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1
Hurwitz, Bonnie Louise. "Viral Community Dynamics and Functional Specialization in the Pacific Ocean." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/265369.
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Viruses are the most abundant biological entity on Earth and outnumber their hosts ten-to-one. Ocean viruses (phages) impact bacterial-driven global biogeochemical cycles through lysis, manipulating host metabolism, and horizontal gene transfer. However, knowledge of virus-host interactions and viral roles in ecosystems remains limited due to few cultured marine phage genomes and non-quantitative culture-independent metagenomes. Here, I develop and apply novel and well-tested bioinformatic techniques to explore Pacific Ocean viral communities using quantitative datasets derived from rigorously-tested preparation methods. To evaluate concentration and purification methods, I examined triplicate metagenomes from a single ocean sample using four protocols. Concentration protocols showed statistical differences in taxonomy whereas purification protocols did not. Specifically, TFF-concentrated metagenomes contained trace bacterial contamination and had fewer abundant taxa as compared to FeCl₃-precipitated metagenomes. K-mer analysis using the complete dataset revealed polymerase choice defined access to "rare" sequences.To explore unknown viral sequences, I organized known and unknown sequence space into 27K high-confidence protein clusters (PCs) from 32 diverse Pacific Ocean Virus (POV) metagenomes, which doubled available PCs and included the first pelagic deep-sea viral metagenomes. Using PCs as a whole-viral-community diversity metric revealed decreases from coastal to open ocean, winter to summer, and deep to surface, that correlate with data from microbial genetic diversity markers (no parallel viral markers exist).Biologically, POV metagenomes showed that viruses likely reprogram central metabolic pathways in microbial communities far beyond the "photosynthesis viruses" paradigm. Gene distribution patterns from 35 viral gene families (31 new) revealed niche-specific (photic vs aphotic zone) altered pathway carbon flux presumably optimized to best locally generate energy and drive viral replication. Further, these PCs define the first "core" (180 genes) and "flexible" (423K genes total) viral community genome. Functionally, core genes again suggest niche-differentation with extensive Fe-S cluster-related genes for electron transport and metabolic enzyme catalysis in photic samples, and manipulation of host pressure-sensitive genes in aphotic samples. Taxonomically, these data deconstruct the culture-based paradigm that tailed viruses dominate in the wild - instead they appear ubiquitous, but not abundant.
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Wilson, Stephanie E. "Mesopelagic zooplankton feeding ecology and effects on particle repackaging and carbon transport in the subtropical and subarctic North Pacific Ocean." W&M ScholarWorks, 2008. http://www.vims.edu/library/Theses/Wilson08.pdf.
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Wright, Jody Jennifer. "Microbial community structure and ecology of Marine Group A bacteria in the oxygen minimum zone of the Northeast subarctic Pacific Ocean." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44834.
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Oxygen minimum zones (OMZs) are intrinsic water column features that arise when the respiratory oxygen (O2) demand during microbial remineralization of organic matter exceeds O2 supply rates in poorly ventilated regions of the ocean. Microbial processes play a key role in mediating biogeochemical cycling of nutrients and radiatively active trace gases in OMZs. Specific roles of individual microbial groups and the ecological interactions among groups that drive OMZ biogeochemistry on a global scale, however, remain poorly constrained. This dissertation focuses on describing microbial community structure in the world’s largest and least studied OMZ, located in the Northeast subarctic Pacific Ocean (NESAP), with a specific emphasis on characterizing the ecology of Marine Group A, an uncultivated candidate phylum of bacteria found to be prevalent in this region. To begin, I performed a survey of microbial community structure in the NESAP at two time points and over a range of depths based on traditional ecological analyses. I applied techniques derived from network theory to identify co-occurrence patterns among microbial groups within the NESAP and determined that MGA bacteria most frequently co-occurred with other MGA bacteria, suggesting that intra-phylum interactions may play a role in governing microbial processes in this region. Through analysis of small subunit ribosomal rRNA (SSU rRNA) gene sequences affiliated with MGA, I identified 8 novel subgroups and established the phylogeny and population structure of both novel and previously detected MGA subgroups. Finally, I provided first insights into the metabolic capacity of this little-known candidate phylum through investigations of metagenomic data obtained from NESAP waters. Analysis of large-insert genomic DNA fragments derived from MGA revealed protein-coding genes associated with adaptation to oxygen deficiency and sulfur-based energy metabolism. These observations may implicate MGA bacteria in the cryptic sulfur cycle, recently discovered to play a central role in biogeochemical cycling within OMZs. This work describes the first survey of microbial community structure in the NESAP OMZ and the first application of co-occurrence networks to study the ecology of deep ocean microbial communities, in addition to the first analysis of the diversity, population structure, and metabolic capacity of the enigmatic bacterial lineage MGA.
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Truong, Triet Minh. "Investigating DNA barcoding potentials and genetic structure in Ozobranchus spp. from Atlantic and Pacific ocean sea turtles." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1392769367.
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Receveur, Aurore. "Ecologie spatiale du micronecton : distribution, diversité et importance dans la structuration de l'écosystème pélagique du Pacifique sud-ouest." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0401.
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L'écosystème océanique Néo-Calédonien dans le Pacifique sud-ouest contient une forte diversité de prédateurs, comme les oiseaux marins ou les cétacés. La récente création du Parc naturel de la mer de corail a ouvert un besoin d'informations solides sur le fonctionnement de cet écosystème remarquable, notamment sur la dynamique du micronecton (organismes entre 1 et 20cm constituant la nourriture des prédateurs supérieurs) et de son rôle central dans les réseaux alimentaires, d'autant plus que ce maillon est le plus méconnu. Dans ce contexte, cette thèse a montré une forte influence de l’environnement sur sa distribution spatiale et saisonnière avec en moyenne plus de micronecton dans le sud que dans le nord, et plus en hiver qu’en été. Les espèces composant le micronecton sont plus riches en crustacés au nord en céphalopodes et poissons au sud. L’abondance de micronecton aurait tendance à diminuer sous l’influence du changement climatique. Enfin, nous avons montré que la répartition spatiale de ce groupe influençait la présence de six groupes de prédateurs : thon jaune, thon germon, dorade coryphène, dauphins, puffin et fou à pieds rougesThe New Caledonian pelagic ecosystem in the southwest Pacific contains a high diversity of predators, such as seabirds and cetaceans. The recent creation of the Natural Park of the Coral Sea created a need for solid information on the functioning of this remarkable ecosystem, particularly on the dynamics of the micronecton (organisms between 1 and 20 cm constituting food of top predators) and its central role in food webs, especially since is the most poorly understood. In this context, this PhD showed a strong influence of environment on its spatial and seasonal distribution with on average more micronekton in the south than in the north, and more in winter than in summer. The species composing the micronecton are riche in crustaceans in the north and in cephalopods and fish in the south. The micronecton abundance would tend to decrease under the influence of climate change. Finally, we showed that the spatial distribution of this group influenced the presence of six groups of predators: yellowfin tuna, albacore tuna, dolphin, dolphin, shearwater and red-footed body
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Rosas, Luis Rigoberto. "La modificación del ecosistema marino reflejada en las poblaciones de las especies de calamares Dosidicus gigas, Illex coindetii, Illex argentinus, Todarodes sagittatus, Doryteuthis gahi y Onykia ingens Dinámica y función de los calamares en los ecosistemas Marine ecosystem change in the squid populations of Dosidicus gigas, Illex coindetii, Illex argentinus, Todarodes sagittatus, Doryteuthis gahi and Onykia ingens Dynamic and function of squid species in the ecosystems." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/131154.
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En esta tesis se revisaron las relaciones que existen entre las poblaciones de dos especies de calamares ommastréfidos Dosidicus gigas y Illex argentinus con las series temporales de la temperatura superficial del mar, clorofila a y las estimaciones de biomasa zooplanctónica, lo que resultó en la comprensión de que la temperatura puede afectar directamente a las poblaciones de organismos productores primarios y a los integrantes del zooplancton, y no así a los organismos juveniles y adultos de ambas especies de calamar. También se observó que en ambas especies la distribución y abundancia de presas potenciales es uno de los principales factores que determinan la localización y en algunos casos migraciones horizontales y verticales en el ecosistema.
Para poder entender las relaciones que las especies de calamares guardan en los ecosistemas fue necesario implementar los estudios ecotróficos en los que se determinó la importancia que representan estos calamares en las redes tróficas como depredadores, así como la interacción entre especies semejantes de calamares con las que pueden compartir su hábitat. Para llevar esta investigación se seleccionaron tres áreas de importancia ecológica y comercial, la primera corresponde al océano Atlántico Sur en la plataforma Patagónica y las islas Malvinas/Falkland en las que se identificaron tres especies de calamar I. argentinus, D. gahi y O. ingens, la segunda corresponde al Noroeste del Mar Mediterráneo donde se identificó a I. coindetii y T. sagittatus y la tercera al océano Pacifico en las costas de México y Perú para D. gigas. Los resultados de este trabajo demuestran que la tendencia de las poblaciones de estas especies es afectada directamente por las presas más abundantes y disponibles en el ecosistema, así como el desarrollo de relaciones intrínsecas entre algunas especies presa y su depredador como fue el caso de D. gigas y el pez V. lucetia.This PhD thesis was focused in the relationships between the ommastrephid squids Dosidicus gigas and Illex argentinus with the time series of sea surface temperature, chlorophyll a and zooplankton biomass. The temperature as factor affected the primary productivity and the abundance of zooplankton, and no effects were found in the populations of juveniles and adult of both squids. In this way the distribution and abundance of squid was related to other factors such as the abundance of prey resources. Then the thesis was complemented with trophic ecology studies performed in the South Atlantic Ocean (Squid species: Doryteuthis gahi, Illex argentinus and Onykia ingens), in the Northwest Mediterranean Sea (Squid species: Todarodes sagittatus and Illex coindetii), and the South Pacific Ocean (Squid Dosidicus gigas). The results showed that the biomass and distribution of squid species are close related to the most abundant and available prey resources, and also it can be found trophic dependencies between some specific prey resources as was observed for Dosidicus gigas and the mesopelagic fish Vinciguerria lucetia .
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Traffichini, Andrea M. "Reconstruction of Northeastern Pacific Ocean Holocene Production Using Marine Mammal Archaeofauna." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/513.
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Changes in marine production play a key role in determining the trophic structure of the northeastern Pacific Ocean. This is a region of great environmental fluctuations due to modern, historical, and paleo-environmental variability recorded throughout the Holocene. These fluctuations are recorded in the bone collagen of the marine mammals that reside in these waters. Marine mammal remains from four previously excavated archaeological deposits on Unalaska Island, Alaska are used as a proxy for marine production changes throughout the Holocene (4,500 BP to 350 BP). Historic and modern samples from museum collections, subsistence harvests, and previously published data provide a distinct contrast to prehistoric marine mammals. Stable carbon and nitrogen isotope ratios (δ13C and δ15N) derived from marine mammal bone collagen correlate to changes in marine production and food web length. The 13C and 15N of prehistoric marine mammal taxa covary through the Holocene, indicating no trophic level change with fluctuations in 13C. Changes in δ13C and δ15N of marine mammals are correlated to periods of environmental fluctuations within the Holocene. Cooler climatic periods (transitional interval, beginning of the Neoglacial Interval, and Little Ice Age) show enrichedδ13C, reflecting primary production increase, compared to warmer climate periods (end of the Neoglacial Interval into the Medieval Climatic Anomaly). Unidentified cetacean bones are isotopically distinguishable into orders Mysticeti (baleen) and Odontoceti (toothed) due to different feeding ecologies. The δ13C depletion in modern pinnipeds compared to prehistoric is likely caused by the effect of increased anthropogenic atmospheric CO2 and resulting decrease in primary production.
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Young, Carina Saxton. "Decadal variability of the Pacific subtropical cells and equatorial sea surface temperature." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31671.
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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2010.Committee Chair: Di Lorenzo, Emanuele; Committee Member: Bracco, Annalisa; Committee Member: Lynch-Stieglitz, Jean. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Schroeder, Robert E. "The ecology of patch reef fishes in a subtropical Pacific atoll: recruitment variability, community structure and effects of fishing predators." Thesis, University of Hawaii at Manoa, 1989. http://hdl.handle.net/10125/18158.
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The ecology of patch reef fishes was studied to quantify the main
factors that affect the natural variability of the fish community and
to determine the effects produced on the community by experimental
removal of predators. Initially, a year-long baseline description was
completed of the physical, biological and ecological characteristics of
8 pristine patch reefs at Midway lagoon. For over 3 subsequent years,
piscivorous predators were spearfished at least monthly, often for days
at a time, on 4 of the 8 reefs. Fish populations were visually
censused throughout the experiment. In all seasons and years of the
project, daily recruitment rate of postlarval fishes to natural patch
reefs was compared to that measured on standardized, artificial reefs
of various sizes and degrees of inter-reef isolation. Finally, all
baseline measurements were replicated and complete collections were
made of all fishes, to validate the visual census method.
Visual censusing was found to be of adequate precision and accuracy
for most resident, non-cryptic species (highest for small patch reefs).
Fishes could be assigned to size classes underwater by visual estimate
with high accuracy. Rotenone collections were highly effective in
quantifying many species commonly missed or underestimated in visual
censuses.
Only a few species composed the bulk of all recruits, while most
species were rare or not seen at all. Variation between species was
related to life history strategies or behavioral requirements. High temporal variability was found at the following scales: 1) Annuallywhere
variability increased with the magnitude of recruitment, and
different species recruited heavily in different years, suggesting that
species specific factors in the plankton are more important than
general oceanographic conditions; 2) Seasonally- pulsing strongly in
summer, and occasionally late fall, when favorable environmental
conditions may maximize growth and survival; and 3) Daily- with 1 or 2
strong peaks (each only a few days long) over a period of several weeks
of low, variable recruitment.
Small-scale spatial variability between replicate attractors
(standardized artificial reefs) and between attractor types (coral and
wire) were both high for a few species recruiting abundantly, although
most recruits are probably substrate generalists. Rigorous visual fish
censuses can adequately document moderate- to long-term temporal
variation in the abundances of recently recruited juveniles on patch
reefs (i.e., based on similar temporal patterns assessed by daily
attractors). Daily total recruitment rate increased, although at
diminishing densities, with (attractor) reef size, and with degree of
inter-reef isolation. Abundances of recently recruited fish censused
on neighboring, natural patch reefs (much larger than attractors)
increased with reef size. The effect of isolation on these natural
reefs was confounded by the stronger effect of reef size. These
results suggest that if optimum size and spacing of reefs is provided,
either by proper design of artificial reefs or selection of marine reserves, managers may enhance fish recruitment and ultimately improve
local fisheries:
Of the 135 fishes censused on the patch reefs studied, only 6
species together accounted for 70% of the total number of all fish,
mainly due to heavy seasonal recruitment pulses. Strong seasonal and
annual variability in recruitment was responsible for most of the
temporal variation in fish abundance. The structure of patch reef fish
communities at Midway was characterized by high unpredictability (e.g.,
great seasonal and/or annual variability in recruitment by common
species, recruitment limitation for most species, and a high turnover
rate detected by frequent sampling). Some predictions of the theory of
island biogeography were also met by these fish communities (e.g.,
species richness correlated strongly with patch reef area, volume and
relief). and total fish abundance. Some populations also exhibited a
degree of long-term stability. Species diversity [H'] was similar
among different size reefs.
The experimental fishing on piscivores produced a catch composed
mainly of lizardfish, due largely to immigration following the removal
of other, competitively superior, highly resident piscivores.
Scorpionfish and moray eels were also dominant predators. The expected
decreases in catch-per-unit-effort were not realized, except for a
quantitatively insignificant family (hawkfish). Conversely, the catch
of the highly migratory lizardfish actually increased as fishing
progressed. Changes in the catch composition for other piscivores related mainly to major changes in reef size or to patterns of large,
inter-year recruitment fluctuations. Census data confirmed the major
trends indicted by catch results. Sharks and jacks were attracted to
the experimental reefs by spearfishing; the study was unable to
determine whether their piscivorous effect was different between reef
treatments.
Patch reef fish communities at Midway were relatively resilient to
long-term, intense fishing pressure on piscivores. However, enhanced
survival of a large, annual, summer recruitment pulse of a common
cardinalfish, synchronized with a temporary but significant reduction
of lizardfish (the most prevalent piscivore) by fishing, suggested that
an effect of predation on reef fish populations is experimentally
detectable and considerable. However, temporal and spatial variability
in recruitment, and reef size differences and changes in size were the
primary factors responsible for the observed temporal patterns in fish
abundance. COlnmunity analysis involves numerous confounding effects
and requires the most careful interpretation for valid conclusions.xvi, 321 leaves, bound : ill. ; 29 cm.
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Prabhakar, Gouri. "Characteristics of Regional Aerosols: Southern Arizona and Eastern Pacific Ocean." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332834.
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Atmospheric aerosols impact the quality of our life in many direct and indirect ways. Inhalation of aerosols can have harmful effects on human health. Aerosols also have climatic impacts by absorbing or scattering solar radiation, or more indirectly through their interactions with clouds. Despite a better understanding of several relevant aerosol properties and processes in the past years, they remain the largest uncertainty in the estimate of global radiative forcing. The uncertainties arise because although aerosols are ubiquitous in the Earth's atmosphere they are highly variable in space, time and their physicochemical properties. This makes in-situ measurements of aerosols vital in our effort towards reducing uncertainties in the estimate of global radiative forcing due to aerosols. This study is an effort to characterize atmospheric aerosols at a regional scale, in southern Arizona and eastern Pacific Ocean, based on ground and airborne observations of aerosols. Metals and metalloids in particles with aerodynamic diameter (Dp) smaller than 2.5μm are found to be ubiquitous in southern Arizona. The major sources of the elements considered in the study are identified to be crustal dust, smelting/mining activities and fuel combustion. The spatial and temporal variability in the mass concentrations of these elements depend both on the source strength and meteorological conditions. Aircraft measurements of aerosol and cloud properties collected during various field campaigns over the eastern Pacific Ocean are used to study the sources of nitrate in stratocumulus cloud water and the relevant processes. The major sources of nitrate in cloud water in the region are emissions from ships and wildfires. Different pathways for nitrate to enter cloud water and the role of meteorology in these processes are examined. Observations of microphysical properties of ambient aerosols in ship plumes are examined. The study shows that there is an enhancement in the number concentration of giant cloud condensation nuclei (Dp>2 μm) in ship plumes relative to the unperturbed background regions over the ocean.
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Hardy, Nicholas C. "A marine geophysical study of the Pacific margins of Colombia and south east Panama." Thesis, University of Birmingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312976.
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Hamidian, Amir Hossein, and n/a. "Cadmium in the marine environment." University of Otago. Department of Chemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20090728.100026.
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Cadmium in the ocean has a nutrient-like cycling pattern: with biological uptake at the surface, subsequent sinking in particulate form and then regeneration as dissolved species in deeper waters. Many measurements have been made over time of the ratio of the concentrations of dissolved Cd to those of PO₄ (Cd/PO₄) in the world ocean and this has become one of the best relationships documented between a trace metal and a nutrient. Combined with the measurements of the Cd/Ca ratio in foraminifera, the Cd/PO₄ ratio has been used to reconstruct the oceanographic circulation patterns that existed during past glacial periods and hence provides information on past climate changes.
In the present study Cd/PO₄ ratios of the Southern Indian Ocean in surface and deep waters were investigated. The slopes of the relationships between Cd and PO₄ concentrations in waters of this region are high compared to the global correlations, and lie between those reported for other parts of the Southern Ocean and the Pacific Ocean. In surface waters of the Southern Indian Ocean, Cd/PO₄ ratios decrease from regions exhibiting high nutrient-low chlorophyll (HNLC) characteristic in the south to oligotrophic waters further north. It is also found that particulate Cd plays an important role in regulating the high Cd/PO₄ ratios reported in waters south of the Polar Front.
Very low Cd/PO₄ ratios were measured in waters associated with the Subtropical Front southeast of New Zealand compared to other Southern Ocean and global oceanic waters. Seasonal variations in the Cd/PO₄ ratios measured for these waters strongly suggest they are associated with a significant biological uptake of dissolved Cd particularly during the phytoplankton growth season in summer.
Dissolved Fe concentrations in the Southern Indian Ocean and seasonal variations of Fe in waters off the Otago Coast (southeast of New Zealand) suggest that Fe may stimulate phytoplankton growth and this might result in lower Cd/PO₄ ratios in surface waters through enhanced Cd uptake relative to PO₄ by the phytoplankton. However there is no distinct relationship between dissolved Fe concentrations and the dissolved Cd/PO₄ ratios measured in these surface waters. This finding is in disagreement with the recent 2006 hypothesis put forward by J.T. Cullen, which proposed that waters exhibiting low dissolved Cd/PO₄ ratios were associated with the HNLC regions. From a consideration of the potential Zn concentrations calculated from Si concentration measurements reported for these waters, it would appear that Zn may play a more important role than Fe in regulating Cd/PO₄ ratios in these waters.
Measurements of dissolved and total Cd concentrations relative to those of PO₄ were also undertaken in the Otago Harbour and immediate surrounding coastal waters. These exhibited higher Cd concentrations and higher Cd/PO₄ ratios than open ocean waters further off the Otago Coast. The particulate Cd concentrations showed a negative correlation with Cd concentrations measured in cockle species (Austrovenus stuchburyi) collected in the harbour, suggesting that particulate Cd is not the source of Cd measured in the tissue of this species.
The concentrations of Cd and other trace metals were also measured in samples of green mussel (Perna canaliculus), ribbed mussel (Aulacomya atra maoriana) and oyster (Saccostrea cucullata) collected from Otago Harbour and possible correlations explored between these concentrations and other parameters such as the shellfish condition indices and environmental gradients in the harbour.
In summary, measurements of dissolved and particulate Cd concentrations in the water column can provide unique information on a number of processes occurring in the global marine environment.
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Posacka, Anna. "Biogeochemical cycling of copper in the Northeast Pacific Ocean : role of marine heterotrophic bacteria." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62937.
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Copper (Cu) is important in regulating microbial activity in the ocean, as it can act both as a limiting nutrient and a toxic inhibitor depending on its concentration. Yet, our knowledge of its biogeochemical cycle is limited in many oceanic regions including the subarctic Northeast (NE) Pacific, as is our knowledge of Cu nutrition in marine heterotrophic bacteria. To address this, I investigated Cu biogeochemical cycling along a coastal‒oceanic transect, Line P, in the subarctic NE Pacific (Chapter 2). I also explored physiological responses to varying Cu availability (limiting to sufficient) of taxonomically diverse heterotrophic bacteria, which include isolates from surface waters of the Line P transect (Flavobacteriia member: Dokdonia sp. Dokd-P16, and Gammaproteobacteria members Pseudoalteromonas sp. strain PAlt-P2 [coastal] and PAlt-P26 [oceanic]), and a member of the marine Roseobacter clade within class Alphaproteobacteria (Ruegeria pomeroyi DSS-3). Several important processes were identified to moderate dissolved Cu along Line P. These include fluvial and sedimentary inputs (near the coast), upwelling of deep, Cu-rich waters in the Alaskan gyre (offshore), atmospheric inputs (offshore), as well as scavenging within the intermediate waters of the Oxygen Minimum Zone (OMZ) across the transect. Bacterial responses to changing Cu availability were diverse. Flavobacteriia member Dokd-P16 reduced its growth rate, carbon metabolism, and Cu quota (Cu:P) under Cu limitation, but enhanced its Mn quota. In contrast, both Pseudoalteromonas spp. were mostly unaffected by different Cu levels. Ruegeria pomeroyi maintained constant growth rates but moderated quotas of several metals (under low Cu: decreased Cu and Co, but increased Mn and Fe quotas), and some aspects of its C metabolism. These findings illuminate on the role of Cu in shaping bacterial species composition in the ocean, and the bacterially-mediated cycles of carbon and bioactive metals (i.e. Fe, Zn, Mn, Co). Copper quotas of heterotrophic bacteria are similar to those of cultured marine phytoplankton. Estimates of Cu partitioning between these planktonic groups in the euphotic zone of the NE Pacific revealed that up to 50% of biogenic Cu could be associated with bacterial biomass. Therefore, marine heterotrophic bacteria should not be overlooked in studies of Cu biogeochemical cycling.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Curtis, Jan. "A case study of explosive cyclogenesis in the eastern Pacific Ocean 14-17 December 1987." Thesis, Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26907.
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Approved for Public release; distribution is unlimitedAn explosive cyclogenesis event that occurred in the eastern Pacific Ocean on 14-17 December 1987 is investigated using the National Meteorological Center (NMC) final analyses and Geostationary Operational Environmental Satellite (GOES) digital imagery. Forecasts for this cyclone by the Navy Operational Global Atmospheric Prediction System (NOGAPS 3.0) and NMC Nested Grid Mesh (NGM) forecasts initialized at 12 UTC 14 December are also evaluated. Quasi-Lagrangian budgets of mass and vorticity are computed to determine the factors responsible for the development of this intense cyclone. The initial surface development occurs within a strong baroclinic zone southeast of a significant short-wave trough aloft. Rapid intensification is accompanied by large cyclonic vorticity advection in the upper troposphere as the surface cyclone moves under the divergent quadrant of a 250mb jet streak. A key element in this development is the superposition between the pre-existing surface low and upper level short-wave trough in a favorable weak static stability environment. These observations support earlier studies that upper level forcing acts as a critical catalyst in initiating eastern ocean explosive development.
http://archive.org/details/casestudyofexplo00curt
Lieutenant Commander, United States Navy
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Norris, Joel R. "Interannual variability in cloudiness, sea surface temperature, and atmospheric circulation over the midlatitude North Pacific during summer." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/10050.
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Payet, Jérôme Patrice. "Ecology and diversity of marine viruses on the Canadian Arctic Shelf, Arctic Ocean." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/40687.
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Viruses are the most abundant, ubiquitous and diverse biological entities in the world’s oceans. Through infection and lysis, viruses play critical roles in shaping marine microbial assemblages, with consequences for ecosystem functioning and biogeochemical processes. Despite their global-scale importance in oceanic processes, relatively little is currently known about the distribution, ecological roles and diversity of marine viruses. Furthermore, this existing knowledge is largely limited to temperate and lower latitude ecosystems, leaving the role of viruses in polar waters relatively unexplored.
The Canadian Arctic Shelf (CAS) is a heterogeneous and productive marine ecosystem within the Arctic Ocean that plays a key role in carbon cycling. Emerging data suggest that the microbial assemblages on the CAS are active and diverse and can respond rapidly to changes in environmental conditions.
This dissertation addresses a knowledge gap regarding marine viruses in polar waters by examining ecology and diversity of marine viruses on the CAS. Toward this end, multiple approaches such as flow cytometry and epifluorescence microscopy, experimental incubations and filtration, molecular techniques (polymerase chain reaction, denaturing gradient gel electrophoresis fingerprint analysis, cloning and sequencing) and statistical analyses were used to investigate 1) spatio-temporal variations in viral distribution and abundance, 2) significance of lysogenic and lytic viral infections and their impacts on host mortality and carbon cycling, 3) patterns in the genetic structure of T4-like viruses (Myoviridae) and phycodnaviruses (Phycodnaviridae), two virus families infecting bacteria and eukaryotic phytoplankton, respectively and 4) phylogenetic diversity and richness of T4-like viruses and phycodnaviruses.
Together, the results of these studies have demonstrated that viruses are abundant, active and diverse components of the CAS microbial assemblages, and are strongly coupled with environmental conditions and microbial abundance, productivity and composition. In addition, these studies indicate that viruses are significant agents of microbial mortality on the CAS, and can influence energy fluxes and carbon cycling.
Overall, this dissertation has increased our understanding of the marine viruses in arctic environments. Moreover, the results stress the need to include viruses in models when studying the influence of climate changes on biogeochemical cycles in the Arctic Ocean.
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Kerrison, P. D. "The effect of ocean acidification on the ecology and physiology of marine macroalgae." Thesis, University of Essex, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559262.
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Ocean acidification (OA) is the decrease in ocean pH due to increasing atmospheric pC02• It is predicted that by the year 2100, the pC02 will rise from ca 385 uatm today to 750 uatrn, with a corresponding decrease in surface ocean pH from 8.1 to 7.8. pH was monitored at five stations around a coastal CO2 vent site in Ischia, Italy and the utility of such areas discussed. An ecological survey of benthic macroalgae revealed a substantial community shift at lower pH toward reduced species richness and diversity. The chlorophytes became more dominant at lower pH, with cover increasing from 45-55% at pH 8.16-7.84, to 67-90% at pH 7.48-7.11. Heavily calcified species disappeared at pH 7.48-7.11, but their total cover did not change significantly between pH 8.16-7.80, suggesting some resilience over this century. At lower pH, the DMSP content in macroalgae from Ischia increased in the chlorophytes while in rhodophytes and phaeophytes it decreased. The dark-adapted algal photophysiology suggested a significant benefit when pH was 7.84-7.80, which was lost at pH 7.48-7.11. Two species of common chlorophyte macroalgae VIva lactuca and VIva clathrata, were incubated under pC02 conditions ranging from 432 to 1514 uatrn, In both species, the results indicated that by the year 2100 there could be a large decrease by 50-58% in DMS production, a reduction in chlororespiration, and increased reproductive output in these species. I conclude that increasing pC02 does not directly fertilise photosynthesis or somatic growth in the Ulvales but, reduces chlororespiration, possibly due to carbon-concentrating mechanism down-regulation. This may be the cause of the large reduction in DMS production seen and may lead to a reallocation of resources towards reproductive output. This may increase the prevalence of chlorophyte macroalgae in the future with major repercussions for coastal ecosystems.
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Yu, Zuojun. "Tropical Instability Waves in the Pacific Ocean: Their Seasonal Variation and Asymmetry About the Equator." NSUWorks, 1992. http://nsuworks.nova.edu/occ_stuetd/67.
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The goals of this research are to understand the dynamical processes that lead to the seasonal variation of the tropical instability waves (TIWs) in the central and eastern Pacific Oceans and to their meridional asymmetry about the equator. Two types of ocean models are used, namely, the fully nonlinear and linearized versions of the 21/2-layer model used by McCreary and Yu (1992). The nonlinear model, which is forced by climatological data, is used to simulate the TIWs and to identify differences in their character at different times of the year. The linearized model is used to investigate the effect of various background states on generating asymmetric unstable waves.
Solutions to the fully nonlinear model simulate the seasonal variation and asymmetry of the TIWs reasonably well. Results from our main run show that the TIWs seen in the upper-layer temperature field share most of the features of the TIWs observed in both the Pacific and Atlantic Oceans: they have periods of 15-20 days, propagate westward, are most active in the summer and fall, and tend to be concentrated north of the equator.
Various budget analyses reveal that the TIWs in the upper layer are a mixed type of barotropic and frontal instabilities, that the Reynolds-stress term associated with these waves significantly weakens the shear within the two branches of the South Equatorial Current (SEC), and that their eddy heating is as large as the surface heat flux during the wave season. The instabilities in the lower layer, which have longer periods of around 30 days, are of the Kelvin-Helmholtz type. Energetics analyses indicate that the seasonal variation of the TIWs is determined by the sharpness of the sea-surface-temperature (SST) front. The same analyses show that their asymmetry is due to the asymmetry about the equator of the two branches of the SEC and of the SST front, but not to the presence of the North Equatorial Countercurrent. These properties are confirmed by the linear instability analysis.
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Gaube, Peter. "Statistical Analysis of Eight Years of Ocean Color and SST Data in the Tropical Pacific." NSUWorks, 2007. http://nsuworks.nova.edu/occ_stuetd/265.
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Eight years of contemporaneous SST and ocean color data were statistically compared and contrasted to quantify their variations over a range of time and space scales. While it is generally accepted that chlorophyll concentrations (a proxy for primary production) on the equator are directly forced by upwelling, it is not clear that a simple correlation between SST and ocean color exists outside the equatorial wave guide or how it may depend on scale. The Tropical Rainfall Measuring Missions microwave imager (TMI) and Sea View Wide Field of View sensor (SeaWiFS) sensors have been in operation simultaneously for a period of nine years. Thus, the resolution of eight full seasonal cycles, including several ENSO cycles, suggest that significant results can be obtained by statistically analyzing the correlations between these satellite observed data sets. The statistical techniques include simple correlations and empirical orthogonal functions. Of particular interest are the possible influences which tropical instability induced circulations have on the marine ecosystem and ocean color. While results presented in this study are consistent with the paradigm that equatorial upwelling causes high productivity in the cold tongue, the overall relationship between SST and CHL (chlorophyll-a) is complex, depending on both time and space scale.
The dominant modes of temporal variability in both data set are shown to vary on a seasonal cycle, with an inter-annual component. In addition negative correlation is found in regions where fronts in both SST and ocean color are disturbed by the passing of tropical instabilities and mesoscale eddies. Several zones are identified where eddy forcing clearly indicates a relationship between enhanced primary production and the influx of relatively cold waters. While it is likely that the coastal regions are dominated by upwelling processes, the previously established dynamics of tropical instabilities lead us to propose that horizontal advection within instability vortices is the dominant process leading to enhanced primary production along the equatorial fronts.
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Cowburn, Benjamin. "Coral reefs and climate change in the Indian ocean : a case study of Watamu Marine National Park, Kenya and other Indian Ocean locations." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:22c16252-bdf9-4724-a2f8-dbd4c6fe7f09.
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Coral reefs are arguably the most threatened marine habitat because of multiple anthropogenic stressors degrading the health and resilience of these systems. In the past 20 years there have been increasing observations of mass coral bleaching and mortality associated with increasing water temperatures in the tropics. Reefs provide ecosystem services worth billions of dollars to people living in tropical coastal areas and are the architects of one of the most beautiful structures found on earth. Conserving these habitats is paramount, and conservation planning must contend with climate change along with local and regional stressors. In this thesis Watamu Marine National Park in Kenya is used as a case study of the current challenges facing the conservation of reefs in a warming world. The Western Indian Ocean suffered dramatic bleaching during 1998, which caused the mortality of 70% of Watamu's corals. Using datasets from the 1980s to present the historical trajectory of Watamu's reef community is presented. The current ecosystem resilience is assessed to suggest how this reef will respond to future climate stress. It appears that Watamu's coral community has remained in an altered state post-1998, which, based on its past thermal stress and current coral community, should be resistant to future bleaching. Watamu's resilience and reef health is compared with other locations in the Indian Ocean, including reefs in Kenya and the Maldives that bleached in 1998 and examples from Mozambique and Sumatra of reefs with little evidence of historical thermal stress. Resilience is a multi-faceted process with different major components and numerous interacting factors, which act synergistically on the reef community. Conservation options and opportunities are discussed for the 6 locations examined, using current resilience models and theory as a framework for identifying priority actions. Local and regional-scale human impacts on shallow marine habitats during the last 50 years has been dramatic, and with global-scale climate change as an additional major threat, the next 50 years will be critical for the future of reefs. The locations visited during this study showed encouraging signs of resilience to past thermal stress, with evidence to suggest that corals are acclimatising and/or adapting to increasing water temperatures. The future of reefs in locations like Watamu is uncertain. Better understanding of reef ecology, appropriate conservation techniques and ultimately greater public concern for reefs is required to ensure that there is a future for these ecosystems in the Indian Ocean.
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Rosas, Navarro Anaid. "Impact of ocean warming and acidification on coccolithophore ecology and calcification in the North Pacific." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664186.
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Los cocolitofóridos son fitoplancton calcificante unicelular cosmopolita involucrado en importantes ciclos biogeoquímicos globales. Esta tesis doctoral se centra en los impactos del calentamiento del océano y la acidificación sobre la morfología y la calcificación de los cocolitofóridos, con especial atención a la especie cosmopolita y dominante Emiliania huxleyi. El estudio incluye experimentos de temperatura usando cepas de E. huxleyi aisladas en el noroeste del océano Pacífico, y el análisis de muestras de agua colectadas a lo largo de un transecto que cubre aguas del Golfo de California y del margen NE del oceáno Pacífico. Este tipo de trabajo es oportuno dado que el calentamiento global y el rápido aumento del CO2 antropogénico en la atmósfera tienen consecuencias notables en el medio marino.
Para aclarar discrepancias que aparecen en la literatura sobre la respuesta de la calcificación a los cambios de temperatura, comparamos tres cepas de E. huxleyi cultivadas bajo condiciones no limitantes de nutrientes ni de luz, a 10, 15, 20 y 25 ºC de temperatura. Las tres cepas mostraron tasas de crecimiento similares en función de la temperatura, con un óptimo en los 20–25 ºC. Se correlacionaron positivamente con la temperatura: la tasa de producción de cocolitos y de elementos particulados (carbono inorgánico particulado (PIC), carbono orgánico particulado (POC), nitrógeno particulado total (TPN)), la masa y tamaño del cocolito, el ancho del ciclo de elementos del tubo de los cocolitos, el número de cocolitos en la cocosfera, la masa de la cocosfera, y la velocidad de hundimiento y la relación PIC : POC de las células individuales. La correlación entre la producción de PIC y la masa/tamaño del cocolito apoya la noción de que la masa del cocolito se puede usar como proxy para la producción de PIC en muestras de sedimentos. Encontramos que los cocolitos incompetos no se deben a la escasez de tiempo a altas producciones de PIC. Las temperaturas de crecimiento subóptimas aumentan el porcentaje de coccolitos malformados en algunas cepas. La relación PIC : POC mostró un mínimo a la temperatura óptima de crecimiento. En el contexto del cambio climático, el calentamiento global podría causar una disminución en la contribución del PIC exportado de los cocolitofóridos, podría ser una conveniencia en algunos genotipos debido a una menor cantidad de malformaciones de cocolitos y podría influir de manera importante sobre las velocidades de hundimiento.
Dado que el calentamiento, la acidificación y la menor disponibilidad de nutrientes pueden ocurrir simultáneamente en los escenarios de cambio climático, existe la pregunta sobre cuál será el efecto neto de los diferentes factores de influencia. Aquí analizamos 68 muestras de agua abarcando una amplia gama de condiciones. Enfocamos el estudio en las principales variaciones morfológicas y de morfotipo de la especie E. huxleyi, y también en las diferentes especies del género Gephyrocapsa. Descubrimos que E. huxleyi tipo O es un morfotipo más frío potenciado por concentraciones más altas de amonio y es más tolerante a valores de pH más bajos que el morfotipo A. El morfotipo A sobre-calcificado compartió nicho con el morfotipo O. Las aberraciones morfológicas observadas y la morfología sub-calcificada se asociaron a condiciones desfavorables, tales como bajas (aunque no las más bajas) concentraciones de nutrientes. La contribución de PIC por litro de G. oceanica fue más alta que la de E. huxleyi, en tercer lugar fue la de G. muellerae. Gephyrocapsa oceanica presentó la mayor afinidad a las aguas más cálidas con menores concentraciones de nutrientes, y G. muellerae la mayor tolerancia a un pH más bajo. En el contexto del cambio climático, G. oceanica y G. muellerae podrían aumentar su abundancia relativa, generando cambios en la producción de PIC.Coccolithophores are cosmopolitan unicellular calcifying phytoplankton involved in important biogeochemical global cycles. This PhD thesis focuses on the impacts of ocean warming and acidification on the morphology and calcification of coccolithophores, with special attention to the cosmopolitan and dominant species Emiliania huxleyi. The study includes temperature experiments using three strains of E. huxleyi isolated in the NW Pacific Ocean, and the analysis of water samples collected along a transect covering the Gulf of California and NE Pacific margin waters. This type of work is timely since global warming and the rapid increase in anthropogenic atmospheric CO2 have remarkable consequences on the marine environment. To clarify discrepancies featuring in the literature about the calcification response to temperature changes, we compared three strains of E. huxleyi grown under non-limiting nutrient and light conditions, at 10, 15, 20 and 25 ºC of temperature. All three strains displayed similar growth rate versus temperature relationships, with an optimum at 20–25 ºC. Over the sub-optimum to optimum temperature range (10–25 ºC), elemental production (particulate inorganic carbon (PIC), particulate organic carbon (POC), total particulate nitrogen (TPN)), coccolith mass, coccolith size, width of the tube element cycle, number of attached coccoliths per coccosphere, coccosphere mass, individual sinking velocity, individual cell PIC : POC ratio, and coccolith production rate, were positively correlated with temperature. The correlation between PIC production and coccolith mass/size supports the notion that coccolith mass can be used as a proxy for PIC production in sediment samples. We found that incompleteness of coccoliths is not due to time shortage at high PIC production. Sub-optimal growth temperatures lead to an increase in the percentage of malformed coccoliths in a strain-specific fashion. The PIC : POC ratio showed a minimum at optimum growth temperature in all investigated strains. In the context of climate change, global warming might cause a decline in coccolithophore’s PIC contribution to the rain ratio, as well as improved fitness in some genotypes due to fewer coccolith malformations; our data also point to an important influence of global warming on sinking velocities. Given that warming, acidification, and lowered nutrient availability might occur simultaneously under climate change scenarios, there is the question about what the net effect of different influential factors will be. Therefore, we analysed 68 summertime samples along a transect at different stations and depths, giving a large range of conditions. The studied regions are expected to be particularly susceptible to both warming and acidification, and are characterized by high seasonal primary production through upwelling events. We focused the study on the coccosphere standing stock variations of the main morphotypes and morphological variations of the species E. huxleyi and on the different species of the genus Gephyrocapsa. We found that E. huxleyi type O is a colder morphotype enhanced by higher ammonium concentrations and is more tolerant to lower pH values than the morphotype A. The over-calcified E. huxleyi type A shared niche with the morphotype O. The observed morphological aberrations and the under-calcified morphology were associated to unfavorable conditions for the cell such as low (though not the lowest) nutrient concentrations. The PIC contribution per liter of G. oceanica was higher than that of E. huxleyi, in third place was that of G. muellerae. Gephyrocapsa oceanica presented the highest affinity to warmer waters with lower nutrient concentrations, and G. muellerae the highest tolerance to lower pH. In the context of climate change, G. oceanica and G. muellerae might increase their relative abundance with subsequent changes in the coccolithophore PIC production.
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Muhlin, Jessica F. "Reproductive Ecology and Characterization of Population Genetic Structure of Fucus vesiculosus Linnaeus in the Northwestern Atlantic." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MuhlinJF2007.pdf.
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Barrios, Suarez Lina Maria. "Taxonomy and general ecology of marine invertebrates from Las Perlas Archipelago, Panamanian Tropical Eastern Pacific." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/65.
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Preheim, Sarah Pacocha. "Ecology and population structure of vibrionaceae in the coastal ocean." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/58184.
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Thesis (Ph.D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and the Woods Hole Oceanographic Institution), 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
Extensive genetic diversity has been discovered in the microbial world, yet mechanisms that shape and maintain this diversity remain poorly understood. This thesis investigates to what extent populations of the gamma-proteobacterial family, Vibrionaceae, are ecologically specialized by investigating the distribution across a wide range of environmental categories, such as marine invertebrates or particles in the water column. Additionally, it seeks to determine whether in situ population distributions directly result from a competitive advantage over other Vibrio populations. This was investigated by in vitro competition assays on mixtures of native, sterilized particles. Generalist populations were found to dominate the associations with marine invertebrates, consistent with a model of high migration dominated population assembly. A majority of populations occurred broadly within and among the different types of invertebrates sampled, with one population being a near perfect generalist with regard to seasons, host taxa and body regions. High variability across host individuals, consistent with a scenario of stochastic clonal expansion, was especially pronounced in crab and zooplankton samples. Specialization, demonstrated by specific and reproducible association with different particle types in the water column, is more common than specialization within invertebrate hosts.
(cont.) Co-existing Vibrio species show strong preferences for different types of particulate matter in the water column suggesting that competition for limited resources influences their evolution. While populations show different growth profiles on particle derived substrates, relative growth advantages of specialist populations in competition with other Vibrio populations on native particles may not be sufficient to explain observed environmental distributions. Instead, populations may gain an advantage on these particles by colonizing the living plant or zooplankton prior to death and degradation into particulate matter. In summary, although vibrios are known commensals of marine invertebrates, evidence suggests that population structure within animals is fairly weak compared to suspended particles in the water column. This highlights the importance of comparing multiple environmental categories and migration among them to investigate population structure and adaptation.
by Sarah Pacocha Preheim.
Ph.D.
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Van, Mooy Benjamin A. S. "Carbon and phosphorus cycling by phylogenetically-defined groups of bacteria in the North Pacific Ocean /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/10985.
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Swezey, Daniel Sergio. "Ocean Acidification on the California Coast| Responses of Marine Bryozoa to a High CO2 Future." Thesis, University of California, Davis, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10036209.
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As a result of human activities, the level of CO2 in the Earth’s atmosphere has increased by nearly 40% since the industrial revolution. The rate of green house gas emission is accelerating, with current trends exceeding those predicted by “worst case” global climate change scenarios. The chemistry of the ocean is fundamentally changing as a result of increasing atmospheric CO2, which dissolves in seawater, making it more acidic, a process referred to as ocean acidification (OA). A rapidly expanding body of science is now being generated to understand the impact of this global environmental change. To date, most studies evaluating OA effects have centered on simplified laboratory analyses that expose single populations to short-term treatments in order to quantify responses of individuals. These designs offer a limited assessment of the degree to which phenotypic plasticity and local adaptation might influence the response of populations to OA.
To address these questions, I carried out studies on members of Phylum Bryozoa, a species-rich clade of calcified colonial marine invertebrates distributed throughout the global ocean. Bryozoans were selected as a model system for this work because the clade exhibits a broad array of growth and calcification strategies, and because of the relative paucity of data regarding their expected response to future acidification. In addition, bryozoans can be subdivided into genetically identical replicate clones, which can then be assigned to separate treatments, allowing variation across treatments to be uniquely partitioned into the variance components of statistical models. In order to culture bryozoans for comparative experiments, I designed and constructed a new flow-through OA system at the Bodega Marine Laboratory, capable of finely manipulating both the temperature and carbonate chemistry of seawater, allowing for controlled laboratory experiments of long duration.
In Chapter 1, I performed a comparative 9-month laboratory experiment examining the effects of ocean acidification on the native Californian bryozoan Celleporella cornuta. C. cornuta was sampled from two regions of coastline that experience different oceanographic conditions associated with variation in the intensity of coastal upwelling. Under different CO2 treatments, the biology of this bryozoan was observed to be remarkably plastic. Colonies raised under high CO2 grew more quickly, invested less in reproduction, and produced skeletons that were lighter compared to genetically identical clones raised under current atmospheric values. Bryozoans held in high CO2 conditions reduced their investment in skeletal carbonate, changed the Mg/Ca ratio of skeletal walls and increased the expression of organic coverings that may serve a protective function. Differences between populations in growth, reproductive investment, and the frequency of organic covering production were consistent with adaptive responses to persistent variation in local oceanographic conditions.
In Chapter 2, I tested whether skeletal mineralogy can vary plastically in some invertebrates using the cosmopolitan bryozoan Membranipora tuberculata as a model. In a 6-month laboratory experiment, I cultured genetic clones of M. tuberculata under a factorial design with varying food availability, temperature, and dissolved CO2 concentrations. Elevated food availability increased growth in colonies while cold temperatures and high CO2 induced degeneration of colony zooids. However, colonies were able to maintain equivalent growth efficiencies under cold, high CO2 conditions, suggesting a compensatory tradeoff whereby colonies increase the degeneration of older zooids under adverse conditions, redirecting this energy to the maintenance of growth. Elevated food and cold temperatures also decreased Mg concentrations in skeletal material, and this skeletal material dissolved less readily under high CO2 conditions. This suggests that these factors interact synergistically to affect dissolution potential in this and other species.
Finally, in Chapter 3, I explore stable isotope values for δ 18O and δ13C in the calcium carbonate structures of the bryozoan Membranipora tuberculata. I tested whether this species accurately records both temperature and pH variability during periods of coastal upwelling by analyzing δ18O and δ 13C in colonies grown in the field and in controlled laboratory cultures. Field-grown colonies were out planted next to a Durafet® pH sensor, which provided a high-resolution record of the temperature and pH conditions these colonies experienced. δ13C was found to negatively co-vary with pH in both laboratory and field growth, and calculated field temperatures derived from laboratory δ18O temperature calibrations aligned with the records from the pH sensor. δ18 Oc values were more depleted under low pH in laboratory trials, which stands in contrast to patterns observed in other taxa. This may indicate that Membranipora utilizes bicarbonate ion (HCO 3-) in its calcification pathway, and could help explain why many bryozoan species appear to exhibit enhanced growth under high CO 2 conditions. (Abstract shortened by ProQuest.)
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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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Scales, Kylie Lisa. "The application of ocean front metrics for understanding habitat selection by marine predators." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3319.
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Marine predators such as seabirds, cetaceans, turtles, pinnipeds, sharks and large teleost fish are essential components of healthy, biologically diverse marine ecosystems. However, intense anthropogenic pressure on the global ocean is causing rapid and widespread change, and many predator populations are in decline. Conservation solutions are urgently required, yet only recently have we begun to comprehend how these animals interact with the vast and dynamic oceans that they inhabit. A better understanding of the mechanisms that underlie habitat selection at sea is critical to our knowledge of marine ecosystem functioning, and to ecologically-sensitive marine spatial planning. The collection of studies presented in this thesis aims to elucidate the influence of biophysical coupling at oceanographic fronts – physical interfaces at the transitions between water masses – on habitat selection by marine predators. High-resolution composite front mapping via Earth Observation remote sensing is used to provide oceanographic context to several biologging datasets describing the movements and behaviours of animals at sea. A series of species-habitat models reveal the influence of mesoscale (10s to 100s of kilometres) thermal and chlorophyll-a fronts on habitat selection by taxonomically diverse species inhabiting contrasting ocean regions; northern gannets (Morus bassanus; Celtic Sea), basking sharks (Cetorhinus maximus; north-east Atlantic), loggerhead turtles (Caretta caretta; Canary Current), and grey-headed albatrosses (Thalassarche chrysostoma; Southern Ocean). Original aspects of this work include an exploration of quantitative approaches to understanding habitat selection using remotely-sensed front metrics; and explicit investigation of how the biophysical properties of fronts and species-specific foraging ecology interact to influence associations. Main findings indicate that front metrics, particularly seasonal indices, are useful predictors of habitat preference across taxa. Moreover, frontal persistence and spatiotemporal predictability appear to mediate the use of front-associated foraging habitats, both in shelf seas and in the open oceans. These findings have implications for marine spatial planning and the design of protected area networks, and may prove useful in the development of tools supporting spatially dynamic ocean management.
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Holmgren, Diego. "Decadal-centennial variability in marine ecosystems of the northeast Pacific Ocean : the use of fish scales deposition in sediments /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5308.
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Santos, Bianca Silva. "Integrating Empirical Data and Ocean Drift Models to Better Understand Sea Turtle Strandings in Virginia." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639566.
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Hundreds of stranded turtles wash up deceased on Virginia’s coastline each year, yet the causes of most stranding events are poorly understood. In this thesis, a carcass drift model was developed for the Chesapeake Bay, Virginia, to predict likely locations of mortality from coastal sea turtle stranding records. First, field studies were carried out to better parameterize the drift characteristics of buoyant sea turtle carcasses, namely, probable oceanic drift times and the impact of direct wind forcing on carcass drift. Based on the duration that tethered, free-floating turtle carcasses were buoyant, we determined that oceanic drift duration of turtle carcasses was highly dependent on water temperature and varied from 2-15 days during typical late spring to early fall bay water conditions. The importance of direct wind forcing for turtle carcass drift was assessed based on track divergence rates from multiple simultaneous deployments of three types of surface drifters: bucket drifters, artificial turtles and real turtle carcasses. Turtle drift along-wind leeway was found to vary from 1-4% of wind speed, representing an added drift velocity of approximately 0.03-0.1 m/s for typical bay wind conditions.
The information obtained from these field studies were used to parameterize the oceanographic carcass drift model, which was applied to reported strandings during 2009-2014. Predicted origin of stranding records with probable cause of death identified as vessel strike were compared to commercial boating data. Locations of potential hazardous turtle-vessel interactions were identified in high traffic areas of the southeastern Chesapeake Bay and James River. Commercial fishing activity of various gear types with known sea turtle interactions were compared in space to predicted mortality locations for stranded turtles classified with no apparent injuries, suggesting possible fisheries-induced mortality. Probable mortality locations for these strandings were found to vary between spring peak and summer off-peak stranding periods, but two distinct hotpots were identified in the southwest and southeast portions of the lower bay. Spatial overlap was noted between potential mortality locations and gillnet, seine, pot, and pound net fisheries. These predictions provide clear space-time locations for focusing future research and prioritizing conservation efforts. Nevertheless, the lack of fine temporal and spatial resolution fishing data limited our ability to quantitatively assess most likely causes for specific stranding events. This study both highlights the importance of addressing these data gaps and provides a meaningful conservation and management tool that can be applied to stranding data of sea turtles and other marine megafauna around the globe.
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Boersch-Supan, Philipp Hanno. "The ecology of scattering layer biota around Indian Ocean seamounts and islands." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/11440.
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The waters of the open ocean constitute the largest living space on Earth but despite its obvious significance to the biosphere, the open ocean remains an unexplored frontier. With a regional focus on the Indian Ocean, this thesis investigates (i) the distribution of pelagic biota on basin scales, (ii) the effect of abrupt topography on pelagic biota and their predator-prey relationships, and (iii) the use of genetic techniques to elucidate population connectivity and dispersal of pelagic taxa. (i) Pelagic scattering layers (SLs) were surveyed with scientific echosounders across the southwest (SWIO) and central Indian Ocean to investigate their vertical and geographical distribution. Structurally distinct SL regimes were found across the Subantarctic Front, and may explain recently observed foraging behaviours of southern elephant seals. Regression models indicated a close relationship between sea surface temperature and mean volume backscatter, with significantly elevated backscatter in the subtropical convergence zone. The heterogeneous distribution of scattering layer biota may have implications for predator foraging and carbon cycling in the Indian Ocean. (ii) Acoustic surveys revealed diverse interactions between SLs, aggregations and topography around islands as well as shallow ( < 200m) and intermediate (200-800m) seamounts at spatial scales from 1 to 100 km. Epi-and mesopelagic backscatter was increased around reefs and banks of the Chagos archipelago, indicating connectivity between oceanic and neritic systems. SWIO seamounts harboured summit-associated aggregations, but the distributions of surrounding SLs did not follow a general pattern. Downstream SL depletion was observed in one location and combined with stomach content analyses, provides an insight into the mechanics of prey flux between open-ocean and seamount ecosystems. (iii) A mitochondrial marker was used to assess the population structure and demography of the hatchetfish Argyropelecus aculeatus in the SWIO. The results are suggestive of a single, well-connected population and indicate a recent population expansion around 0.14 million years ago. This highlights that even highly abundant mesopelagic populations are vulnerable to global climatic changes. Dispersal and recruitment are key ecological processes structuring seamount communities and are directly relevant for the management of exploited populations. Genetic barcoding was evaluated as a means to identify cryptic larval specimens of eels (leptocephali) and spiny lobsters (phyllosomata). Identification success was limited, but indicated the presence of 3-4 phyllosoma clades and 5-6 leptocephalus clades along the SWIR.
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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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Nees, Heather A. "Diffuse flow chemistry and associated biological changes after an eruption at 9(degrees)50'North along the East Pacific Rise /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 115 p, 2008. http://proquest.umi.com/pqdweb?did=1629573671&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Conroy, Brandon J. "Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1477068157.
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Large river plumes and frontal zones are important physical features influencing plankton distribution in the marine environment. In the western tropical North Atlantic Ocean (WTNA) the Amazon River plume may extend over an area reaching 1.5 x 106 km2. The freshwater plume creates a low-density lens in the surface 25m and supplies silicon and phosphorus to the WTNA. These physical and chemical gradients create an ideal environment for large-scale blooms of diatom diazotroph associations (DDAs), a symbiotic relationship between nitrogen-fixing cyanobacteria and chain-forming diatoms. While the physical and chemical properties of the plume with regard to influences on phytoplankton have been reported, zooplankton distributions and the fate of enhanced primary production in the plume are largely unknown. I investigated mesozooplankton (>200 μm) composition and grazing in the Amazon River plume-influenced WTNA in spring (May-June 2010) and fall (Sept.-Oct. 2011). Changes in zooplankton distribution and grazing occurred over the sea surface salinity (SSS) gradient from low salinity and mesohaline plume waters to high salinity oceanic waters. Distinct communities were identified in each season along the salinity gradient with several taxa primarily constrained in the surface plume waters (e.g., Lucifer faxoni). The plume appears to function as an “extended estuary”, with a number of taxa (e.g., decapods, euphausiids, and fish larvae) utilizing the plume as a nursery habitat or dispersal mechanism for larval stages. Mesozooplankton grazing was elevated in plume waters compared to oceanic waters and was 2-3 times higher in the fall vs. spring. These patterns suggest a lag in the peak mesozooplankton abundance and grazing in response the observed spring DDA bloom, at least in low salinity plume waters. Comparison of micro- and mesozooplankton grazing along the SSS gradient supported a transition from an “export” food web in waters with SSS < 33 where mesozooplankton grazing dominated and potential for export via fecal pellet production is higher, to a “retention” food web at SSS above 33 where microzooplankton grazing was highest and recycling of nutrients in surface waters is predicted. Using molecular techniques to investigate feeding on DDAs and other N- fixers, I found that copepods consumed DDAs (Hemialus-Richelia and Rhizosolenia- Richelia, diatom-diazotroph respectively) as well as the colonial cyanobacterium Trichodesmium. Investigation of mesozooplankton grazing more broadly on other cyanobacteria with 16S rRNA sequencing revealed consumption of Synechococcus, Prochlorococcus, and the unicellular diazotroph UCYN-A Candidatus Atelocyanobacterium thalassa. Together, these results have important implications for our understanding of biogeochemical cycling in the WTNA, and other regions with abundant DDAs (e.g., the Mekong and Congo River plumes).
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Amir, Omar A. "Biology, ecology and anthropogenic threats of Indo-Pacific bottlenose dolphins in east Africa." Doctoral thesis, Stockholm : Department of zoology, Stockholm university, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-34472.
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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: In progress. Paper 5: Submitted.
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LEFEVRE, MIREILLE. "Variations spatio-temporelles du peuplement zooplanctonique du lagon de l'ile de moorea (archipel de la societe, polynesie francaise)." Paris 6, 1986. http://www.theses.fr/1986PA066327.
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Apres une 1ere partie decrivant le milieu etudie, l'auteur definit les principales especes holoplanctoniques rencontrees puis met en evidence les variations dans la repartition spatiale des especes, notamment les copepodes qui constituent le taxon la plus abondant, et les variations d'abondance de la biomasse planctonique au cours de cycles mensuels et nycthemeraux
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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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Ferrero, Richard C. "Life history and multivariate analyses of habitat selection patterns among small cetaceans in the central North Pacific Ocean /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5475.
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Kyryliuk, Dmytro. "Total suspended matter derived from MERIS data as an indicator of coastal processes in the Baltic Sea." Thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137165.
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Davidson, Fiona. "Predicting Glass Sponge (Porifera, Hexactinellida) Distributions in the North Pacific Ocean and Spatially Quantifying Model Uncertainty." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40028.
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Predictions of species’ ranges from distribution modeling are often used to inform marine management and conservation efforts, but few studies justify the model selected or quantify the uncertainty of the model predictions in a spatial manner. This thesis employs a multi-model, multi-area SDM analysis to develop a higher certainty in the predictions where similarities exist across models and areas. Partial dependence plots and variable importance rankings were shown to be useful in producing further certainty in the results. The modeling indicated that glass sponges (Hexactinellida) are most likely to exist within the North Pacific Ocean where alkalinity is greater than 2.2 μmol l-1 and dissolved oxygen is lower than 2 ml l-1. Silicate was also found to be an important environmental predictor. All areas, except Hecate Strait, indicated that high glass sponge probability of presence coincided with silicate values of 150 μmol l-1 and over, although lower values in Hecate Strait confirmed that sponges can exist in areas with silicate values of as low as 40 μmol l-1. Three methods of showing spatial uncertainty of model predictions were presented: the standard error (SE) of a binomial GLM, the standard deviation of predictions made from 200 bootstrapped GLM models, and the standard deviation of eight commonly used SDM algorithms. Certain areas with few input data points or extreme ranges of predictor variables were highlighted by these methods as having high uncertainty. Such areas should be treated cautiously regardless of the overall accuracy of the model as indicated by accuracy metrics (AUC, TSS), and such areas could be targeted for future data collection. The uncertainty metrics produced by the multi-model SE varied from the GLM SE and the bootstrapped GLM. The uncertainty was lowest where models predicted low probability of presence and highest where the models predicted high probability of presence and these predictions differed slightly, indicating high confidence in where the models predicted the sponges would not exist.
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Bertsos, Maxwell John. "Spatial Variation in Tooth Shape of Miocene Populations of Carcharocles Megalodon Across Ocean Basins." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1481898781240992.
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Gregori, Casamayor Maria Dolors. "Symbionts in Mesozooplankton Communities from NE Atlantic Ocean: Ecology and Recruitment of Parasites to the Marine Trophic Web." Doctoral thesis, Universidad de Alicante, 2014. http://hdl.handle.net/10045/41642.
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Sörman, Laurien Elvira. "Patching up the garbage patch: a drop in the ocean? : A comparative study examining low levels of effective multinational cooperation on plasticpollution in the Pacific Ocean." Thesis, Uppsala universitet, Statsvetenskapliga institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295972.
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Lindh, Markus V. "Bacterioplankton population dynamics in a changing ocean." Doctoral thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-38712.
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Bacterioplankton is characterized by high diversity, short generation times and rapid turnover. Despite their small size, these numerous microorganisms are a fundamental piece of aquatic ecosystems by channeling carbon to higher trophic levels through dissolved organic matter utilization. Yet, several gaps remain in our knowledge and understanding of bacterioplankton populations regarding detailed temporal dynamics, and mechanisms determining biogeographical patterns and potential responses to climate change. The aim of this thesis was to examine responses in bacterioplankton community composition and function when challenged by natural and anthropogenically-induced change in environmental conditions. High temporal resolution analysis of bacterioplankton population dynamics in the Baltic Sea indicated detailed seasonal responses. It also showed a similar but wide spectrum of niche differentiation patterns within several major bacterial groups. Analysis of geographic distributions of marine bacterial populations revealed bimodal occupancy-frequency patterns in bacterial communities, indicating that the presence of many locally rare taxa along with a few locally abundant taxa were explained by stochastic variation in colonization and extinction rates. Experimental manipulations with natural marine bacterioplankton assemblages revealed both specialist and generalist strategies in utilizing specific dissolved organic carbon compounds. When subjected to experimentally increased sea surface temperatures, lowered pH and additions of terrigenous carbon, some populations decreased in relative abundance while others were stable; concomitantly, many populations increased in relative abundance. Shifts in bacterial community composition were shown to correlate with changes in community functioning, but detection of such correlations depended largely on the detail of phylogenetic analysis and successional stage of the communities. The results in this thesis suggest that both natural and anthropogenically-induced changes in environmental conditions promote simultaneous adjustment and replacement of bacterial populations tightly linked with metabolic plasticity. These trade-offs play a significant role for understanding the relationship between bacterioplankton population dynamics and potential shifts in carbon cycling properties. We also show the importance of regional effects in shaping bacterial community composition, crucial for interpreting bacterioplankton distribution patterns. In conclusion, this thesis emphasizes the critical importance of connecting analysis of bacterioplankton population dynamics with examination of ecological mechanisms to improve our understanding of factors that regulate the distribution and activity of distinct bacterioplankton populations.Hälften av all fotosyntes på vår planet utförs av växtplankton. De producerar organiskt material som utgör grunden för näringskedjan i havet. Ungefär hälften av det organiska material som produceras av växtplankton utnyttjas inte direkt, utan omsätts istället av bakterieplankton som lever och växer fritt i vattenmassan eller på olika partiklar. Bakterieplankton spelar därmed en nyckelroll i ekosystemet genom sin konsumtion av organiskt kol som för energi högre upp i näringskedjan. Trots deras nyckelroll i akvatiska miljöer vet vi fortfarande mycket lite om bakteriernas detaljerade säsongsmönster, mekanismer bakom rumsliga mönster och hur olika populationer kan komma att svara på klimatförändringar. Målet med denna avhandling var att undersöka hur specifika populationers dynamik och ekosystemfunktion påverkas av naturliga eller klimatorsakade förändringar i havsmiljön. Våra resultat av högupplöst säsongsbunden dynamik i Östersjöns bakteriesamhälle avslöjar en liknande bred uppdelning av ekologiska strategier inom varje större grupp av bakterier, både i relativ abundans och temporal fördelning. Utbredning i rum och tid av många lokalt ovanliga populationer jämfört med få lokalt vanliga populationer förklarades genom stokastisk variation i kolonisations- och utdöendehastigheter. Vidare tyder experimentella studier med tillsatser av olika kolkällor på att marina bakterier har olika ekologiska strategier, där populationer är specialister eller generalister i utnyttjandet av enskilda kolkällor. Med hjälp av experiment med naturliga bakteriesamhällen bekräftade vi tydliga temperatureffekter på bakteriesamhällets sammansättning, och en mindre effekt av lägre pH - som dock tillsammans med förhöjd temperatur bidrog till en tydlig synergistisk effekt på artsammansättningen. Ökad temperatur tillsammans med tillsats av terrestert kol gav också en stor effekt på bakteriesamhällets struktur och ekosystemfunktion och pekar på en potentiellt viktig påverkan av ökad framtida nederbörd och avrinning från vattendrag till havet. Samtliga tre experiment med fokus på klimatpåverkan bekräftade förekomsten av populationer som försvann eller minskade i relativ abundans vid klimatpåverkan (känslighet), medan andra var stabila (resistens). Samtidigt svarade många populationer positivt på klimatorsakade förändringar i havsmiljön och ökade i relativ abundans (respons) samtidigt som bakteriernas ekosystemfunktion påverkades positivt. Sammanfattningsvis visar denna avhandling att vissa nya bakteriepopulationer kan etablera sig och ersätta andra samtidigt som vissa befintliga populationer anpassar sin livsstrategi och ekologi till förändringar i havsmiljön. Vi visar också vikten av regionala effekter, d.v.s. kolonisation och utdöende, för bakteriesamhällets struktur, viktigt för tolkningen av biogeografiska mönster och den genomiska potentialen hos specifika populationer. Denna avhandling poängterar därmed betydelsen av att koppla studier av ekologiska mekanismer till både rumsliga och temporala spridningsmönster hos bakterier och till populationers kapacitet att svara på och anpassa sig till förändringar i havsmiljön.
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Lail, Erin M. "Biogeochemical cycling of domoic acid and its isomers in the ocean /." Electronic version (PDF), 2006. http://dl.uncw.edu/etd/2006/laile/erinlail.pdf.
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Titjen, Jeremy Quentin. "Tertiary limestones and sedimentary dykes on Chatham Islands, southwest Pacific Ocean, New Zealand." The University of Waikato, 2007. http://hdl.handle.net/10289/2411.
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The Chatham Islands are located in the SW Pacific Ocean, approximately 850 km to the east of the South Island of New Zealand. This small group of islands is situated near the eastern margin of the Chatham Rise, an elongated section of submerged continental crust that represents part of the Late Paleozoic-Mesozoic Gondwana accretionary margin. The location and much of the geology of the Chatham Islands are attributed to intra-plate basaltic volcanism, initiated during the Late Cretaceous, in association with development of a failed rifting system to the south of the Chatham Rise. Despite the volcanic nature of much of the geology, the majority of the Cenozoic sedimentary stratigraphic record on the islands comprises non-tropical skeletal carbonate deposits whose deposition was often coeval with submarine volcanics and volcaniclastic deposits. This has resulted in complex stratigraphic relationships, with the volcanic geology exerting a strong influence on the geometry and distribution of the carbonate deposits. These limestones, despite some general field descriptions, have been little studied and are especially poorly understood from a petrographic and diagenetic perspective. The carbonate geology in detail comprises eleven discrete limestone units of Late Cretaceous through to Pleistocene age which were studied during two consecutive field expeditions over the summers of 2005 and 2006. These limestone occurrences are best exposed in scattered coastal outcrops where they form prominent rugged bluffs. While many of the younger (Oligocene to Pliocene) outcrops comprise of poorly exposed, thin and eroded limestone remnants (it;5 m thick), older (Late Paleocene to Early Oligocene) exposures can be up to 100 m in thickness. The character of these limestones is highly variable. In outcrop they display a broad range of textures and skeletal compositions, often exhibit cross-bedding, display differing degrees of porosity occlusion by cementation, and may include rare silicified horizons and evidence of hardground formation. Petrographically the limestones are skeletal grainstones and packstones with a typical compositional makeup of about 70% skeletal material, 10% siliciclasts, and 20% cement/matrix. Localised increases in siliciclastics occur where the carbonates are diluted by locally-derived volcaniclastics. The spectrum of skeletal assemblages identified within the Chatham Island limestones is diverse and appears in many cases to be comparable to the bryozoan dominant types common in mainland New Zealand and mid-latitude Australian cool-water carbonates in general. However, some key departures from the expected cool-water carbonate skeletal makeup have been identified in this study. The occurrence of stromatolitic algal mats in Late Cretaceous and Early Eocene carbonate deposits indicates not cool-temperate, but certainly warm-temperate paleoclimatic conditions. A change to cool-temperate conditions is recorded in the limestone flora/fauna from the mid-Late Miocene times following the development and later northward movement of the Subtropical Front. An uncharacteristic mix of shallow-shelf (bryozoans) and deeper water fauna (planktic foraminifera), together with their highly fragmented and abraded nature, is indicative of the likely remobilisation and redistribution of carbonate, primarily during episodic storm events. The Chatham Islands limestones formed within the relative tectonic stability of an oceanic island setting, which was conducive to ongoing carbonate accumulation throughout much of the Cenozoic. This contrasts markedly with other mainland New Zealand shelf carbonates which formed over sporadic and short-lived geological periods, experiencing greater degrees of burial cementation controlled by a relatively more active tectonic setting. As a consequence of the tectonically stable setting, the Chatham Islands limestones have experienced little burial and exhibit a paucity of burial cementation effects. They remain commonly soft and friable. Detailed petrographic investigations have shown the limestones are variably cemented by rare uneven acicular spar fringes, poorly to well-developed syntaxial rim cements about echinoderm fragments, and equant/blocky microsparite. Staining of thin sections and cathodoluminescence petrography show these spar cement generations are non-ferroan and their very dull- to non-luminescent nature supports precipitation from Mn-poor oxygenated waters, likely of an either meteoric or combined marine/shallow burial origin. Micrite is the dominant intra- and inter-particle pore fill and occurs both as a microbioclastic matrix and as precipitated homogenous and/or micropeloidal cement. The rare fringing cements often seen in association with homogenous and/or micropeloidal micrite may be indicative of true early marine (seafloor) cement precipitation and localised hardground development. An interesting feature of the geology of the Chatham Islands is the occurrence of carbonate material within sedimentary dykes. The locations of the dykes are in association with volcanic and volcaniclastic deposits. Similarities between dyke characteristics at Red Bluff on Chatham Island with mainland occurrences from East Coast and Canterbury Basins (North and South Islands, respectively) on mainland New Zealand have been recognised. They show complex structures including sidewall striations, internal flow structures as revealed by grain sorting, and extra-clast inclusions of previous fill lithologies which are characteristic of carbonate injection. This is in contrast to other dykes which are known to be of a passive fill origin. Multiple phases of carbonate sediment injection can be recognised by crosscutting relationships enabling the determination of a parasequence of events. Possible injection mechanisms are most likely associated with sediment overloading or hydrothermal pressurisation associated with emplacement of submarine volcanics. The Chatham Islands provide an exciting example of a geologically unique and complex non-tropical carbonate depositional setting. The production of carbonates is controlled by volcanic and volcaniclastic sediment input with the types of carbonate deposits and water depth variations related to thermal uplift/subsidence in association with global eustatic sealevel and temperature changes associated with development of Southern Ocean water fronts from the Late Cretaceous-Cenozoic. Carbonate deposition on the Chatham Islands is considered to relate to a rather variable and small scale oceanic, high energy, cool-water carbonate ramp setting whose geometry was continually evolving/changing as a consequence of periodic volcanic episodes.
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Appadoo, Chandani. "Some aspects of the biogeography and ecology of intertidal and shallow subtidal marine gammaridean amphipods of Mauritius (Indian Ocean)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0001/MQ34159.pdf.
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Helber, Robert William 1967. "Upper ocean upwelling, temperature, and zonal momentum analyses in the western equatorail [sic] Pacific [electronic resource] / by Robert William Helber." University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000073.
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Includes vita.Title from PDF of title page.
Document formatted into pages; contains 119 pages.
Thesis (Ph.D.)--University of South Florida, 2003.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
ABSTRACT: The air-sea interaction thermodynamics of the western equatorial Pacific, the Earth's largest region of warm SST, is a major component of the global climate system. Along the equator, warm pool thermodynamics and momentum are influenced by equatorial ocean visco-inertial boundary layer dynamics that occur within a few degrees of the equator because of the sign reversal of the Coriolis force. Designed to study this system, COARE Enhanced Monitoring Array (EMA) observations of temperature, salinity, velocity, and surface meteorology were centered at 0, 156°E from February 1992 through April 1994. They sampled variability on the equator over larger space/time-scales than the concurrent Intensive Flux Array (IFA) centered at 2°S, 156°E. The EMA data are examined within the context of the larger scale equatorial Pacific and the El Niño conditions that occurred at that time.
ABSTRACT: There is a structural change in the equatorial Pacific near the dateline resulting from the winds that are strong, steady, and easterly in the east and generally weak, punctuated by westerly wind bursts, in the west. East of the dateline the EUC's speed and transport increases downstream, while in the west it tends to be zonally uniform, consistent with the extra-tropical ocean interior water pathways that tend to converge on the equator east of the dateline. At 0°, 156°E in the western Pacific deep, seasonal upwelling (appearing stronger after the peak of the 1991/92 El Niño than during the following weaker El Niño year) occurs within the thermocline in boreal summer with magnitudes as large as upwelling in the eastern Pacific cold tongue. This large upwelling is associated with large downward turbulent heat flux and large turbulent shear stress.
ABSTRACT: While the inferred mixing is quantitatively inconclusive because of unresolved potential errors, it is consistent with the visco-inertial boundary layer concepts from early theory [e.g. Arthur 1960; Robinson 1960; Stommel 1960; and Charney and Spiegel 1971]. These findings suggest that the equatorial thermodynamics differ from those of the IFA. Further process experimentation is necessary to quantify these results.
System requirements: World Wide Web browser and PDF reader.
Mode of access: World Wide Web.
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Ho, Chun Ming. "Interactive effects of hypoxia and ocean acidification on biofilms and the subsequent effects on the larval settlement of the marine invertebrate Crepdiula onyx." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/498.
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Hypoxia and ocean acidification (OA) are amongst the major environmental threats to marine ecosystems worldwide. Biofilms, the signpost to guide larval settlement of many benthic invertebrates, are known to be responsive to environmental changes and thus can become the crucial factor for the response of benthic invertebrate communities. This study aimed at investigating the individual and interactive effects of hypoxia and OA on biofilms and the subsequent effects on larval settlement. Biofilms collected from two sites (clean, hypoxic) were treated with a factorial design of low dissolved oxygen and/or low pH conditions in microcosms and the bacterial cell density and viability (by LIVE/DEAD® cell viability assays) were analyzed. Larval settlement preference was tested with the marine invertebrate, Crepidula onyx. The total bacterial cell densities of biofilms of the hypoxia and hypoxia and OA combination treatment were lower than that of the control biofilms for both sites. There was generally no significant difference in cell viability among control and different treatments for both sites. While the larval settlement rate on hypoxia and hypoxia and OA combination treated biofilms was significantly lower. In conclusion, this study revealed that hypoxia and OA are likely to affect larval settlement by alteration of biofilms, and this may lead to alterations in future coastal communities.
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Blaj, Teodora. "Late Eocene through Oligocene calcareous nannofossils from the paleo-equatorial Pacific Ocean – taxonomy, preservation history, biochronology and evolution." Doctoral thesis, Stockholm : Department of geology and geochemistry, Stockholm university, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27600.
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