Hindcasts from the Directional Ambient Noise Estimation System (DANES) model were compared to in situ ambient noise measurements to determine the accuracy of the U.S. Navy's ambient noise model. One hundred fifty eight (158) sonobuoy ambient noise measurements were acquired at eight locations in the Northeast Pacific (NEPAC) Ocean during November and December 1980. For each sonobuoy observation a DANES hindcast was made using archived fields from Fleet Numerical Oceanography Center for the simultaneous time and location. The difference between the predictions and measurements was calculated. A maximum mean error of 4.9 dB occurred at 200 Hz which appeared to be due to errors in the DANES Historical Temporal Shipping (HITS) data base. The model was insensitive to synoptic shipping, sound speed profiles and wind field inputs when the HITS data base was utilized.

Zinc (Zn) and cadmium (Cd) have nutrient-type vertical distributions reflecting control driven by biological uptake in surface waters and remineralization of sinking biogenic particles at depth. Both metals show strong correlations with major algal nutrients (Cd with phosphate (PO43-) and Zn with silicic acid (Si)) in the world ocean. Through their roles as micronutrients and toxins to marine phytoplankton, Zn and Cd can influence surface biological community composition. Preserved Zn and Cd records have been employed as proxies to gain insight into nutrient distributions, circulation, and organic carbon export in the paleocean. A thorough and mechanistic understanding of the biogeochemical cycling of Zn and Cd is necessary for accurate paleoceanographic reconstructions as well as predicting alterations in metal supply to the modern surface ocean and its impacts on primary productivity due to oceanic changes. My dissertation aims to further this understanding through an investigation of Zn and Cd distributions in the subarctic northeast Pacific through samples collected along the Line P transect. A major focus of this dissertation was identifying and characterizing depletions of metals in O2-depleted waters relative to global and basin scale metal:macronutrient correlations. Dissolved Cd profiles from the subarctic northeast Pacific and the eastern North Atlantic show a deficit of Cd relative to regional Cd:PO43- relationships. Particulate Cd and Cd stable isotopes (ε112/110Cd) from low-O2 North Atlantic waters and published sedimentary data from the subarctic northeast Pacific point to a previously undocumented water-column metal removal process acting in O2-depleted waters. Metal sulphide formation, likely in association with particulate microenvironments, can explain the observed deficits. Other metals with similar sulphide coordination chemistry should also form metal sulphides if this process is occurring. Dissolved Zn from Line P showed distributions and Zn:Si relationships that are consistent with the removal of metal in O2-depleted waters through sulphide formation. A first order approximation of the Cd deficit suggests that sulphide formation may be an important sink term in the global Cd cycle. Surface and upper nutricline Zn:Si and Cd:PO43- relationships in the chronically iron (Fe)-limited subarctic northeast Pacific showed distinct trends, which differ from those seen in Fe-replete regions. Distributions suggest the formation of surface biogenic particles with high Cd:PO43- and Zn:Si, leaving surface waters depleted in metals relative to macronutrients and resulting in high metal:macronutrient ratios in the nutricline as these particles sink and are remineralized. This is consistent with understandings of phytoplankton physiology and uptake of divalent metals under Fe-limitation, and corresponds well with global data for dissolved Cd:PO43- patterns in Fe-limited regions. Subsurface high Cd:PO43- and Zn:Si may also be influenced by the advection of water enriched in trace metals. The distinct shallow remineralization horizon observed for Zn compared to Si in the subarctic northeast Pacific by this and previous work presents a fundamentally different distribution than observed in global Zn:Si compilations. Directed sampling in the subarctic northeast Pacific should help elucidate the mechanism behind the oceanographically distinct distributions in this basin. Dissolved ε112/110Cd from Line P demonstrates a remarkably uniform subarctic northeast Pacific deepwater reflecting an advected source signal. Particulate ε112/110Cd samples show an active Cd cycle, which is not imprinted upon the dissolved phase. Particulate ε112/110Cd from 200-600 m depth is among the lightest ε112/110Cd ever reported for natural telluric samples. This may be an important sink for light Cd in the global ocean, which at present is heavy with respect to known sources. Line P surface waters with very low Cd concentrations are not accurately represented by a closed-system Rayleigh model, which can describe ε112/110Cd in the Southern Ocean. This suggests spatially and/or temporally variable surface ε112/110Cd fractionation. A large difference is observed in reported dissolved ε112/110Cd at very low Cd concentrations between different instrumentations. An intercalibration is necessary to determine if this is an analytical artefact or reflects real oceanic variability. / Graduate

It is well recognized that humans have had a significant role in transforming terrestrial landscapes, yet comparatively little research has examined the long-term impacts of humans on marine ecosystems. As an applied field of research, marine historical ecology draws on archaeological, ecological, and other archival information to reveal the dynamics of marine social-ecological systems. This thesis examines the enduring history of relationships between ancient Indigenous fisheries and marine systems in the northeast Pacific. Specifically, I advance the development and application of two methodologies for 1) quantifying the composition of ancient fish landings, 2) estimating ancient ocean temperatures from archaeological fish bone assemblages, and 3) assessing the scale of ancient shellfish harvests using a regression-based approach. This thesis presents a novel method for estimating the ‘ancient Mean Temperature of the Catch’ (aMTC) using Indigenous fisheries catch records from two archaeological sites in the northeast Pacific. Despite different catch compositions, I observe an increase in aMTC over a 5,000-year period at two contemporaneously occupied archaeological sites in southwestern British Columbia, Canada. Given that preindustrial fisheries data are ubiquitous in coastal archaeological sites, this method has the potential to be applied globally to broaden the temporal and geographic scale of ocean temperature baselines. Furthermore, the regression-based methodology presented in this thesis has broad applicability to archaeological shellfish assemblages, as it allows for reconstructing size frequency distributions of ancient shellfish harvests and refined estimates of clam biomass. Together, these methods offer a long-term perspective on the enduring relationships between Indigenous peoples and marine environments in the northeast Pacific. Furthermore, the methods advanced in this thesis shed light on ancient oceanographic conditions and fisheries practices, which can be used to inform contemporary management efforts. Ultimately, these insights aim to contribute towards ecologically sustainable and socially just operating space for Canada’s Pacific fisheries. / Graduate / 2023-04-10

A two part project spanning four and one half years was designed to investigate a number of aspects of the natural history of Octopus dofleini in the Northeast Pacific. The tag-release recapture (Part I) involved weekly SCUBA dives, during daylight hours, at three sites on Southern Vancouver Island, British Columbia, Canada. A total of 320 octopuses were sighted during 616 dives (Part I) and 151 of those octopuses were tagged or recaptured. The ratio of dives per octopus sighted was 1.93:1 and the ratio of dives per octopus tagged or recaptured was 4.08:1. A total of 98 octopuses were tagged (Part I) and 30 of those octopuses were recaptured two or more times for a recapture rate of 30.61%. Statistical analysis of data weighted to provide uniform effort showed Site 1 (Tanner Rock) to have a significantly greater number of large octopuses while Site 2 (Tozier Rock) had a significantly greater number of very small octopuses. An analysis of the data on octopus sex ratios found no significant difference between the number of males and females at each site even though there had been a significant difference in the ratio within Site 2. Analysis of data on annual distribution of octopus body weight combined with the results from the recapture of individual octopuses led to the proposal of a four year lifespan for female Octopus dofleini and an undetermined, but longer, lifespan for males of the species. An examination of the data on octopus movement showed that a peak number of small octopuses (approximately 250 g) appeared at the sites in February. The evidence showed that over the next 19 to 22 months the octopuses grew from approximately 250 grams to a pre adult body weight of 13.8 kg for males (in September) and 14.7 kg for females (in December). No octopuses between 16 and 19.5 kg were captured suggesting a movement of octopuses of that body weight away from the sites. Small numbers of octopuses weighing between 19.5 kg and 28 kg were captured mainly during the first half of the year. An analysis of octopus position data showed that Octopus dofleini does not maintain a constant distance from its nearest neighbour. Nearest neighbour distance was not significantly influenced by the size or sex of the neighbour nor by changes in water temperature. A highly significant correlation was found between estimated den volume and octopus body weight. There were no significant relationships between den surroundings, number of exits, den type and den depth when compared to den usage suggesting that Octopus dofleini is an opportunistic animal using whatever shelter of appropriate volume it discovers. The major food item at all sites as determined by midden heap contents was the Red Rock Crab, Cancer productus. An examination of the physical condition of each octopus captured revealed 21.2% of the animals had either scars or amputated arms or both. Correlations examining the relationships between water temperature and growth rate, body weight, sex and nearest neighbour distance were nonsignificant. Part 11 of the project was the physical measuring and describing of each den at each site. During the 126 SCUBA dives done another 127 octopuses were sighted. As octopuses were captured only when it was necessary to examine the inside of the den there were only 11 octopuses captured during the second part of the project. In total, 447 octopuses were sighted during 742 dives. This results in an effort per octopus sighted of 1.66 dives per octopus. / Graduate

Rogue waves are unexpected, individual ocean surface waves that are disproportionately large compared to the background sea state. They present considerable risk to mariners and offshore structures when encountered in large seas. Rogue waves have gone from seafarer’s folktales to an actively researched and debated phenomenon. In this work an easily derived spectral parameter, as an indicator of rogue wave risk, is presented, and further evidence for the generation mechanism responsible for these abnormal waves is provided. With the additional goal of providing a practical rogue wave forecast, the ability of a standard wave model to predict the rogue wave probability is assessed. Current forecasts, like those at the European Centre for Medium-Range Weather Forecasts (ECMWF), rely on the Benjamin Feir Index (BFI) as a rogue wave predictor, which reflects the nonlinear process of modulation instability as the generation mechanism for rogue waves. However, this analysis finds BFI has little predictive power in the real ocean. From the analysis of long term sea surface elevation records in nearshore areas and hourly bulk statistics from open ocean and coastal buoys in the Northeast Pacific, crest-trough correlation shows the highest correlation with rogue wave probability. These results provide evidence in support of a probabilistic prediction of rogue waves based on random linear superposition and should replace forecasts based on modulation instability. Crest-trough correlation was then forecast by a regional WAVEWATCH III ® wave model with moderate accuracy compared with the high performance of forecasting significant wave height. Results from a case study of a large fall storm October 21-22, 2021, are presented to show that the regional wave model produces accurate forecasts of significant wave height at high seas and presents a potential rogue wave probability forecast. / Graduate