Thesis ( doctoral)--Göteborg University, 2005. / Includes bibliographical references.

Na presente dissertação eu estudei a distribuição potencial dos corais de águas profundas ao longo da margem continental brasileira e o efeito da resolução das variáveis ambientais em modelos de adequabilidade de habitat (MAH). Primeiramente foi determinada a distribuição potencial de corais de águas profundas a partir de modelos de adequabilidade de habitat de máxima entropia (MaxEnt). Os modelos foram alimentados com diversas camadas de dados SIG de variáveis ambientais e dados de ocorrência de espécies extraídos de bancos de dados e de novos registros. Foram estudados os grupos Scleractinia e Octocorallia, assim como quatro espécies de corais formadores de recifes (Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata e Enallopsammia rostrata) e duas espécies de escleractínios não formadores de recifes (Cladocora debilis e Deltocyathus spp.). O nicho ambiental ocupado pelos táxons foi representado a partir de uma análise multivariada, sendo determinada a sobreposição entre os nichos. A partir disso foi avaliada a similaridade e equivalência de nicho ambiental entre as espécies. Os modelos resultantes indicaram que Scleractinia apresenta distribuição potencial na margem continental leste e sudeste do Brasil (porção Central e Sul), enquanto que Octocorallia apresenta uma distribuição potencial mais ampla abarcando toda a margem continental brasileira, com maior adequabilidade nas margens norte e nordeste. Assim, as áreas de distribuição potencial compartilhada entre octocorais e escleractínios foram aquelas ao largo da porção leste e sudeste do Brasil, sendo estas prioritárias para futuras pesquisas. Os nichos ambientais específicos indicaram menos tolerância de Scleractinia a altas temperaturas em comparação com Octocorallia. Os octocorais ocuparam uma maior amplitude do gradiente ambiental, principalmente relacionado às condições de carbono orgânico particulado, oxigênio dissolvido e temperatura. Isto possivelmente permite aos octocorais habitar a porção norte da margem continental brasileira, onde os modelos de escleractínios indicaram baixa adequabilidade de habitat. A margem continental sudeste do Brasil teve a maior adequabilidade para as espécies de escleractínios formadores de recifes profundos. Isto é de grande valor para planos de conservação nesta área que atualmente apresenta atividades de extração de óleo e gás e que, futuramente, pode ser explotada para a extração de minério. Além disso, as espécies formadoras de recifes ocuparam nichos ambientais similares e, portanto, mudanças nas condições ambientais, como por exemplo as associadas às mudanças climáticas, podem afetar todas elas. Contudo, seus nichos não são equivalentes e, portanto, cada uma delas faz um uso diferente do espaço ambiental da margem continental brasileira. Por último, foram desenvolvidos modelos MaxEnt para Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata e Enallopsammia rostrata em duas resoluções de análise, uma de baixa (i.e., com um tamanho de pixel de aproximadamente 1000 m2) e uma de alta resolução (i.e., pixel de aproximadamente 100 m2) para determinar o efeito da resolução das variáveis ambientais utilizadas na performance e na extensão de área predita de modelos de adequabilidade de habitat. A diferença na extensão da área adequada predita por ambas resoluções foi medida de acordo a três limiares de corte diferentes. Os resultados indicaram diferenças na performance dependendo da resolução, com maior performance nos modelos de alta resolução. Além disso, a extensão de área adequada predita foi geralmente maior nos modelos de baixa resolução, com algumas exceções dependendo da espécie e do limiar de corte. Estes resultados ressaltam a importância da resolução das variáveis ambientais e suas implicações no uso de MAH no planejamento e manejo de Áreas Marinhas Protegidas (MPAs). / In this thesis I studied the deep-sea coral distribution along the Southwestern Atlantic Ocean and the effect of the environmental variables resolution on habitat suitability models (HSM). In the second chapter, I developed HSM based on the Maximum Entropy (MaxEnt) algorithm to identify the potential distribution of deep-water corals. To perform the models, I have used species presence data from existing datasets together with new species records and global environmental variables. I used the main environmental variables to identify suitable areas by modeling niches of different coral taxa. The studied taxa were Scleractinia and Octocorallia, as well as four reef-forming scleractinian species (Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata and Enallopsammia rostrata), and two non-reef-building scleractinians (Cladocora debilis and Deltocyathus spp.). Furthermore, I used multivariate approach to compare their environmental occupied niche in order to assess the spatial niche overlap and test niche similarity and equivalence. The resulting cold-water coral models showed that the most suitable areas occur along the west and southwestern continental margin of Brazil, which permitted to determine areas of priority for future exploration/research to determine conservation areas. Specific environmental niches suggested lower tolerance to high temperatures for Scleractinia than for Octocorallia. Besides, octocorals occupied a wider range of the environmental gradient, which was mainly related to particulate organic carbon, oxygen and temperature. This probably enables them to inhabit the northern part of Brazil where scleratinian models classified as poor habitats for this group. In addition, the Southwestern Brazilian continental margin encloses the most suitable habitats for deep reef-building species. This has important implications for conservation plans in that area already facing gas and oil exploitation and probably future mineral extraction. On the other hand, results suggest that different scleractinian cold-water coral species occupy similar environmental niches and, for this reason, I concluded that changes in environmental conditions, such as those associated to climate change, may affect them all. However, their niches are not equivalent and this suggests that each environmental factor could affect each species in different ways. In the third chapter, I performed HSM based on Maximum Entropy for Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata and Enallopsammia rostrata with two different environmental variables resolution, a low (i.e., a coarse resolution data with pixel size of ca. 1000 m2) and a high resolution (pixel of ca. 100 m2) to determine the effect of the environmental variables resolution on habitat suitability model performances and spatial extent of predicted suitable areas. From the final suitability maps, the changes in area extent depending of both resolution models were measured based in different thresholds. The results showed different performances of the models depending on data resolution, with higher performance at higher resolution. Furthermore, the predicted area varied between resolutions and threshold chosen. These results highlight the importance of environmental variables resolution and their implications for the use of HSM in planning and managing Marine Protected Areas (MPAs).

Na presente dissertação eu estudei a distribuição potencial dos corais de águas profundas ao longo da margem continental brasileira e o efeito da resolução das variáveis ambientais em modelos de adequabilidade de habitat (MAH). Primeiramente foi determinada a distribuição potencial de corais de águas profundas a partir de modelos de adequabilidade de habitat de máxima entropia (MaxEnt). Os modelos foram alimentados com diversas camadas de dados SIG de variáveis ambientais e dados de ocorrência de espécies extraídos de bancos de dados e de novos registros. Foram estudados os grupos Scleractinia e Octocorallia, assim como quatro espécies de corais formadores de recifes (Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata e Enallopsammia rostrata) e duas espécies de escleractínios não formadores de recifes (Cladocora debilis e Deltocyathus spp.). O nicho ambiental ocupado pelos táxons foi representado a partir de uma análise multivariada, sendo determinada a sobreposição entre os nichos. A partir disso foi avaliada a similaridade e equivalência de nicho ambiental entre as espécies. Os modelos resultantes indicaram que Scleractinia apresenta distribuição potencial na margem continental leste e sudeste do Brasil (porção Central e Sul), enquanto que Octocorallia apresenta uma distribuição potencial mais ampla abarcando toda a margem continental brasileira, com maior adequabilidade nas margens norte e nordeste. Assim, as áreas de distribuição potencial compartilhada entre octocorais e escleractínios foram aquelas ao largo da porção leste e sudeste do Brasil, sendo estas prioritárias para futuras pesquisas. Os nichos ambientais específicos indicaram menos tolerância de Scleractinia a altas temperaturas em comparação com Octocorallia. Os octocorais ocuparam uma maior amplitude do gradiente ambiental, principalmente relacionado às condições de carbono orgânico particulado, oxigênio dissolvido e temperatura. Isto possivelmente permite aos octocorais habitar a porção norte da margem continental brasileira, onde os modelos de escleractínios indicaram baixa adequabilidade de habitat. A margem continental sudeste do Brasil teve a maior adequabilidade para as espécies de escleractínios formadores de recifes profundos. Isto é de grande valor para planos de conservação nesta área que atualmente apresenta atividades de extração de óleo e gás e que, futuramente, pode ser explotada para a extração de minério. Além disso, as espécies formadoras de recifes ocuparam nichos ambientais similares e, portanto, mudanças nas condições ambientais, como por exemplo as associadas às mudanças climáticas, podem afetar todas elas. Contudo, seus nichos não são equivalentes e, portanto, cada uma delas faz um uso diferente do espaço ambiental da margem continental brasileira. Por último, foram desenvolvidos modelos MaxEnt para Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata e Enallopsammia rostrata em duas resoluções de análise, uma de baixa (i.e., com um tamanho de pixel de aproximadamente 1000 m2) e uma de alta resolução (i.e., pixel de aproximadamente 100 m2) para determinar o efeito da resolução das variáveis ambientais utilizadas na performance e na extensão de área predita de modelos de adequabilidade de habitat. A diferença na extensão da área adequada predita por ambas resoluções foi medida de acordo a três limiares de corte diferentes. Os resultados indicaram diferenças na performance dependendo da resolução, com maior performance nos modelos de alta resolução. Além disso, a extensão de área adequada predita foi geralmente maior nos modelos de baixa resolução, com algumas exceções dependendo da espécie e do limiar de corte. Estes resultados ressaltam a importância da resolução das variáveis ambientais e suas implicações no uso de MAH no planejamento e manejo de Áreas Marinhas Protegidas (MPAs). / In this thesis I studied the deep-sea coral distribution along the Southwestern Atlantic Ocean and the effect of the environmental variables resolution on habitat suitability models (HSM). In the second chapter, I developed HSM based on the Maximum Entropy (MaxEnt) algorithm to identify the potential distribution of deep-water corals. To perform the models, I have used species presence data from existing datasets together with new species records and global environmental variables. I used the main environmental variables to identify suitable areas by modeling niches of different coral taxa. The studied taxa were Scleractinia and Octocorallia, as well as four reef-forming scleractinian species (Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata and Enallopsammia rostrata), and two non-reef-building scleractinians (Cladocora debilis and Deltocyathus spp.). Furthermore, I used multivariate approach to compare their environmental occupied niche in order to assess the spatial niche overlap and test niche similarity and equivalence. The resulting cold-water coral models showed that the most suitable areas occur along the west and southwestern continental margin of Brazil, which permitted to determine areas of priority for future exploration/research to determine conservation areas. Specific environmental niches suggested lower tolerance to high temperatures for Scleractinia than for Octocorallia. Besides, octocorals occupied a wider range of the environmental gradient, which was mainly related to particulate organic carbon, oxygen and temperature. This probably enables them to inhabit the northern part of Brazil where scleratinian models classified as poor habitats for this group. In addition, the Southwestern Brazilian continental margin encloses the most suitable habitats for deep reef-building species. This has important implications for conservation plans in that area already facing gas and oil exploitation and probably future mineral extraction. On the other hand, results suggest that different scleractinian cold-water coral species occupy similar environmental niches and, for this reason, I concluded that changes in environmental conditions, such as those associated to climate change, may affect them all. However, their niches are not equivalent and this suggests that each environmental factor could affect each species in different ways. In the third chapter, I performed HSM based on Maximum Entropy for Solenosmilia variabilis, Lophelia pertusa, Madrepora oculata and Enallopsammia rostrata with two different environmental variables resolution, a low (i.e., a coarse resolution data with pixel size of ca. 1000 m2) and a high resolution (pixel of ca. 100 m2) to determine the effect of the environmental variables resolution on habitat suitability model performances and spatial extent of predicted suitable areas. From the final suitability maps, the changes in area extent depending of both resolution models were measured based in different thresholds. The results showed different performances of the models depending on data resolution, with higher performance at higher resolution. Furthermore, the predicted area varied between resolutions and threshold chosen. These results highlight the importance of environmental variables resolution and their implications for the use of HSM in planning and managing Marine Protected Areas (MPAs).

Human population growth and global industrial development are driving potentially irreversible anthropogenic impacts on the natural world, including altering global climate and ocean conditions and exposing oceanic environments to a wide range of pollutants. While there are numerous studies highlighting the variable effects of climate change and pollution on marine organisms independently, there are very few studies focusing on the potential interactive effects of these stressors. The deep-sea is under increasing threat from these anthropogenic stressors, especially cold-water coral (CWC) communities which contribute to nutrient and carbon cycling, as well as providing biogenic habitats, feeding grounds, and nurseries for many fishes and invertebrates. The primary goals of this dissertation are to assess the vulnerability of CWCs to independent and interacting anthropogenic stressors in their environment; including natural hydrocarbon seepage, hydrocarbon and dispersant concentrations released during an accidental oil spill (i.e. Deepwater Horizon), and the interacting effects of climate change-related factors and hydrocarbon/dispersant exposure. To address these goals, multiple stressor experiments were implemented to assess the effects of current and future conditions [(a) temp: 8C and pH: 7.9; (b) temp: 8C and pH: 7.6; (c) temp: 12C and pH: 7.9; (d) temp: 12C and pH: 7.6] and oil spill exposure (oil, dispersant, oil + dispersant combined) on coral health using the CWC Lophelia pertusa. Phenotypic response was assessed through observations of diagnostic characteristics that were combined into an average health rating at four points during exposure and recovery. Regardless of environmental condition, average health significantly declined during 24-hour exposure to dispersant alone and increased temperature resulted in a delay in recovery (72 hours) from dispersant exposure. The overall gene expression patterns varied by coral colony, but the dispersant exposure elicited the strongest response. Gene ontology (GO) enrichment analysis revealed that L. pertusa likely experienced varying stages of the cellular stress response (CSR) during exposure to oil, dispersant, and a decrease in pH. The most severe responses were associated with the dispersant exposure including GO terms related to apoptosis, the immune system, wound healing, and stress-related responses. However, the oil exposure induced an upregulation of metabolic pathways and energy transfer but a downregulation of cell growth and development, indicating that the coral nubbins could have been reallocating resources and reducing growth to maintain cellular homeostasis. The decrease in seawater pH elicited a similar response to oil through the enrichment of terms associated with a reduction in the cell cycle and development. Interestingly, the increase in temperature did not elicit a CSR that was detectable in the gene expression data. To further investigate the influence of hydrocarbon exposure on CWCs, comparisons of gene expression profiles were conducted using Callogorgia delta colonies that live in close proximity to active hydrocarbon seepage (“seep”) areas with no current active seepage (“non-seep”) at two different sites in the Gulf of Mexico. There were fewer differentially expressed genes in the “seep” versus “non-seep” comparison (n=21) than the site comparison (n=118) but both analyses revealed GO terms indicating slight alterations in natural biological housekeeping processes, as opposed to a CSR. Our results indicate that distinct stages of the CSR are induced depending on the intensity of stress. This bolsters the idea that there is a stress response shared by all corals in response to a variety of stressors. These data provide evidence that CWCs can be more negatively impacted, both on the phenotypic and molecular levels, by exposure to chemical dispersants than to hydrocarbons alone. Gaining an understanding of how these communities respond, not only to independent stressors, but the combination of these stressors, provides vital information about how CWC communities will fair in current and future conditions. / Biology

Deep-water or cold-water corals are abundant and highly diverse, greatly increase habitat heterogeneity and species richness, thereby forming one of the most significant ecosystems in the deep sea. Despite this remote location, they are not removed from the different anthropogenic disturbances that commonly impact their shallow-water counterparts. The global decrease in seawater pH due to increases in atmospheric CO2 are changing the chemical properties of the seawater, decreasing the concentration of carbonate ions that are important elements for different physiological and ecological processes. Predictive models forecast a shoaling of the carbonate saturation in the water column due to OA, and suggest that cold-water corals are at high risk, since large areas of suitable habitat will experience suboptimal conditions by the end of the century. The main objective of this study was to explore the fate of the deep-water coral community in time of environmental change. To better understand the impact of climate change this study focused in two of the most important elements of deep-sea coral habitat, the reef forming coral Lophelia pertusa and the octocoral community, particularly the gorgonian Callogorgia delta. By means of controlled experiments, I examined the effects of long- and short-term exposures to seawater simulating future scenarios of ocean acidification on calcification and feeding efficiency. Finally In order to understand how the environment influences the community assembly, and ultimately how species cope with particular ecological filters, I integrated different aspects of biology such functional diversity and ecology into a more evolutionary context in the face of changing environment. My results suggest that I) deep-water corals responds negatively to future OA by lowering the calcification rates, II) not all individuals respond in the same way to OA with high intra-specific variability providing a potential for adaptation in the long-term III) there is a disruption in the balance between accretion and dissolution that in the long term can shift from net accretion to net dissolution, and IV) there is an evolutionary implication for certain morphological features in the coral community that can give an advantage under stresfull conditions. Nevertheless, the suboptimal conditions that deep-water corals will experience by the end of the century could potentially threaten their persistence, with potentially negative consequences for the future stability of this already fragile ecosystem. / Biology

Ocean acidification is the reduction in seawater pH due to the absorption of anthropogenic carbon dioxide by the oceans. Reductions in seawater pH can inhibit the precipitation of aragonite, a calcium carbonate mineral used by marine calcifiers such as corals. Lophelia pertusa is a cold-water coral that forms large reef structures which enhance local biodiversity on the seafloor, and is found commonly from 300-600 meters on hard substrata in the Gulf of Mexico. The present study sought to investigate the potential impacts of ocean acidification on L. pertusa in the Gulf of Mexico through combined field and laboratory analyses. A field component characterized the carbonate chemistry of L. pertusa habitats in the Gulf of Mexico, an important step in establishing a baseline from which future changes in seawater pH can be measured, in addition to collecting in situ data for the design and execution of perturbation experiments in the laboratory. A series of recirculating aquaria were designed and constructed for the present study, and support the maintenance and experimentation of live L. pertusa in the laboratory. Finally, experiments testing L. pertusa's mortality and growth responses to ocean acidification were conducted in the laboratory, which identified thresholds for calcification and a range of sensitivities to ocean acidification by individual genotype. The results of this study permit the monitoring of ongoing ocean acidification in the deep Gulf of Mexico, and show that ocean acidfication's impacts may not be consistent across individuals within populations of L. pertusa. / Biology