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Copley, Jonathan Timothy Peter. "Ecology of deep-sea hydrothermal vents." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246235.
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Howell, Kerry Louise. "The ecology of deep-sea asteroids." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268842.
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Billett, David. "The ecology of deep-sea Holothurians." Thesis, University of Southampton, 1988. https://eprints.soton.ac.uk/384501/.
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MAGAGNINI, MIRKO. "Viral ecology in the deep sea." Doctoral thesis, Università Politecnica delle Marche, 2009. http://hdl.handle.net/11566/242345.
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BARONE, GIULIO. "The Ecology and Diversity of Benthic Deep-Sea Fungi." Doctoral thesis, Università Politecnica delle Marche, 2019. http://hdl.handle.net/11566/263530.
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I funghi sono ovunque sulla Terra e contano oltre 2 milioni di specie, di cui solo il 10% è stato descritto. Il contributo fungino ai processi ecologici in ecosistemi terrestri è nodale. Tuttavia, la diversità e l’ecologia fungina negli ecosistemi bentonici di acque profonde sono ancora sconosciute. Questa tesi propone un’analisi dettagliata della letteratura corrente sull’ecologia dei funghi e fornisce nuove informazioni sulla loro abbondanza e diversità in campioni di sedimenti di acque profonde raccolti in tutto il mondo.
Negli ultimi decenni, la diversità fungina è stata descritta da in numerosi habitat bentonici di acque profonde, ma le informazioni quantitative sul loro ruolo ecologico sono carenti. Questa tesi mostra che l'abbondanza fungina non diminuisce all'aumentare della profondità dell'acqua, contrariamente ad altri eucarioti. Piuttosto, l’abbondanza fungina è generalmente alta e correlata alla disponibilità di risorse trofiche ed in particolare alle concentrazioni di carboidrati, che in questi ecosistemi includono la frazione più refrattaria. Questo studio rivela anche una ricchezza relativamente elevata di OTU fungine, in gran parte assenti nelle banche dati pubbliche, suggerendo che i sedimenti bentonici ospitano nuovi taxa anche ad alto livello tassonomico. Infine, la composizione delle comunità fungine varia nei diversi ecosistemi bentonici profondi in funzione di fattori biologici e ambientali. In particolare, le condizioni termoaline e l'ossigeno disciolto spiegano significativamente le variazioni osservate ad ampia scala spaziale.
Nel complesso, questo studio suggerisce che i funghi possono essere responsabili della degradazione di quelle risorse inaccessibili ad altri gruppi microbici e che i funghi sono una componente significativa, anche se largamente trascurata, delle comunità microbiche bentoniche di profondità. Pertanto, i funghi dovrebbero essere inclusi nei modelli per lo studio di reti trofiche e cicli biogeochimici.<br>Fungi occur in every environment of Earth and account for more than 2 million species of which we only roughly described the 10%. Fungal contribution to ecological processes in terrestrial and aquatic ecosystems is pivotal and well recognised. However, fungal diversity and ecology are yet largely unknown in benthic deep-sea ecosystems. Thus, this thesis provides a deep analysis of the current literature about fungal ecology along with laboratory analyses on fungal abundance and diversity in deep-sea sediment samples collected worldwide.
In the last few decades, fungi have been described from numerous benthic deep-sea habitats accounting for substantial diversity. However, quantitative information is missing hampering conclusions regarding their ecological role. The results of this thesis indicate that fungal abundance does not decline with increasing water depth, conversely to other eukaryotes. Rather, fungal abundance is generally high and strongly correlated to trophic resource availability and in particular with carbohydrate concentrations, which in deep-sea sediments include the less bioavailable fraction. This study also reveals that benthic deep-sea ecosystems host a relatively high fungal OTUs richness, whose majority did not match public databases, suggesting that benthic deep-sea sediments host novel taxa even at high taxonomic level. Also, assemblage composition considerably varies across benthic deep-sea ecosystems in function of biological and environmental factors such as thermohaline conditions and dissolved oxygen which significantly explain patterns of fungal assemblage composition over a wide spatial scale.
Overall, this study suggests that fungi can be responsible for the degradation of those resources inaccessible to other microbial groups and that fungi are a significant, although largely overlooked, component of the benthic deep-sea assemblages which should be included in food-web and biogeochemical cycle models.
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Premke, Katrin. "Aggregations of Arctic deep-sea scavenging amphipods at large food falls = Ökologische Untersuchungen nekrophager Amphipoden in der arktischen Tiefsee /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.loc.gov/catdir/toc/fy0706/2006506722.html.
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Ashford, Oliver Simon. "Illuminating the deep : an exploration of deep-sea benthic macrofaunal ecology in the Northwest Atlantic Ocean." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:228c4d19-56a8-41e1-a1da-9ca13fe2eef1.
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Understanding of the fundamental ecology of deep-sea ecosystems remains immature relative to more familiar shallow-water and terrestrial habitats, despite more than two hundred years of scientific investigation. This thesis aims to progress knowledge of deep-sea benthic ecology by the analysis of over three hundred box core samples collected from the Northwest Atlantic continental slope as part of the international NEREIDA programme. Aspects of the ecology of Peracarida (Crustacea) are studied, and this is facilitated by the coupling of a large faunal dataset with extensive environmental information. To further enhance the power of this dataset, phylogenetic and functional characteristics of assemblages are investigated. Using community phylogenetic methodology, it is demonstrated that the peracarid assemblages studied are structured more strongly by variation in environmental parameters than they are by competitive interactions. Analyses demonstrate that the intensity of bottom trawling, seafloor temperature, current speed, food availability, sediment characteristics and physical habitat heterogeneity all influence deep-sea peracarid assemblage biodiversity metrics. Further, the importance of high poriferan biomass for the promotion of peracarid assemblages of high density, biomass, richness and diversity is highlighted. Of relevance to the management of deep-sea ecosystems, the results of this thesis suggest that caution should be exercised when applying species distribution models to data-deficient environments, whilst the location of spatial closures in the NAFO Regulatory Area may not be fully optimal for the protection of all components of diverse benthic assemblages against the impacts of bottom trawling. The importance of deep-sea diversity is demonstrated by the finding of positive biodiversity â ecosystem functioning relationships. However, the form of these relationships is found to be dependent on the biodiversity and ecosystem functioning metrics employed, and a hypothesis for a generalised form of biodiversity â ecosystem functioning relationships is proposed. Finally, this thesis calls for more ambitious deep-sea ecological investigations, and it is hoped that its findings will encourage future research initiatives, helping to further illuminate this enigmatic and fascinating environment.
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Davies, Gareth John. "Aspects of the biology and ecology of deep-sea Scaphopoda (Mollusca)." Thesis, Heriot-Watt University, 1987. http://hdl.handle.net/10399/1005.
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Durkin, Alanna G. "The ecology of deep-sea chemosynthetic habitats, from populations to metacommunities." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/488249.
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Biology<br>Ph.D.<br>Chemosynthetic ecosystems are habitats whose food webs rely on chemosynthesis, a process by which bacteria fix carbon using energy from chemicals, rather than sunlight-driven photosynthesis for primary production, and they are found all over the world on the ocean floor. Although these deep-sea habitats are remote, they are increasingly being impacted by human activities such as oil and gas exploration and the imminent threat of deep-sea mining. My dissertation examines deep-sea chemosynthetic ecosystems at several ecological scales to answer basic biology questions and lay a foundation for future researchers studying these habitats. There are two major varieties of chemosynthetic ecosystems, hydrothermal vents and cold seeps, and my dissertation studies both. My first chapter begins at cold seeps and at the population level by modeling the population dynamics and lifespan of a single species of tubeworm, Escarpia laminata, found in the Gulf of Mexico. I found that this tubeworm, a foundation species that forms biogenic habitat for other seep animals, can reach ages over 300 years old, making it one of the longest-lived animals known to science. According to longevity theory, its extreme lifespan is made possible by the stable seep environment and lack of extrinsic mortality threats such as predation. My second chapter expands the scope of my research from this single species to the entire cold seep community and surrounding deep-sea animals common to the Gulf of Mexico. The chemicals released at cold seeps are necessary for chemosynthesis but toxic to non-adapted species such as cold-water corals. Community studies in this area have previously shown that seeps shape community assembly through niche processes. Using fine-scale water chemistry samples and photographic mapping of the seafloor, I found that depressed dissolved oxygen levels and the presence of hydrogen sulfide from seepage affect foundation taxa distributions, but the concentrations of hydrocarbons released from these seeps did not predict the distributions of corals or seep species. In my third chapter I examine seep community assembly drivers in the Costa Rica Margin and compare the macrofaunal composition at the family level to both hydrothermal vents and methane seeps around the world. The Costa Rica seep communities have not previously been described, and I found that depth was the primary driver behind community composition in this region. Although this margin is also home to a hybrid “hydrothermal seep” feature, this localized habitat did not have any discernible influence on the community samples analyzed. When vent and seep communities worldwide were compared at the family-level, geographic region was the greatest determinant of community similarity, accounting for more variation than depth and habitat type. Hydrothermal vent and methane seeps are two chemosynthetic ecosystems are created through completely different geological processes, leading to extremely different habitat conditions and distinct sets of related species. However, at the broadest spatial scale and family-level taxonomic resolution, neutral processes and dispersal limitation are the primary drivers behind community structure, moreso than whether the habitat is a seep or a vent. At more local spatial scales, the abiotic environment of seeps still has a significant influence on the ecology of deep-sea organisms. The millennial scale persistence of seeps in the Gulf of Mexico shapes the life history of vestimentiferan tubeworms, and the sulfide and oxygen concentrations at those seeps determine seep and non-seep species’ distributions across the deep seafloor.<br>Temple University--Theses
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Cornelius, Nils. "Biodiversity and ecology of benthic foraminiferans from the Antarctic deep sea." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416476.
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Summit, Melanie. "Ecology, physiology, and phylogeny of subseafloor thermophiles from mid-ocean ridge environments /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/11020.
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McCliment, Elizabeth. "Phylogenetic and metabolic diversity of microbial communities inhabiting deep-sea hydrothermal ecosystems." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 217 p, 2007. http://proquest.umi.com/pqdweb?did=1397900421&sid=7&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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De, Angelis Marie Agatha. "Studies of microbial methane oxidation in deep-sea hydrothermal vent environments /." Thesis, Connect to this title online; UW restricted, 1989. http://hdl.handle.net/1773/11040.
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Hassack, E. "Aspects of biogeography, systematics and ecolomorphology of deep-sea Tanaidacea (Crustacea, Peracarida)." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376146.
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Holden, James Francis. "Ecology, diversity, and temperature-pressure adaptation of the deep-sea hyperthermophilic Archaea Thermococcales /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/11044.
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Attrill, Martin John. "The biology and ecology of the major deep-sea benthic decapod crustacea from the Porcupine Sea-bight." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363784.
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Campos-Creasey, Lucia de Siqueira. "A study of the feeding biology of deep-sea echinoids from the North Atlantic." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316314.
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Herrera, Monroy Santiago. "Evolutionary and ecological genomics in deep-sea organisms." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97372.
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Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>Hydrothermal vents and coral ecosystems are conspicuous biological hot spots in the deep-sea. These ecosystems face increasing threats from human activities. Having thorough taxonomic inventories as well as understanding species' relatedness, genetic diversity, connectivity patterns, and adaptive potential is fundamental for the implementation of conservation strategies that help mitigate these threats. This thesis provides fundamental high-priority knowledge in taxonomic, evolutionary, and ecological aspects of deep-sea coral and vent species, by harnessing the power of genomic tools and overcoming long-standing methodological barriers. First, I develop bioinformatic tools that help guide the design of studies aiming to characterize eukaryotic genome diversity using restriction-site associated DNA sequencing. Using these tools I find that the predictability of restriction site frequencies in eukaryotic genomes is chiefly determined by the phylogenetic position of the target species and the recognition sequence of the selected restriction enzyme. These tools are then applied to test global-scale historical biogeographic hypotheses of vent fauna using barnacles as model. Phylogeographic inferences suggest that the western Pacific was the place of origin of the major vent barnacle lineage, followed by circumglobal colonization eastward along the southern hemisphere during the Neogene. I suggest that the geological processes and dispersal mechanisms discussed here can explain distribution patterns of many other marine taxa in addition to barnacles. Regional-scale analyses indicate that vent barnacle populations are well connected within basins and ridge systems, and that their diversity patterns do not conform to the predictions from the hypothesis that seamounts are centers of endemism. I then move on to resolve long-standing questions regarding species definitions in recalcitrant deep-sea coral taxa, by unambiguously resolving evolutionary relationships and objectively inferring species boundaries. Finally, I explore the adaptive potential of deep-sea coral species to environmental changes by examining a case of adaptation to shallow water from the deep sea. Candidate positive-selection markers shared between pairs of shallow and deep populations are identified as likely makers for genomic regions involved in adaptation. Overall, the results from this thesis constitute critical baseline data with which to assess potential effects of anthropogenic disturbances on deep-sea ecosystems.<br>by Santiago Herrera Monroy.<br>Ph. D.
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Leary, David Kenneth. "International law and the genetic resources of the deep sea /." Leiden [u.a.] : Nijhoff, 2006. http://www.loc.gov/catdir/toc/fy0710/2007270488.html.
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Galkiewicz, Julia Parker. "Microbial Ecology and Functional Genomics of Deep-Water Coral-Associated Microbes." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3111.
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Lophelia pertusa is a cosmopolitan cold-water coral, often found in aphotic waters (>200m). Aggregations of L. pertusa (reefs) provide important habitat to many invertebrate and fish species and act as biodiversity hotspots in the deep sea. The health and diversity of these reefs is of vital importance to deep-sea ecosystems, and the microbial consortia associated with L. pertusa form the most basic ecological level. Deciphering the diversity and function of these microbes provides insight into the roles they play in maintaining reef health. This dissertation takes microbiological techniques that are used in shallow-water coral microbial research and applies them to L. pertusa. A flaw in a primer set, which is commonly used in the molecular genetics method Polymerase Chain Reaction (PCR) to obtain data on coral-associated microbes, is discussed and an alternative approach is presented. In addition, two culture-based studies are employed to catalogue diversity and explore functional differences in strains of both bacteria and fungi. The cultured bacteria were tested for resistance against six antibiotics that affect a variety of cellular targets to elucidate strain level differences. The first cultured fungi ever described from L. pertusa were identified by molecular techniques and assayed using Biolog plates to test their metabolic capabilities. Preliminary data analysis on metagenomic libraries of the microbial-size fraction of L. pertusa is presented and discussed in the context of microbial diversity and function, bridging the gap between culture-based work on function and culture-independent work on diversity.
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Le, Goff-Vitry Marie-CeÌcile. "Molecular ecology of the deep-sea coral Lophelia pertusa in the North East Atlantic." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398819.
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Szuman, Magdalena Katarzyna. "Forward seismic modelling and spectral decomposition of deepwater slope deposits in outcrop and subsurface." Thesis, University of Aberdeen, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=105419.
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This project aimed to constrain the interpretation uncertainties associated with reflection seismic data of deep-water slope deposits. The basic premise of the project is that seismic data is affected by small-scale architectural elements and even conventional low-frequency data may contain clues of the sub-seismic geometries. These can be decoded by understanding the interaction between internal elements and the seismic wavelet. A series of outcrop-derived forward seismic models was created, representing different types of outcrop based slope deposits. The seismic interpretation of the forward models was based on amplitude analysis supplemented by instantaneous attributes and spectral decomposition. In order to create realistic synthetic seismograms, input models included geometries whose thickness was as low as 1% of the resolution limit. By revealing the influence of small-scale structures on synthetic seismic data at the high end of the spectrum (70Hz to 100Hz), the knowledge of tuning effects and the interaction between interfering reflections at lower frequencies (i.e. 20, 40 and 60Hz) could potentially be significantly improved. The gained experience was then applied to real seismic data. It was proven that small-scale geometries have an additional, highly significant effect on the composite reflection. Because of the inherent non-uniqueness in seismic reflection, the specific seismic forward models of particular outcrop analogues can only be used as guides to the seismic interpretation of the particular architectural elements of a subsurface deposit and not as definite models against which one can definitely pattern match real and modelled seismic data. as burial depth increases, so does the non-uniqueness of the seismic interpretation of seismic data from deposits whose internal geometries are around/below the tuning thickness.
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Vardaro, Michael Fredric. "Temporal changes in gas hydrate mound topography and ecology: deep-sea time-lapse camera observations." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/541.
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A deep-sea time-lapse camera and several temperature probes were deployed on the Gulf of Mexico continental shelf at a biological community associated with a gas hydrate outcropping to study topographic and hydrologic changes over time. The deployment site, Bush Hill (GC 185), is located at 27°47.5' N and 91°15.0' W at depths of ~540m. The digital camera recorded one still image every six hours for three months in 2001, every two hours for the month of June 2002 and every six hours for the month of July 2002. Temperature probes were in place at the site for the entire experimental period. The data recovered provide a record of processes that occur at gas hydrate mounds. Biological activity was documented by identifying the fauna observed in the time-lapse record and recording the number of individuals and species in each image. 1,381 individual organisms representing 16 species were observed. Sediment resuspension and redistribution were regular occurrences during the deployment periods. By digitally analyzing the luminosity of the water column above the mound and plotting the results over time, the turbidity at the site was quantified. A significant diurnal pattern can be seen in both luminosity and temperature records, indicating a possible tidal or inertial component to deep-sea currents in this area. Contrary to expectations, there was no major change in shape or size of the gas hydrate outcrop at this site on the time frame of this study. This indicates that this particular mound was more stable than suggested by laboratory studies and prior in situ observations. The stable topography of the gas hydrate mound combined with high bacterial activity and sediment turnover appears to focus benthic predatory activity in the mound area. The frequency and recurrence of sediment resuspension indicates that short-term change in the depth and distribution of surface sediments is a feature of the benthos at the site. Because the sediment interface is a critical environment for hydrocarbon oxidation and chemosynthesis, short-term variability and heterogeneity may be important characteristics of these settings.
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Shires, Rizpah. "The taxonomy, morphology and ecology of novel deep-sea agglutinated foraminifers in the Northeast Atlantic." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386542.
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Bird, Christopher Stephen. "The tropho-spatial ecology of deep-sea sharks and chimaeras from a stable isotope perspective." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/416886/.
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Chondrichthyans (sharks, rays and chimaera) are one of the most speciose groups of higher order predators on the planet and are often cited as playing an important functional role in many ecosystems. However, most studies to date have focused on oceanic and shelf habitats, and there is limited information on the ecological role that chondrichthyans play in the deep-sea. This research aims to examine the trophic and spatial ecology of deep-sea chondrichthyans using stable isotope analysis. Stable isotopes of carbon and nitrogen vary among different trophic levels and between spatially separated areas, and therefore provide a potential tool for uncovering some ecological characteristics of deep-water chondrichthyans. In this study, I found that on a global scale, oceanic sharks appear to transfer nutrients over large spatial scales, whereas sharks found in shelf habitats couple ecologically varied food webs close to their capture location. Although global data is limited for deep-sea sharks, in the northeast Atlantic it appears that sharks found on seamounts are more tightly coupled to pelagic production than their counterparts on the continental slopes. Continental slope habitats may provide access to more isotopic niches, where sharks integrate nutrients from benthic and pelagic nutrient pathways. On the other hand, chimaeras appear to fill a unique role feeding on benthic prey items that are inaccessible to other fishes (e.g hard shelled benthic animals). Depth gradients in nutrient availability are reflected in the bathymetric distribution patterns of chondrichthyan families, with depth segregations likely reducing interspecific competition for resources. For some of the largest shark species in this ecosystem, such as Portuguese dogfish (Centroscymnus coelolepis) and leafscale gulper shark (Centrophorus squamosus), whole life-history ecology was recovered from sequential analysis of eye lens proteins. Both these species appear to undertake relatively consistent latitudinal migrations linked with ontogeny and reproductive development. This study reveals the ecological characteristic of diverse deep-sea chondrichthyan assemblages, and how trophic and spatial behaviours facilitate the transfer of nutrients in these ecosystems. Subsequently, chondrichthyans likely play an important role in deep-sea ecosystems and should be managed appropriately within fisheries.
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Gomez, Carlos E. "Ecological and physiological constraints of deep-sea corals in a changing environment." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/535228.
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Biology<br>Ph.D.<br>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.<br>Temple University--Theses
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Schrenk, Matthew Owen. "Exploring the diversity and physiological significance of attached microorganisms in rock-hosted deep-sea hydrothermal environments /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/10965.
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Xu, Ting. "Population connectivity, local adaptation, and biomineralization of deep-sea mussels (Bivalvia: Mytilidae) in Northwestern Pacific." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/495.
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The discovery of deep-sea chemosynthesis-based ecosystems including hydrothermal vents and cold seeps has greatly expanded our view of life on Earth. Nevertheless, for many benthic organisms in these ecosystems, little is known about where they come from, how scattered populations are connected by larval dispersal, and how they adapt to the local environments. Mussels of Bathymodiolus platifrons (Bivalvia: Mytilidae) are one of the dominant and foundation species in deep-sea chemosynthesis-based ecosystems. They are known to have a wide geographic distribution, and are also one of the few deep-sea species capable of living in both hydrothermal vents [in Okinawa Trough (OT)] and methane seeps [in the South China Sea (SCS) and Sagami Bay (SB)]. Previous population genetics studies of B. platifrons mostly relied on one to several genes, which suffered from the lack of sensitivity required to resolve their fine-scale genetic structure, and were unable to reveal their adaptation to the local environments. With the repaid development of molecular techniques, it is now possible to address their demographic mechanisms and local adaptation from a genome-wide perspective. Therefore, in the first part of my thesis, I aimed to generate genome-wide single nucleotide polymorphisms (SNPs) for B. platifrons via a combination of genome survey sequencing and the type IIB endonuclease restriction-site associated DNA (2b-RAD) approach, assess the potential use of SNPs in detecting fine-scale population genetic structure and signatures of diversifying selection, as well as their cross-species application in other bathymodioline mussels. Genome survey sequencing was conducted for one individual of B. platifrons. De novo assembly resulted in 781 720 sequences with a scaffold N50 of 2.9 kb. Using these sequences as a reference, 9307 genome-wide SNPs were identified from 28 B. platifrons individuals collected from a methane seep in the SCS and a hydrothermal vent in the middle OT (M-OT), with nine outlier SNPs showed significant evidence of diversifying selection. The small FST value (0.0126) estimated based on the neutral SNPs indicated high genetic connectivity between the two populations. However, the permutation test detected significant differences (P < 0.00001), indicating the two populations having clearly detectable genetic differentiation. The Bayesian clustering analyses and principle component analyses (PCA) performed based on either the neutral or outlier SNPs also showed that the two populations were genetically differentiated. This initial study successfully demonstrated the applicability of combining genome sequencing and 2b-RAD in population genomics studies of B. platifrons. Besides, using the survey genome of B. platifrons as a reference, a total of 10 199, 6429, and 3811 single nucleotide variants (SNVs) were detected from three bathymodioline mussels Bathymodiolus japonicus, Bathymodiolus aduloides, and Idas sp. These results highlighted the potential of cross-species and cross-genus applications of the B. platifrons genome for SNV/SNP identification among different bathymodioline lineages, which can be further used in various evolutionary and genetic studies. To have a deeper understanding of how individuals of B. platifrons are connected among and adapt to their habitats, in the second part of my thesis, I used both mitochondrial genes and genome-wide SNPs to conduct a more comprehensive population genetics/genomics study of B. platifrons. Three mitochondrial genes (i.e. atp6, cox1, and nad4) and 6398 SNPs generated by 2b-RAD were obtained from 110 B. platifrons individuals from six representative locations along their known distribution range in the Northwestern Pacific. The small FST values based on both types of genetic markers all revealed high genetic connectivity of B. platifrons, which may have been driven by the strong ocean currents (i.e. Kuroshio Current, North Pacific Intermediate Water). However, when using SNP datasets rather than mitochondrial genes, individuals in the SCS were identified as a distinct genetic group, indicating the Luzon Strait may serve as a dispersal barrier that limits their larval exchange between the SCS and the open area in the Northwestern Pacific. Moreover, a genetic subdivision of B. platifrons in the southern OT (S-OT) from those in M-OT and SB was observed when using 125 outlier SNPs for data analyses. The outlier-associated proteins were found to be involved in various biological processes, such as DNA and protein metabolism, transcription and translation, and response to stimulus, indicating local adaptation of B. platifrons even they are confronted with extensive gene flow in the OT-SB region. Furthermore, by using SNP datasets, populations in S-OT were revealed to be the source of gene flow to those in the SCS, M-OT, and SB. Overall, these results offered novel perspectives on the potential forces that may have led to the genetic differentiation and local adaptation of B. platifrons, which can serve as an example for other deep-sea species with high dispersal potential, and contribute to the designation of marine protected areas and conservation of deep-sea chemosynthesis-based ecosystems. Molluscan shell formation is one of the most common and abundant biomineralization processes in metazoans. Although composed of less than 5 wt% of the molluscan shells, shell matrix proteins (SMPs) are known to play multiple key roles during shell formation, such as providing a gel-like micro-environment to favour mineral precipitation, promoting crystal nucleation, as well as guiding and inhibiting crystal growth. To date, all studies on SMPs have focused on molluscs in terrestrial and shallow-water ecosystems with no reports for those living in the deep ocean. Herein, the third part of my thesis was to study the shell proteomes of B. platifrons and its shallow-water relative Modiolus philippinarum with the aim to bridge such knowledge gaps in biomineralization studies. A total of 94 and 55 SMPs were identified from the shell matrices of B. platifrons and M. philippinarum, respectively, with 31 SMPs shared between two species. These SMPs can be assigned into six broad categories, comprising calcium binding, polysaccharide interaction, enzyme, extracellular matrix-related proteins, immunity-related proteins, and those with uncharacterized functions. Many of them, such as tyrosinases, carbonic anhydrases, collagens, chitin-related proteins, peroxidases, as well as proteinase and proteinase inhibitor domain-containing proteins, have been widely found in molluscan shell matrices and other metazoan calcified tissues (e.g. exoskeletons of corals, tubes of tubeworms), whereas some others, such as cystatins, were found for the first time in molluscan shell matrices, and ferric-chelate reductase-like proteins and heme-binding proteins were to be detected for the first time in metazoan calcified tissues. This is the first report of the shell proteome of deep-sea molluscs, which will support various follow-up studies to better understand the functions of these SMPs, especially in relation to environmental adaptation. Overall, my population genetics/genomics studies have improved our understanding of the population dynamics, genetic connectivity, fine-scale genetic structure, and local adaptation of B. platifrons in the Northwestern Pacific, and my proteomics study has shed light on the biomineralization processes of molluscs in the deep ocean.
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Jerosch, Kerstin. "Identification of seafloor provinces - specific applications at the deep-sea Håkon Mosby mud vulcano and the North Sea = Identifikation von Meeresboden-Provinzen : Fallstudien am Tiefsee-Schlammvulkan Håkon Mosby und in der Nordsee /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2007. http://www.loc.gov/catdir/toc/fy0712/2007398197.html.
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Godbold, Jasmin Annica. "Marine benthic biodiversity-ecosystem function relations in complex systems." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24847.
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DeLeo, Danielle Marie. "Characterizing the Effects of Anthropogenic Disturbance on Deep-sea Corals of the Gulf of Mexico." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/407865.
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Biology<br>Ph.D.<br>Cold-water corals are an important component of deep-sea ecosystems as they establish structurally complex habitats that support benthic biodiversity. These communities face imminent threats from increasing anthropogenic influences in the deep sea. Following the 2010 Deepwater Horizon blowout, several spill-impacted coral communities were discovered in the deep Gulf of Mexico, and subsequent mesophotic regions, although the exact source and extent of this impact is still under investigation, as is the recovery potential of these organisms. At a minimum, impacted octocorals were exposed to flocculant material containing oil and dispersant components, and were visibly stressed. Here the impacts of oil and dispersant exposure are assessed for the octocoral genus Paramuricea. A de novo reference assembly was created to perform gene expression analyses from high-throughput sequencing data. Robust assessments of these data for P. biscaya colonies revealed the underlying expression-level effects resulting from in situ floc exposure. Short-term toxicity studies, exposing the cold-water octocorals Paramuricea type B3 and Callogorgia delta to various fractions and concentrations of oil, dispersant and oil/dispersant mixtures, were also conducted to determine overall toxicity and tease apart the various components of the synergistic exposure effects. Finally, alterations in Paramuricea B3 gene expression profiles were inspected to characterize genome-wide changes induced by each treatment and putative genes under differential regulation. The experimental results provide evidence for a relatively high toxicity of chemical dispersants as compared to oil additions alone, elucidating the implications of applying oil dispersants to future oil spills. My findings revealed signatures of cellular stress in floc-exposed corals associated with xenobiotic metabolism, immune and inflammatory responses as well as transcriptional suppression of vital cellular components like ribosomal proteins. The data also suggests poor recovery potential in our coral samples exposed to floc. In addition, promising biomarker candidates were identified from the differential expression data for use in future spill-impact monitoring.<br>Temple University--Theses
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Ramos, Diana Gouveia. "Taxonomy, distribution and ecology of the order Phyllodocida (Annelida, Polychaeta) in deep-sea habitats of the Iberian margin." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/15380.
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Mestrado em Biologia Marinha<br>The polychaetes are mostly marine annelids, with a worldwide distribution, which constitute a food source of benthic and demersal communities, representing this way a relevant importance in an ecological approach. Most species are typical from marine ecosystems, and they are usually distributed from the intertidal zone to abyssal depths occupying a huge variety of habitats, from estuarine and sandy muds to coral reefs and deep-sea muds (Glasby et al., 2000). They live frequently associated with marine chemosynthetic ecosystems, such as hydrothermal vents, mud volcanoes, or cold seeps, that host a high biodiversity of fauna. The present work represents a taxonomic review of the polychaetes belonging to the order Phyllodocida, sampled in many oceanographic cruises from 2002 to 2012, in the Bay of Biscay, Gorringe Bank, Atlantis seamount, Alboran Sea and eastern Mediterranean, in several ecosystems such as mud volcanoes, cold seeps, submarine mounds and deep sea corals. This work includes a detailed knowledge of the biodiversity in deep sea ecosystems, made by a morphological study using identification keys, diagnosis and descriptions of the families, genera and species of the order Phyllodocida using the available bibliography, and also an ecological study of the order. In some cases, a determination to a species level was not possible but taxonomic remarks are given which will be a basis for further study of those specimens, preferably including the use of molecular tools, in order to achieve more clear results.<br>Os poliquetas são anelídeos maioritariamente marinhos, com ampla distribuição global, que constituem uma fonte de alimento para as comunidades bentónicas e demersais representando assim uma relevante função ecológica. A maioria das espécies é típica de ambientes marinhos
distribuindo-se de um modo geral desde a zona intertidal até profundidades abissais, e ocupando uma grande variedade de habitats, como sedimentos lodosos e/ou arenosos das zonas estuarinas, costeiras e profundas, recifes de coral, entre outros (Glasby et al., 2000). Vivem frequentemente associados a ecossistemas quimiossintéticos marinhos, tais como fontes hidrotermais, vulcões de lama ou fontes frias, os quais albergam uma enorme diversidade de seres vivos. O presente trabalho consiste numa revisão taxonómica dos poliquetas pertencentes à ordem Phyllodocida, colhidos em diversas campanhas oceanográficas decorrentes desde 2002 a 2012, em diversas áreas da margem Ibérica desde o Golfo da Biscaia ao Golfo de Cádis (Oceano Atlântico) e Mar de Alborão (Mediterrâneo Ocidental), em diferentes habitats batiais, mas principalmente em vulcões de lama, e recifes de coral de profundidade. Adicionalmente, foram analisadas algumas amostras colhidas em montes submarinos do Atlântico e na região Oriental do Mar Mediterrâneo. O estudo pretende contribuir para o conhecimento da biodiversidade em ecossistemas marinhos profundos, a partir do estudo morfológico e taxonómico de espécies da Ordem Phyllodocida (Polychaeta). São referidos aspetos de habitat e distribuição através do uso de bibliografia disponível, e ainda a partir de um estudo ecológico da ordem. Em alguns casos não foi possível a determinação ao nível de espécie apresentando-se apenas considerações taxonómicas que servirão de base a um estudo futuro mais detalhado, preferencialmente com base em análises moleculares, de forma a obter uma identificação mais precisa dos mesmos.
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Kaye, Jonathan Zachary. "Ecology, phylogeny and physiological adaptations of euryhaline and moderately halophilic bacteria from deep-sea and hydrothermal-vent environments /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/11064.
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Thureborn, Petter. "Microbial Ecosystem Functions Along the Steep Oxygen Gradient of the Landsort Deep, Baltic Sea." Doctoral thesis, Södertörns högskola, Miljövetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-30910.
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Through complex metabolic interactions aquatic microbial life is essential as a driver of ecosystem functions and hence a prerequisite for sustaining plant and animal life in the sea and on Earth. Despite its ecological importance, information on the complexity of microbial functions and how these are related to environmental conditions is limited. Due to climate change and eutrophication, marine areas facing oxygen depletion are increasing and predicted to continue to do so in the future. Vertically steep oxygen gradients are particularly pronounced in the Baltic Sea. In this thesis, therefore, the ecosystem functions of microbial communities were investigated, using metagenomics, to understand how they were distributed along the steep oxygen gradient at the Landsort Deep, the deepest point of the Baltic Sea. Furthermore, microbial communities from the Landsort Deep transect were compared to microbial communities of other marine environments to establish whether the environment at this site resulted in a characteristic community. To reveal what microbial community functions and taxa were active in the anoxic sediment a metatranscriptomic approach was used. Results showed a marked effect of the coupled environmental parameters dissolved oxygen, salinity and temperature on distribution of taxa and particularly community functions. Microbial communities showed functional capacities consistent with a copiotrophic life-style dependent on organic material sinking through the water column. The eutrophic condition with high organic load was further reflected in the metatranscriptome of the anoxic sediment community, which indicated active carbon mineralisation through anaerobic heterotrophic-autotrophic community synergism. New putative linkages between nitrogen and- sulphur metabolisms were identified at anoxic depths. Furthermore, viable Cyanobacteria in the anoxic sediment was evident from the transcript analyses as another reflection of marine snow. High abundance and expression of integron integrases were identified as a characteristic feature of the Landsort Deep communities, and may provide these communities with a mechanism for short-term-adaptation to environmental change. In summary, this thesis clearly documents what impact eutrophication and oxygen depletion have on microbial community functions. Furthermore, it specifically advances the mechanistic insight into microbial processes in anoxic deep-water sediment at both genomic and transcriptional level. Given the predicted progress of oxygen depletion in marine and brackish environments, this work advances information necessary to estimate effects on marine and in particular brackish ecosystem functions where anoxic conditions prevail.<br>Mikroorganismer är essentiella för fungerande ekosystemfunktioner i akvatiska miljöer och därmed en förutsättning för övrigt växt- och djurliv på vår planet. Trots deras ekologiska nyckelroll är kunskapen om mikroorganismernas funktion och komplexitet samt hur dessa är relaterade till miljön begränsad. På grund av eutrofiering och klimatförändringar har marina områden som lider av syrebrist ökat och en ytterligare utbredning av marina och bräckta områden med syrebrist är predicerad i framtiden. Stora områden av Östersjön kännetecknas av vertikala syregradienter med syresatt ytvatten och anoxiskt bottenvatten. I denna avhandling undersöktes därför med metagenomik hur mikrobiella ekosystems funktioner var utbredda längs den vertikala syregradienten i Östersjöns djupaste del, Landsortsdjupet. Dessutom jämfördes de mikrobiella samhällena från Landsortsdjupet med mikrobiella samhällen från andra marina miljöer för att utröna om den karakteristiska miljön i Landsortsdjupet återspeglade de mikrobiella samhällen som lever där. För att undersöka vilka mikroorganismer samt vilka mikrobiella ekosystemfunktioner som var aktiva i det anoxiska sedimentet i Landsortsdjupet användes metatranskriptomik. Resultaten visade en stark korrelation mellan miljöparametrarna syrehalt, salinitet och temperatur och fördelningen av mikrobiell taxa och i synnerhet mikrobiell funktion längs Landsortsdjupets transekt. De mikrobiella samhällena uppvisade en funktionell kapacitet förenlig med en livsstrategi beroende av organiskt material som sjunker genom vattenkolonnen som en konsekvens av eutrofiering. Eutrofa förhållanden med hög halt av organiskt material var även återspeglad i metatranskriptomet från det anoxiska sedimentet, som indikerade aktiv mineralisering av organiskt kol genom anaerob heterotrof-autotrof synergism. Nya möjliga kopplingar mellan kväve- och svavelmetabolism identifierades i det anoxiska vattnet. Vidare visade resultat från metatranskriptom-analys att livsdugliga cyanobakterier var abundanta i det mörka och anoxiska sedimentet, vilket även detta kan vara en konsekvens av sjunkande organiskt material. Hög abundans och hög transkribering av integrongener kunde identifieras som ett karakteristiskt kännetecken hos de mikrobiella samhällena i Landsortsdjupet vilket skulle kunna förse dem med en mekanism för anpassning till miljöförändringar. Sammanfattningsvis dokumenterar denna avhandling tydligt vilken påverkan eutrofiering och syrebrist har på mikrobiella funktioner. Dessutom för den specifikt kunskapen om mikrobiella processer i anoxiska djupvattensediment framåt på både genom- och transkriptionsnivå. Mot bakgrund av en predicerad ökning av syrebristen i marina miljöer, bidrar denna avhandling med information som är viktig för att kunna förutse vilka effekter anoxiska förhållanden kan komma att få på ekosystemfunktioner i marina miljöer och i brackvattenmiljöer i synnerhet.
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Rutherford, Alexander Fenner. "Abundance and Distribution of Major and Understudied Archaeal Lineages at Globally Distributed Deep-Sea Hydrothermal Vents." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1555.
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Deep-sea hydrothermal vents are some of the most biologically productive ecosystems on Earth, yet receive little to no input of photosynthetically derived organic matter. The trophic system at hydrothermal vents is based primarily on the reduction-oxidation (redox) of inorganic chemicals by Bacteria and Archaea. However, the distributional patterns of the microorganisms that colonize deep-sea hydrothermal vent deposits and their link to the geologic setting are still not deeply understood.
The goal of the studies presented in this thesis was to quantify the abundance, and distribution of major and understudied vent colonizing archaeal groups from globally distributed and geochemically distinct hydrothermal vent fields. The archaeal community composition was analyzed using quantitative PCR with lineage specific functional gene primers that target methanogens, and 16S rRNA gene primers designed or optimized from this study for the Thermococcales, Archaeoglobus, Ignicoccus and marine Nanoarchaeota.
Overall, a general relationship was demonstrated between the geochemical differences of the hydrothermal vent fields and the archaeal community structure. The archaeal community assemblage varied dramatically from hydrothermal vents with different vent host rocks along the Mid-Atlantic Ridge and Eastern Lau Spreading Center. In contrast, two vent fields in the East Pacific, 9°N on the EPR and Guaymas Basin that are basalt and basalt-sediment hosted were found to have similar community composition. These observed differences may be driven in part by the metabolically available chemical energy as hydrogen oxidizing lineages of the methanogens and Archaeoglobus were found in higher abundance in the samples from vent field that had a high concentration of end-member hydrogen and the heterotrophic Thermococcales constituted a higher proportion of the archaeal community at the less enriched vent fields. Interestingly, the Nanoarchaeota and the genus of its only confirmed symbiont, Ignicoccus, were found to have an inconsistent proportional relationship, with the Nanoarchaeota comprising a larger proportion of the archaeal community at the ultramafic and fast spreading basalt vent fields and Ignicoccus at the ultra-slow spreading basalt and andesite hosted vent fields.
There was also a more localized pattern identified within the hydrothermal vent deposit. The chemosynthetic lineages of the methanogens and Archaeoglobus constituted a higher proportion of the archaeal community in chimney samples compared to Thermococcales that was found in a higher proportion at horizontal flange samples. This archaeal proportional shift could be driven by energetic micro-niches within the vent deposit, as the chemolithotrophic lineages colonize the area closest to the venting source, and the heterotrophic Thermococcales dominate in more mature structures further from the venting source.
Quantitative assessments of the archaeal community composition from this study provided added insight into the dynamic geologic influence on the archaeal lineages that colonize deep-sea hydrothermal vents, on a global and local scale.
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Amon, D. "Bone-eating worms and wood-eating bivalves : characterising the ecology of deep-sea organic falls from multiple ocean basins." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/361854/.
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Large organic inputs to the deep seafloor such as the remains of whales or pieces of wood are termed ‘organic falls’. Despite over 30 years of research on these interesting deep-sea habitats, we still have only a basic understanding of their taxonomic composition and for some ocean basins, no natural or experimental studies have ever been conducted. The degree of connectivity between these isolated habitats, as well as how quickly organic matter is remineralised by specialist organic-fall fauna (e.g bone-eating Osedax worms and wood-eating Xylophaga molluscs) is poorly known. In this thesis, I report the discovery of the first Antarctic whale fall and the diverse assemblage of fauna encrusting it (Chapter 2). The microdistribution of fauna on the whale bones provided evidence for the ‘oil-gradient’ hypothesis that more lipid-rich bones support a greater abundance of sulfophilic bacterial mats, which are also correlated with the abundance of grazing fauna. The abundance of Osedax species on bones however, showed a negative correlation with the bacterial-mat cover, and hence the greatest abundance was on bones predicted to have the lowest lipid content. The Osedax species discovered were investigated in detail (Chapter 3) and revealed two new species and a third previously-known species; Osedax rogersi sp. nov., Osedax crouchi sp. nov. (described in this thesis and associated paper) and Osedax antarcticus. The new species, O. crouchi as well as another new species, Osedax nordenskioeldi sp. nov. (also described in this thesis and associated paper) and Osedax antarcticus were also found on implanted whale bones off Smith Island in the Bransfield Strait. These two localities are approximately 1800 km apart demonstrating the remarkable dispersal capability of species within this genus. As well as the Antarctic study, I report on wood and bone-colonisation experiments on the Southwest Indian Ridge at two seamounts. A large number of species were found colonising the deployments; 53 species at Coral Seamount and 38 species at Atlantis Bank seamount with only 11 species in common and several putative new species present. Apart from Xylophaginae and Idas bivalves, few organic-fall specialists were present, possibly as there were major differences between the two seamounts suggesting that there were barriers to dispersal (Chapter 4). The wood deployments from each seamount were investigated in further detail using X-ray micro-computed tomography to examine the nature of intact Xylophaga borings, the comparative abundances and population size structures of the species, their rates of growth and their consumption rates of wood (Chapter 5). Two more sets of samples from the Mid-Cayman Spreading Centre and the Tongue of the Ocean, Bahamas were scanned also. The wood at each deployment site was colonized by a different species of Xylophaga. This novel analysis has shown that an individual Xylophaga can bore between 0.235 and 0.606 cm3 of wood per year depending on the species, emphasising the importance of the genus Xylophaga with regard to wood remineralisation in the deep sea and its role as an ecosystem engineer.
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Churchill, Diana A. "Investigating Trophic Interactions of Deep-sea Animals (Sharks, Teleosts, and Mobile scavengers) in the Gulf of Mexico Using Stable Isotope Analysis." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2214.
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The deep-sea is the largest habitat on earth, containing over 90 percent of the world’s oceans and home to over 20,000 species. Deep-sea ecosystems are increasingly impacted by human activities including fishing and oil extraction. To understand potential impacts on deep-sea food webs, it is crucial to gather baseline data in these systems. I quantified the trophic interactions of three groups of deep-water animals across a range of trophic levels living in the northern and eastern Gulf of Mexico using stable isotope analysis. First, I propose methods for correcting δ15N values for the presence of nitrogenous metabolic waste products (e.g., urea) in muscle tissue using chemical extractions and/or species-specific mathematical normalizations. Significant differences in δ15N, %N, and C:N values as a result of extractions were observed in eight of ten shark and all three hagfish species. The δ15N values increased, but shifts in %N and C:N values were not unidirectional. Mathematical normalizations for δ15N values were successfully created for four shark and two hagfish species. I then describe the trophic interactions of three consumer assemblages. Carbon isotopic values indicate a heavy reliance on allochthonous nutrient inputs from surface waters. Nitrogen isotopic values reveal somewhat atypical taxa as top predators in the deep sea. Shark, teleost, and invertebrate species across a wide range of body sizes are feeding at a similar trophic level. This apparent lack of size structuring could be the result of a high degree of opportunistic scavenging or perhaps feeding at many trophic levels simultaneously in an oligotrophic system. There was a high degree of isotopic niche overlap among species within each consumer assemblage, perhaps the result of limited nutrient resources in the deep-sea. In general, individuals from the northern sampling stations displayed higher δ13C and δ15N values than those from the eastern sites. With the exception of a few species, there were no strong relationships between body size and isotopic values. The present study is among the first characterizations of the trophic structure of deep-sea organisms in the Gulf of Mexico and establishes system baselines for future studies describing deep-water systems and investigating anthropogenic impacts.
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Auel, Holger. "The ecology of Arctic deep-sea copepods (Euchaetidae and Aetideidae) : aspects of their distribution, trophodynamics and effect on the carbon flux /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 1999. http://www.gbv.de/dms/bs/toc/271112123.pdf.
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Macleod, Adrian K. A. "The role of marine renewable energy structures and biofouling communities in promoting self-sustaining populations of non-native species." Thesis, University of the Highlands and Islands, 2013. https://pure.uhi.ac.uk/portal/en/studentthesis/the-role-of-marine-renewable-energy-structures-and-biofouling-communities-in-promoting-selfsustaining-populations-of-nonnative-species(0c7f0d89-74e8-4468-83c9-4216e4f2b1a8).html.
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Novel environments and biological communities created by the large-scale deployment of Marine Renewable Energy Devices (MREDs) have the potential to promote the spread of non-native species (NNS). Knowledge of how community composition resident on MREDs is shaped by geography, local hydrodynamics and the duration of deployment, will clarify how these technologies will interact with natural habitats, including the provision of suitable habitat for NNS. A network of navigation buoys was used to study biofouling communities in areas proposed for MRED deployment. Significant differences in community structure were observed in different geographic areas. A significant reduction in number of taxa present and community wet-weight was observed where buoys were deployed in greater tidal flow rates. However, overall community composition was not significantly different between ‘high’ (>1 ms-1) and ‘low’ (<1 ms-1) flow areas and for buoys deployed for different time durations (1-7 years). These finding have important implications for the longevity of devices and their interaction with natural habitats, including proposed ‘artificial reef’ effects. In total five non-native species were identified on the buoys sampled, supporting the need to monitor MREDs as the industry grows. Hydrodynamic and biotic features of the epibenthic communities were used to predict the presence of the most prevalent NNS, the amphipod Caprella mutica, in addition to other native amphipod species. Caprella mutica presence was found to be significantly affected by increasing flow speed compared with the native amphipod Jassa herdmani. Behavioural flume studies investigating flow-related processes governing the presence of non-native amphipods supported these findings. This study details how the hydrodynamic and biological environments created by MREDs determine their suitability for the establishment of self-sustaining populations, and therefore their dispersal potential for NNS. These findings inform design criteria and management options to minimise the biosecurity risk that these structures will pose as the industry expands.
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Gontikaki, Evangelia. "Carbon cycling in continental slope sediments : the role of benthic communities." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=128351.
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Previous pulse-chase experiments have revealed a wide diversity of benthic response patterns to organic matter (OM) input depending on environmental setting, benthic community structure and experimental conditions i.e. quantity and quality of the added OM. However, the mechanisms and interaction of environmental and biological factors that produce an observed response pattern are poorly understood. The present thesis set out to improve our current understanding on the set of parameters that determine benthic response patterns. The core of this study was based on two pulse-chase experiments in two bathyal settings: the Faroe-Shetland Channel (FSC) and the SW Cretan slope in the E. Mediterranean (E. Med). The sub-zero temperatures in the FSC enabled the observation of the benthic response in “slow-motion” and showed that the response is not static but instead might go through various “phases”. In the warm E. Med, C processing rates were considerably lower compared to previous measurements in adjacent regions. The discrepancy was attributed to the particularly refractory sedimentary OM at the sampling station with apparent consequences for the physiological state of the bacterial community. Both experiments showed that bacterial metabolism and its regulation is a key factor determining the reaction of the benthic community to OM inputs. This thesis provided further understanding on the short-term fate of organic C in deep-sea sediments but also raised certain issues that could be addressed in future studies.
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Arellano, Shawn Michelle 1977. "Embryology, larval ecology, and recruitment of "Bathymodiolus" childressi, a cold-seep mussel from the Gulf of Mexico." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8154.
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xx, 198 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.<br>"Bathymodiolus" childressi is a mixotrophic mussel from Gulf of Mexico cold seeps. There is no genetic differentiation of mussels among the seeps, suggesting wide dispersal of their larvae. This dissertation describes larval biology, ecology, and recruitment dynamics for "B." childressi. Cleavage is spiral at a rate of one per 3-9 hours, with blastula larvae hatching by 40 hours at 7-8 à à °C. At 12-14 à à °C, D-shell veligers developed by day 8 without being fed. Egg size and shell morphology indicate planktotrophy, but feeding was not observed. Embryos developed normally from 7-15 à à °C and 35-45 ppt. Although survival of larvae declined with temperature, some survived at 25 à à °C. Larval survivorship was similar at 35 and 45 ppt. Oxygen consumption increased from blastulae to trochophores and was higher for "B." childressi than for shallow-water mussel trochophores. Estimated energy content of "B." childressi eggs was greater than the energy content of shallow-water mussel eggs. An energetic model predicts that the eggs provide sufficient energy for "B." childressi trochophores to migrate into the euphotic zone. In fact, "B." childressi veligers were found in plankton tows of surface waters.
The influence of recruitment on fine-scale distributions of adults at the Brine Pool cold seep was examined through manipulative field experiments. The "Bathymodiolus" childressi population at this site has a distinct bimodal size structure that shifts across an environmental gradient. New recruits of "B." childressi are abundant in the inner zone, where methane and oxygen are high and sulfide is low, leading to the inference that larvae settle preferentially there. Experiments were placed in the inner and outer zones and 2-m away from the bed. The number of larvae collected in traps did not differ among the three zones, nor did settlement density. Juveniles survived and grew in all zones, but more caged than uncaged juveniles survived. Mortality of uncaged juveniles was similar in all zones, suggesting that predation does not cause the bimodal distribution. These results suggest that the bi-modal distribution cannot be attributed to settlement preferences or juvenile mortality, but instead to migration or early post-settlement mortality.
This dissertation includes my co-authored materials.<br>Adviser: Craig M. Young
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Proud, Roland Hudson. "A biogeography of the mesopelagic community." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/12025.
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There are a large number of research vessels and fishing vessels equipped with echosounders plying the world ocean, making continual observations of the ocean interior. Developing data collation programmes (e.g. Integrated Marine Observing System) and automated, repeatable analyses techniques enable the upper c. 1,200 meters of the world ocean to be sampled routinely, and for their characteristic deep scattering layers (DSLs) to be compared. Deep scattering layers are comprised of zooplankton (e.g. euphausiids) and fish, particularly myctophids or lantern fish, and comprise the majority of sub-surface biomass. Here we present, by the analysis of a global acoustic dataset, a mesopelagic biogeography of the sea. This was accomplished by (i) the collation and processing of a global active acoustic dataset, (ii) the development of a standardised and automated method of sound scattering layer (SSL) extraction and description, (iii) the derivation of the environmental drivers of DSL depth and biomass, (iv) the definition of a mesopelagic biogeography based on the drivers of DSL metrics and (v) the prediction, using output from the NEMO-MEDUSA-2.0 coupled model, of how the metrics and biogeography may change by 2100. Key findings include, the development of the Sound Scattering Layer Extraction Method (SSLEM) the inference that primary production, water temperature and wind stress are key drivers in DSL depth and biomass and that mesopelagic fish biomass may increase by 2100. Such an increase is a result of increased trophic efficiency from the shallowing of DSLs and rising water temperatures, suggesting, that as the climate warms the ocean is becoming more efficient. The biophysical relationships and biogeography derived here, serve to improve our understanding of mesopelagic mid-trophic level dynamics in open-ocean ecosystems. This will aid both fisheries and conservation management, which now adopt more holistic approaches when monitoring and evaluating ecosystem health and stability.
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Fusaro, Abigail Jean. "Spatial and temporal population genetics at deep-sea hydrothermal vents along the East Pacific Rise and Galápagos Rift." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45148.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Includes bibliographical references.<br>Ecological processes at deep-sea hydrothermal vents on fast-spreading mid-ocean ridges are punctuated by frequent physical disturbance. Larval dispersal among disjunct vent sites facilitates the persistence of sessile invertebrate species in these geologically and chemically dynamic habitats despite local extinction events. Regional population extension and rapid recolonization by the siboglinid tubeworm Riftia pachyptila have been well documented along the East Pacific Rise and the Galápagos Rift. To analyze spatial and temporal population genetic patterns and the processes governing them at ephemeral and disjunct habitats, a suite of 12 highly variable microsatellite DNA markers were developed for this species. Eight of these loci were used to assess the regional and within-ridge genetic structure of recent colonists and resident adults collected from nine sites in the eastern Pacific Ocean over period of three to seven years. A significant seafloor eruption during the seven-year sampling period allowed investigation into the role of local extinction in population genetic diversity at the Tica vent site at 9°N EPR, while collections within two and five years of an eruption that created the Rosebud vent field at 86°W GAR provided insights into genetic diversity input over population establishment. For the first time, this thesis demonstrated significant genetic differences between Riftia populations on the East Pacific Rise and Galápagos Rift. Moreover, the separate treatment of colonist and resident subpopulations revealed a high potential for local larval retention at vent sites. This mechanism for recruitment likely sustains disjunct populations and supports the recolonization of locally extinct areas after disturbance events, while episodic long-distance dispersal maintains genetic coherence of the species.<br>(cont.) Temporal population genetic consideration at the Tica site on the East Pacific Rise suggests that the 2005-2006 seafloor eruption had little to no discernable effect on local population genetic composition. Yet local populations appear to exhibit a small degree of genetic patchiness, with a high degree of relatedness (half-sibs) among subsets of individuals within both colonist and resident cohorts. This thesis broadens the application of recently developed molecular techniques to study the effect of ridge-crest processes and offers new perspectives into marine dispersal, gene flow, and population differentiation.<br>by Abigail Jean Fusaro.<br>Ph.D.
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Cho, Walter W. "Faunal biogeography, community structure, and genetic connectivity of North Atlantic seamounts." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45312.
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Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Includes bibliographical references.<br>The mechanisms of faunal dispersal across ocean basins are key unknowns toward understanding of the modern biogeography and biodiversity of deep-sea fauna. Seamounts are considered to play a defining role in faunal evolution, acting as regional centers of speciation, "stepping-stones" for dispersal, and/or refugia for deep-sea populations. The overarching goal of this dissertation was to examine the role of seamounts in structuring marine biodiversity and biogeography. This study focused on North Atlantic seamounts, specifically the New England seamount chain, the Corner Rise seamounts, and Muir seamount, areas damaged and threatened by deep-sea fisheries and currently a focus of conservation efforts. Videographic analyses of biological community structure revealed distinct faunal assemblages, dominated by the Porifera, Cnidaria, and Echinodermata and structured by geographic region, depth regions (with apparent taxonomic breaks at 1300 m, 2300 m, and 2600 m), and substrate type (including natural/anthropogenic and abiotic substrates and biotic substrates). Amongst these assemblages, seven highly specific coral host- invertebrate associate relationships were identified. To investigate whether or not these broad community patterns were discernible at a genetic level, the 16S mtDNA gene was utilized as a genetic "barcode" within the Class Ophiuroidea, through which 22 putative species were identified, including four target species (Asteroschema clavigera, Ophiocreas oedipus, Ophioplinthaca abyssalis, and Ophioplinthaca chelys) for subsequent population genetic studies. Analyses of mitochondrial 16S and COI gene sequences revealed evidence for recent population expansion and estimates of recent high gene flow across all four species throughout the North Atlantic seamount region.<br>(cont.) However, genetic differentiation within populations of A. clavigera and 0. chelys within seamount regions was significant, suggesting that historical diversification has been mediated by a long-distance dispersal mechanism that homogenizes this genetic signal on a regional scale. In addition, comparisons of all ophiuroid populations revealed no congruent pattern of historical migration amongst seamounts, which may also be attributed to the varying levels of host specificity and reproductive strategy of each ophiuroid species. These results will guide future studies and conservation efforts to protect seamount communities vulnerable to deep-sea fishery activities.<br>by Walter W. Cho.<br>Ph.D.
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Georgian, Sam Ellis. "ENVIRONMENTAL AND ENERGETIC CONSTRAINTS ON COLD-WATER CORALS." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/382890.
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Biology<br>Ph.D.<br>Cold-water corals act as critical foundation species in the deep sea by creating extensive three-dimensional habitat structures that support biodiversity hotspots. There is currently a paucity of data concerning the environmental requirements and physiology of cold-water corals, severely limiting our ability to predict how resilient they will be to future environmental change. Cold-water corals are expected to be particularly vulnerable to the effects of ocean acidification, the reduction in seawater pH and associated changes to the carbonate system caused by anthropogenic CO2 emissions. Here, the ecological niche and physiology of the cold-water coral Lophelia pertusa is explored to predict its sensitivity to ocean acidification. Species distribution models were generated in order to quantify L. pertusa’s niche in the Gulf of Mexico with regard to parameters including seafloor topography, the carbonate system, and the availability of hard substrate. A robust oceanographic assessment of the Gulf of Mexico was conducted in order to characterize the current environmental conditions at benthic sites, with a focus on establishing the baseline carbonate system in L. pertusa habitats. Finally, an experimental approach was used to test the physiological response of biogeographically separated L. pertusa populations from the Gulf of Mexico and the Norwegian coast to ocean acidification. Based on my findings, it appears that L. pertusa already persists near the edge of its viable niche space in some locations, and therefore may be highly vulnerable to environmental change. However, experimental results suggest that some populations may be surprisingly resilient to ocean acidification, yielding broad implications for the continued persistence of cold-water corals in future oceans.<br>Temple University--Theses
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Roterman, Christopher Nicolai. "The evolution and population genetics of hydrothermal vent megafauna from the Scotia Sea." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:8a84f6c4-e067-4c7c-bc9e-34e59c8e6ef3.
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This project used a variety of genetic markers to investigate the evolution and population genetics of hydrothermal vent fauna that were recovered from the Scotia Sea, in the Atlantic sector of the Southern Ocean. The origins of one of these species, an undescribed species of Kiwa sp. found on the East Scotia Ridge (ESR) and its constituent family Kiwaidae, a group of vent and seep-associated decapod squat lobsters (infraorder Anomura) was investigated using a concatenated nine-gene dataset and key divergences were dated using fossil calibrations. These results confirm earlier research showing Kiwaidae reside in the superfamily Chirostyloidea, but form a monophyletic clade with the non-chemosynthetic family Chirostylidae and not Eumunididae. Chirostyloid families diverged in the Cretaceous, although extant Kiwaidae radiated in the Eocene, consistent with many other chemosynthetic taxa that appear recently derived. The basal tree position of Pacific species (and the Alaska location of a likely stem-lineage kiwaid fossil) suggests kiwaids originated in the East Pacific. Within a Southern Hemisphere clade, the divergence between the southeastern Pacific K. hirsuta and a non-Pacific lineage (Kiwa sp. ESR and Southwest Indian Ridge kiwaids) is no earlier than 25.9 Ma, consistent with a spread from the Pacific into the Scotia Sea and beyond via now-extinct active ridge connections or mediated by a Miocene onset of the Antarctic Circumpolar Current (ACC) through a newly-opened Drake Passage. This project also investigated the population genetics of three undescribed species found at two vent fields ~ 440 km apart at either end of the ESR: Kiwa sp., a peltospirid gastropod and Lepetodrilus sp. limpets. Lepetodrilus sp. was also found at the Kemp Caldera, a submerged part of the South Sandwich Islands (SSI). Analyses of cytochrome c oxidase subunit 1 (COI) as well as microsatellite loci developed from Roche 454 sequence libraries revealed no differentiation along the ESR for all three species consistent with panmixia, or the dominance of non-equilibrium processes between vent field colonies within a metapopulation, possibly enhanced further by cold-induced arrested larval development. Despite apparent connectivity along the ESR, both COI and microsatellites revealed differentiation between ESR limpets and Kemp Caldera limpets ~ 95 km to the east, possibly owing to the hydrographic isolation of the caldera. Both COI and microsatellite diversity patterns were consistent with recent (< 1 Ma) demographic expansions for all three species (although the influence of selection sweeps on COI cannot be discounted); a pattern observed worldwide at vent communities and may reflect demographic instability over time as a consequence of the stochastic birth and death of vent colonies within a metapopulation. Different COI bottleneck ages between the three species (excluding the influence of possible selection) as well as the absence of kiwaids and peltospirids at Kemp, have been attributed to differences in life history, in particular larval morphology and presumed dispersal strategy. These results highlight the role of larval dispersal of vent fauna along active spreading ridges, both in maintaining vent metapopulations across vent colonies prone to stochastic birth and extinction in the short term, but also in the spread of taxa globally and the formation of biogeographic provinces. The likelihood that the three species presented here exist at vents east of the ESR and SSI, prompts further exploration along ridges in the South Atlantic, in order to investigate the effect of the ACC in enhancing gene flow and delineating biogeographic provinces.
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McNichol, Jesse Christopher. "Productivity, metabolism and physiology of free-living Chemoautotrophic Epsilonproteobacteria." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106734.
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Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 145-161).<br>Chemoautotrophic ecosystems at deep-sea hydrothermal vents were discovered in 1977, but not until 1995 were free-living autotrophic Epsilonproteobacteria identified as important microbial community members. Because the deep-sea is food-starved, the autotrophic metabolism of hydrothermal vent Epsilonproteobacteria may be very important for deep-sea consumers. However, quantifying their metabolic activities in situ has remained difficult, and biochemical mechanisms underlying their autotrophic physiology are poorly described. To gain insight into environmental processes, an approach was developed for incubations of microbes at in situ pressure and temperature (25 MPa, 24°C) with various combinations of electron donors/acceptors (H₂ , O₂ and NO₃- and ¹³HCO₃-) as a tracer to track carbon fixation. During short (18-24 h) incubations of low-temperature vent fluids from Crab Spa (9°N East Pacific Rise), the concentration of electron donors/acceptors and cell numbers were monitored to quantify microbial processes. Measured rates were generally higher than previous studies, and the stoichiometry of microbially-catalyzed redox reactions revealed new insights into sulfur and nitrogen cycling. Single-cell, taxonomically-resolved tracer incorporation showed Epsilonproteobacteria dominated carbon fixation, and their growth efficiency was calculated based on electron acceptor consumption. Using these data, in situ primary productivity, microbial standing stock, and average biomass residence time of the deep-sea vent subseafloor biosphere were estimated. Finally, the population structures of the most abundant genera Sulfurimonas and Thioreductor were shown to be strongly influenced by pO₂ and temperature respectively, providing a mechanism for niche differentiation in situ. To gain insights into the core biochemical reactions underlying autotrophy in Epsilonprotebacteria, a theoretical metabolic model of Sulfurimonas denitrificans was developed. Validated iteratively by comparing in silico yields with data from chemostat experiments, the model generated hypotheses explaining critical, yet so far unresolved reactions supporting chemoautotrophy in Epsilonproteo bacteria. For example, it provides insight into how energy is conserved during sulfur oxidation coupled to denitrification, how reverse electron transport produces ferredoxin for carbon fixation, and why aerobic growth yields are only slightly higher compared to denitrification. As a whole, this thesis provides important contributions towards understanding core mechanisms of chemoautrophy, as well as the in situ productivity, physiology and ecology of autotrophic Epsilonproteobacteria.<br>by Jesse Christopher McNichol.<br>Ph. D.
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Román, Moreno Sara. "Ecology and biodiversity of the deep-sea meiobenthos from the Blanes Canyon and its adjacent slope (NW Mediterranean) = Ecología y biodiversidad del meiobentos profundo del Cañón de Blanes y su talud adyacente (NO Mediterráneo)." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/456986.
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Submarine canyons are major topographic structures forming deep incisions in shelfs and continental margins around the globe. Due to their topographic characteristics, canyons influence both local hydrodynamic conditions and the transfers of organic material and sediment from shelfs to deep seafloor. This leads to changes in sediment characteristics and organic enrichment that play a key role in deep-sea the functioning, and particularly affect benthic communities.
Metazoan meiobenthos are the most abundant deep-sea infauna, with nematodes being dominant. Due to their small size, meiofauna is intimately related with the sediment so that the physical properties are highly influencing the assemblages harbored by a given ecosystem. Therefore, habitat heterogeneity, a particularly relevant canyons feature plays a key role in shaping meiofaunal distribution and biodiversity.
Blanes canyon (NW Mediterranean) has been intensively explored during the last years, mostly in relation with the fishery activities in the area. However, as in many other canyons, the meiobenthic component had been almost neglected.
Within this context and in the frame of the Spanish research project Dos Mares, the present thesis, focus on the metazoan meiofauna in the Blanes Canyon system. Samples were obtained by the multicore deployments from 500 to 2,000 m depth during four oceanographic campaigns (spring and autumn in 2012-2013). The main objective was to increase the knowledge and further understanding of the patterns and trends of meiofaunal density, diversity and community composition, as well as on its main environmental drivers, with a particular emphasis on the dominant nematode assemblages.
Our results indicate that Blanes Canyon exhibits: marked sediment variability, high food availability (i.e., Organic Carbon, Chlorophyll a, Chloroplastic Pigments Equivalents) compared to the adjacent slope, together with higher density, and diversity, and more marked differences in community composition and distribution, both at higher (i.e., meiofauna) and lower (i.e., nematodes and kinorhynchs) taxon level.
The observed temporal variability is only partly explained by the seasonal patterns of food input, derived from phytoplanctonic production, where major oceanographic processes such as recurrent dense shelf water cascading events; seem to play a key role. Moreover, the topographically heterogeneous environment associated to the canyon bathymetric gradient, combined with the existence of recurrent, non-seasonal food pulses, are better explaining the observed meiofaunal trends, particularly those concerning nematodes.
However, among all gradients analysed, the greatest effect on nematode communities occurred at small-scale (cm), both in the canyon and on the slope, with the highest abundance at the surface sediment layer leading to a marked diversity decrease along the vertical sediment profile.
This Thesis includes the first known study on Mediterranean deep-sea kinorhynchs, which contributes to increase the current knowledge on its diversity and distribution, as seven over the nine species found in the canyon system turned to be undescribed.
Our results allowed us to avoid suggesting generalizations in the description of meiofauna patterns in the canyon, highlighting those different taxa may show different bathymetric-related responses, this being particularly relevant in the case of the rare taxa (e.g., the kinorhynchs). They also support the consideration of submarine canyons as hotspots of faunal density, biomass and diversity, confirming its key role in shaping the patterns and trends shown by benthic fauna.
Finally, the overall results of this Thesis strongly suggest that the Blanes Canyon system is not functioning as a purely natural environment. The high sedimentation rates in the canyon axis suggest that the indirect but regular effects of bottom trawling are driving the structure, and possibly the functioning, of the associated meiobenthos, all along the axis down to at least, 1,750 m depth.<br>Los cañones submarinos son una de las principales estructuras geomorfológicas del margen continental y un recurso de heterogeneidad del fondo marino. Su abrupta topografía influye en el régimen hidrodinámico local, interrumpiendo y amplificando las corrientes e incrementando los flujos de partículas. Juegan un papel importante en el transporte entre plataforma y océano profundo atrapando, acumulando y canalizando sedimentos y materia orgánica con importantes consecuencias para la diversidad, funcionamiento y dinámica del bentos.
La meiofauna es un componente importante del bentos. Dado su pequeño tamaño, está íntimamente relacionada con el sedimento y sus posibles alteraciones (p. ej., alteración de las tasas de sedimentación, resuspensión).
Esta Tesis se centra en el Cañón de Blanes (NO Mediterráneo), lugar de importante actividad pesquera. Partiendo de muestras recogidas en primavera y otoño de 2012 y 2013, el principal objetivo ha sido incrementar el conocimiento y las pautas y tendencias de las comunidades de meiofauna (densidad, biomasa, diversidad y estructura) del Cañón de Blanes, así como de su talud adyacente con especial énfasis en los nematodos.
Las elevados tasas de sedimentación detectados en el cañón (hasta los 1,750 m), sugieren un efecto indirecto de la pesca de arrastre, que estaría afectando a la meiofauna, sugiriendo la parcial antropogenización de los ambientes profundos del cañón.
La variabilidad temporal observada obedece a: entradas estacionales de materia orgánica (derivadas de la producción primaria), procesos de formación de aguas profunda y heterogeneidad topográfica, combinados con entradas recurrentes no estacionales de materia orgánica. Sin embargo, la variabilidad a pequeña escala (cm) causa un mayor efecto en la estructura y diversidad de la comunidad de nematodos, principalmente debido a la disminución en diversidad a lo largo del perfil vertical del sedimento.
El Cañón de Blanes muestra mayor variabilidad en el sedimento y disponibilidad de materia orgánica que el talud adyacente, así como una mayor variabilidad en la composición y estructura de las comunidades meiofaunales. Nuestros resultados apoyan la relevancia del papel de los cañones submarinos en la distribución de la fauna bentónica, así como su consideración como hot spots de densidad, biomasa y diversidad.
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Leiva, Dueñas Carmen. "The environmental change in coastal ecosystems during the Late Holocene as recorded in seagrass sedimentary archives." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/674010.
Full textAbstract:
Coastal ecosystems, especially the vegetated areas, are among the most threatened ecosystems in the world, undergoing a fast and constant decline. Their losses are of serious concern due to their elevated production, providing many ecosystem services essential to the well-being of our societies. Behind the regressive trends of the coastal ecosystems, there is a plethora of adverse human pressures, going from local and regional impacts, including anthropogenic activities in and outside the coastal regions, to large-scale drivers of change, such as the global warming. Nevertheless, there is a critical lack of long-term information about the vegetated coastal ecosystems, information that can provide baseline ecological data of their natural dynamics and vulnerability.
Seagrasses are marine plants, engineering species that form underwater meadows, which, among many other services, provide essential habitat for many other organisms. Seagrasses meadows are experiencing a widespread decline since the early 20th century. This regression is accelerated for the Mediterranean endemic seagrass species Posidonia oceanica. Long-term studies are of particular interest in P. oceanica meadows because this species is a large-slow growing and long-lived seagrass, which substantial changes and responses manifest over time scales of decades to centuries. A deeper understanding of seagrass long-term dynamics can help managers to apply meadow-specific actions and act at the appropriate temporal scales. The discipline of paleoecology allows the study of long-term ecosystem dynamics on time scales of centuries to millennia, and it can be used in seagrass meadows thanks to the organic deposits accumulated below P. oceanica meadows. Paleoreconstructions using seagrass deposits are still scarce and have mainly focused on allogenic (externally controlled) processes.
In this dissertation, a paleoecological approach at a regional spatial-scale was used to explore the long-term dynamics of the autogenic and biotic ecological components of Mediterranean seagrass meadows, mainly P. oceanica meadows. Initially, we investigated the usefulness of several biogeochemical proxies and a technique (FTIR-ATR spectroscopy) so far unexplored in seagrass deposits, as well as which were the main biogeochemical processes recorded by them. We described the long-term dynamics of the seagrass ecosystem, the main drivers of change, and their relative importance. The results indicated that seagrass long-term dynamics are oscillating. Even though most meadows showed regressive trends during the last 150 years, seagrass trends varied spatially, with the main spatial differences occurring at the inter-regional level. Differences in long-term dynamics between local sites seemed mostly dependent on the environmental background of each site, which also affected seagrass long- term resilience. The major factors responsible for long-term variability of seagrass ecosystem dynamics were multiple and at both, local and large spatial scales. However, the balance between the contribution of local and large-scale drivers varied spatially. The influence of climate seemed especially crucial in meadows surrounded by more turbid waters, under the influence of higher fluvial discharges. These meadows showed lower long-term ecosystemic resilience.
In summary, this research showed that seagrass long-term dynamics can be studied through their paleoecological record, providing a valuable frame of reference for evaluating the magnitude of current changes and consequences of combined diverse impacts on these marine ecosystems. The results of this thesis indicated that despite some spatial variability of the long-term dynamics, the major changes occurred over the last century, predominating trends of seagrass decline or community compositional changes. Moreover, our results point to a more acute negative impact of present climate change in meadows where light availability is compromised due to local factors. The overall spatial variability regarding seagrass long-term dynamics highlights the need for meadow-specific local management with background information, information that can be obtained from paleoecological studies.<br>Los ecosistemas costeros, especialmente aquellos dominados por macrófitos sumergidos o semi-sumergidos, se encuentran entre los ecosistemas más amenazados del mundo, sufriendo un rápido y constante declive. Sus pérdidas son motivo de grave preocupación debido a su elevada producción, y a que proporcionan muchos servicios ecosistémicos esenciales para el bienestar de nuestras sociedades. Detrás de las tendencias regresivas de los ecosistemas costeros, se encuentra una plétora de presiones humanas adversas, que van desde impactos locales y regionales, incluidas actividades antropogénicas dentro y fuera de las regiones costeras, hasta agentes de cambio a gran escala, como el calentamiento global. Sin embargo, existe una falta crítica sobre el cambio a largo plazo de los ecosistemas costeros vegetados, información que puede proporcionar datos ecológicos de referencia sobre sus dinámicas naturales y vulnerabilidad.
Las fanerógamas marinas son plantas superiores creadoras de estructuras tridimensionales complejas que, entre otros muchos servicios, dan lugar a un hábitat de elevada biodiversidad. Estos macrófitos están experimentando un declive generalizado desde principios del siglo XX, regresión especialmente acelerada para la especie endémica mediterránea, Posidonia oceanica. Los estudios a largo plazo son de particular interés en las praderas de P. oceánica, pues al ser una planta marina de gran tamaño, de crecimiento lento y de vida larga, sus cambios y respuestas sustanciales se manifiestan en escalas de tiempo de décadas a siglos. Una comprensión más profunda de la dinámica a largo plazo de las fanerógamas marinas puede ayudar a los gestores a aplicar acciones específicas y actuar en las escalas temporales adecuadas. La disciplina de la paleoecología permite el estudio de la dinámica de los ecosistemas a largo plazo en escalas de tiempo de siglos a milenios, y se puede aplicar en praderas de fanerógamas de P. oceanica gracias a los depósitos orgánicos acumulados bajo ellas. Las reconstrucciones paleoecológicas que usan suelos de praderas marinas aún son escasas y las que hay se han centrado principalmente en procesos alogénicos del ecosistema (controlados externamente).
En esta tesis se ha hecho uso de reconstrucciones paleoecológicas en praderas de fanerógamas mediterráneas, principalmente de P. oceánica, a una escala espacial regional con el objetivo de explorar la dinámica a largo plazo de los componentes ecológicos autogénicos y bióticos. Inicialmente, se investigó la utilidad de varios proxies (indicadores) biogeoquímicos y de una técnica (espectroscopía FTIR-ATR) hasta ahora inexplorados en depósitos de praderas marinas, así como cuáles eran los principales procesos biogeoquímicos registrados por estos depósitos. Los resultados obtenidos permitieron describir la dinámica a largo plazo de las praderas marinas, así como sus principales impulsores del cambio a largo plazo y su importancia relativa. Se observó que la dinámica a largo plazo es oscilante, y que la mayoría de las praderas mostraban tendencias regresivas durante los últimos 150 años. Sin embargo, estas tendencias de declive variaban espacialmente, ocurriendo las principales diferencias a escala interregional. Las diferencias en la dinámica a largo plazo entre localidades parecían depender principalmente del contexto ambiental de cada sitio, lo que también afectaba a la resiliencia a largo plazo de las praderas. Los resultados revelan que los principales factores responsables de la variabilidad a largo plazo son múltiples, incluyendo factores de carácter local pero también regional y global. Sin embargo, la contribución relativa entre los factores de influencia local y de gran escala varia espacialmente. La influencia del clima parece especialmente crucial en praderas creciendo en aguas más turbias, bajo la influencia de descargas fluviales más abundantes. Estas praderas mostraron una menor resiliencia ecosistémica a largo plazo.
En resumen, esta investigación ha demostrado que las dinámicas a largo plazo de las fanerógamas marinas se pueden estudiar a través de su registro paleoecológico, proporcionando un valioso marco de referencia para evaluar la magnitud de cambios actuales y las consecuencias de diversos impactos combinados en estos ecosistemas marinos. Los resultados de esta tesis revelan que, a pesar de cierta variabilidad espacial de las dinámicas a largo plazo, los cambios más importantes han ocurrido durante el último siglo, predominando las tendencias de declive de la fanerógama o cambios en la composición de las comunidades que alberga. Además, nuestros resultados apuntan a un impacto negativo más agudo del actual cambio climático en aquellas praderas donde la disponibilidad de luz se ve comprometida debido a causas locales. La variabilidad espacial general de las dinámicas a largo plazo de las praderas marinas destaca la necesidad de una gestión local específica a cada pradera, con información previa contextual, información que se puede obtener a partir de estudios paleoecológicos.
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Fries, Jacqueline Lee. "Chemical Investigation of Antarctic Marine Organisms & Their Role in Modern Drug Discovery." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6084.
Full textAbstract:
The chemicals produced by biological systems, whether proteins, peptides, or terpenes, will always provide an intriguing topic for researchers. Invisibly controlling every aspect of nature, these molecules are responsible for life, evolution, and death. Specifically, here is described the secondary metabolites produced by Antarctic marine organisms as well as others, and how they are used to defend or attract other animals while potentially providing health benefits to mankind. This is done through collection, extraction, and separation of individual specimens. The respective mixtures of compounds after isolation are then analyzed via spectroscopic methods such as nuclear magnetic resonance spectroscopy, mass spectrometry, and X-ray crystallography. Once identified, these compounds are tested in biological assays to provide a hypothesis for their use in nature or evidence that there may be a use for them in medicine.
For this thesis, the Antarctic organisms described are an alga, Pocamium cartilagineum, an amphipod, Paradexamine fissicauda, a sponge, Dendrilla membranosa, and one undescribed and two known deep sea coral species, Briareopsis aegeon and Plumarella delicatissima. Beyond these specific specimens, their chemistry as well as natural products from other origins were combined to create a diverse compound library for biological screening against human pathogens. This was done using computational modeling and statistical analysis of the compound library and its comparison to other known chemical libraries. The diversity and impact of these molecules are assessed.