Don't mind if I do: Arctic humpback whales respond to winter foraging opportunities before migration.

Migration patterns are fundamentally linked to the spatio-temporal distributions of prey. How migrating animals can respond to changes in their prey's distribution and abundance remains largely unclear. During the last decade, humpback whales (Megaptera novaeangliae) used specific winter foraging sites in fjords of northern Norway, outside of their main summer foraging season, to feed on herring that started overwintering in the area. We used photographic matching to show that whales sighted during summer in the Barents Sea foraged in northern Norway from late October to February, staying up to three months and showing high inter-annual return rates (up to 82%). The number of identified whales in northern Norway totalled 866 individuals by 2019. Genetic sexing and hormone profiling in both areas demonstrate a female bias in northern Norway and suggest higher proportions of pregnancy in northern Norway. This may indicate that the fjord-based winter feeding is important for pregnant females before migration. Our results suggest that humpback whales can respond to foraging opportunities along their migration pathways, in some cases by continuing their feeding season well into winter. This provides an important reminder to implement dynamic ecosystem management that can account for changes in the spatio-temporal distribution of migrating marine mammals.

Accuracy of Multiple Pulse Oximeters in Stable Critically Ill Patients.

BACKGROUND: An accurate SpO2 value is critical in order to optimally titrate oxygen delivery to patients and to follow oxygenation guidelines. Limited prospective data exist on real-world performance of pulse oximeters in critically ill patients. The objective of this study was to assess accuracy and bias of the SpO2 values measured by several oximeters in hospitalized subjects. METHODS: We included stable adults in the ICU with an arterial catheter in place. Main exclusion criteria were poor SpO2 signal and SpO2 > 96%. In each subject, we simultaneously evaluated 4 oximeters: Nonin (Plymouth, Minnesota) embedded in the FreeO2 device (OxyNov, Québec City, Québec, Canada), Masimo (Radical-7, Masimo, Irvine, California), Philips (FAST, Philips, Amsterdam, the Netherlands), and Nellcor (N-600, Medtronic, Minneapolis, Minnesota). Arterial blood gases were drawn and simultaneously each oximeters' SpO2 values were collected. SpO2 values were compared to the reference (arterial oxygen saturation [SaO2 ] value) to determine bias and accuracy. The ability for oximeters to detect hypoxemia and the impact of oximeters on oxygen titration were evaluated. RESULTS: We included 193 subjects (153 male, mean age 66 y) in whom 211 sets of measurements were performed. The skin pigmentation evaluated by Fitzpatrick scale showed 96.2% of subjects were light skin (types 1 and 2). One oximeter overestimated SaO2 (Philips, +0.9%), whereas the 3 others underestimated SaO2 (Nonin -3.1%, Nellcor -0.3%, Masimo -0.2%). SaO2 was underestimated with Nonin oximeter in 91.3% of the cases, whereas it was overestimated in 55.2% of the cases with Philips oximeter. Moderate hypoxemia (SaO2 86-90% or PaO2 55-60 mm Hg) was detected in 92, 33, 42, and 11% of the cases with Nonin, Nellcor, Masimo, and Philips, respectively. CONCLUSIONS: We found significant bias and moderate accuracy between the tested oximeters and the arterial blood gases in the studied population. These discrepancies may have important clinical impact on the detection of hypoxemia and management of oxygen therapy.

Round-trip migration and energy budget of a breeding female humpback whale in the Northeast Atlantic.

In the northern hemisphere, humpback whales (Megaptera novaeangliae) typically migrate between summer/autumn feeding grounds at high latitudes, and specific winter/spring breeding grounds at low latitudes. Northeast Atlantic (NEA) humpback whales for instance forage in the Barents Sea and breed either in the West Indies, or the Cape Verde Islands, undertaking the longest recorded mammalian migration (~ 9 000 km). However, in the past decade hundreds of individuals have been observed foraging on herring during the winter in fjord systems along the northern Norwegian coast, with unknown consequences to their migration phenology, breeding behavior and energy budgets. Here we present the first complete migration track (321 days, January 8th, 2019-December 6th, 2019) of a humpback whale, a pregnant female that was equipped with a satellite tag in northern Norway. We show that whales can use foraging grounds in the NEA (Barents Sea, coastal Norway, and Iceland) sequentially within the same migration cycle, foraging in the Barents Sea in summer/fall and in coastal Norway and Iceland in winter. The migration speed was fast (1.6 ms-1), likely to account for the long migration distance (18 300 km) and long foraging season, but varied throughout the migration, presumably in response to the calf's needs after its birth. The energetic cost of this migration was higher than for individuals belonging to other populations. Our results indicate that large whales can modulate their migration speed to balance foraging opportunities with migration phenology, even for the longest migrations and under the added constraint of reproduction.

Spatial variation in mercury concentrations in polar bear (Ursus maritimus) hair from the Norwegian and Russian Arctic.

We examined spatial variation in total mercury (THg) concentrations in 100 hair samples collected between 2008 and 2016 from 87 polar bears (Ursus maritimus) from the Norwegian (Svalbard Archipelago, western Barents Sea) and Russian Arctic (Kara Sea, Laptev Sea, and Chukchi Sea). We used latitude and longitude of home range centroid for the Norwegian bears and capture position for the Russian bears to account for the locality. We additionally examined hair stable isotope values of carbon (δ13C) and nitrogen (δ15N) to investigate feeding habits and their possible effect on THg concentrations. Median THg levels in polar bears from the Norwegian Arctic (1.99 µg g-1 dry weight) and the three Russian Arctic regions (1.33-1.75 µg g-1 dry weight) constituted about 25-50% of levels typically reported for the Greenlandic or North American populations. Total Hg concentrations in the Norwegian bears increased with intake of marine and higher trophic prey, while δ13C and δ15N did not explain variation in THg concentrations in the Russian bears. Total Hg levels were higher in northwest compared to southeast Svalbard. δ13C and δ15N values did not show any spatial pattern in the Norwegian Arctic. Total Hg concentrations adjusted for feeding ecology showed similar spatial trends as the measured concentrations. In contrast, within the Russian Arctic, THg levels were rather uniformly distributed, whereas δ13C values increased towards the east and south. The results indicate that Hg exposure in Norwegian and Russian polar bears is at the lower end of the pan-Arctic spectrum, and its spatial variation in the Norwegian and Russian Arctic is not driven by the feeding ecology of polar bears.

Haematology and clinical blood chemistry in harbour porpoises (Phocoena phocoena) from the inner Danish waters.

Harbour porpoises (Phocoena phocoena) in the Baltic Sea are under increasing pressure from anthropogenic activities, which affect the overall health of populations. Individuals' haematologic and biochemistry parameters are known to be linked to a population's health status and are therefore useful tools for cross-population comparisons and to assess health patterns of a population through time. However, it is often difficult to acquire data representing the full range of values and assess the influence of intrinsic and extrinsic factors. Here, we present the range of haematology and blood chemistry values obtained from 46 wild (n = 54 blood samples) individuals incidentally caught in pound-nets and five porpoises in long-term human care (n = 449 blood samples) from an outdoor semi-open facility in Denmark. Although it was not possible to formally test the differences between samples from free-ranging and captive individuals, lymphocyte values were lower for free-ranging animals whereas eosinophils and white blood cell values were higher in captive individuals. Aspartate aminotransferase and alanin aminotransferase values were also lower for captive individuals compared to free-ranging ones. Age group did not influence any of the blood parameters tested for free-ranging individuals. Sodium values were higher for males compared to females. Values were higher and lower in the fall for platelets and lactic acid dehydrogenase, respectively, compared to the other seasons. Based on samples yielded by individuals in long-term human care, haemoglobin, mean cell volume, white blood cells, absolute lymphocyte count, and alkaline phosphatase values were all influenced by health status based on clinical examination. These are therefore candidate parameters to assess health status of wild porpoises. Our results underline that it is essential to obtain ranges of reference values for all haematologic and biochemistry markers in order to assess health status of free-ranging individuals. Individuals in human care provide the opportunity to observe biological and ecological determinates (e.g. age, season) of long-term biomarker response patterns and to assess the suite of biomarkers best suited to predict individual health status.

Novel feeding interactions amplify the impact of species redistribution on an Arctic food web.

Species are redistributing globally in response to climate warming, impacting ecosystem functions and services. In the Barents Sea, poleward expansion of boreal species and a decreased abundance of Arctic species are causing a rapid borealization of the Arctic communities. This borealization might have profound consequences on the Arctic food web by creating novel feeding interactions between previously non co-occurring species. An early identification of new feeding links is crucial to predict their ecological impact. However, detection by traditional approaches, including stomach content and isotope analyses, although fundamental, cannot cope with the speed of change observed in the region, nor with the urgency of understanding the consequences of species redistribution for the marine ecosystem. In this study, we used an extensive food web (metaweb) with nearly 2,500 documented feeding links between 239 taxa coupled with a trait data set to predict novel feeding interactions and to quantify their potential impact on Arctic food web structure. We found that feeding interactions are largely determined by the body size of interacting species, although species foraging habitat and metabolic type are also important predictors. Further, we found that all boreal species will have at least one potential resource in the Arctic region should they redistribute therein. During 2014-2017, 11 boreal species were observed in the Arctic region of the Barents Sea. These incoming species, which are all generalists, change the structural properties of the Arctic food web by increasing connectance and decreasing modularity. In addition, these boreal species are predicted to initiate novel feeding interactions with the Arctic residents, which might amplify their impact on Arctic food web structure affecting ecosystem functioning and vulnerability. Under the ongoing species redistribution caused by environmental change, we propose merging a trait-based approach with ecological network analysis to efficiently predict the impacts of range-shifting species on food webs.

Pelagic vs Coastal-Key Drivers of Pollutant Levels in Barents Sea Polar Bears with Contrasted Space-Use Strategies.

In the Barents Sea, pelagic and coastal polar bears are facing various ecological challenges that may explain the difference in their pollutant levels. We measured polychlorinated biphenyls, organochlorine pesticides, polybrominated diphenyl ethers in fat, and perfluoroalkyl substances in plasma in pelagic and coastal adult female polar bears with similar body condition. We studied polar bear feeding habits with bulk stable isotope ratios of carbon and nitrogen. Nitrogen isotopes of amino acids were used to investigate their trophic position. We studied energy expenditure by estimating field metabolic rate using telemetry data. Annual home range size was determined, and spatial gradients in pollutants were explored using latitude and longitude centroid positions of polar bears. Pollutant levels were measured in harp seals from the Greenland Sea and White Sea-Barents Sea as a proxy for a West-East gradient of pollutants in polar bear prey. We showed that pelagic bears had higher pollutant loads than coastal bears because (1) they feed on a higher proportion of marine and higher trophic level prey, (2) they have higher energy requirements and higher prey consumption, (3) they forage in the marginal ice zones, and (4) they feed on prey located closer to pollutant emission sources/transport pathways.

Data on European seafood biomass production by country, sectors, and species in 2004-2014 and on ecological characteristics of the main species produced.

In this data article, we present the 2004-2014 average European seafood production volume by production sector, country, and species. The production data originates from the Food and Agriculture Organisation of the United Nations (FAO) and covers three production sectors: Marine fisheries, marine aquaculture, and freshwater production. We present the main ecological characteristics of each species produced or harvested. These species characteristics were retrieved from various published sources and include biological sensitivity to harvesting and temperature ranges for the most important species. These indices were weighted by each species production volume in order to produce maps of European country's color-coded by their overall temperature range, maximum temperature, and biological sensitivity within each production sector.

Seasonal, Oceanographic and Atmospheric Drivers of Diving Behaviour in a Temperate Seal Species Living in the High Arctic.

The harbour seal (Phoca vitulina) population in Svalbard marks the northernmost limit of the species' range. This small population experiences environmental extremes in sea and air temperatures, sea ice cover and also in light regime for this normally temperate species. This study deployed Conductivity Temperature Depth Satellite Relay Data Loggers (CTD-SRDLs) on 30 adult and juvenile harbour seals in 2009 and 2010 to study their foraging behaviour across multiple seasons. A total of 189,104 dives and 16,640 CTD casts (mean depth 72 m ± 59) were recorded. Individuals dove to a mean depth of 41 m ± 24 with a maximum dive depth range of 24 - 403 m. Dives lasted on average 204 sec ± 120 with maximum durations ranging between 240 - 2,220 sec. Average daily depth and duration of dives, number of dives, time spent diving and dive time/surface time were influenced by date, while sex, age, sea-ice concentration and their interactions were not particularly influential. Dives were deeper (~150 m), longer (~480 sec), less numerous (~250 dives/day) and more pelagic during the winter/early spring compared to the fall and animals spent proportionally less time at the bottom of their dives during the winter. Influxes of warm saline water, corresponding to Atlantic Water characteristics, were observed intermittently at depths ~100 m during both winters in this study. The seasonal changes in diving behaviour were linked to average weekly wind stresses from the north or north-east, which induced upwelling events onto the shelf through offshore Ekman transport. During these events the shelf became flooded with AW from the West Spitsbergen Current, which presumably brought Atlantic fish species close to shore and within the seals' foraging depth-range. Predicted increased in the influx of AW in this region are likely going to favour the growth and geographic expansion of this harbour seal population in the future.

West Greenland harbour porpoises assayed for antibodies against Toxoplasma gondii: false positives with the direct agglutination method.

We assayed blood/tissue fluid samples from 20 harbour porpoises Phocoena phocoena from western Greenland coastal waters for antibodies against the protozoan parasite Toxoplasma gondii by the direct agglutination test (DAT). Nine individuals (45%) were interpreted to be seropositive at 1:40 dilution and 4 (20%) were seropositive up to 1:160. Samples from these individuals were assayed by an enzyme-linked immunosorbent assay (ELISA), and tissue samples of the DAT-positive animals were tested by a nested polymerase chain reaction (nPCR). Results from both methods were negative, suggesting the absence of infection in the tested animals. After chloroform clean-up, all were negative when re-assayed by DAT. We concluded that infection with T. gondii was absent in all 20 animals, despite the initially positive DAT results, and that the false positives resulted from non-specific adherence to tachyzoites in the DAT assay which could be removed by the chloroform clean-up method. Our results suggest that detecting antibodies against T. gondii using the DAT or the modified agglutination technique, particularly on samples from Arctic marine animals which often are rich in lipids, may lead to false positive results. For such samples, the use of ELISA or PCR on available tissue samples may be advocated as confirmatory tests in order to avoid false positives and overestimating seroprevalence.

The use of an air bubble curtain to reduce the received sound levels for harbor porpoises (Phocoena phocoena).

In December 2005 construction work was started to replace a harbor wall in Kerteminde harbor, Denmark. A total of 175 wooden piles were piled into the ground at the waters edge over a period of 3 months. During the same period three harbor porpoises were housed in a marine mammal facility on the opposite side of the harbor. All animals showed strong avoidance reactions after the start of the piling activities. As a measure to reduce the sound exposure for the animals an air bubble curtain was constructed and operated in a direct path between the piling site and the opening of the animals' semi-natural pool. The sound attenuation effect achieved with this system was determined by quantitative comparison of pile driving impulses simultaneously measured in front of and behind the active air bubble curtain. Mean levels of sound attenuation over a sequence of 95 consecutive pile strikes were 14 dB (standard deviation (s.d.) 3.4 dB) for peak to peak values and 13 dB (s.d. 2.5 dB) for SEL values. As soon as the air bubble curtain was installed and operated, no further avoidance reactions of the animals to the piling activities were apparent.

Acoustic behaviour of echolocating porpoises during prey capture.

Porpoise echolocation has been studied previously, mainly in target detection experiments using stationed animals and steel sphere targets, but little is known about the acoustic behaviour of free-swimming porpoises echolocating for prey. Here, we used small onboard sound and orientation recording tags to study the echolocation behaviour of free-swimming trained porpoises as they caught dead, freely drifting fish. We analysed porpoise echolocation behaviour leading up to and following prey capture events, including variability in echolocation in response to vision restriction, prey species, and individual porpoise tested. The porpoises produced echolocation clicks as they searched for the fish, followed by fast-repetition-rate clicks (echolocation buzzes) when acquiring prey. During buzzes, which usually began when porpoises were about 1-2 body lengths from prey, tag-recorded click levels decreased by about 10 dB, click rates increased to over 300 clicks per second, and variability in body orientation (roll) increased. Buzzes generally continued beyond the first contact with the fish, and often extended until or after the end of prey handling. This unexplained continuation of buzzes after prey capture raises questions about the function of buzzes, suggesting that in addition to providing detailed information on target location during the capture, they may serve additional purposes such as the relocation of potentially escaping prey. We conclude that porpoises display the same overall acoustic prey capture behaviour seen in larger toothed whales in the wild, albeit at a faster pace, clicking slowly during search and approach phases and buzzing during prey capture.

Temporary shift in masked hearing thresholds in a harbor porpoise (Phocoena phocoena) after exposure to seismic airgun stimuli.

An auditory study was conducted to derive data on temporary threshold shift (TTS) induced by single impulses. This information should serve as basis for the definition of noise exposure criteria for harbor porpoises. The measurements of TTS were conducted on a harbor porpoise by measuring the auditory evoked potentials in response to amplitude-modulated sounds. After obtaining baseline hearing data the animal was exposed to single airgun stimuli at increasing received levels. Immediately after each exposure the animal's hearing threshold was tested for significant changes. The received levels of the airgun impulses were increased until TTS was reached. At 4 kHz the predefined TTS criterion was exceeded at a received sound pressure level of 199.7 dB(pk-pk) re 1 microPa and a sound exposure level (SEL) of 164.3 dB re 1 microPa(2) s. The animal consistently showed aversive behavioral reactions at received sound pressure levels above 174 dB(pk-pk) re 1 microPa or a SEL of 145 dB re 1 microPa(2) s. Elevated levels of baseline hearing sensitivity indicate potentially masked acoustic thresholds. Therefore, the resulting TTS levels should be considered masked temporary threshold shift (MTTS) levels. The MTTS levels are lower than for any other cetacean species tested so far.

Auditory brainstem response in a harbor porpoise show lack of automatic gain control for simulated echoes.

The auditory brainstem response (ABR) response to simulated echolocation clicks was studied in a harbor porpoise, Phocoena phocoena, to determine the relationship between the animal's perceived echo strength and the simulated target distance. In one experiment the click level at the listening post was kept constant while delay was changed, in another, the level was varied to approximate spreading losses. Results of both experiments indicate that there is no automatic gain control in the hearing system of this harbor porpoise.