The deep sea. for a long time. had been perceived as a homogenous and stable environment, with little diversity. The discovery of island habitats such as hot vents. cold seeps and whale carcasses revealed the presence of high biomasses in the deep sea. Species richness on island habitats is low however, compared to the species richness on abyssal plains (Tunnicliffe 1991: Stecher et al. 2003). A study addressing species richness on abyssal plains concludes there to be tens of millions of new species (Grassle and Maciolek 1992). Other authors dispute these numbers and suggest a total deep-sea species richness of approximately half a million (May 1993). The discrepancy in these numbers by multiple orders of magnitude emphasize how under-sampled the deep sea is. The Northeast Pacific is recognized as a biogeographic species province both in the intertidal. shallow subtidal (Valentine 1966: Roy et al. 1994) as well as in hydrothermally active areas (Van Dover et al. 2002). The Northeast Pacific hydrothermally active areas are unique in that they appear to foster single dominant species within ecosystems: e.g. Ridgeia piscesae (Vestimentifera. Annelida) (Southward et al. 1995): Lepetodrilus fucensis (Gastropoda, Mollusca) (McLean 1993). Xylophaga washingiona BARTSCH (Bivalvia. Mollusca) is the only described species of deep-sea wood-boring clams in the Northeast Pacific (Bartsch 1921). We investigated the species richness of deep-sea wood-boring clams (Family Pholadidae. Subfamily Xylophagainae) in the Northeast Pacific by means of strategically placed, experimental wood blocks. The objective of the study was to a) assess the morphological diversity and separate the specimens into distinct morphological taxa: b) to use genetic markers (CO 1. 18S) to discern the genetic diversity within the morphological taxa and c) to elucidate the phylogenetic relationships among the new species. We discovered eight morphological taxa (B. F. G. M. R, T. U. X), defined by a set of characters. previously used to describe new pholad species. The most distinguishing characters were the morphologies of the siphon and mesoplax (accessory plates). The CO1 gene sequences showed little diversity within the morphological Taxa B. F, G. U and X. The 18S gene data split Taxa B and T into B1. B2 and T1, T2, respectively. There was no genetic diversity within 18S sequences of Taxon R. Thus. we discovered at least six new species: Xylophaga species B1. F. G, R. U and Xylopholas species X. I cannot confirm the statuses of Taxa M and T due to missing morphological characters as well as the unavailability of their CO1 sequences. The newly discovered species increase the number of deep-sea, wood-boring species from one to seven, in the Northeast Pacific. Globally, a total of 41 species have been described. Given the discoveries in this study, this number is likely an underestimate of the global species richness of the Xylophagainae. The phylogenetic relationships of the genus leveI remain inconclusive due to too few samples. Species relationships emerged. placing Species G and R as most closely related. as well as B1 and X washingtona. Additional samples from all ocean basins are necessary to further investigate the relationships and origins of the deep-sea woodborers. Future avenues that need to be explored are threefold: a) Ancestry: Has there been one or multiple invasions into the Northeast Pacific, with subsequent adaptive radiations? Where do this/these ancestor species come from? b) Support for Diversity: What mechanisms allow the deep-sea wood-boring clams to co-occur? What are the deep-sea wood-boring clams' micro-niches? c) Effects of Diversity : What is the role of the wood-boring clams in species communities inhabiting deep-sea wood?

Estimating the efficiency with which energy is transferred to higher trophic levels demands estimates of adult and juvenile copepod biomass production rates. Adult rates (egg production) are well studied; however. our knowledge of how juvenile biomass production rates (BPR) vary in situ remains incomplete and has been limited by difficulties associated with measuring somatic growth rate in the field. This problem may be resolved with the application of new methods that either: a) directly estimate BPR without additional estimates of growth or biomass, and/or: h) improve estimates of development and growth rate that may then be applied to estimates of biomass. The objective of this thesis is to develop a routinely applicable method that may be used to gain greater insight into how production of juvenile copepods is regulated in the field. I have developed a field method for estimating BPR, development and growth of marine copepods that is based on measuring the in situ rate of decay of the crustacean moulting enzyme, chitobiase. The method may be generalized to the community level because the relationship between chitobiase activity liberated into seawater after moult and individual body size was found to be common to three calanoid and one harpacticoid copepod species. This relationship. and the rate of decay of chitobiase in the water column, can be used to estimate the community-level BPR and size-class specific stage durations. Estimates of stage duration based on the turnover rate of chitobiase in the water column were in good agreement (within 5-15%) with both conventional incubation techniques and literature-based estimates. The approach was also used to estimate community-level BPR during a two-year time series in the Straight of Georgia (2004 and 2005) and two broad-scale spatial surveys encompassing shelf, slope and open ocean regions in the subarctic NE Pacific during the spring and late summer of 2004. This thesis presents the development and field validation of a novel method of estimating rates of juvenile copepod production. development, and growth that may be used to further characterize how variation of these rates is regulated in the field. The results of field studies using this approach suggest that: (i) the chitobiase-based method can be routinely used to estimate production rates that are broadly applicable to copepod communities; (ii) even when food is abundant. poor food quality can negatively influence copepod community production rates over relatively short timescales and; (iii) contemporary predictive models of in situ copepod growth rate may not be globally applicable because the relative influence of temperature. individual body weight, and chlorophyll a concentration on in situ growth rate varies with region and copepod community composition.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (p. 182-199).

Thesis (Ph. D.)--University of Washington, 1997. / Includes bibliographical references (leaves 182-199).

The attribution of recent global warming to anthropogenic emissions is now well established. However, the relation of recent changes in other properties of the climate system to human activities is not as clearly understood. The aim of this thesis is to improve our understanding of this relation in the case of two of these properties, namely the diurnal temperature range (DTR) and modes of tropospheric variability. The DTR, the difference between daily maximum and minimum temperatures, has decreased over global land areas at a rate comparable to the mean warming. Model simulations including the effects of human emissions produce a comparable change, albeit of smaller magnitude. This decrease results from increased reflection of solar radiation by clouds moderated by decreasing soil moisture, mostly through its effect on the ground heat capacity. Recent trends in indices of some modes of atmospheric variability suggest the possibility that forced climate change may manifest itself through a projection onto these pre-existing modes. Model simulations indicate that this is plausible in the case of sea level pressure, but only partly so in the case of surface air temperature. On the interannual time scale examined in this thesis, these projections are consistent with a linear interpretation, rather than a nonlinear one. These results are, however, sensitive to the representation of small scale processes in the models. For instance, the DTR response depends strongly on the representation of cloud and land surface processes. Further examination of the response of one of the tropospheric modes, namely the Southern Annular Mode which represents the meridional shift of the mid latitude jet in the Southern Hemisphere, indicates that it is sensitive to the parametrisation of sub-grid scale mixing in the ocean. Nevertheless, these results suggest that the recent changes are consistent with enhanced greenhouse warming, and indicate that they are likely to continue into the foreseeable future. / Graduate

Subsequent to the Last Glacial Maximum (LGM), complex coastal response resulted from deglaciation, eustatic sea-level change, and a relatively thin, flexible lithosphere in the Queen Charlotte Islands (QCI) region of northwestern Canada. Presented here is an interdisciplinary study that combines the methodologies and schools of thought from geology, biology, and geography to address a research problem that spans these disciplines, specifically to illustrate the environment, temporal and spatial dimensions of isostatic crustal adjustment and the Late Quaternary coastline of the northeast Pacific continental shelf. Molluscan distribution, lithology, and published sub-bottom profiles are used to deduce sea-levels, outline the influence of glacially-induced crustal displacement, and reconstruct the paleoenvironment of the northeast Pacific Late Quaternary coastline, including the absence of ice and the presence of emergent coastal plains. These data are used to ascertain the region's suitability as a home for an early migrating coastal people. A series of paleogeographic maps and isostatic crustal displacement maps chart the sequence of evolving landscapes and display temporal changes in the magnitudes and extent of crustal flexure as a forebulge developed. The wave-length and amplitude of the glacially-induced forebulge supports thermal and refraction modeling of a thin (~25 km thick) lithosphere beneath Queen Charlotte (QC) Sound and Hecate Strait. Glacial ice at least 200 m thicker than present water depth began retreating from Dixon Entrance after 14,000 and prior to 12,640 14C years BP, generating 50 m of uplift in northern Hecate Strait. The position of the forebulge remained essentially constant after 12,750 14C years BP, implying a fixed ice-front and continued ice presence on the British Columbia (BC) mainland until ~10,000 14C years BP. A 3-dimensional model shows two ice-free terrains emerged: one extended eastward from the QCI, the other developed in QC Sound. By ~11,750 14C years BP a landbridge connected the BC mainland and QCI. Malacological evidence indicates a paucity of Arctic molluscan faima subsequent to glaciation, perhaps a consequence of shallow, narrowed straits, and the presence of ice sheets that interfered with ocean currents. Water temperature, sedimentation rates, turbidity, and photoperiod are factors that limited invertebrate colonization during the Late Pleistocene - Early Holocene. The oldest dated mollusc to colonize QCI region subsequent to LGM was Macoma nasuta at 13,210 14C years BP. Once habitat and sea-surface temperatures were conducive, rates of recolonization appear to be limited only by the availability of ocean currents to bring temperate pelagic larvae into the region from outlying areas. Between ~11,000 and 10,000 14C years BP the appearance of Clinocardium ciliatum and Serripes groenlandicus, concurrent with the disappearance, or significant reduction in number and productivity of temperate intertidal molluscs, indicates the onset of a short interval of cool sea-surface temperatures coincident with the Younger Dryas cooling event. Five molluscan species: Macoma incongrua, Musculus taylori (cf), Mytilimeria nuttallii, Tellina nucidoides, Mytilus edulis/Mytilus trossulus previously categorized as possessing a Recent geologic range were collected in sediments dating older than 10,000 14C years BP. Fossil mollusc shells indicate edible intertidal biomass densities well within commercially harvested levels on southern Moresby Island by 8,800 14C years BP, and on northern Graham Island by 8,990 14C years BP. The presence and productivity of nutritious intertidal molluscs indicates the QCI region had a suitable climate, possessed open ocean conditions, and provided subsistence resources for potential early humans subsequent to at least 13,210 14C years BP. Three-dimensional modeling shows subaerially exposed land that could have been inhabited by plants, animals, including coastal-migrating early humans. Early coastlines that have not been drowned, and which may harbour early archaeological sites, are identified along the western and northern coasts of QCI and the BC mainland. / Graduate

The 1980 Vancouver Island Seismic Project (VISP) was conducted to investigate lithospheric structure associated with the underthrusting oceanic Juan de Fuca plate and the overriding continental America plate. The principal components of the survey were: (l) an onshore-offshore refraction line, which was approximately perpendicular to the continental margin (line 1), and (2) a refraction line which ran along the length of Vancouver Island approximately parallel with the continental margin (line IV). Lines I and IV were originally interpreted by Spence el a.1. (1985) and McMechan and Spence (1983), respectively. However since the original interpretations of these lines, deep multichannel seismic reflection data have been obtained on southern Vancouver Island as part of the 1984 LITHOPROBE project and off the west coast of the island during a marine survey in 1985. This study was undertaken to resolve differences between the subsurface structures proposed in the original interpretations of lines I and IV and those suggested by the more recently acquired deep reflection data. The vertical two-way traveltimes to prominent reflectors, observed in the onshore-offshore deep reflection data, were used as a constraint in constructing velocity models which are consistent with both the reflection and refraction data. The traveltimes and amplitudes observed in the VISP refraction data were modeled using a two-dimensional raytracing and asymptotic ray theory synthetic seismogram routine. The principal difference between the model originally interpreted for line I and the revised model involves the introduction of a twice repeated sequence of a low velocity zone (≈ 6.4 km/s) above a thicker high velocity zone (≈ 7.1 km/s) for the underplated region directly above the subducting Juan de Fuca plate in place of the single high velocity block underlain by a thick low velocity zone. The revised model for line IV is significantly different from the originally interpreted model. The two low-high velocity zones of line 1 are continued along the length of the island at depths between 10 and 35 km. Below this, the structure of the subducted plate is included to maintain consistency with the revised model developed for line 1. Additional features of the revised onshore-offshore model corresponding to line 1 include an oceanic lithosphere that dips approximately 3° beneath the continental slope, then 14° to 16° beneath the continental shelf and Vancouver Island, and an average velocity for the upper oceanic mantle of 8.22 km/s. Two separate two-dimensional models were needed to explain the data collected along line IV as a result of considerable azimuthal coverage due to a 30° change in profile direction. The revised models developed for line IV are consistent with the revised model developed for line 1. The velocity in the upper 10 km ranges from 5.5 km/s to approximately 6.7 km/s. Below 10 km the velocity structure is consistent with that interpreted for line 1 and shows some variations along strike of the subduction zone. Several possible interpretations can be made for the origin of the sequence of layers directly above the subducting plate beneath Vancouver Island. The two favored interpretations are: (1) a. three stage tectonic process consisting of: stage 1 — offscraping of sediment from the top of the subducting plate forms the uppermost low velocity layer in the sequence; stage 2 — an imbricated package of mafic rocks derived by continuous accretion from the top of the subducting oceanic crust forms the first high velocity layer; and stage 3 — stages 1 and 2 repeat themselves with stage 2 currently occurring; or (2) remnant, pieces of oceanic lithosphere left stranded above the current subducting plate during two previous episodes of subduction in which the subduction thrust jumped further westward isolating the remnant. The revised model along line IV indicates that this process of subduction underplating could have been a pervasive feature of this convergent margin. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Five profiles of the silver concentration in the subArctic Northeast Pacific Ocean yield a broad correlation between the Ag content and dissolved Si. However, silver is depleted at intermediate depths where the 02 content is low, implying removal from oxygen-deplete waters. An eighteen-month series of measurements of dissolved and particulate Ag from Saanich Inlet, BC indicate that Ag concentrations in near-surface waters are influenced by processes occurring outside the inlet. Dissolved silver was not detected in sulphide-bearing deep waters in the fjord. Ag in sediment-trap particles was associated with both biogenic and mineral phases. The Ag/biogenic Si ratio of the particles is related to the concentration of dissolved Ag in the surface waters suggesting a direct link between availability of the metal and its sequestration by diatoms.

The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. Recent research indicates that there has been a warming trend in ocean temperatures over the last 50 years. Hence, we sought to identify and demonstrate how a particularly germane SST dataset can be used within the scope of global climate change research. For this project we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline, as well as mean monthly SSTs for ice-free regions of the Arctic, using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. By providing detailed information concerning both dataset generation and data limitations, we aimed to make these data comprehensible to an expanded audience concentrating on life sciences rather than the traditionally physical science-based community. Furthermore, by making these data freely and publically available in multiple formats, including GIS (geographic information systems) layers, we expand their visibility and the extent of their use. We then used the dataset to describe SST patterns of nearshore (< 20 km offshore) regions of 16 North Pacific ecoregions, and of ice-free regions of 20 Arctic ecoregions, as delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Our work creates a better understanding of present temperature regimes in these critically sensitive areas, from which we can draw several basic conclusions. 1) AVHRR SST measurements alone are sufficient to identify temperature patterns pertinent to determining health of ecosystems; 2) Within the nearshore North Pacific, ecoregions along the California Current System are most vulnerable to habitat-altering SST changes; 3) sea ice distribution is a major factor affecting SSTs in Arctic ecoregions, causing concern for the welfare of Arctic species. / Graduation date: 2012

Approved for public release, distribution is unlimited / This study examines Southern Hemisphere mid-latitude wave variations connected to the Antarctic Oscillation (AAO) to establish connections with the 15- to 25-day wave activity in the western North Pacific monsoon trough region. The AAO index defined from the leading empirical orthogonal functions of 700 hPa height anomalies led to seven distinct circulation patterns that vary in conjunction with the 15- to 25-day monsoon trough mode. For nearly one half of the significant events the onset of 15- to 25-day monsoon trough convective activity coincided with a peak negative AAO index and the peak in monsoon trough convection coincided with a peak positive index. The remaining events either occur when the AAO is not significantly varying or when the AAO-related Southern Hemisphere mid-latitude circulations do not match 15- to 25-day transitions. When a significant connection occurs between the Southern Hemisphere mid-latitude circulations related to the AAO and the 15- to 25-day wave activity in the western North Pacific monsoon trough, the mechanism is via equatorward Rossby-wave dispersion. When wave energy flux in the Southern Hemisphere is directed zonally, no connection is established between the AAO and the alternating periods of enhanced and reduced convection in the western North Pacific monsoon trough. / Captain, United States Air Force