Seabed fluid flow-related processes: evidence and quantification based on high-resolution imaging techniques and GIS analyses

This work provides new insights on different aspects of seabed fluid flow processes based on seafloor observations. The methods used entirely rely on ROV-based high-resolution imaging and mapping techniques. Optical data are used to produce visual maps of the seafloor, in the form of geo-referenced video- and photo-mosaics, whereas acoustic techniques allow mapping the micro-bathymetry of the seabed, as well as the signal reflectivity of the sediment surface and of the water column. This work presents three case studies, about two sites of seabed fluid flow: the Menez Gwen hydrothermal vent on the MAR and the REGAB pockmark in the Lower Congo Basin. On the technical side, some of the high-resolution techniques used in this thesis are not commonly used by the marine scientific community. This is particularly the case for large-area photo-mosaics. Although the interest in mosaicking is growing, there are still no tools freely and readily available to scientists to routinely construct large-area photo-mosaics. Therefore, this work presents a MATLAB toolbox for large-area photo-mosaicking (LAPM toolbox), which was developed as part of this thesis

Default versus configured-geostatistical modeling of suspended particulate matter in Potter Cove, West Antarctic Peninsula

The glacier retreat observed during the last decades at Potter Cove (PC) causes an increasing amount of suspended particulate matter (SPM) in the water column, which has a high impact on sessile filter feeder? species at PC located at the West Antarctic Peninsula. SPM presents a highly-fluctuating dynamic pattern on a daily, monthly, seasonal, and interannual basis. Geostatistical interpolation techniques are widely used by default to generate reliable spatial information and thereby to improve the ecological understanding of environmental variables, which is often fundamental for guiding decision-makers and scientists. In this study, we compared the results of default and configured settings of three geostatistical algorithms (Simple Kriging, Ordinary Kriging, and Empirical Bayesian) and developed a performance index. In order to interpolate SPM data from the summer season 2010/2011 at PC, the best performance was obtained with Empirical Bayesian Kriging (standard mean = −0.001 and root mean square standardized = 0.995). It showed an excellent performance (performance index = 0.004), improving both evaluation parameters when radio and neighborhood were configured. About 69% of the models showed improved standard means when configured compared to the default settings following a here proposed guidelineFil: Neder, Camila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Sahade, Ricardo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Abele, Doris. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Pesch, Roland. Jade University of Applied Sciences; AlemaniaFil: Jerosch, Kerstin. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; Alemani

Remote sensing and GIS-based analysis of hydrocarbon seeps: Detection, mapping, and quantification

The thesis aims to elucidate the transport and fate of hydrocarbon emissions from deep-sea seeps through the water column towards the atmosphere. An array of hydroacoustic, satellite, and optical imaging techniques was employed to detect, map, and quantify such seeps and accompanying oil and gas emissions. The major finding is that gas transport via bubbles is the overwhelming mechanism, to transfer hydrocarbons to the hydrosphere. However, only at seeps that discharge oil and gas (oily gas bubbles) these emissions might reach the sea surface and atmosphere. At other sites gas dissolves in the water column, thus not representing a primary source of atmospheric methane and higher hydrocarbon concentrations. Therefore it is suggested to focus research on oil seeps when aiming to study the potential effect of marine hydrocarbon seeps on the present climate

Development and validation of spatial distribution models of marine habitats, in support of the ecological valuation of the seabed

The marine environment is subjected to increasing anthropogenic pressure. Although there is a willingness of the different activities to minimize their impacts, there is a strong need for the assessment of the ecological value of the seabed, comprising both the abiotic substrate and the living organisms related to it (together called a ‘habitat’). Therefore, ‘habitat mapping’ is crucial, not only for the assessment of the ecological value at a certain moment, but also to follow its evolution over time. Because of the world-wide application of marine habitat mapping, there is currently a great variety in approaches, methodologies to use, as also in the ways habitats are classified. Therefore, it is of utmost importance that attempts are being made to propose more ‘common approaches’ in marine habitat mapping. The general aim of this study is to apply and develop straightforward and statistically sound methodologies for highly reliable sedimentological and habitat modelling, in support of a more sustainable management of our seas. To achieve these aims, this thesis is subdivided into 2 themes: 1) Best coverage data for habitat mapping; and 2) Integration of datasets in the view of habitat mapping

Benthic mapping of the Bluefields Bay fish sanctuary, Jamaica

Small island states, such as those in the Caribbean, are dependent on the nearshore marine ecosystem complex and its resources; the goods and services provided by seagrass and coral reef for example, are particularly indispensable to the tourism and fishing industries. In recognition of their valuable contributions and in an effort to promote sustainable use of marine resources, some nearshore areas have been designated as fish sanctuaries, as well as marine parks and protected areas. In order to effectively manage these coastal zones, a spatial basis is vital to understanding the ecological dynamics and ultimately inform management practices. However, the current extent of habitats within designated sanctuaries across Jamaica are currently unknown and owing to this, the Government of Jamaica is desirous of mapping the benthic features in these areas. Given the several habitat mapping methodologies that exist, it was deemed necessary to test the practicality of applying two remote sensing methods - optical and acoustic - at a pilot site in western Jamaica, the Bluefields Bay fish sanctuary. The optical remote sensing method involved a pixel-based supervised classification of two available multispectral images (WorldView-2 and GeoEye-1), whilst the acoustic method comprised a sonar survey using a BioSonics DT-X Portable Echosounder and subsequent indicator kriging interpolation in order to create continuous benthic surfaces. Image classification resulted in the mapping of three benthic classes, namely submerged vegetation, bare substrate and coral reef, with an overall map accuracy of 89.9% for WorldView-2 and 86.8% for GeoEye-1 imagery. These accuracies surpassed those of the acoustic classification method, which attained 76.6% accuracy for vegetation presence, and 53.5% for bottom substrate (silt, sand and coral reef/ hard bottom). Both approaches confirmed that the Bluefields Bay is dominated by submerged aquatic vegetation, with contrastingly smaller areas of bare sediment and coral reef patches. Additionally, the sonar revealed that silty substrate exists along the shoreline, whilst sand is found further offshore. Ultimately, the methods employed in this study were compared and although it was found that satellite image classification was perhaps the most cost-effective and well-suited for Jamaica given current available equipment and expertise, it is acknowledged that acoustic technology offers greater thematic detail required by a number of stakeholders and is capable of operating in turbid waters and cloud covered environments ill-suited for image classification. On the contrary, a major consideration for the acoustic classification process is the interpolation of processed data; this step gives rise to a number of potential limitations, such as those associated with the choice of interpolation algorithm, available software and expertise. The choice in mapping approach, as well as the survey design and processing steps is not an easy task; however the results of this study highlight the various benefits and shortcomings of implementing optical and acoustic classification approaches in Jamaica.Persons automatically associate tropical waters with spectacular views of coral reefs and colourful fish; however many are perhaps not aware that these coral reefs, as well as other living organisms inhabiting the seabed are in fact extremely valuable to our existence. Healthy coral reefs and seagrass assist in maintaining the sand on our beaches and fish populations and are thereby crucial to the tourism and fishing industries in the Caribbean. For this reason, a number of areas are protected by law and have been designated fish sanctuaries or marine protected areas. In order to understand the functioning of theses areas and effectively inform management strategy, the configuration of what exists on the seafloor is crucial. In the same vein that a motorist needs a road map to navigate unknown areas, coastal stakeholders require maps of the seafloor in order to understand what is happening beneath the water’s surface. The location of seafloor habitats within fish sanctuaries in Jamaica are currently unknown and the Government is interested in mapping them. However a myriad of methods exist that could be employed to achieve this goal. Remote sensing is a broad grouping of methods that involve collecting information about an object without being in direct physical contact with it. Many researchers have successfully mapped marine areas using these techniques and it was believed crucial to test the practicality of two such methods, specifically optical and acoustic remote sensing. The main question to be answered from this study was therefore: Which mapping approach is better for benthic habitat mapping in Jamaica and possibly the wider Caribbean? Optical remote sensing relates to the interaction of energy with the Earth’s surface. A digital photograph is taken from a satellite and subsequently interpreted. Acoustic/ sonar technology involves the recording of waveforms reflected from the seabed. Both methods were employed at a pilot site, the Bluefields Bay fish sanctuary, situated in western Jamaica. The optical remote sensing method involved the classification of two satellite images (named WorldView-2 and GeoEye-1) and this process was informed using known positions of seafloor features, this being known as supervised image classification. With regard to the acoustic method, a field survey utilising sonar equipment (BioSonics DT-X Portable Echosounder) was undertaken in order to collect the necessary sonar data. The processed field data was modelled in order to convert lines of field point data to one continuous map of the sanctuary, a process known as interpolation. The accuracy of each method was then tested using field knowledge of what exists in the sanctuary. The map resulting from the image classification revealed three seafloor types, namely submerged vegetation, coral reef and bare seafloor. The overall map accuracy was 89.9% for the WorldView-2 image and 86.8% for GeoEye-1 imagery. These accuracies surpassed those attained from the acoustic classification method (76.6% for vegetation presence and 53.5% for bottom type - silt, sand and coral reef/ hard bottom). Similar to previous studies undertaken, it was shown that the seabed of Bluefields Bay is primarily inhabited by submerged aquatic vegetation (including seagrass and algae), with contrastingly smaller areas of bare sediment and coral reef. Ultimately, the methods employed in this study were compared and the pros and cons of each were weighed in order to deem one method more suitable in Jamaica. Often, the presence of cloud and suspended matter in the water block the view of the seafloor making image classification difficult. On the contrary, acoustic surveys are capable of operating throughout cloudy conditions and attaining more detailed information of the ocean floor, otherwise not possible with optical remote sensing. A major step in the acoustic classification process however, was the interpolation of processed data, which may introduce additional limitations if careful consideration is not given to the intricacies of the process. Lastly, the acoustic survey certainly required greater financial resources than satellite image classification. In answer to the main question of this study, the most cost effective and feasible mapping method for Jamaica is satellite image classification (based on the results attained). It must be stressed however that the effective implementation of any method will depend on a number of factors, such as available software, equipment, expertise and user needs, that must be weighed in order to select the most feasible mapping method for a particular site

Caracterização geomorfológica e sedimentológica do eixo E-W do Complexo Estuarino de Paranaguá

Resumo: As baías de Antonina e Paranaguá possuem uma área de ? 258,4 km², aporte fluvial máximo de 178 m³s-1 e correntes de maré mais intensa na vazante (0,9 ms-1) respondendo aos mecanismos de transporte, erosão e deposição diferente de outros estuários. O objetivo foi estabelecer as características da cobertura sedimentar atual e o contexto de sua distribuição no eixo E-W do Complexo Estuarino de Paranaguá pela integração espacial de parâmetros ambientais (batimetria, declividade, padrões sedimentológicos e velocidades das correntes de maré) de forma a identificar uma dinâmica de preenchimento. Foi utilizada analise estatística multivariada para delimitar padrões sedimentológicos. A área de estudo foi divida em pixels (150 m), onde os dados de batimetria, declividade (TIN), velocidade da corrente de maré e padrões sedimentológicos (IDW) foram convertidos para raster, com o posterior cálculo do centróide por pixel. Para integrar as informações georeferenciadas foi utilizada análise espacial Spatial Join. Totalizaram 6138 pixels (? 13,8 x 107 m²), com profundidade média de 4,3 m e máximas de ? 20 m. As áreas com profundidades menores que 2m e declividades menores que 0,1° totalizam 1500 pixels (? 3,3 x 107 m²), dos quais 847 pixels foram caracterizados como planícies de maré e 653 pixels como desembocaduras fluviais. As profundidades maiores que 6 m equivalem a 1771 pixels (? 3,9 x 107 m²) com declividades variáveis (0,5° - 2°) nas margens. A região intermediária as planícies de maré e canais apresentam profundidades entre 2 e 6m correspondente a 1887 pixels (? 4,2 x 107 m²), declividade de 0,1° a 2°. Foram encontrados 3 grupos sedimentológicos distintos, com predomínio do Grupo 1. As áreas de planícies de maré apresentam sedimentos finos, e quando integradas com dados de velocidade de correntes de maré tiveram correlação positiva, exceto nas regiões de desembocadura dos rios, pois os fluxos atuantes são fluviais e os sedimentos arenosos. A margem S do estuário caracterizada como planície de maré apresentou altas concentrações de carbonatos, as quais interferiram no diâmetro médio nas analises estatísticas. As maiores profundidades estão associadas às velocidades de correntes mais intensas, indicando competência do fluxo em carrear sedimentos. Por isso, o padrão de preenchimento do estuário dependente da hidrodinâmica local e não somente do aporte de sedimentos

Epibenthic biodiversity, habitat characterisation and anthropogenic pressure mapping of unconsolidated sediment habitats in Algoa Bay, South Africa

Implementation of an ecosystem-based management approach for marine systems requires a comprehensive understanding of the biophysical marine environment and the cumulative human impacts at different spatio-temporal scales. In Algoa Bay, South Africa, this study describes the epibenthic communities occurring in unconsolidated marine habitats. It further investigates the potential abiotic factors that influence their distribution and abundance, compares epibenthic communities with existing habitat information and evaluates the protection status of the marine environment in the Bay. Seabed imagery, covering a total area of 171.4m², and sediment samples were collected from 13 stations from which 106 epibenthic species were identified. Multivariate analyses revealed two statistically distinct communities that did not align with the Algoa Bay benthic habitat types defined in the current National Biodiversity Assessment (NBA, 2012). Further assessment indicated that community differences were driven by the presence of rock substrate. A range of abiotic factors were tested against the epibenthic communities to explore patterns and identify potential drivers. The combination of abiotic factors depth, mean grain size, mean bottom temperature and mean bottom current explained 55% fitted variation in epibenthic data. The degree of long-term variability in several of these parameters were likewise identified as explanatory variables, including bottom temperature, current speed and dissolved oxygen. The link between abiotic factors and the epibenthic communities observed indicate that these variables can act as surrogates for habitat mapping in the future. The existing and proposed Marine Protected Area (MPA) in conjunction with the NBA 2012 habitat types does well in protecting the majority of habitats in the Bay, however there remain habitats that lack protection. Utilising the benthic communities and potential drivers identified in this study, the proposed MPA boundary delineations should be somewhat altered to include missing habitat types

Spatial analysis of marine categorical information using indicator kriging applied to georeferenced video mosaics of the deep-sea Håkon Mosby Mud Volcano.

The exact area calculation of irregularly distributed data is in the focus of all territorial geochemical balancing methods or definition of protection zones. Especially in the deep sea environment the interpolation of measurements into surfaces represents an important gain of information, because of cost- and time-intensive data acquisition.The geostatistical interpolation method indicator kriging therefore is applied for an accurate mapping of the spatial distribution of benthic communities following a categorical classification scheme at the deep-sea submarine Håkon Mosby Mud Volcano. Georeferenced video mosaics were obtained during several dives by the Remotely Operated Vehicle Victor6000 in a water depth of 1260 m. Mud volcanoes are considered as significant source locations for methane indicated by unique chemoautotrophic communities as Beggiatoa mats and pogonophoran tube worms. For the detection and quantification of their spatial distribution 2840 georeferencedvideo mosaics were analysed by visual inspection. Polygons, digitised on the georeferenced images within a GIS, build the data basis for geostatistically interpolated mono-parametric surface maps. Indicator kriging is applied to the centroids of the polygons calculating surfacemaps.The quality assessment of the surface maps is conducted by leave-one-out cross-validation evaluating the fit of the indicator kriging variograms by using statistical mean values. Furthermore, the estimate was evaluated by a validation dataset of the visual inspection of 530 video mosaics not included within the interpolation, thus, proving the interpolated surfaces independently. With regard to both validating mechanisms, we attained satisfying results and we provided each category applied for the identification of biogeochemical habitats with apercentage probability value of occurrence

Uso experimental de câmeras digitais para o estudo da concentração de sólidos em suspensão em sistemas aquáticos continentais.

O aumento da demanda sobre os recursos hídricos tem provocado modificações nas características dos sistemas aquáticos e isso exige o desenvolvimento de novas ferramentas que possibilitem monitorar a dinâmica e as características desses ambientes. Neste contexto, o sensoriamento remoto é uma ferramenta que torna possível a aquisição de informações sobre o comportamento espectral da água para análise espacial e temporal de ambientes aquáticos. As câmeras digitais também têm sido bastante empregadas para o monitoramento das feições espectrais da água e ganhado destaque por ser um método rápido e de baixo custo. Neste estudo, fez-se uso de uma câmera digital para ajustar um sistema de monitoramento automático de qualidade da água, com foco em medidas da turbidez, baseado em imagens digitais. Foram realizadas em laboratório simulações de respostas espectrais da água a partir do total de sólidos em suspensão para o solo contendo partículas orgânicas e inorgânicas e para solo contendo apenas partículas inorgânicas. Foi desenvolvido a partir das relações espectrais contidas em imagens digitais e o total de sólidos em suspensão um modelo empírico para este solo, que mostrou boa correlação entre as imagens digitais de TSS, sendo mais eficiente operando entre a faixa de 0,03g/L a 0,7g/L de TSS. In situ o modelo foi comparado com as estimativas de turbidez realizadas in situ para o reservatório da REPI em Wenceslau Braz – MG e no lago do campus da UNIFEI em Itajubá – MG. As convergências observadas entre os valores medidos e estimados a partir das imagens digitais foram consideradas satisfatórias. No entanto, a complexidade óptica para águas continentais dificulta a implementação de um modelo empírico universal, o que exige parametrizações locais

Factors influencing the distribution of the lusitanian and the mediterranean pine voles (Microtus lusitanicus and M. duodecimcostatus) in Portugal:a multiscale approach

Tese de doutoramento, Biologia (Ecologia), 2010, Universidade de Lisboa, Faculdade de CiênciasThe main goal of this thesis was to determine the environmental factors influencingthe distribution of two closely related voles in Portugal. More specifically the aimwas to analyse and compare the environmental preferences of the Lusitanian pinevole (Microtus lusitanicus (Gerbe, 1879)) and the Mediterranean pine vole (Microtusduodecimcostatus Sélys-Longchamps, 1839), at different scales of analysis, andalso to quantify the importance of spatial autocorrelation component in speciesdistribution models.At a national level the distribution pattern of pine voles was associated with climatevariables, landscape units, and soil types. The environmental associations at alandscape scale reflected the importance of habitat connectivity and heterogeneityfor the Lusitanian pine vole, and of open areas, free of shrubs, for theMediterranean pine vole. At a local scale, the high importance of verges, especiallyfor the Lusitanian pine vole, highlights the several advantages of these particularvegetation structures for small mammals.The sympatric area of both pine voles was consistently narrow in national andregional distribution maps. Results indicated that the local coexistence of the twovoles should be a rare event.Vole distribution data were characterized by strong spatial autocorrelation evenafter accounting for several significant environmental effects. At the largest scalethe spatial effects were the most important. At a finer scale, these effects, althoughstill important, played a secondary role when explaining the species distributionsand segregation.Furthermore, novel information was provided on space use, social behaviour,activity patterns, and habitat selection of Lusitanian pine vole.The discrimination of the two species in the field, and in a potential sympatric area,was possible using presence signs, namely the proportion of burrow openings.Multiple factors may influence the distribution of pine voles in Portugal. Some ofthese factors gain importance at specific spatial scales and others can only bediscussed using more than one scale approach.This research was funded by Fundação para a Ciência e Tecnologia (SAPIENS project POCI/BIA-BDE/57053/2004 and a PhD grant PRAXIS/SFRH/BD/21403/2005)