Energy intake and utilisation by nursing bearded seal (Erignathus barbatus) pups from Svalbard,Norway

In this study we measure energy intake via milk in nursing bearded seal (Erignathus barbatus) pups and determine how this energy is allocated into metabolism and storage of new tissues. This was accomplished using longitudinal mass gain records and the doubly labelled water technique on nursing pups in combination with cross-sectional data on changes in milk composition from bearded seal mothers. The pups (n=3) were all less than a week old at the start of the experiments. Pups gained 3.3±0.4 kg·day^-1 of which 50% was fat, 14% protein and 36% water. Average daily water influx for the pups was 69.5±9.0 ml · kg^-1· day^-1. Average CO₂ production during the study period was 0.99±0.10 ml·g^-1·h^-1, which corresponds to a field metabolic rate of 642±67 kJ·kg^-1· day^-1, or 6.0±0.5 times the predicted basal metabolic rate according to Kleiber (1975). The pups drank an average of 7.6±0.5 kg of milk daily. This corresponds to a daily energy intake of 154±8 MJ, 47±14% of which was stored as new body tissue. Despite this high energy intake bearded seal pups do not get as fat as do other nursing phocids. This is in part due to their larger body size but also due to their very active aquatic lifestyle and the lower and more consistent fat content of the milk compared to other phocid species. Bearded seal mothers forage during lactation and may also be involved in teaching their pups to feed independently. All these data suggest that the lactation strategy of bearded seals differs from the phocid norm.     

Vocalizations of bearded seals (Erignathus barbatus) and their influence on the soundscape of the western Canadian Arctic

The soundscape is a crucial habitat feature for marine mammals. This study investigates the contribution of bearded seal vocalizations to the soundscape in the western Canadian Arctic, and also the vocal characteristics of bearded seals relative to sea ice conditions. Passive acoustic data were recorded near Sachs Harbour between August 2015 and July 2016. Sound pressure levels (SPL) in the 50–1,000 Hz and 1–10 kHz bands increased as the total duration of all bearded seal vocalizations increased, and this relationship was moderated by sea ice concentration. Bearded seals in this region had an overlapping vocal repertoire with bearded seals in other areas of the Arctic, and had seven additional vocalizations that have not been previously documented for this region. This study is the first detailed assessment of the influence of bearded seal calls on SPL, which shows the high potential of bearded seals to influence underwater sound levels during the mating season. Bearded seals live in a changing Arctic seascape, and their influence on the soundscape may shift as sea ice continues to diminish. It is imperative that acoustic monitoring continues within the Arctic, and this study provides a baseline for future monitoring as the Arctic continues to change.     

Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway

The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals (Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110 animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity in males was determined according to the size of the testes and bacula. Females were defined as being sexually mature according to findings of mature follicles or corpora lutea/albicantia. Von Bertalanffy growth curves were applied to both standard length and body mass, and asymptotic values for males and females were 231.1 ± 11.4 cm and 269.9 ± 26.2 kg, and 233.1 ± 7.5 cm and 275.3 ± 47.8 kg, respectively. Maximum recorded lengths and masses were 254 cm and 313 kg in males and 242 cm and 358 kg in females. All males older than 6 years were found to have been sexually mature. Females were found to attain sexual maturity at about 90% of the asymptotic length, corresponding to an age of 5 years. In males a significant decrease in condition was observed from June to August, with a subsequent increase in September. In adult females, condition decreased from May to June and increased again from June to September. The conditional changes seen are likely to be due to the extra energetic cost and reduced food intake associated with reproduction, lactation and molt. Accepted: 28 July 1998     

The role of sea ice for vascular plant dispersal in the Arctic

Sea ice has been suggested to be an important factor for dispersal of vascular plants in the Arctic. To assess its role for postglacial colonization in the North Atlantic region, we compiled data on the first Late Glacial to Holocene occurrence of vascular plant species in East Greenland, Iceland, the Faroe Islands and Svalbard. For each record, we reconstructed likely past dispersal events using data on species distributions and genetics. We compared these data to sea-ice reconstructions to evaluate the potential role of sea ice in these past colonization events and finally evaluated these results using a compilation of driftwood records as an independent source of evidence that sea ice can disperse biological material. Our results show that sea ice was, in general, more prevalent along the most likely dispersal routes at times of assumed first colonization than along other possible routes. Also, driftwood is frequently dispersed in regions that have sea ice today. Thus, sea ice may act as an important dispersal agent. Melting sea ice may hamper future dispersal of Arctic plants and thereby cause more genetic differentiation. It may also limit the northwards expansion of competing boreal species, and hence favour the persistence of Arctic species.     

Seasonal sea ice cover as principal driver of spatial and temporal variation in depth extension and annual production of kelp in Greenland

We studied the depth distribution and production of kelp along the Greenland coast spanning Arctic to sub‐Arctic conditions from 78 ºN to 64 ºN. This covers a wide range of sea ice conditions and water temperatures, with those presently realized in the south likely to move northwards in a warmer future. Kelp forests occurred along the entire latitudinal range, and their depth extension and production increased southwards presumably in response to longer annual ice‐free periods and higher water temperature. The depth limit of 10% kelp cover was 9–14 m at the northernmost sites (77–78 ºN) with only 94–133 ice‐free days per year, but extended to depths of 21–33 m further south (73 ºN–64 ºN) where >160 days per year were ice‐free, and annual production of Saccharina longicruris and S. latissima, measured as the size of the annual blade, ranged up to sevenfold among sites. The duration of the open‐water period, which integrates light and temperature conditions on an annual basis, was the best predictor (relative to summer water temperature) of kelp production along the latitude gradient, explaining up to 92% of the variation in depth extension and 80% of the variation in kelp production. In a decadal time series from a high Arctic site (74 ºN), inter‐annual variation in sea ice cover also explained a major part (up to 47%) of the variation in kelp production. Both spatial and temporal data sets thereby support the prediction that northern kelps will play a larger role in the coastal marine ecosystem in a warmer future as the length of the open‐water period increases. As kelps increase carbon‐flow and habitat diversity, an expansion of kelp forests may exert cascading effects on the coastal Arctic ecosystem.     

Climate change impacts on wildlife in a High Arctic archipelago – Svalbard,Norway

The Arctic is warming more rapidly than other region on the planet, and the northern Barents Sea, including the Svalbard Archipelago, is experiencing the fastest temperature increases within the circumpolar Arctic, along with the highest rate of sea ice loss. These physical changes are affecting a broad array of resident Arctic organisms as well as some migrants that occupy the region seasonally. Herein, evidence of climate change impacts on terrestrial and marine wildlife in Svalbard is reviewed, with a focus on bird and mammal species. In the terrestrial ecosystem, increased winter air temperatures and concomitant increases in the frequency of ‘rain‐on‐snow’ events are one of the most important facets of climate change with respect to impacts on flora and fauna. Winter rain creates ice that blocks access to food for herbivores and synchronizes the population dynamics of the herbivore–predator guild. In the marine ecosystem, increases in sea temperature and reductions in sea ice are influencing the entire food web. These changes are affecting the foraging and breeding ecology of most marine birds and mammals and are associated with an increase in abundance of several temperate fish, seabird and marine mammal species. Our review indicates that even though a few species are benefiting from a warming climate, most Arctic endemic species in Svalbard are experiencing negative consequences induced by the warming environment. Our review emphasizes the tight relationships between the marine and terrestrial ecosystems in this High Arctic archipelago. Detecting changes in trophic relationships within and between these ecosystems requires long‐term (multidecadal) demographic, population‐ and ecosystem‐based monitoring, the results of which are necessary to set appropriate conservation priorities in relation to climate warming.     

A natural antipredation experiment: predator control and reduced sea ice increases colony size in a long‐lived duck

Anthropogenic impact on the environment and wildlife are multifaceted and far‐reaching. On a smaller scale, controlling for predators has been increasing the yield from local natural prey resources. Globally, human‐induced global warming is expected to impose severe negative effects on ecosystems, an effect that is expected to be even more pronounced in the scarcely populated northern latitudes. The clearest indication of a changing Arctic climate is an increase in both air and ocean temperatures leading to reduced sea ice distribution. Population viability is for long‐lived species dependent on adult survival and recruitment. Predation is the main mortality cause in many bird populations, and egg predation is considered the main cause of reproductive failure in many birds. To assess the effect of predation and climate, we compared population time series from a natural experiment where a trapper/down collector has been licensed to actively protect breeding common eiders Somateria mollissima (a large seaduck) by shooting/chasing egg predators, with time series from another eider colony located within a nature reserve with no manipulation of egg predators. We found that actively limiting predator activity led to an increase in the population growth rate and carrying capacity with a factor of 3–4 compared to that found in the control population. We also found that population numbers were higher in years with reduced concentration of spring sea ice. We conclude that there was a large positive impact of human limitation of egg predators, and that this lead to higher population growth rate and a large increase in size of the breeding colony. We also report a positive effect of warming climate in the high arctic as reduced sea‐ice concentrations was associated with higher numbers of breeding birds.     

First record of sympagic hydroids (Hydrozoa,Cnidaria) in Arctic coastal fast ice

We report on the first record of interstitial cnidarians in sea ice. Ice core samples were collected during eight field periods between February 2003 and June 2006 in the coastal fast ice off Barrow, Alaska (71°N, 156°W) at four locations. A total of 194 solitary, small (0.2–1.1 mm) elongated specimens of a previously unknown interstitial hydroid taxon were found. By cnidome composition and the occurrence of a highly retractable pedal disc formed by epidermal tissue only, the specimens are tentatively assigned to representatives of the family Protohydridae, subclass Anthomedusae. The hydroids were found almost exclusively in the bottom 10 cm-layer (at the ice–water interface) of 118 ice cores, with abundances ranging from 0 to 27 individuals per core section (0–4,244 ind m⁻²) and a grand mean of 269 ind m⁻² in bottom 10 cm-layer sections. Abundances were lower in December and late May than in months in between with considerable site variability. A factor analysis using 12 variables showed that hydroid abundance correlated highest with abundances of copepod nauplii and polychaete juveniles suggesting a trophic relationship.     

Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century

The primary habitat of polar bears is sea ice, but in Western Hudson Bay (WH), the seasonal ice cycle forces polar bears ashore each summer. Survival of bears on land in WH is correlated with breakup and the ice‐free season length, and studies suggest that exceeding thresholds in these variables will lead to large declines in the WH population. To estimate when anthropogenic warming may have progressed sufficiently to threaten the persistence of polar bears in WH, we predict changes in the ice cycle and the sea ice concentration (SIC) in spring (the primary feeding period of polar bears) with a high‐resolution sea ice‐ocean model and warming forced with 21st century IPCC greenhouse gas (GHG) emission scenarios: B1 (low), A1B (medium), and A2 (high). We define critical years for polar bears based on proposed thresholds in breakup and ice‐free season and we assess when ice‐cycle conditions cross these thresholds. In the three scenarios, critical years occur more commonly after 2050. From 2001 to 2050, 2 critical years occur under B1 and A2, and 4 under A1B; from 2051 to 2100, 8 critical years occur under B1, 35 under A1B and 41 under A2. Spring SIC in WH is high (>90%) in all three scenarios between 2001 and 2050, but declines rapidly after 2050 in A1B and A2. From 2090 to 2100, the mean spring SIC is 84 (±7)% in B1, 56 (±26)% in A1B and 20 (±13)% in A2. Our predictions suggest that the habitat of polar bears in WH will deteriorate in the 21st century. Ice predictions in A1B and A2 suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century.     

Sea ice loss increases genetic isolation in a high Arctic ungulate metapopulation

Sea ice loss may have dramatic consequences for population connectivity, extinction–colonization dynamics, and even the persistence of Arctic species subject to climate change. This is of particular concern in face of additional anthropogenic stressors, such as overexploitation. In this study, we assess the population‐genetic implications of diminishing sea ice cover in the endemic, high Arctic Svalbard reindeer (Rangifer tarandus platyrhynchus) by analyzing the interactive effects of landscape barriers and reintroductions (following harvest‐induced extirpations) on their metapopulation genetic structure. We genotyped 411 wild reindeer from 25 sampling sites throughout the entire subspecies' range at 19 microsatellite loci. Bayesian clustering analysis showed a genetic structure composed of eight populations, of which two were admixed. Overall population genetic differentiation was high (mean F_ST = 0.21). Genetic diversity was low (allelic richness [AR] = 2.07–2.58; observed heterozygosity = 0.23–0.43) and declined toward the outer distribution range, where populations showed significant levels of inbreeding. Coalescent estimates of effective population sizes and migration rates revealed strong evolutionary source–sink dynamics with the central population as the main source. The population genetic structure was best explained by a landscape genetics model combining strong isolation by glaciers and open water, and high connectivity by dispersal across winter sea ice. However, the observed patterns of natural isolation were strongly modified by the signature of past harvest‐induced extirpations, subsequent reintroductions, and recent lack of sea ice. These results suggest that past and current anthropogenic drivers of metapopulation dynamics may have interactive effects on large‐scale ecological and evolutionary processes. Continued loss of sea ice as a dispersal corridor within and between island systems is expected to increase the genetic isolation of populations, and thus threaten the evolutionary potential and persistence of Arctic wildlife.     

Local snow melt and temperature—but not regional sea ice—explain variation in spring phenology in coastal Arctic tundra

The Arctic is undergoing dramatic environmental change with rapidly rising surface temperatures, accelerating sea ice decline and changing snow regimes, all of which influence tundra plant phenology. Despite these changes, no globally consistent direction of trends in spring phenology has been reported across the Arctic. While spring has advanced at some sites, spring has delayed or not changed at other sites, highlighting substantial unexplained variation. Here, we test the relative importance of local temperatures, local snow melt date and regional spring drop in sea ice extent as controls of variation in spring phenology across different sites and species. Trends in long‐term time series of spring leaf‐out and flowering (average span: 18 years) were highly variable for the 14 tundra species monitored at our four study sites on the Arctic coasts of Alaska, Canada and Greenland, ranging from advances of 10.06 days per decade to delays of 1.67 days per decade. Spring temperatures and the day of spring drop in sea ice extent advanced at all sites (average 1°C per decade and 21 days per decade, respectively), but only those sites with advances in snow melt (average 5 days advance per decade) also had advancing phenology. Variation in spring plant phenology was best explained by snow melt date (mean effect: 0.45 days advance in phenology per day advance snow melt) and, to a lesser extent, by mean spring temperature (mean effect: 2.39 days advance in phenology per °C). In contrast to previous studies examining sea ice and phenology at different spatial scales, regional spring drop in sea ice extent did not predict spring phenology for any species or site in our analysis. Our findings highlight that tundra vegetation responses to global change are more complex than a direct response to warming and emphasize the importance of snow melt as a local driver of tundra spring phenology.     

Killer whales (Orcinus orca) in the Canadian Arctic: Distribution,prey items,group sizes,and seasonality

Killer whales (Orcinus orca) have a global distribution, but many high‐latitude populations are not well studied. We provide a comprehensive review of the history and ecology of killer whales in the Canadian Arctic, for which there has previously been little information. We compiled a database of 450 sightings spanning over 15 decades (1850–2008) to document the historical occurrence, distribution, feeding ecology, and seasonality of killer whales observed throughout the region. Sighting reports per decade increased substantially since 1850 and were most frequent in the eastern Canadian Arctic. The mean reported group size was 8.3 (median = 4, range 1–100), but size varied significantly among regions and observed prey types. Observations of predation events indicate that Canadian Arctic killer whales prey upon other marine mammals. Monodontids were the most frequently observed prey items, followed by bowhead whales (Balaena mysticetus), phocids, and groups of mixed mammal prey. No killer whale sightings occurred during winter, with sightings gradually increasing from early spring to a peak in summer, after which sightings gradually decreased. Our results suggest that killer whales are established, at least seasonally, throughout the Canadian Arctic, and we discuss potential ecological implications of increased presence with declining sea ice extent and duration.     

Effects of ocean warming and acidification on survival,growth and skeletal development in the early benthic juvenile sea urchin (Heliocidaris erythrogramma)

Co‐occurring ocean warming, acidification and reduced carbonate mineral saturation have significant impacts on marine biota, especially calcifying organisms. The effects of these stressors on development and calcification in newly metamorphosed juveniles (ca. 0.5 mm test diameter) of the intertidal sea urchin Heliocidaris erythrogramma, an ecologically important species in temperate Australia, were investigated in context with present and projected future conditions. Habitat temperature and pH/pCO₂ were documented to place experiments in a biologically and ecologically relevant context. These parameters fluctuated diurnally up to 10 °C and 0.45 pH units. The juveniles were exposed to three temperature (21, 23 and 25 °C) and four pH (8.1, 7.8, 7.6 and 7.4) treatments in all combinations, representing ambient sea surface conditions (21 °C, pH 8.1; pCO₂ 397; Ω_Ca 4.7; Ω_Ar 3.1), near‐future projected change (+2–4 °C, ?0.3–0.5 pH units; pCO₂ 400–1820; Ω_Ca 5.0–1.6; Ω_Ar 3.3–1.1), and extreme conditions experienced at low tide (+4 °C, ?0.3–0.7 pH units; pCO₂ 2850–2967; Ω_Ca 1.1–1.0; Ω_Ar 0.7–0.6). The lowest pH treatment (pH 7.4) was used to assess tolerance levels. Juvenile survival and test growth were resilient to current and near‐future warming and acidification. Spine development, however, was negatively affected by near‐future increased temperature (+2–4 °C) and extreme acidification (pH 7.4), with a complex interaction between stressors. Near‐future warming was the more significant stressor. Spine tips were dissolved in the pH 7.4 treatments. Adaptation to fluctuating temperature‐pH conditions in the intertidal may convey resilience to juvenile H. erythrogramma to changing ocean conditions, however, ocean warming and acidification may shift baseline intertidal temperature and pH/pCO₂ to levels that exceed tolerance limits.     

Seasonal trends in body mass, food intake and resting metabolic rate, and induction of metabolic depression in arctic foxes (Alopex lagopus) at Svalbard

 Post-absorptive resting metabolic rates (RMRs), body mass and ad libitum food intake were recorded on an annual cycle in captive arctic foxes (Alopex lagopus) at Svalbard. During the light season in May and in the dark period in November, RMR during starvation and subsequent re-feeding were also measured. In contrast to earlier findings, the present study indicated a seasonal trend in post-absorptive RMR (in W · kg⁻¹ and W · kg^−0.75). The values in the light summer were 15% and 11% higher than the values in the dark winter, suggesting a physiological adaptation aiding energy conservation during winter in arctic foxes. Body mass and ad libitum food intake varied inversely through the year. A significant reduction in RMR (in W and W · kg^−0.75) with starvation (metabolic depression) was recorded both in May and November, indicating an adaptation to starvation in arctic foxes. The lack of metabolic depression during a period of starvation that was concomitant with extremely cold ambient temperatures in November 1994 indicates that metabolic responses to starvation may be masked by thermoregulatory needs. At very low ambient temperatures, arctic foxes may require increased heat production which cannot be achieved via below-average rates of metabolism. Accepted: 7 June 1999     

Copepods in spring annual sea ice at Terra Nova Bay (Ross Sea,Antarctica)

The aim of this study was to investigate patterns of abundance, distribution, temporal changes and species composition of the dominant ice-associated copepods in the spring annual pack ice, platelet ice and water column at Terra Nova Bay, Ross Sea, during late spring 1997. Ice cores were drilled for temporal and spatial scales. Stephos longipes and Harpacticus furcifer dominated the sea ice meiofauna in terms of numbers in the lower few centimeters of the bottom ice associated with high chlorophyll a and phaeopigment levels. Nauplii dominated the S. longipes population (91.6%) and occurred in extremely high concentrations. In contrast, copepodids were the dominant stages in H. furcifer. How H. furcifer carries out its entire life cycle and how it differs from ecologically similar species such as Drescheriella glacialis should be examined in more detail.     

Parmales species (siliceous marine nanoplankton) in surface sediments of the Weddell Sea, Southern Ocean: indicators for sea ice environment?

The distribution pattern of the Parmales, a recently described order of siliceous marine nanophytoplankton, is described and quantified in surface sediments of the Atlantic sector of the Southern Ocean. Additional samples were investigated from the Bransfield Strait and the eastern Bellingshausen Sea. Highest abundances occurred in nearshore areas of the southern and southeastern Weddell Sea. Due to the distribution of Parmales species, which is strictly linked to these neritic areas, influenced most of the year by sea ice, it is suggested that the presence of Parmales species may be an indicator of sea ice influence probably useful in later down core studies.     

Cryosphere: ice on Niwot Ridge and in the Green Lakes Valley,Colorado Front Range

Background: Subsurface ice preserved as ice lenses and within rock glaciers as well as glacial and lake ice provides sensitive indicators of climate change and serve as a late-season source of meltwater.

Aims: We synthesise the results of geomorphological, geophysical and geochemical studies during the period of 1995–2014, building on a long history of earlier work focused on ice and permafrost studies on Niwot Ridge and the adjacent Green Lakes Valley (GLV), which is part of the Niwot Ridge Long Term Ecological Research Site.

Methods: These studies are discussed in the context of how bodies of ice and rock glaciers reflect changing local climate. We review recent results from geophysical investigations (resistivity, seismic refraction and ground-penetrating radar) of the shallow subsurface, ongoing monitoring of the Arikaree Glacier, three rock glaciers and lake ice in the GLV, and interpretations of how subsurface ice melt regulates the flow and chemistry of alpine surface water after seasonal snowfields melt.

Results and conclusions: Permafrost conditions reported from Niwot Ridge in the 1970s are generally absent today, but ice lenses form and melt seasonally. Ice is present permanently within the Green Lakes 5 rock glacier and at nearby favourable sites. The Arikaree Glacier has shown a marked decline in cumulative mass balance during the past 12 years after a 30-year period when net mass balance was ca. 0. Duration of seasonal lake ice increases with elevation in GLV, but duration has decreased at all seven lakes that have been monitored during the last three decades. This decrease has been most marked at the lowest elevation where it amounted to a reduction of about 1 d year^?1 and least at Green Lake 5 where the loss has been at a rate of 0.5 d year^?1. Surface temperature measurements from rock glaciers have not shown strong trends during the past 15 years. It has been suggested that almost all of the 2.5-mm year^?1 increase in stream discharge from the upper GLV in September and October has been derived from melting of subsurface ice.     

Morphometrics,body condition,and growth of the ringed seal (Pusa hispida saimensis) in Lake Saimaa: Implications for conservation

Morphometrics and growth of the critically endangered Saimaa ringed seal (Pusa hispida saimensis), which inhabits a freshwater lake in Finland were studied using data from 344 carcasses. This study presents the first detailed information on ringed seal pup growth and body condition from birth to the age of one year. Newborn pups were on average 68 cm long and weighed 5 kg. Pups attained the majority of their first year growth during the nursing period. Body condition and growth declined after weaning, but pups recovered from postweaning nutritional deprivation at the age of 8 mo. The seals achieved their maximum body length, girth, and mandible size around the age of 4 yr, and asymptotic body mass two years later. Baculum growth indicated that males reached sexual maturity at age 5–6 yr. The Saimaa ringed seals' asymptotic body length and mass were 132 cm and 59 kg, respectively, which is similar to medium sized marine ringed seals. Saimaa ringed seals' survival to adulthood is extremely low due to high bycatch mortality; furthermore climate change may hamper pup growth and elevate mortality. Therefore we recommend continuation of fishing closures to improve pup survival.