Marine Mammals Research Articles

Quantifying Sound Exposure in a Pool: Comparing Hydrophones on a Grid with a Sound-Recording Tag on a California Sea Lion (Zalophus californianus)

Investigating anthropogenic acoustic disturbance and sound exposure in marine mammals requires evaluation of experimental approaches used to measure the sound levels experienced by the subjects. In previous research, exposure of California sea lions (Zalophus californianus) to eight narrow noise bands was estimated as the mean sound pressure level (SPL) measured by hydrophones placed at multiple locations and depths in a pool. We compare this method of SPL estimation with SPLs measured with a sound recording tag (“D-tag”). Measurements were taken from (1) hydrophones at locations on a grid; (2) a D-tag at the same locations; (3) a D-tag attached in its housing to a harness on a sea lion swimming freely in the pool; (4) a D-tag in its housing in one position in the pool; (5) a D-tag on the sea lion in one position in the pool; and (6) a D-tag turning in one location in the pool without its housing, in its housing, and on the sea lion while she rotated on her body axis. The SPLs recorded by the D-tag on a free-swimming sea lion were ~8 to 10 dB lower than those measured by the grid hydrophones, and the differences varied by frequency. These differences in SPL are caused by a combination of the directionality associated with the D-tag itself, the presence of the housing, acoustic effects of the sea lion’s body, and periods that the D-tag was out of the water during respirations. Measuring mean sound levels in test pools using hydrophones deployed on grids is valid; however, attaching tags to wild marine mammals may be more feasible than using hydrophone grids at sea. We summarize considerations when selecting a method to fit the design of future research.

Monitoring Bottlenose Dolphin (Tursiops truncatus) Welfare During a Functional Neuroimaging Study

The development of non-invasive methods to study brain structure and function has enabled a flowering of cognitive neuroscience in humans and nonhuman species. Herein, we describe the development of protocols for functional magnetic resonance imaging (fMRI) of a bottlenose dolphin (Tursiops truncatus), including protocols to monitor the health and welfare of the subject over the course of our five-year study. A Welfare Control Plan (WCP) was designed to monitor, enhance, and protect our subject’s welfare throughout the course of the study. The WCP was developed so our team of marine mammal veterinarians, trainers, and researchers could (1) identify study procedures that might negatively impact the individual’s welfare and propose measures to mitigate them, (2) define and implement protocols for monitoring the individual’s welfare throughout the study, and (3) determine the study’s temporary or final endpoints. Overall, behavioral, physiological, and health welfare indicators showed that the dolphin’s quality of life was not negatively impacted by participating in our functional neuroimaging study. Our study provides an example of how innovative, ambitious, and logistically complex animal studies can successfully be performed while protecting the welfare of participating animals through adequate planning, enough human and economic resources, and full human/institutional commitment to animal welfare.

Effectively managing area-based management tools: A new toolkit for the conservation of marine mammals

Marine mammals play crucial roles in marine ecosystem function yet are threatened by increasing pressures from anthropogenic activities within marine ecosystems. Area-based Management Tools (ABMT) are key for their conservation and protection, yet their effectiveness is often hindered by lack of resources, technical capacity and political support. Yet, ABMTs are grounded in local, national, regional, and international agreements and policy frameworks including the Kunming-Montreal Global Biodiversity Framework (GBF). To support marine managers, the “Marine Mammals Management Toolkit” was developed and is composed of three core components, including the Self-Assessment Tool (SAT), founded on the Protected Area Management Effectiveness (PAME) framework, and is a multiple-choice tool that enables managers to evaluate the effectiveness of management plans regarding marine mammals through the production of a Management Effectiveness Score (MES). The SAT has been utilised across 24 MPAs in 18 countries. Two case studies are provided on its application. The Stellwagen Bank National Marine Sanctuary (SBNMS) evaluated their existing management plan, and scored an MES value of 7.8 with the Bermuda Marine Mammal Sanctuary (BMMS) scoring 4.7. The results of the SAT enabled the Bermudian Government to make informed decisions in developing a Marine Spatial Plan for the BMMS, and enables SBNMS to set a baseline to track effectiveness over the life-time of SBNMS and respective management plans; guiding local and national policy, as well as enabling Bermuda and the United States of America to contribute to their international commitments.

Using unmanned aerial vehicles to estimate body volume at scale for ecological monitoring

Abstract Demographic data are essential to construct mechanistic models to understand how populations change over time and in response to global threats like climate change. Existing demographic data are either lacking or insufficient for many species, particularly those that are challenging to obtain direct measurements from that can be used to estimate demographic rates, like marine mammals. A method for collecting accurate demographic data to construct robust demographic models at scale would fill this knowledge gap for difficult‐to‐access species. We introduce a novel, non‐invasive method to estimate the 3D body size (volume) of pinnipeds (seals, sea lions and walruses) that will allow monitoring at high spatial and temporal scales. Our method integrates 3D structure‐from‐motion photogrammetry data collected via planned flight missions using off‐the‐shelf, multirotor unmanned aerial vehicles (UAVs). We apply and validate this method on the grey seal Halichoerus grypus, a pinniped species that spends much of its time at sea but is predictably observable during its annual breeding season. We investigate the optimal ground sampling distance (GSD) for surveys by calculating the success rates and accuracy of volume estimates of individuals at different altitudes. Based on current technology, we establish an optimal GSD of at least 0.8 cm px−1 for animals similar in size to UK grey seals (~1.2–2.5 m length), making our method reproducible and applicable to other species. We found volume estimates were accurate and could be successfully estimated for up to 68% of hauled‐out seals in study areas. Our method accurately estimates individual body volume of pinnipeds in a time‐ and cost‐effective manner while minimising disturbance. While the approach is applied to pinnipeds here, the method could be adapted to further taxa that are otherwise challenging to obtain direct measurements from. Our proposed approach therefore has the potential to fill demographic research gaps, which will improve our ability to protect and conserve species into the future.

Unstable pathogen profile in spotted seal (Phoca largha) gut microbiota and limited turnover with habitat microbiome.

It is vital that we monitor the gut microbiota of sentinel species such as spotted seals (Phoca largha) and their association with habitat microbiomes, which can provide critical data for assessing the health of marine mammals and their potential ecological influences. In this study, PacBio technology was used to sequence the full-length bacterial 16S rRNA gene from the feces of captive and wild spotted seals, as well as samples from a wild population and their habitats. Based on the pathogen identification results, the gut microbiota of wild and captive spotted seals showed similar levels of pathogen richness and abundance. In particular, the pathogen profiles in wild spotted seals were more variable, with a high risk of disease in a minority of individuals. Meanwhile, the gut microbiota of spotted seals was significantly less diverse than their habitat microbiomes. Firmicutes and Proteobacteria dominated the gut microbiota of spotted seals and their habitat microbiomes, respectively. Furthermore, network analysis revealed that the gut microbiota of spotted seals was simple and weak. The ratios of microbial turnover between spotted seal gut microbiota and their habitat microbiomes were further analyzed using SourceTracker, and the estimated values were low (< 0.1%). These results provide baseline data on pathogen profiles in spotted seals and their potential interactions with habitat microbiomes.

Epidemiological data of an influenza A/H5N1 outbreak in elephant seals in Argentina indicates mammal-to-mammal transmission.

H5N1 high pathogenicity avian influenza virus has killed thousands of marine mammals in South America since 2022. Here we report epidemiological data and full genome characterization of clade 2.3.4.4b H5N1 HPAI viruses associated with a massive outbreak in southern elephant seals (Mirounga leonina) at Península Valdés, Argentina, in October 2023. We also report on H5N1 viruses in concurrently dead terns. Our genomic analysis shows that viruses from pinnipeds and terns in Argentina form a distinct clade with marine mammal viruses from Peru, Chile, Brazil and Uruguay. Additionally, these marine mammal clade viruses share an identical set of mammalian adaptation mutations which were also present in tern viruses. Our combined ecological and phylogenetic data support mammal-to-mammal transmission and occasional mammal-to-bird spillover and suggest multinational transmission of H5N1 viruses in mammals. We reflect that H5N1 viruses becoming more evolutionary flexible and adapting to mammals in new ways could have global consequences for wildlife, humans, and/or livestock.

Persistent organic pollutants among seafood processing workers in West Greenland

The Greenlandic population is highly exposed to persistent organic pollutants (POPs) through the consumption of traditional marine food, including marine mammals. Central to Greenland's economy and cultural identity, the fishing industry employes about 15% of the working population.This study investigated POP exposure, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFASs), among seafood processing workers at the Greenlandic west coast. We examined determinants for the POPs including age, smoking habits, ethnicity, and working place. Additionally, we explored the association between POPs and the prevalence of asthma, allergy, and lung function.With samples taken during 2016–2018, the study encompassed 382 workers, primarily of Inuit descent (93%), employed across three large factories located in Nuuk, Sisimiut, and Ilulissat, four smaller factories in settlements (Kangaatsiaq, Ikerasaarsuk, Sarfannguaq, Qeqertarsuaq), and four factory trawlers. Data collected include clinical examinations, questionnaires on ethnicity, occupational exposure status, health indicators, and smoking habits, and serum selenium and POP analyses. We used ANCOVA with adjustment for relevant confounders to assess differences in POPs between groups (e.g. ethnic groups and working place), and multiple linear and logistic regressions were used to assess associations between POPs and lung function, allergy and asthma.Significant differences in POPs were observed among ethnic groups; Faroese workers had the highest concentrations of lipophilic POPs (lipPOPs; PCBs and OCPs), while Inuit workers exhibited highest PFASs. All subsequent analyses were focused on the Inuit workers (n = 337). The PFASs were significantly higher in workers at small factories, followed by large factories and trawlers, whereas no differences were seen for lipPOPs. The differences between the working places were most likely due to differences in lifestyle and diet, but occupational exposures cannot be excluded.LipPOP and PFAS concentrations associated positively with selenium, and PFASs positively associated with lung function. However, upon adjustment of selenium, the associations between PFASs and lung function became non-significant and attenuated towards null. No significant associations were found between POPs and the prevalence of asthma or allergy.Compared to the general population in the same area and period, the seafood processing workers exhibited 2–6 times higher POP levels. The higher exposure level among seafood processing workers, as well as the difference across workplaces, underscore the need for further investigation of environmental and occupational sources of POPs in this population. These findings may contribute to future public health strategies and regulatory measures to reduce POP exposure in Arctic populations.

A comprehensive epidemiological approach documenting an outbreak of H5N1 highly pathogenic avian influenza virus clade 2.3.4.4b among gulls, terns, and harbor seals in the Northeastern Pacific

Highly pathogenic avian influenza viruses (HPAIV) H5N1 clade 2.3.4.4b continue to have unprecedented global impacts on wild birds and mammals, with especially significant mortality observed in colonial surface-nesting seabirds and in some marine mammal species. In July of 2023 H5N1 HPAIV 2.3.4.4b was detected in Caspian terns nesting on Rat Island, Washington USA. An estimated 1,800–1,900 adult terns populated the breeding colony, based on aerial photographs taken at the start of the outbreak. On a near-weekly basis throughout July and August, we counted and removed carcasses, euthanized moribund birds, and collected swab and tissue samples for diagnostic testing and next-generation sequencing. We directly counted 1,101 dead Caspian tern adults and 520 dead chicks, indicating a minimum 56% loss of the adult colony population and potential impacts to reproductive success. Combining the observed mortality on Rat Island with HPAI-related Caspian tern deaths recorded elsewhere in Washington and Oregon, we estimate that 10–14% of the Pacific Flyway population was lost in the summer of 2023. Comparatively few adult Glaucous-winged gulls (hybrids) nesting on Rat Island died (~3% of the local population), although gull chick mortality was high. Sixteen harbor seals in the immediate or nearby area stranded during the outbreak, and H5N1 HPAIV was detected in brain and/or lung tissue of five seals. These cases are the first known detections of HPAIV in a marine mammal on the Pacific coast of North America. Phylogenetic analyses support the occurrence of at least three independent avian-mammalian virus spillover events (tern or gull to harbor seal). Whole genome sequencing indicated that H5N1 HPAIV may have been introduced to Washington from Caspian terns in Oregon. Ongoing monitoring and surveillance for H5N1 HPAIV in the marine environment is necessary to understand the epidemiology of this virus, assess conservation impacts to susceptible species, and provide support for data-driven management and response actions.

Neurodegenerative Diseases: What Can Be Learned from Toothed Whales?

Neurodegeneration involves a wide range of neuropathological alterations affecting the integrity, physiology, and architecture of neural cells. Many studies have demonstrated neurodegeneration in different animals. In the case of Alzheimer's disease (AD), spontaneous animal models should display two neurohistopathological hallmarks: the deposition of β-amyloid and the arrangement of neurofibrillary tangles. However, no natural animal models that fulfill these conditions have been reported and most research into AD has been performed using transgenic rodents. Recent studies have also demonstrated that toothed whales - homeothermic, long-lived, top predatory marine mammals - show neuropathological signs of AD-like pathology. The neuropathological hallmarks in these cetaceans could help to better understand their endangered health as well as neurodegenerative diseases in humans. This systematic review analyzes all the literature published to date on this trending topic and the proposed causes for neurodegeneration in these iconic marine mammals are approached in the context of One Health/Planetary Health and translational medicine.

Estimating Demographic Parameters for Bearded Seals, Erignathus barbatus, in Alaska Using Close-Kin Mark-Recapture Methods.

Reliable estimates of population abundance and demographics are essential for managing harvested species. Ice-associated phocids, "ice seals," are a vital resource for subsistence-dependent coastal Native communities in western and northern Alaska, USA. In 2012, the Beringia distinct population segment of the bearded seal, Erignathus barbatus nauticus, was listed as "threatened" under the US Endangered Species Act requiring greater scrutiny for management assessments. We sought to estimate requisite population parameters from harvested seals by using close-kin mark-recapture (CKMR) methods, the first such application for marine mammals. Samples from 1758 bearded seals harvested by Bering, Chukchi, and Beaufort Sea communities during 1998-2020 were genotyped, genetically sexed, and aged by tooth annuli. After rigorous quality control, kin relationships were established for 1484 seals including two parent-offspring pairs (POPs) and 25 potential second-order kin pairs. Most of the second-order kin were half-sibling pairs (HSPs), but four were potential grandparent-grandchild pairs (GGPs). There were no full sibling pairs, suggesting a lack of mate fidelity. Mitochondrial DNA analysis identified 17 potential HSPs as paternally related, providing substantial evidence of persistent heterogeneity in reproductive success among adult males. The statistical CKMR model incorporates probabilities associated with POPs, HSPs, and GGPs and assumes known ages and a stable population. Our top model accommodates heterogeneity in adult male breeding success and yields an abundance estimate of ~409,000 with a coefficient of variation (CV) = 0.35, which is substantially greater than the "non-heterogeneity" model estimate of ~232,000 (CV = 0.21), an important difference for managing a harvested species. Using CKMR methods with harvested species provides estimates of abundance with the added opportunity to acquire information about adult survival, fecundity, and breeding success that could be applied to other species of concern, marine and terrestrial.

Despite the perception that it is rare, by-catch of marine mammals can lead to population decline

Abstract By-catch, the unintentional capture of non-target species in fishing gear, is often described as a rare event when it pertains to marine mammals. Yet, it is the greatest threat to many marine megafauna species, especially small cetaceans. How can both of these statements be true simultaneously? The adjective “rare” is itself rarely defined in a precise and quantitative way. Data collection features are crucial to understand the processes leading to a perception of rarity in samples on by-catch of marine mammals and other protected, endangered and threatened species (PETS). Statistical principles in the design of monitoring schemes must be upheld to ensure sample representativeness when scaling up impact estimates to the level of whole fisheries. Random allocation of observers or monitoring technologies (e.g. Remote Electronic Monitoring) can be strengthened to test the hypothesis that by-catch is a rare event and not only a rarely registered event, especially in monitoring schemes that are not dedicated to PETS by-catch. Even if by-catch is a rare event at the level of a single fishing operation, given the large total number of the latter, and their expansive spatial and temporal extent, by-catch may still impact significantly marine mammal populations.

The impact of anthropogenic sound on marine mammals: A review

This paper aims to review and evaluate published literature on the impact of anthropogenic sound on marine mammals. A systematic method was utilized to access research works of literature on “Impact of Anthropogenic Sound on Marine Mammals”. A total of seventy-seven (77) research papers published between the years 1959 to 2022 were accumulated and used for this review. A subjective approach was used to select the topics: impact of anthropogenic sound and marine mammals. In this paper, six (6) detrimental impacts of anthropogenic sound on marine mammals were evaluated and presented. Anthropogenic sounds originate from a variety of sources such as explosions, commercial shipping, seismic exploration, sonar, research sound source, acoustic deterrent devices and pingers, polar icebreakers, industrial activities, offshore drilling, construction, small ships, boats, and personal watercraft. Among the main impacts identified were that anthropogenic sounds affect marine mammals by causing hearing loss, masking, change in behavior, habituation shift and mass stranding. A mini checklist of several species of marine mammals and different types of anthropogenic noise that affect them are presented. Marine mammals are capable of self-generating their own sounds and they are also affected by anthropogenic sounds that are not native to their natural environments. The published literature that was reviewed established that the global marine mammal population dynamics, abundance, distribution, navigation, ecology and behavior are all affected by anthropogenic sounds. This review highlights the fact that more extensive studies on the impact of anthropogenic sound on marine mammals should be done in neotropical countries since there are gaps of such information on research and published data in these biodiversity-rich regions.

An overview on the production, management and impact of microplastic contamination on marine species and marine environments: A review

The purpose of this paper is to review and evaluate published literature on the production, management and impact of microplastic contamination on marine species and marine environments. A systematic method was utilized to access research works of literature on “production, management and impact of microplastic contamination on marine species and marine environments”. A total of Sixty-two (62) research papers published between the years 1972 to 2022 was accumulated and used for this review. A subjective approach was used to select the topics: production, management and impact of microplastic contamination. In this paper, four (4) effects of microplastics on organisms and the environment was assessed. Additionally, the formation and classification of microplastics were evaluated. Subsequently, the paper delves into the production and the management of global plastic production as well as the sources of contamination. Further, this review assessed the quantity of microplastics in the gastrointestinal tract and edible muscles of various fish species. A mini checklist of sixty-one (61) fish species from thirty (30) families dwelling in nine (9) different marine habitats, all contaminated by microplastics was also presented in this review. Moreover, possible solutions to overcome the impact of microplastics on organisms and aquatic environments were also mentioned in this article. The published works of literature established that the global plastic production is constantly increasing with a growing world population thus leading to mismanagement of plastic resources and introducing them to the environment. Microplastics can cause serious complications in humans, marine organisms such as fishes, crustaceans, marine mammals and sea birds and even contribute to the degradation of mangrove forests and the coastal environment. This review highlights the fact that more extensive studies on the impact of microplastic contamination in organisms and the environment should be done in neotropical countries since there is a dearth and gaps of such information on research and published data in these biodiversity rich regions.

The impact of climate change on the ecology, reproduction and distribution of marine mammals and the possible legislation, conservation and management approaches to protect these marine mammal species: A systematic review

The impact of climate change on the ecology, reproduction and distribution of marine mammals and the possible legislation, conservation and management approaches to protect these marine mammal species: A systematic review

Questionnaire surveys to investigate marine mammal fisheries bycatch: systematic review and best practice

Bycatch is the most significant threat to marine mammals globally. There are increasing requirements for national governments to fulfil their obligations to international agreements and treaties to assess fisheries catch and bycatch of non-target species. Questionnaire surveys represent one low-cost method to collect data to estimate fisheries catch and bycatch of vulnerable species including marine mammals. Questionnaire surveys can be particularly advantageous when bycatch is being investigated on large spatial and temporal scales, or in data-poor areas. This review aims to provide the necessary guidance required to design and conduct questionnaire studies investigating marine mammal bycatch. To do so, a systematic review was conducted of the methods used in 91 peer-reviewed or grey literature questionnaire studies from 1990 to 2023 investigating marine mammal bycatch. Literature was searched, screened, and analysed following the RepOrting standards for Systematic Evidence Syntheses (ROSES) protocols. A narrative synthesis and critical evaluation of the methods used were conducted and best practice recommendations are proposed. The recommendations include suggestions for how to generate representative samples, the steps that should be followed when designing a questionnaire instrument, how to collect reliable data, how to reduce under-reporting and interviewer bias, and how weighting or model-based bycatch estimation techniques can be used to reduce sampling bias. The review’s guidance and best practice recommendations provide much-needed resources to develop and employ questionnaire studies that produce robust bycatch estimates for marine mammal populations where they are currently missing. Recommendations can be used by scientists and decision-makers across the globe. Whilst the focus of this review is on using questionnaires to investigate marine mammal bycatch, the information and recommendations will also be useful for those investigating bycatch of any other non-target species.

The arginine/ornithine binding protein ArgT plays an essential role in Brucella neotomae/Brucella melitensis to prevent intracellular killing and contribute to chronic persistence in the host

ABSTRACT Brucella species are facultative intracellular bacterial pathogens that cause the contagious zoonotic disease, brucellosis. Brucella spp. infect a wide range of animals, including livestock, wild animals, and marine mammals. Compared with other invasive bacterial pathogens, partial information is available on the virulence factors of Brucella that enable them to survive in the host. Here, we performed transposon-based random mutagenesis of B. neotomae and identified the arginine/ornithine binding protein, ArgT, as one of the crucial virulence determinants of Brucella. Deleting ArgT from B. neotomae or B. melitensis resulted in its attenuation in macrophages, which was restored upon complementation with an ArgT expression plasmid. We observed that macrophages infected with ΔArgT-B. neotomae produced elevated levels of NO due to the inability of these mutants to deplete the host intracellular arginine through their importer. Furthermore, defective survival of ΔArgT B. neotomae and B. melitensis was observed in the infected mice, which correlated with enhanced NO production in the mice. Our studies revealed that ArgT plays a vital role in preventing intracellular killing and contributes to the chronic persistence of B. neotomae/B. melitensis in the host. This study highlights the essential role of arginine in clearing intracellular infections and the subversion of this host defence mechanism by intracellular pathogens for their chronic persistence.

A review of climate change impacts on migration patterns of marine vertebrates in Arctic and Subarctic ecosystems

Climate change is impacting marine ecosystems throughout the circumpolar Arctic, altering seasonal habitats and the food bases for fishes, seabirds, and marine mammals. Arctic and Subarctic regions provide resources for resident species and for species that migrate to the north from more southerly regions. Changes in northerly latitudes thus impact endemic as well as non-endemic animals. Herein, we review what is known about climate-driven changes in the migration patterns of Arctic and Subarctic marine vertebrates, including: 1) Arctic residents with seasonal movements – those fishes, seabirds, and marine mammals that complete their entire life cycle within the Arctic but exhibit seasonal movements; 2) Breeding migrants – many seabirds enter the Arctic to breed and subsequently migrate south in the fall; and 3) Summer visitors for feeding – certain species of boreal fishes, seabirds and marine mammals arrive during the northern summer to feed on abundant prey though they breed elsewhere. Migratory movements are often driven by the timing and extent of sea ice, which defines suitable habitat for some animals and limits access to open water and prey for others. Longer open-water seasons, warmer ocean temperatures, and stronger winds have resulted in earlier production blooms in spring and often, extended open-ocean plankton blooms into late summer, resulting in altered prey types and distributions. A common thread among taxa is that shifts in distribution and timing of migrating animals indicate they are traveling farther north, or shifting longitudinally, and migrations are occurring over longer seasonal time frames. Species performing multiple lifetime migrations or long-distance migrants may need to adjust migration timing or routing iteratively to match changes in marine productivity. Altered animal distributions or phenology, and reduced sea ice, affects access to animals that are critical nutritional, economical, and cultural components of Indigenous people’s lives in the Arctic. Ongoing changes challenge the resilience and adaptability of Arctic people and ecosystems, and will require adaptive research and management approaches.

Exploring novel North Water Polynya ecosystems under climate change

Climate change is rapidly reshaping species distributions in the Arctic, which could profoundly impact ecosystem structure and function. While considerable effort has focused on projecting future species distributions, assessing the impacts of range-shifting species on recipient communities and subsequent disruptions to food webs remains largely unstudied. Here, we address this gap by combining species distribution models and ecosystem models to explore the emergence of novel ecosystems in the North Water Polynya. The North Water Polynya is an open-water area between Greenland and Canada, surrounded by sea ice and one of the world’s most productive ocean ecosystems. Using existing literature and projections from species distribution models of four marine species, we develop six plausible future ecosystem scenarios for the North Water Polynya. These scenarios include changing biomass of primary producers, changing biomass and size structure of copepods, shifting abundances of forage fish species, and the establishment of killer whales. We find that the biomass of higher trophic levels show pronounced decreases in response to the decrease in pelagic primary producers, with polar bear biomass halving compared to present conditions. Changes in the copepod size structure has the largest impact on the entire ecosystem compared to the other novel ecosystem scenarios, suggesting a strong reliance of higher trophic levels on large, lipid-rich copepods. We further show that increasing capelin with a simultaneous decrease in Arctic cod biomass causes large decreases in the biomass of marine mammals such as polar bear, beluga and ringed seal. Finally, we show the establishment of killer whales as a key novel predator could have cascading top-down effects on the North Water Polynya ecosystem. The framework presented here provides an approach for exploring the emergence of novel ecosystems and highlights how climate change could disrupt a high Arctic ecosystem.

A pictorial key to the adult and larval nasal mites (Halarachnidae) of marine mammals.

Mites in the family Halarachnidae are common endoparasites infesting the nasal tissues of a variety of marine mammals. These mites are easily transmissible and compromise the health of their hosts, especially in captive environments. While these mites are noted by marine mammal caretakers, they may easily be misidentified due to repeated revisions to halarachnid mite taxonomy and reclassification of misidentified specimens. Species identification currently requires multiple taxonomic keys, knowledge of revisions to species classifications through time, and training in acarology, which is impractical for marine mammal clinicians. Therefore, to summarize the known taxonomy and aid in future identification of halarachnid mites, we present a pictorial key composed of illustrations based on existing literature and images obtained by scanning electron microscopy (SEM) and high-resolution light microscopy (LM). Illustrations are organized into flow charts for the identification of both adult and larval stages. Dorsal shield silhouettes are also provided to facilitate the identification of adults. We hope that this key be used to simplify future taxonomic research, provide a standard for species identification, and aid in the diagnosis of halarachnid infestations in captive and rehabilitated marine mammal populations.

Are narwhals critical for the meat supply in East Greenland ?

In East Greenland, the recommendations for the closure of the narwhal (Monodon monoceros) hunt coincide with a pressing demand to continue hunting for meat to supply local communities. By analysing catch statistics and estimating average meat yields, the available meat from marine mammals, polar bears (Ursus maritimus), and muskox (Ovibos moschatus) in East Greenland can be assessed. On average, there was approximately 426 tonnes of meat available per year during this period. However, this quantity declined due to reduced catches of hooded seals (Cystophora cristata) and ringed seals (Phoca hispida) after 2007. This decline was somewhat offset by the inclusion of new species in the hunt, such as dolphins (Delphinidae), killer whales (Orcinus orca), and pilot whales (Globicephala melas). The average annual meat availability per inhabitant decreased from 150 kg before 2008 to 94 kg afterward. Narwhals consistently contributed approximately 5–6% of the total annual meat supply in Greenland over the observed period, which suggests that narwhal meat is not critical for the overall food supply. The inclusion of the need for meat in discussions surrounding sustainable harvest levels has been a point of controversy, particularly in cases where an urgent halt to hunting is needed.