Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. / Includes bibliographical references (leaves 107-114). Also available on microfiche.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 125-127). / Microfiche. / xii, 151 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 244-258). / Microfiche. / 258 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 196-205).

>Magister Scientiae - MSc / Seamounts are poorly understood ubiquitous undersea features, with less than 4% sampled for scientific purposes globally. Consequently, the fauna associated with seamounts in the Indian Ocean remains largely unknown, with less than 300 species recorded. One such feature within this region is Walters Shoal, a shallow seamount located on the South Madagascar Ridge, which is situated approximately 400 nautical miles south of Madagascar and 600 nautical miles east of South Africa. Even though it penetrates the euphotic zone (summit is 15 m below the sea surface) and is protected by the Southern Indian Ocean Deep-Sea Fishers Association, there is a paucity of biodiversity and oceanographic data. Thus, a multidisciplinary cruise was initiated in May 2014 on the FRS Algoa as a component of the African Coelacanth Ecosystem Programme. The research presented here focuses exclusively on the diversity, bathymetric distribution patterns and biogeographic affiliations of the sponge fauna of this seamount. Sponges were sampled using SCUBA and a roughed epibenthic sled, from the peak and down two opposing slopes of the seamount, to a depth of 500 m. Two hundred and fifty-five sponge specimens were collected, comprising 78 operational taxonomic units (OTU’s), 23 of which are known to science, 26 which are possibly new, 16 that could only be identified to higher taxonomic levels and 13 that could only be designated as morphospecies. Thirteen OTU’s are formally described here, four which are known, and nine possibly new to science. Sponge assemblages demonstrated no significant difference according to location on the shoal, with several species shared by both the western and eastern flanks. In contrast, sponge assemblages differed significantly according to depth, with the mesophotic zone (31 – 150 m) acting as a transition between the shallow (15 – 30 m) and submesophotic (> 150 m) zones. Species richness and the number of putative new species was highest in the submesophotic zone. Biogeographical affiliations were found with both the Western Indo-Pacific and Temperate Southern African realms based on the 23 known species recorded. No affiliations were found with the West Wind Drift Island Province, as has been documented previously for the fish fauna of this seamount, possibly due to the incomplete nature of the online database (World Porifera Database) used to assess affinities. Thirty-nine percent of the known sponge species found at Walters Shoal Seamount are widely distributed in the Indian Ocean, 35% are found exclusively within the Western Indian Ocean region, with this study representing the southernmost distribution record for several of these, and 26% have a restricted distribution around South Africa. / National Research Foundation (NRF)

The Dellwood Seamount Area, an area of approximately 10,000 square km., about 185 km. west of the northern tip of Vancouver Island is located at or near the northernmost end of the Juan de Fuca plate. The main purpose of the study was to test the hypothesis that the Dellwood Knolls mark the site of a short spreading segment connected to the Explorer Spreading Segment at one end by a transform fault trending along the southwestern slope of Paul Revere Ridge; and meeting the Queen Charlotte right lateral transform fault at the other end. An analysis of more than 950 km. of continuous seismic reflection profiles, in conjunction with other geophysical data, shows that (i) the Revere -Dellwood fault zone is a dextral transform fault zone connecting the Explorer and Dellwood spreading segments. (ii) The Queen Charlotte transform fault dies out at the southeastern end of the Scott Channel near the northeastern end of the Dellwood Spreading Segment. (iii) In the channel between the Dellwood Knolls (one of two possible locations of the Dellwood Spreading Segment), the sediments and volcanic basement are cut by normal faults, a feature which is characteristic of spreading centres with median valleys. The heat flow in this channel and in the Revere - Dellwood fault zone is high. (iv) The lower continental slope sediments west of Queen Charlotte Sound is faulted and crumpled and may be the northerly extension of the Scott Islands fault, zone and a site of slow contemporaneous or recently ceased subduction. The deformation of the thick turbidite sequence in the Winona Basin may also be due to subduction. Basalt from the area is chemically intermediate between tholeiitic and alkalic types. That from the Northwest Dellwood Knolls, however, is least differentiated and less than 1 myr. old in contrast to basalt from the sediment-draped Southeast Dellwood Knolls, the latter basalt having Mn-coating up to 50 mm. thick and is thus relatively old. This suggests that spreading may be occurring at the Northwest Dellwood Knolls and not in the channel between the knolls. The texture of basalts from the Dellwood Seamount Range vary depending on size of pillow and depth below pillow surface, but the mineralogy is essentially similar. An unusual rock probably best described as a plagio-clase-olivine basalt porphyry was also recovered from the Dellwood Seamount Range. Non-volcanic rocks recovered include glacial erratics, an authigenic sandstone comprising glacial fragments in an iron-rich cement, a laminated limonitic sediment and manganese nodules. The Dellwood Spreading Segment may have originated by left lateral transcurrent offset from the Explorer Spreading Segment, the offset caused by a change in the direction of motion of the Juan de Fuca plate. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Using the oceanographic ship, the Endeavor; the University of British Columbia undertook a study of Bowie Seamount (53°18', 135°41') during the summer of 1968. Receiving a proton precession magnetometer for the cruise from PNL, a magnetic field survey was included in the study. The magnitude of the observed anomaly was about 850 gammas. The regional was determined by data taken in an airborne magnetic survey done in 1958 by the Dominion Observatory. Corresponding to the topography, the contour plot of the magnetic field showed a strong linear trend from the SW to the NE. In addition, despite fairly symmetrical bathymetry, the observed anomaly is decidedly unsymmetrical, implying a non-uniform intensity of magnetization. This seems to be confirmed by the use of a three dimensional, model - assuming uniform magnetization - developed by Manik Talwani. Using the least squares best fit intensity of magnetization, a large discrepancy was found between the model and the observed anomaly. In light of the fact that the earth's magnetic field has reversed directions many times in its history, the above discrepancy may well be due to the fact that the lava flows of the seamount span at least one time boundary separating a normal and a reversed magnetic period. This is given some credence in that an age determination was made on one sample yielding an age of about 100,000 years, a normal period in the earth's magnetic history. This together with the fact that the magnetic anomaly over most of the seamount is negative yields the above conclusion. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Bear Seamount (39° 55’ N; 67° 30’ W) is the westernmost peak of extinct undersea volcanoes in the New England Seamount Chain (Moore et al., 2003). It is located on the continental slope off Georges Bank, and is governed by unique environmental factors and currents that may be unlike those of the other seamounts (Moore et al., 2003). Previous cruises to this seamount have been successful in capturing abundant fishes, cephalopods and invertebrates (Moore et al., 2003; Moore et al., 2004; Moore et al., 2008), but only the distribution patterns of the fishes and cephalopods have been examined, leaving a lack of information on the deep-sea crustaceans. The diversity, catch per unit effort (CPUE) and biogeography of trawl-vulnerable micronekton in the vicinity of Bear Seamount were investigated, with primary focus on baseline data collection. Sixty-six species of pelagic Crustacea (Decapoda, Lophogastrida, and Euphausiacea) were collected at 35 trawl stations in the spring of 2003 and 2004 and fall of 2014 with the International Young Gadoid Pelagic Trawl (IYGPT) and a Polytron Midwater Rope Trawl (PMRT). Depths sampled ranged from the surface to 1700 m, with most trawls sampling primarily below 1000 m. When comparing relative biogeography of the nekton in IYGPT samples, the assemblage on the south side of the seamount was the most diverse, while the summit assemblage was the most abundant and species rich. In the PMRT samples, the summit assemblage was the most diverse and species rich while the assemblage on the west side had the greatest abundance. Overall CPUE was dominated by cold temperate species, typical of mid- to higher latitudes in the North Atlantic. Eusergestes arcticus and Meganyctiphanes norvegica were particularly dominant in both the IYGPT and PMRT samples. At least two species were new records for Northwest Atlantic waters and may have traveled by means of currents and/or from nearby seamounts.

Ultra-slow spreading ridges have a full spreading rate of less than 20 mm/yr, and show deviations from the fundamental characteristics identified at faster spreading rates; however, they are poorly studied compared to faster spreading ridges. In this thesis we aim to build on previous studies in order to further characterise the unique processes occurring at the ultra-slow spreading Southwest Indian ridge (SWIR). This is an exploratory study utilising novel and existing bathymetry, gravity, video imagery data to understand tectonic and volcanic processes along the ridge crest from triple junction to triple junction. We conduct a series of studies which focus on the axial valley morphology, large seamount morphology, the distribution of small seamounts and large seamounts on the ridge, and admittance studies. We show that the long wavelength trends in geophysical data, geochemical data, and axial valley morphology are well correlated. These variations reflect along-axis changes in the crustal and mantle structure, governed by the thermal structure of the ridge. Seamounts provide important morphological evidence of the volcanic and tectonic processes beneath the Earth's surface. We use detailed morphological investigations to show that volcanic and erosional processes on six large seamounts are controlled by the local faulting and melt migration mechanisms. We investigate the distribution of seamounts on the ridge using a numerical algorithm, and demonstrate a lower seamount density than faster spreading ridges. We show that the seamount population statistics vary along the ridge due to changes in the degree of partial melting, magma conduit availability, and melt focussing mechanisms; the locations of three proximal hotspots coincide with increases in the estimated magmatic flux. Finally, best fit elastic thicknesses are determined using a 3D windowed admittance technique, which was tested using synthetic data. We construct a combined convection-flexure model to account for misfits between the observed data and existing flexural theoretical models. The average elastic thickness varies between 7 km and 12 km, and we show a strong dependence on spreading rate.

A taxonomic revision of 29 species distributed in 12 vetigastropod families collected in a 60-260 m depth range at Canopus Bank, a seamount off NE Brazil, is performed based on detailed shell morphology. Their distribution and bathymetric ranges are re-examined based on specimens from Canopus and the MZSP collection. Three possibly new species are revealed and tentatively described: Arene aff. brareus can be distinguished by a large shell for the genus; sculpture consisting of spiral cords ornamented by large, semi-hollow, scale-like spines; cords separated by equally wide, deep interspaces and thin axial growth lines more visible in the interspaces; protoconch sculptured by small, subsutural axial lamellae; and color ranging from white to intense reddish, darker on spiral cords, and lighter at the base, with a yellow apex. Parviturbo aff. tuberculosus can be told apart from local congeners by its slightly taller than wide shell, which is profusely sculptured by a reticulate pattern of equally strong axial ribs and spiral cords, with angular nodules at the intersections. Calliostoma sp.1 shows no close affinities with any other local congener and is characterized by a small shells with convex whorls and a large, rounded apex; ivory white ground color with honey yellow apex and spiral cords; sculpture consisting of 4-6 narrow, nodulous spiral cords per whorl; suture marked by a suprasutural cord; inflated and mostly smooth base; narrow, shallow, and axially sculptured umbilicus. Moreover, three species have their distributions expanded northward from SE to NE Brazilian waters: Emarginula suspira Simone & Cunha, 2014, Hemimarginula hemitoma Simone & Cunha, 2014, and Homalopoma boffi Marini, 1975. Three species have their northern range limit expanded from Bahia state to Ceará state: Arene flexispina Leal & Coelho, 1985 and Turbo heisei Prado, 1999; a single NE Brazilian species is newly reported from northern waters: Haplocochlias risoneideneryae Barros, Santos, Santos, Cabral & Acioli, 2002; and another species, previously known only from Pernambuco state, is newly reported from Ceará state, also in NE Brazil: Solariella quinni Barros & Pereira, 2008. Two Caribbean species are firstly reported in the SW Atlantic: Dentistyla dentifera (Dall, 1889) and Gaza cf. fischeri (Dall, 1889); and a species previously reported from the Venezuelan shelf is firstly recorded in Brazilian waters: Parviturbo annejoffeae Rubio, Rolán & Lee, 2015. The bathymetric ranges of 11 species are expanded. High-resolution photographs of the type specimens, SEM images, and comparisons with local congeners are also provided / Uma revisão taxonômica de 29 espécies distribuídas em 12 famílias de vetigastrópodes coletadas a 60-260 m de profundidade no Banco de Canopus, uma montanha submarina do Nordeste do Brasil, é fornecida com base na morfologia detalhada da concha. Sua distribuição e intervalos batimétricos são reexaminados com base em espécimes de Canopus e da coleção do MZSP. Três espécies possivelmente novas são reveladas e tentativamente descritas: Arene aff. briareus pode ser distinguido por uma concha grande para o gênero; escultura constituída por cordas espirais ornamentadas por espinhos grandes, semi-ocos e escalares; cordas separadas por intervalos igualmente amplos e profundos e linhas de crescimento axiais finas mais visíveis nos inter-espaços; protoconcha esculturada por pequenas lamelas axiais subsuturais; e cor variando de branco a avermelhado intenso, mais escura nas costelas espirais, e mais clara na base, com um ápice amarelo. Parviturbo aff. tuberculosus pode ser distinguida dos congéneres locais pela sua concha mais alta do que larga, profusamente esculturada por um padrão reticulado de costelas axiais igualmente fortes e cordas espirais, com nódulos angulares nas intersecções. Calliostoma sp.1 não apresenta estreitas afinidades com qualquer outro congênere local e é caracterizado por uma concha pequena com voltas convexas e um grande ápice arredondado; cor branco-marfim com ápice e cordas espirais amarelo mel; escultura de 4-6 cordas espirais estreitas e nodulosas por volta; sutura marcada por um cordão suprasutural; base inflada e lisa; umbílico estreito, raso e axialmente esculturado. Três espécies têm suas distribuições expandidas para o norte, de águas do SE para o NE do Brasil: Emarginula suspira Simone & Cunha, 2014, Hemimarginula hemitoma Simone & Cunha, 2014, e Homalopoma boffi Marini, 1975. Três espécies têm seu limite de extensão norte expandido da Bahia para o Ceará: Arene flexispina Leal & Coelho, 1985 e Turbo heisei Prado, 1999; Uma única espécie brasileira do NE é relatada para águas do Norte: Haplocochlias risoneideneryae Barros, Santos, Santos, Cabral & Acioli, 2002; E uma outra espécie, anteriormente conhecida apenas do estado de Pernambuco, é reportada para o estado do Ceará: Solariella quinni Barros & Pereira, 2008. Duas espécies caribenhas são registradas pela primeira vez no Atlântico sudoeste: Dentistyla dentifera (Dall, 1889) e Gaza cf. fischeri (Dall, 1889); e uma espécie reportada previamente para a plataforma venezuelana é registrada pela primeira vez no Brasil: Parviturbo annejoffeae Rubio, Rolán & Lee, 2015. As distribuições batimétricas de 11 espécies são expandidas. Fotografias dos espécimes tipo, imagens MEV e comparações com congêneres locais são fornecidas