on the reef flat. Once a motu is present, the shoreline should prograde until reaching a critical reef-flat width. Our conceptual model of reef-flat evolution and motu formation is governed by understanding the hydrodynamics of the system and subsequent response of sediment transport. / by Alejandra C. Ortiz. / Ph. D.