Queen Charlotte Strait (QCSt), along the glacial Pacific margin of Canada, preserves seabed geomorphological records of past tectonic, glacial, and oceanographic processes, particularly since the Last Glacial Maximum. These records can provide an analogue for predicting future seabed and sediment dynamics in contemporary ice-covered region and their surroundings under global warming. The present study identifies and maps the seabed geomorphology and stratigraphy of QCSt by analyzing extensive multibeam bathymetry data, sub-bottom profiles, seafloor images, surface sediments, sediment cores, and 14C dates. The analysis of seabed morphology, erosional and depositional patterns, and sedimentary lithofacies of the late glacial marine geology and post-glacial stratigraphy in QCSt collectively allows interpretation of the sequence of processes that formed, shaped, and filled this region. Four primary stratigraphic units were delineated: bedrock, moraines, glaciomarine deposits, and postglacial deposits, along with their seafloor distributions. Seabed features recognized in specific areas include active or relict sand and gravel bedforms, gas masking in thick hemipelagic muds, fan deltas, landslide-gully-fan systems, channels, iceberg lineations, and glass sponge reefs. A series of NNE-SSW-oriented moraines generally indicate ice-sheet retreat eastward toward the Coast Mountains during the last deglaciation, while arcuate moraines northwest of Malcolm Island, curving approximately southward, reflect valley-glacier retreat toward the northern mountains of Vancouver Island. The unconformity atop the glaciomarine deposits, leveled banks, terraces, and other truncated bedforms may indicate past lower sea levels.

Analysis of multibeam sonar and LiDAR data permits interpretation of submarine landforms in eastern Northumberland Strait, part of the St. Lawrence Estuary system, eastern Canada. Landforms are interpreted in the light of multiple forcing mechanisms, principally: (1) glaciation; (2) postglacial relative sea-level fluctuations; (3) spatial variability of tidal currents; and (4) modern sea-ice impact. Bedrock exposures testify to relatively thin glacial sediments. Glacial landforms comprise ribbed moraines and glacial meltwater channels. The study area was emergent in the early Holocene, as evidenced by fluvial channels and former lakes in the Cape Tormentine area. Today, spatially varying tidal forces are strong determinants of geomorphology, and several landforms zones are identified: (1) tidal-swept zones at Abegweit Passage and Caribou, characterized by seafloor scour and scattered bedform fields; (2) the area of weak tidal circulation between the Abegweit and Caribou zones - a low-relief sediment depocenter with littoral zone ridge-and-runnel beach systems, and estuaries; (3) transition zones located between the central depocentre and the tidal-current zones feature sediment drifts; (4) the tidal gyre at East Point, Prince Edward Island, which has formed Milne Bank; and (5) an area east of Caribou, where weaker tidal forces and stronger wave influence are evidenced by alongshore transport embayments between Milne Bank and Souris and the east-facing coast north of Cape Bear, where sediment is trapped in compartments isolated from one another. Modern sea-ice disturbance of the seabed (range -1 to -8 m) is most extensive in the Pictou Banks area.

Based on high-resolution multibeam-sonar data and low-resolution (GEBCO) bathymetry data, we classify the geomorphology of Canada’s Pacific margin within the four bioregions designated by Fisheries and Oceans Canada for management of biological resources. We designate 14 units. Nine continental shelf units are fiords, bedrock terrain, offshore banks, Haida Gwaii platform, Haida Gwaii shelf, Vancouver Island shelf, incised shelf, glacial trough, and major delta. On the continental slope, we identify the canyon zone, the accretionary wedge (off Vancouver Island), and the transform (Queen Charlotte Fault) terrain. The abyssal zone is treated as a single unit with two components: seafloor-spreading terrain, and abyssal plain with fans, seamounts, and channels. Hexactinellid sponge reefs of various morphologies are found in three of the continental shelf geomorphic units and cover up to 10% of the seafloor in the glacial trough category. Examples based on multibeam sonar imagery are used to display the chief characteristics of the 14 units, as well as the geomorphic diversity within them. Compared with Canada's east-coast glaciated passive margin, geomorphic similarities include: (1) the panoply of glacial landforms and (2) shelf terrain dissected by sub-glacial meltwater. Major differences include: (1) the presence of unique “tectonic” terrains on the Pacific continental slopes; (2) hexactinellid sponge bioherm reefs that are unique to the Pacific margin; (3) the absence of glacio-tectonic terrains on the Pacific shelves; and (4) the absence of “classic” trough-mouth fans on the Pacific margin.

Global warming during the Paleocene-Eocene Thermal Maximum (PETM) is hypothesized to have had a profound effect on the paleohydrologic cycle, including enhanced seasonality and increased water and sediment discharge. Although the PETM may represent the closest geologic analog for future global climate changes, the effects of this event on ancient coastal systems are poorly understood. We examined drill core from two locations in eastern Texas that preserve a record of tidally influenced deltaic sedimentation associated with the paleo-Colorado River that drained up to 2 x 10(6) km(2) of central North America, approximately two-thirds of the area of the modern Mississippi River catchment. In these cores, the development of a regionally extensive sand-rich unit (the Carrizo Formation) at the onset of the PETM is identified from a negative carbon isotope excursion and supported by detrital zircon U-Pb geochronology and pollen occurrence data. The basal Carrizo Formation indicates that the onset of the PETM was characterized by an increase in the delivery of coarser-grained sediments and progradation of the coastline, which occurred despite rising sea level. Using a mass-balance framework for equilibrium deltaic systems, we estimate that sediment delivery to the coastline increased by ca. 46% (2-sigma: 13% to 167%). Our findings of enhanced sediment delivery to the coast are consistent with proxy climatic and sedimentologic data indicating heightened precipitation seasonality in the interior of North America during the PETM. Thus, the effects of a regional change in climate forced by greenhouse events were transmitted downstream by large river systems to produce shifts in coastal sediment supply, progradation, and coastline evolution.

The Newfoundland and Labrador Shelves Bioregion, located on the glaciated continental shelf and adjacent continental slope of eastern Canada, is classified into units that reflect its great physiographic diversity. There are ten shelf units: bedrock zone, fjord systems, major inlet, shelf-crossing troughs, four types of offshore banks, basin, and disturbed (glaciotectonic) terrain. There are three units on the continental slope: channelized areas, trough-mouth areas, and large sedimentary drifts. A series of vignettes illustrates both the distinguishing characteristics of the principal geomorphic units and the morphologic diversity within them. A sediment mobility analysis reveals that wave-and current-generated disturbances are dominant and largely depth-controlled within the shelf units, while the south-flowing Labrador Current impacts sediment transport and mobility along the continental slope.

ABSTRACTPrevious interpretation of the nature and distribution of subaerial glacial landforms established that Frobisher Bay in southeastern Baffin Island was glaciated in the Late Wisconsinan by ice flowing southeast from the Foxe–Baffin Ice Dome. New seafloor mapping within the bay has revealed submarine glacial landforms that are described and interpreted in the context of their subglacial, ice‐marginal, glaciomarine and marine process environments. Interpretation of the evidence confirms that ice occupied Frobisher Bay, flowing from the northwest to southeast, parallel to the orientation of the bay. Relatively rapid ice velocities are indicated by the presence of ice‐moulded bedrock and megaridges flanking a deep trough (>700 m) along the faulted southern flank of Frobisher Bay. In shallower regions, areal scouring and channelisation indicate the widespread presence of glacial ice. As ice retreated to the northwest towards the Foxe Ice Dome, De Geer and recessional moraines were deposited at the ice front. The latter correlate spatially with the extensive Frobisher Bay Moraine System on land. Two iceberg ploughmark populations are evident, with smaller relict features in shallow water in rare locations in the northwest of the bay, and larger relict and modern ploughmarks in deeper water in outer Frobisher Bay.

This map depicts the geomorphology of the Chatham Sound area, British Columbia, and is based on bathymetry and backscatter data from multibeam sonar surveys, complemented by 3.5 kHz subbottom profiler data, grab samples, cores, and bottom photographs. The map encompasses three physiographic areas: 1) the easternmost portion of Dogfish Banks; 2) the north-south oriented Hecate trough; and 3) the maze of channels and inlets east of Hecate trough. The morphological and textural complexity reflects the underlying bedrock, glacial history, a complex pattern of postglacial relative sea-level change, and modern oceanographic processes. Hexactinellid sponge reefs are a significant component of the seafloor mosaic. The criteria for reef identification were positive relief, low backscatter strength, and acoustic transparency.

Aim: The aim of this project is to use pectin- and chitosan-modified solid lipid nanoparticles for bovine lactoferrin to enhance its cellular uptake and transport. Methods: Solid lipid particles containing bovine lactoferrin (bLf) were formulated through the solvent evaporation technique, incorporating stearic acid along with either chitosan or pectin modification. bLf cellular uptake and transport were evaluated in vitro using the human adenocarcinoma cell line Caco-2 cell model. Results and Discussion: The bLf-loaded SLPs showed no significant effect on cytotoxicity and did not induce apoptosis within the eight-hour investigation. The use of confocal laser scanning microscopy confirmed that bLf follows the receptor-mediated endocytosis, whereas the primary mechanism for the cellular uptake of SLPs was endocytosis. The bLf-loaded SLPs had significantly more cellular uptake compared to bLf alone, and it was observed that this impact varied based on the time, temperature, and concentration. Verapamil and EDTA were determined to raise the apparent permeability coefficients (App) of bLf and bLf-loaded SLPs. Conclusion: This occurred because they hindered efflux by interacting with P-glycoproteins and had a penetration-enhancing influence. These findings propose the possibility of an additional absorption mechanism for SLPs, potentially involving active transportation facilitated by the P-glycoprotein transporter in Caco-2 cells. These results suggest that SLPs have the potential to be applied as effective carriers to improve the oral bioavailability of proteins and peptides.

Seafloor habitat maps are an important management tool used to delineate distinct regions of the seabed based on their biophysical properties. Spatially continuous bathymetry and backscatter-derived terrain features are commonly used as proxies for environmental conditions and processes that affect species distributions. Multi-scale approaches are increasingly applied to assess the relevant scales at which species co-occur. As the optimal scale(s) may be unknown, features can be calculated at multiple successive scales, yet this results in numerous highly correlated features that may negatively impact model interpretability. To address this increased dimensionality, feature selection approaches can be used to identify the most relevant features. Here, filter and wrapper approaches are assessed to select features from a highly dimensional multi-scale dataset. Terrain features describing the seabed were calculated across ten scales at two coastal sites in Placentia Bay, Newfoundland, Canada. Five species assemblages were identified using ground-truth underwater video sampling. Features predicting the presence of assemblages were assessed using the two selection methods, and the set of chosen features was modelled using three machine learning algorithms: extreme gradient boosting (XGB), random forest (RF), and support vector machines (SVM). The XGB model with features selected by scale-factor from the Boruta wrapper algorithm had the highest accuracy according to cross-validation- (61.67%, kappa 0.49). Bathymetry and terrain attributes were the most important predictors of assemblage occurrence across various analysis scales encompassing both broader and fine-scale variability of the seabed. The proposed feature reduction and selection approach improved the overall accuracy of predictions, and the resulting biological complexity captured in our habitat maps established baseline data for an ecologically significant coastal region.

The Quaternary history of the Atlantic Canadian inner shelf shares some similarities with the North Sea and northern United States of America (US) Atlantic coast, with the influence of large-scale glaciation and subsequent sea level transgression being the main drivers of seafloor morphology, sedimentology, and uppermost stratigraphy. The geology of the inner shelf, generally confined to 100 m water depth for this study, is an important constraint on the development of offshore renewables, in particular wind energy. Offshore wind has seen rapid growth, particularly in Europe and Asia, where the industry has now experienced decades of production. In the US, one small-scale production farm and many hundreds of MW are in the production pipeline. In contrast, offshore wind in Canada, despite onshore installed wind capacity that ranks highly globally, lacks any operating turbines and there are no plans for development in the wind resource-rich Atlantic Canadian region. In this study, the geological constraints on offshore wind in Atlantic Canada are explored. Generally, the available offshore wind resource is high, and thus the main geophysical constraint on the development of offshore wind energy converters is the inner shelf geology. Several sites with available high-resolution geophysical data are selected for in-depth analysis and comparison with production and planned offshore wind farm sites found elsewhere. In general, a lack of sufficiently thick Quaternary sedimentation—necessary for the most common bottom-fixed foundations for wind turbines—will make developing offshore wind in Atlantic Canada challenging when compared with North Sea and US Atlantic Coast locations. A few locations may be suitable geologically, such as Sable Island Bank in Nova Scotia (thick package of sands), Northumberland Strait between Prince Edward Island and Nova Scotia (shallow firm seabed and sandbanks), Baie des Chaleurs in New Brunswick/Québec (thick, low relief fine sediments), and St. George's Bay, Newfoundland (shallow, postglacially modified moraine).

We describe a revised understanding of the extent and dynamics of the Cordilleran Ice Sheet on the continental shelf of northern British Columbia, Canada. During the Local Last Glacial Maximum ice streams occupied two of the three shelf‐crossing troughs in Queen Charlotte Sound (Goose Island Trough and Mitchell's Trough). A 25‐km‐wide outlet glacier – the Hecate Glacier – flowed south in Hecate Strait, parallel to the modern coast. It reached a grounding line at the head of Moresby Trough, beyond which an ice shelf may have extended to the edge of the continental shelf. The southern part of the independent Haida Gwaii Ice Cap formed piedmont lobes dissected by tunnel valleys. An emergent area east of the ice cap corresponds with the ‘Hecate Refugium’. Subsequently grounded ice retreated from the shelf troughs. The Hecate Glacier retreated incrementally towards the north. Mainland ice then stabilized along a north–south margin near modern coasts, marked by submarine moraines in the Chatham Sound region and elsewhere. This margin was probably contemporaneous with the margin at Mt. Buxton in the south of the study area, dated at c. 17.6 to 16.6 ka (Darvill et al. 2018). Off southern Haida Gwaii, following a retreat, a glacier margin was established east of Juan Perez Sound, proximal to a sandur plain graded to a water level of −150 m. Proglacial lakes to the north of here were the likely source for an outburst flood that created gravel bedforms and an area of sea‐floor scour. In a final phase, diminished mainland ice was confined to fjords, and retreat inland is marked by a succession of submarine moraines, beginning with a moraine at the Douglas Channel sill. The study has implications for the migration pathways for human migration into the Americas following deglaciation.

Hexactinellid sponges form extensive reefs in coastal and shelf waters of the northwestern margin of North America. The framework-constructed reefs are unique to this region, and create a diverse array of reef structures in water depths of 20-240 m. The reefs develop morphologies on a continuum ranging from thin-bedded biostromal reefs to steep sided bioherms and ridges >20 m in height. The diverse morphologic types likely result from local variations of the seafloor tidal current regime and suspended sediment delivery as well as the ecologic development of the reef controlled by the characteristics of the benthic community dominated by reef-forming sponges. Measured ecological parameters in the various reef forms indicate differences in sponge cover in morphologic end members. Some reef morphologies, such as ridges, have large areas that support sponge growth, while in waveform morphologies the most favorable sponge growing situations are on the top and slope of the waveforms. Biostromal reefs possess gradients of most suitable reef growing habitat where patchiness results in significantly different densities of sponges on the reef surface.

The inner shelf off southwest Newfoundland, bordering the Laurentian Channel, was mapped with multi-beam sonar between depths of 200 and ∼20 m, overlapping with coverage by marine/terrestrial LiDAR from maximum depths of 30 m to above sea level. The new data provide the first clear view of linkages between terrestrial and nearshore coastal systems and the inner shelf. Offshore sand reservoirs associated with adjacent sandy coastal barriers and spits are thin (∼2 m), and isolated from one another, so that bedrock is the dominant seafloor terrain on the inner most shelf. The offshore sand reservoirs link with complex nearshore bar systems, from which it is inferred that sediment exchange with terrestrial systems can occur. Several isolated sand bodies are interpreted as residuals from former coastal systems destroyed during the Holocene transgression. The new data reveal the unexpected existence of a submarine canyon that facilitates transport of sediment from the inner shelf into the deep glacial trough of the Laurentian Channel.

Douglas Channel is a 140 km-long fjord system on Canada's west coast where steep topography, high annual precipitation and glacially over-deepened bathymetry have resulted in widespread slope failures. A 5 year project involving numerous marine expeditions to the remote area produced a comprehensive assessment of the magnitude and frequency of slope failures in the region. A classification scheme is presented based on morphology and failure mechanism: (1) debris flows are the most common in all parts of the fjord - they are often small with a subaerial component where fjord wall slope is very high or tend to exceed volumes of 10(6) m(3) where fjord wall slope is lower, allowing for accumulation of marine sediments; (2) large failures of oversteepened glacial sediments occurring at transgressive moraines and glaciomarine plateaus following deglaciation - the largest is at Squally Channel with an estimated volume of 10(9) m(3); (3) fjord wall failures that involve bedrock slump or rock avalanche; (4) translation of marine sediments; (5) composite/other slides; and (6) two scallop-shaped sackungen, or deep-seated gravitational slope deformations of granodiorite with volumes exceeding 60 x 10(6) m(3). The postglacial marine sedimentary record shows evidence of large-scale slope failures of all styles that were especially active following deglaciation. The Holocene marks a transition to a lower frequency and change to primarily debris flows and smaller rock slides. Slope failures that may be capable of generating tsunamis and may be damaging to coastal infrastructure have occurred in all parts of Douglas Channel through much of the Holocene. Here we present a morphological analysis with volume estimates and age control using multibeam bathymetry, high-resolution sub-bottom data and sediment cores. The study details an extensive analysis of slope failures in a fjord network that can be extended to other fjord environments.

Quaternary glaciations played a critical role in producing the modern landscape of the seafloor of southeastern Canada. Glacial landscapes such as cross-shelf troughs, fjords, recessional moraines and tunnel valleys were sculpted by the Laurentide Ice Sheet. Following deglaciation, relative sea level rise led to the formation of sandy bedforms and tidal scours on the continental shelf. In contrast, the deep-water margin was not directly modified by the ice sheet, but was significantly influenced by it. Large quantities of glacigenic sediments were distributed along the continental slope during the last glacial maximum through turbidity currents, contour currents and submarine landslides. Turbidity currents eroded submarine canyons and deposited submarine fans, which are among the largest sediment accumulations in southeastern Canada. Although the continental shelf and the deep-water margin have contrasting landscapes, they are genetically linked to tectonics and the pattern of retreat of the Laurentide Ice Sheet. This chapter gives an overview of the landscape and landforms of the seafloor of southeastern Canada and details how its glacial heritage played a major role in sculpting the modern seabed.