Eclipse Sound Research Articles

Proximity analysis between icebreakers and narwals in Tasiujaq, Nunavut, Canada

AbstractIcebreaker vessels in the Canadian Arctic are used to monitor and maintain open shipping lanes during summer and fall. Icebreaker operating routes often overlap with important habitats of endemic Arctic marine mammals, leading to potential interactions and disturbance. In this study, we examined the frequency, proximity, and duration of encounter events between narwhals (Monodon monoceros) and icebreaker vessels in Tasiujaq (Eclipse Sound), Nunavut, an important summering area for this species. We combined tracking data from 25 narwhals equipped with satellite telemetry devices in Tasiujaq between 2016 and 2018 with automatic identification system (AIS) data for the same period from 7 icebreaker vessels. We defined an encounter event between a narwhal and an icebreaker as the total consecutive occurrences of an individual within 50 km of a vessel within 1 hour. For all years combined, 17 out of 25 narwhals had at least 1 encounter with an icebreaker and all 7 icebreakers were involved in at least 1 encounter. The closest distance (closest point of approach) recorded was <1 km and the longest cumulative duration of encounter events for 1 narwhal with 1 icebreaker was 121.6 hours (n = 27 encounter events over 17 days). Proximity and continuous exposure of narwhals to high levels of noise are a key concern when considering short‐ and long‐term effects on behavior and fitness of this species.

Surveillance for Zoonotic Pathogens and Inuit Qaujimajatuqangit of Ringed Seals (nattiit) (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada

Ringed seals (Pusa hispida) (nattiq (s.), nattiit (pl.) [Inuktut]) provide an important food staple for Nunavummiut (Indigenous residents of Nunavut). We studied the health of nattiit harvested by hunters from Baffin Island, Nunavut, via Inuit Qaujimajatuqangit and veterinary science. We conducted serological surveys and polymerase chain reaction (PCR) for select zoonotic pathogens, including Brucella spp., Erysipelothrix rhusiopathiae, Leptospira interrogans, and Toxoplasma gondii, in 55 nattiit from Frobisher Bay (FB) and 58 nattiit from Eclipse Sound (ES). We used a digestion assay to determine the presence of Trichinella spp. larvae in muscle samples from these seals. We conducted interviews with nine Local Knowledge Holders (LKHs) from Iqaluit (FB) and nine from Pond Inlet (ES) to gather their observations about nattiq health. The hunters evaluated nattiq health through a combination of behavior, nutritional condition, and appearance of skin and organs. They rarely observed severely ill nattiit. Hunters from ES but not from FB observed declining nattiit population numbers. In both regions, they observed increased numbers of harp seals (Phoca groenlandica). Frequencies of natural exposure among nattiit from FB and ES, based on seroprevalence, were 20.5% and 37% for Brucella spp., 25% and 11% for E. rhusiopathiae, 93% and 100% for L. interrogans, and 10% and 27% for T. gondii, respectively; PCR was negative for these pathogens in organs and tissues of seropositive animals. We did not detect larvae of Trichinella spp. Knowledge and experience from the LKHs in assessing nattiq health, complemented by negative findings from direct detection methods, provide reassurance about the safety of nattiit as country food, despite their exposure to some zoonotic pathogens in their natural environment.

Impact of ship noise on the underwater soundscape of Eclipse Sound in the northeastern Canadian Arctic

Eclipse Sound, in the northeastern Canadian Arctic, has experienced a substantial increase in ship traffic due to growing tourism and industrial development in the region. This study aims to describe the natural soundscape as well as to assess the noise levels associated with shipping. Underwater sound recordings were collected at two locations: Eastern Eclipse Sound (72° 43.730 N, 76° 13.519 W, 670 m) leading to Baffin Bay, and Milne Inlet (72° 15.260 N, 80° 34.205 W, 313 m) situated near the southwest end of Eclipse Sound. To capture the dynamic nature of the soundscape, the data from these two locations were divided into three seasons: late spring, summer, and early fall. These periods were selected to account for the changing contribution of sea ice to the soundscape during the sea ice break-up, two months of open water, and the sea ice freeze-up.By analyzing ship tracks and underwater acoustic recordings, we identified patterns of ship traffic and estimated underwater noise levels due to ships. Noise emitted by ships is quantified by vessel type, including three cargo ship types, passenger ships, pleasure craft, and icebreakers. Individual ship transits through the region introduce transient noise at frequencies from <20 Hz to >20 kHz, with durations lasting from a few minutes to >6 h. The impact of ship noise on the soundscape is significant, resulting in increases in sound levels by 15 to >30 dB when ships are within 10 km and measurable ship noise below 200 Hz at distances of >50 km.

Occurrence and antimicrobial resistance of Salmonella species and potentially pathogenic Escherichia coli in free-living seals of Canadian Atlantic and eastern Arctic waters.

Seal populations in Canadian waters provide sustenance to coastal communities. There is potential for pathogenic and/or antimicrobial-resistant bacteria to transfer to humans through inadvertent faecal contamination of seal products. The objective of this study was to investigate the occurrence and potential antimicrobial resistance of Salmonella spp., Escherichia coli and Listeria monocytogenes in faecal samples collected from grey seals (Halichoerus grypus) in the Gulf of St. Lawrence and from ringed seals (Pusa hispida) in Frobisher Bay and Eclipse Sound, Nunavut, Canada. Grey seals were harvested during commercial hunts or during scientific sampling; ringed seals were collected by Inuit hunters during subsistence harvests. Virulence genes defining pathogenic E. coli were identified by PCR, and antimicrobial susceptibility testing was performed on recovered isolates. In grey seals, E. coli was detected in 34/44 (77%) samples, and pathogenic E. coli (extraintestinal E. coli [ExPEC], enteropathogenic E. coli [EPEC] or ExPEC/EPEC) was detected in 13/44 (29%) samples. Non-susceptibility to beta-lactams and quinolones was observed in isolates from 18 grey seals. In ringed seals from Frobisher Bay, E. coli was detected in 4/45 (9%) samples; neither virulence genes nor antimicrobial resistance was detected in these isolates. In ringed seals from Eclipse Sound, E. coli was detected in 8/50 (16%) samples and pathogenic E. coli (ExPEC and ExPEC/EPEC) in 5/50 (10%) samples. One seal from Eclipse Sound had an E. coli isolate resistant to beta-lactams. A monophasic Salmonella Typhimurium was recovered from 8/50 (16%) seals from Eclipse Sound. All Salmonella isolates were resistant to ampicillin, streptomycin, sulfisoxazole and tetracycline. L. monocytogenes was not detected in any sample. These findings suggest that seals may act as important sentinel species and as reservoirs or vectors for antimicrobial-resistant and virulent E. coli and Salmonella species. Further characterization of these isolates would provide additional insights into the source and spread of antimicrobial resistance and virulence genes in these populations of free-living seals.

Killer Whale (Orcinus orca) Pulsed Calls in the Eastern Canadian Arctic

&#x0D; Killer whales (Orcinus orca) produce a variety of acoustic signal types used for communication: clicks, whistles, and pulsed calls. Discrete pulsed calls are highly stereotyped, repetitive, and unique to individual pods found around the world. Discriminating amongst pod specific calls can help determine population structure in killer whales and is used to track pod movements around oceans. Killer whale presence in the Canadian Arctic has increased substantially, but we have limited understanding of their ecology, movements, and stock identity. Two autonomous passive acoustic monitoring (PAM) hydrophones were deployed in the waters of Eclipse Sound and Milne Inlet, in northern Baffin Island, Nunavut, Canada, in August and September 2017. Eleven killer whale pulsed call types, three multiphonic and eight monophonic, are proposed and described using manual whistle contour extraction and feature normalization. Automated detection of echolocation clicks between 20 and 48 kHz demonstrated little to no overlap between killer whale calls and echolocation presumed to be narwhal, which suggests that narwhal remain audibly inconspicuous when killer whales are present. Describing the acoustic repertoire of killer whales seasonally present in the Canadian Arctic will aid in understanding their acoustic behaviour, seasonal movements, and ecological impacts. The calls described here provide a basis for future acoustic comparisons across the North Atlantic and aid in characterizing killer whale demographics and ecology, particularly for pods making seasonal incursions into Arctic waters.

Changes in sea ice and range expansion of sperm whales in the eclipse sound region of Baffin Bay, Canada.

Sperm whales (Physeter macrocephalus) are a cosmopolitan species but are only found in ice‐free regions of the ocean. It is unknown how their distribution might change in regions undergoing rapid loss of sea ice and ocean warming like Baffin Bay in the eastern Canadian Arctic. In 2014 and 2018, sperm whales were sighted near Eclipse Sound, Baffin Bay: the first recorded uses of this region by sperm whales. In this study, we investigate the spatiotemporal distribution of sperm whales near Eclipse Sound using visual and acoustic data. We combine several published open‐source, data sets to create a map of historical sperm whale presence in the region. We use passive acoustic data from two recording sites between 2015 and 2019 to investigate more recent presence in the region. We also analyze regional trends in sea ice concentration (SIC) dating back to 1901 and relate acoustic presence of sperm whales to the mean SIC near the recording sites. We found no records of sperm whale sightings near Eclipse Sound outside of the 2014/2018 observations. Our acoustic data told a different story, with sperm whales recorded yearly from 2015 to 2019 with presence in the late summer and fall months. Sperm whale acoustic presence increased over the 5‐year study duration and was closely related to the minimum SIC each year. Sperm whales, like other cetaceans, are ecosystem sentinels, or indicators of ecosystem change. Increasing number of days with sperm whale presence in the Eclipse Sound region could indicate range expansion of sperm whales as a result of changes in sea ice. Monitoring climate change‐induced range expansion in this region is important to understand how increasing presence of a top‐predator might impact the Arctic food web.

Satellite‐tracked sperm whale migrates from the Canadian Arctic to the subtropical western North Atlantic

FIGURE S1. Sperm whale (Physeter macrocephalus) photographed on September 27, 2018, in Eclipse Sound, Nunavut, Canada (72°48′N, 77°41′W; photo credit: Joshua M. Jones). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Vessel risks to marine wildlife in the Tallurutiup Imanga National Marine Conservation Area and the eastern entrance to the Northwest Passage

The Arctic is changing rapidly due to climate change, which is allowing unprecedented levels of vessel traffic to transit the region. Vessel traffic can negatively affect marine wildlife in a number of ways, particularly in areas where vessels overlap with high concentrations of ecologically important species, and the significance of these impacts are of increased concern when the wildlife are also culturally important. Tallurutiup Imanga National Marine Conservation Area, located in Lancaster Sound, Nunavut, Canada, at the eastern entrance to the Northwest Passage, is experiencing the greatest levels of vessel traffic in the Canadian Arctic, and is important habitat for marine wildlife, including marine mammals and seabirds. Here, we examined the overlap between vessel traffic, including modeled underwater noise levels, and the distribution of two cetacean species, beluga and narwhal, and three seabird species, thick-billed murre, northern fulmar, and black-legged kittiwake. Narwhal had the highest vessel risk in Eclipse Sound and Milne Inlet, all three seabirds had high vessel risk at the eastern entrance to Eclipse Sound, with additional areas for northern fulmar at southern Devon Island and for black-legged kittiwake at Prince Leopold Island, and belugas had the highest vessel risk along southern and eastern Devon Island. Our results provide crucial information for implementing monitoring, conservation, and management initiatives for species inhabiting this protected area, and allow for a better understanding of the potential cultural implications of vessel-based marine wildlife impacts that will affect traditional subsistence hunting and local livelihoods.

Using western science and Inuit knowledge to model ship-source noise exposure for cetaceans (marine mammals) in Tallurutiup Imanga (Lancaster Sound), Nunavut, Canada

Tallurutiup Imanga (TI) is a National Marine Conservation Area (NMCA) established in 2019 at the eastern entrance of the Northwest Passage in Lancaster Sound, Nunavut, Canada, to protect 110,000 square kilometres of core habitat for cetaceans. This study examines the potential impacts of underwater noise from increased ship traffic in TI NMCA on three cetaceans: narwhal, beluga whale, and bowhead whale. Automatic Identification System data from 2015 to 2018 were used to spatially analyse ship traffic in the area. Sound propagation loss was modelled using vessel positions along major routes and then used to model vessel acoustic noise outputs. Areas populated by narwhal, beluga and bowhead whales were identified using western science and Inuit knowledge and then overlapped with the vessel noise outputs. Results indicate that an increasing number of ships are transiting important habitat areas for cetaceans and that this has resulted in some areas where the National Oceanic and Atmospheric Association 120 dB behavioural threshold for marine mammals has been exceeded. This suggests that in some areas of TI NMCA ship noise may negatively impact marine mammal hearing and behaviour, with the highest potential exposures in Eclipse Sound and Milne Inlet.

Narwhal Abundance in the Eastern Canadian High Arctic in 2013

In summer, narwhals (Monodon monoceros) migrate from Baffin Bay to northeastern Canada and northwest Greenland, where they are hunted by Inuit for subsistence. To prevent localized depletion, management of narwhals is based on summer stocks. The High Arctic Cetacean Survey (HACS), conducted in August 2013, was the first survey to estimate abundance of all 4 Canadian Baffin Bay narwhal summer stocks, as well as putative stocks in Jones Sound and Smith Sound, in the same summer. Narwhal abundance was estimated using a double-platform aerial survey. Distance sampling methods were used to estimate detection probability away from the track line. Mark-recapture methods were used to correct for the proportion of narwhals missed by visual observers on the track line (i.e., perception bias). We used a data-driven approach to identify single and duplicate sightings, using 4 covariates to compare differences in sightings made by front and rear observers based on: time of sighting, declination angle, group size, and species identity. Abundance in fjords was estimated using density surface modelling to account for their complex shape and uneven coverage. Estimates were corrected for availability bias (narwhals that are not available for detection because they are submerged when the aircraft passes overhead) using a new analysis of August dive behaviour data from narwhals equipped with satellite-linked time depth recorders. Corrected abundance estimates were 12,694 (95% CI: 6,324–25,481) for the Jones Sound stock; 16,360 (95% CI: 3,833–69,836) for the Smith Sound stock; 49,768 (95% CI: 32,945–75,182) for the Somerset Island stock; 35,043 (95% CI: 14,188–86,553) for the Admiralty Inlet stock; 10,489 (95% CI: 6,342–17,347) for the Eclipse Sound stock; and 17,555 (95% CI: 8,473–36,373) for the East Baffin Island stock. Total abundance for these 6 stocks was estimated at 141,908 (95% CI: 102,464–196,536). Sources of uncertainty arise from the high level of clustering observed, in particular in Admiralty Inlet, Eclipse Sound, and East Baffin Island, as well as the difficulty in identifying duplicate sightings between observers when large aggregations were encountered.

Offshore bedrock geology of Eclipse Sound and Pond Inlet: connecting the structure and stratigraphy of Bylot and northern Baffin islands

Understanding the Mesoproterozoic and younger structural history of the Eclipse Sound/Pond Inlet area is essential for the interpretation of its Archean to Paleoproterozoic geological history and could have important implications for mineral and petroleum exploration models in the northern Baffin Bay area. The identification of potentially active faults is critical for understanding possible earthquake-related hazards in the area. The integrated interpretation of 1970s-vintage marine seismic data with hill-shaded bathymetry, aeromagnetic data, and onshore geology maps has facilitated the identification of probable Mesoproterozoic (Bylot Supergroup) to Holocene strata on and below the sea floor and a suite of episodically reactivated northwest-striking horst- and graben-bounding normal faults and fault zones. Fault displacement likely occurred during the development of the Mesoproterozoic Borden basin and the Cretaceous–Paleogene opening of Baffin Bay, and in some cases may continue today. Some faults become more west-trending toward the south, which requires parts of these faults to have intermittently accommodated transtensional and (or) transpressional motion, possibly explaining local folds and out-of-graben thrusting. Numerous previously unrecognised faults have been documented, with faults beneath Eclipse Sound (Eclipse Trough) spaced at 5 to 7 km intervals, and at least one fault zone (Cape Hay Fault Zone) that appears to be at least 250 km in length, suggesting faults of similar spacing and scale may be present under Baffin Bay. This study uses a multi-thematic office-based methodology that inexpensively, and with little environmental impact, facilitates the mapping of structures that intersect the sea floor in areas where glaciers have exposed bedrock.

Trace element and stable isotope analysis elucidate stock structure in a narwhal (Monodon monoceros) population with no genetic substructure

Chemical composition of tissues can act as a biological tag to discriminate among groups of animals that inhabit different areas. In Canada, subsistence hunting of the Baffin Bay narwhal (Monodon monoceros Linnaeus, 1758) population is managed as stocks represented by summer aggregations. However, narwhals are highly mobile and are hunted during the migration while stocks mix. Thus, information that can help managers decipher the stock origin of hunted individuals to prevent overexploitation of animals adapted to particular summering grounds is needed. Stable isotope and trace element analyses were conducted on narwhal skin tissues from five stocks in the eastern Canadian Arctic from 1990 to 2015. Discriminant analysis showed a significant difference between Admiralty Inlet and Eclipse Sound stocks in the summer residency period and both differed from Jones Sound and Somerset Island. During the migration season, there was more overlap and less distinction among stocks, but 75% of animals were classified correctly to their defined stocks in both periods. Together stable isotope and trace element analyses are useful for delineating stocks and could be used to complement other stock discrimination approaches.

Landfast sea ice-benthic coupling during spring and potential impacts of system changes on food web dynamics in Eclipse Sound, Canadian Arctic

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 627:33-48 (2019) - DOI: https://doi.org/10.3354/meps13071 Landfast sea ice-benthic coupling during spring and potential impacts of system changes on food web dynamics in Eclipse Sound, Canadian Arctic Doreen Kohlbach1,*, Steven H. Ferguson1, Thomas A. Brown2, Christine Michel1 1Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba R3T 2N6, Canada 2Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll PA37 1QA, UK *Corresponding author: doreen.kohlbach@awi.de ABSTRACT: We investigated the role of sea ice-derived carbon in the food web of Eclipse Sound, Canadia Arctic during the spring ice-covered season to understand the potential ecological impact of changes to the sea-ice habitat. Chlorophyll a (chl a) concentrations in the bottom of sea ice (438.2 ± 154.2 µg l-1, 19.8 ± 6.6 mg m-2) were more than 2 orders of magnitude higher than in surface waters (0.9 ± 0.7 µg l-1). Fatty acid (FA) composition showed that algal communities in the bottom sea ice comprised higher abundances of diatoms compared to surface waters. Benthic invertebrates (ophiuroids, polychaetes) and sediments had high proportions of diatom-associated FAs in their lipid composition. H-Print estimates of the proportional contributions of sea ice-derived carbon to the carbon pool of the benthic community were substantial, ranging on average between 77 and 85%. High carbon stable isotope values (δ13C) in benthic invertebrates and sediments (δ13C: -19.6 to -11.6‰) further suggests that a large portion of the benthic carbon pool was of sea-ice origin, while surface waters were significantly lower (δ13C: -22.32 ± 2.17‰). In this ecosystem where landfast ice is present for most of the year, strong sea ice-benthic coupling emphasizes the dependency of the food web on ice productivity. As timing and magnitude of sea ice-derived carbon will change under alterations of climatic conditions and possibly with increased shipping activities in the study region, the adaptive capacity of sea ice-dependent species is anticipated to play a key role in determining future food webs. KEY WORDS: Sea ice · Ice algae · Carbon sources · Climate change · Fatty acids · Stable isotopes · Canadian Arctic · Eclipse Sound · Pond Inlet Full text in pdf format Supplementary material PreviousNextCite this article as: Kohlbach D, Ferguson SH, Brown TA, Michel C (2019) Landfast sea ice-benthic coupling during spring and potential impacts of system changes on food web dynamics in Eclipse Sound, Canadian Arctic. Mar Ecol Prog Ser 627:33-48. https://doi.org/10.3354/meps13071 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 627. Online publication date: September 26, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Spring distribution of ringed seals (Pusa hispida) in Eclipse Sound and Milne Inlet, Nunavut: implications for potential ice-breaking activities

Resource development in Arctic waters is proceeding rapidly leading to increased interactions with Arctic wildlife. As sea ice extent decreases, the demand for shipping and ice-breaking operations will expand into winter and spring with greater impact on ice-dependent pinnipeds. However, knowledge of the distribution of these species, such as ringed seals (Pusa hispida (Schreber, 1775)), during spring within areas of resource development is lacking. Baffinland Iron Mines Corporation’s Mary River iron ore port in southern Milne Inlet, Nunavut opened in 2015 with proposed ice-breaking activities in spring — an important period in ringed seal seasonal life-history. We conducted infrared and photographic aerial surveys in June 2016 and 2017 to overlay the proposed ice-breaking route with ringed seal hotspots (i.e., areas of higher density). We identified four areas of overlap where proposed ice-breaking would traverse through ringed seal hotspots: eastern and western Eclipse Sound (a ringed seal pupping ground identified by local knowledge), the middle of Milne Inlet, and southern Milne Inlet. We identified potential negative implications of spring ice-breaking operations on ringed seals such as displacement, separation of mothers and pups, destruction of resting and birth lairs, and vessel–seal collisions. Results are relevant to policy decision-makers who can develop mitigation strategies in the rapidly melting and developing Arctic.

Seasonal vessel activity risk to seabirds in waters off Baffin Island, Canada

Millions of seabirds use the waters off Baffin Island. Considering current and future vessel activity in this region, it is important to understand where vulnerability to anthropogenic threats is highest to enable sound wildlife management and regulatory decisions. Using kernel density analysis on at-sea survey data spanning 1970 to 1983 and 2007 to 2016, we identified marine areas of high density for five of the most abundant species sighted: Dovekie Alle alle, Thick-billed Murre Uria lomvia, Black-legged Kittiwake Rissa tridactyla, Northern Fulmar Fulmarus glacialis and Black Guillemot Cepphus grylle, in summer (June–August) and fall (September–November). We quantified the level of vessel activity from vessel traffic data spanning 2011 to 2015. Overlapping these data layers, we identified regions where high vessel activity posed the highest risk to these species. Navy Board Inlet, Eclipse Sound, Frobisher Bay, Hudson Strait and the northern Labrador Shelf were consistently identified as areas of highest risk to multiple species of seabirds in summer and autumn. These waters not only encompass important summer foraging areas near colonies and post-breeding/migratory habitat but are also frequently navigated by vessels servicing busy communities. The level of vessel activity we found for the study area is relatively low compared to waters where many Arctic species overwinter (e.g., Thick-billed Murres off Newfoundland and Labrador). However, identifying current high-risk areas in Arctic waters is important for the conservation and management of Arctic seabirds as industrial and commercial development in this region expands and leads to higher levels of vessel activity.

Baffin Bay narwhal (Monodon monoceros) select bathymetry over sea ice during winter

Arctic pack ice structure and extent have been changing due to warming. Thus, understanding important habitat features for marine mammals that depend on sea ice, such as narwhal (Monodon monoceros), during winter will provide insight into impacts of future changes within the pack ice. The objective of this study was to determine narwhal habitat selection for bathymetry, sea ice concentration, thickness, and floe size during the winter season. Nineteen narwhals were equipped with SPLASH tags in Admiralty Inlet and Eclipse Sound (2009–2011), with 50% of the transmitters lasting until April allowing for analysis of the entire winter season. Generalized linear mixed models indicated that both sexes selected similar bathymetric habitat likely corresponding to higher prey densities of Greenland halibut. This preference for prey habitat occurred regardless of the mobile pack ice structure or amount of open water at the ocean surface. In addition, we found evidence of a potential relationship between increased winter movements and decreased ice extent over the 2009–2011 period. Together these findings suggest that changes to sea ice structure likely will not negatively impact narwhal directly in the winter. However, indirect effects of changing sea ice, such as changing prey densities and distribution, increased presence of killer whales (Orcinus orca) as predators, increased interspecies competition for prey, and increased anthropogenic activities could influence winter habitat selection of narwhal. In conclusion, the extensive winter movements indicate that narwhal may be more flexible in their selection of winter habitat than previously believed.

Spatial distribution of narwhal (Monodon monoceros) diving for Canadian populations helps identify important seasonal foraging areas

In Canada, narwhals (Monodon monoceros L., 1758) are divided into the Baffin Bay (BB) and northern Hudson Bay (NHB) populations. Satellite tracking of 21 narwhals from BB and NHB provided information on their diving behaviour and was used to identify foraging regions. Previous research from hunted narwhals indicated that narwhals in both populations depend on benthic prey to meet their dietary needs. To evaluate home ranges and define areas important for benthic foraging, we conducted kernel density analysis on narwhal locations and focused on areas where deep diving occurs, as a proxy for foraging, in the winter, spring, and migratory periods. These analyses revealed important areas for foraging for BB narwhals on the summer grounds in Eclipse Sound, and the winter grounds in Davis Strait, as well as on the migratory pathway between regions. Similarly, important areas were identified for the NHB narwhal population in northwestern Hudson Bay in summer, in NHB and Hudson Strait on the migration, and to the east of the entrance to Hudson Strait in the winter. This, along with an analysis of the absolute dive depths, provides information on seasons and regions important for foraging, which is particularly relevant with increasing industrial activities in the Arctic.

Crag-and-tail features: convergent ice flow through Eclipse Sound, Baffin Island, Arctic Canada

Elongate glacial landforms are typically orientated in the direction of ice flow (Benn & Evans 2010). They are often preserved in the submarine environment, providing information on past ice-sheet extent and flow pathways. The northeastern margin of the Laurentide Ice Sheet (LIS) covered much of eastern Baffin and Bylot islands during the Last Glacial Maximum (Dyke et al. 2002). Numerous elongate landforms on the seafloor of Eclipse Sound and Pond Inlet indicate the direction of ice flow around Bylot Island in the Canadian Arctic (Fig. 1b; Bennett et al. 2014). Fig. 1. Multibeam swath bathymetry, longitudinal profile, cross-section and sub-bottom acoustic profile of elongate submarine features in Eclipse Sound, Arctic Canada. ( a ) Location of study area (red box; map from IBCAO v. 3.0). ( b ) Sun-illuminated multibeam-bathymetric image of convergent crag-and-tails. Acquisition system Kongsberg Simrad EM300. Frequency 30 kHz. Grid-cell size 10 m. ( c ) Ice-flow lines inferred from crag-and-tails (white lines). Glacier flow is from SW to NE (white arrow). Crag-and-tails are roughly distributed in arcs of decreasing radius from SW to NE (red lines). ( d ) Longitudinal profile through a crag-and-tail (located in (b)). VE×4. ( e ) Cross-profile through crag-and-tails. Black arrows mark five sedimentary tails. VE×8. ( f ) Shallow sub-bottom profile across Eclipse Sound showing …

Benthic faunal assimilation pathways and depth-related changes in food-web structure across the Canadian Arctic

Climate changes in the Arctic are expected to decrease the currently tight pelagic–benthic coupling, yet large-scale, regional understanding of the origin of food for benthic organisms across both biological productivity and depth gradients is still missing. The organic matter assimilation pathways of benthic organisms, along with food-web structure, were investigated at shelf and slope locations spanning 2000km across the Canadian Arctic using stable carbon and nitrogen isotope analysis. Three potential food sources and over 75 benthic taxa belonging to four feeding guilds were analyzed, but the δ13C end-members for the benthic food-webs could not be clearly discerned. While spatial patterns of δ13C for pelagic particulate organic matter were linked to phytoplankton biomass at the time of sampling, sediment δ13C values reflected the relative composition of terrestrial and marine organic matter. On average, benthic primary consumers were enriched in 13C by 5 and 7‰ compared to the potential organic matter sources sampled in sediment and the water column, respectively. The δ13C discrepancy between identified sources of organic matter and benthic organisms suggests that an uncharacterized food source provided a significant carbon source to these animals. We propose that the 13C enrichment of benthic organisms may be largely caused by the assimilation of ice algae (which were not sampled in this study), particularly in regions of known high ice-algal standing stock such as Barrow Strait and Eclipse Sound. The δ15N values of bottom-water particulate organic matter and of benthic primary consumers increased with depth due to greater degradation of the settling organic material. The δ15N values of secondary consumers did not increase with depth, leading to a decrease of their trophic position compared with shallower regions and likely reflecting an increase in omnivory due to scarcity of prey at depth. This study emphasizes the potential importance of sea-ice algae as a carbon source for benthic communities in the Canadian Arctic and suggests that distinct food-web structures prevail over the shelf and slope.

Geographic variation in cranial morphology of narwhals (Monodon monoceros) from Greenland and the eastern Canadian Arctic

We analyzed variation in nine non-metric and eight metric variables in the skulls of 132 narwhals (Monodon monoceros) from five localities in Greenland (Inglefield Bredning, Melville Bay, Uummannaq, Disko Bay, and Scoresby Sound) and one in the eastern Canadian Arctic (Eclipse Sound). Metric variables were used to compare the combined Disko Bay and Uummannaq samples with the samples from Inglefield Bredning and Scoresby Sound using three different multivariate techniques for each sex. None of the results were significant. Seven of the non-metric variables were independent of age and sex and were used in comparing samples from the six localities. No differences were found among the four localities in West Greenland, but differences were found in two of the non-metric variables between the combined West Greenland sample and the one from Scoresby Sound. A major shortcoming of the analysis based on metric data was the small sample size from several of the areas, which resulted in low statistical power. Genetic as well as environmental factors could explain the differences detected here between narwhals living along the west and the east coasts of Greenland.