Exchange of “signature” calls in captive belugas (Delphinapterus leucas)

Belugas (Delphinapterus leucas) produce echolocation clicks, burst pulses, and whistles. The sounds of 3 captive belugas were recorded using 2 hydrophones at the Port of Nagoya Public Aquarium. There were stable individual differences in the pulse patterning of one type of pulsed sounds (PS1 call), suggesting that belugas use these as “signature” calls. Eighty-eight percent of PS1 calls initiated PS1 calls from other animals within 1 s. PS1 calls repeated by the same individual occurred primarily when other belugas did not respond within 1 s of the first call. Belugas delayed successive PS1 calls when other belugas responded with a PS1 call within 1 s. There was no clear temporal pattern for whistles. It appears that the time limit for responding to calls is 1 s after the initial call. If other individuals do not respond to the PS1 call of a beluga within 1 s, belugas tend to repeat the call and wait for a response. The results of this study suggest that the belugas exchange their individual signatures by using PS1 calls, in a manner similar to that of signature whistles used by bottlenose dolphins.     

Age structure, growth, mortality, and density of belugas (Delphinapterus leucas) in the Canadian Arctic: responses to environment?

Environmental constraints on life-history traits are expected to increase with seasonality in resources such as food and appropriate breeding habitat. Seasonality is highest at polar latitudes, where environmental constraints can be stronger than biotic factors, such as density and its effect on intraspecific competition. In this study, the age structure, body-length distribution, mortality, and density were studied and compared among five beluga populations of the Canadian Arctic: eastern Beaufort Sea (EBS), Baffin Bay (BB), Cumberland Sound (CS), western (WHB), and eastern Hudson (EHB) Bay, to test the prediction that density-dependent effects on these life-history traits should be inversely related to latitude. Growth, but not mortality, showed a significant positive relationship with latitude. Winter density also increased with winter latitude, consistent with the prediction of greater risk of mortality associated with density-independent effects, such as ice entrapment in winter. Age distributions differed among populations, with animals harvested at the highest-latitude population (EBS) being the oldest and attaining the longest adult body lengths, compared to lower-latitude populations (WHB and EHB). The latitudinal variation in growth, adult body size, and winter density is congruent with the hypothesis that environmental seasonality may impose stronger constraints on life-history traits of beluga with increasing latitude.     

Life strategy and diet of Calanus glacialis during the winter�Cspring transition in Amundsen Gulf, south-eastern Beaufort Sea

The copepod Calanus glacialis plays a key role in the lipid-based energy flux in Arctic shelf seas. By utilizing both ice algae and phytoplankton, this species is able to extend its growth season considerably in these seasonally ice-covered seas. This study investigated the impacts of the variability in timing and extent of the ice algal bloom on the reproduction and population success of C. glacialis. The vertical distribution, reproduction, amount of storage lipids, stable isotopes, fatty acid and fatty alcohol composition of C. glacialis were assessed during the Circumpolar Flaw Lead System Study. Data were collected in the Amundsen Gulf, south-eastern Beaufort Sea, from January to July 2008 with the core-sampling from March to April. The reduction in sea ice thickness and coverage observed in the Amundsen Gulf in 2007 and 2008 affected the life strategy and reproduction of C. glacialis. Developmental stages CIII and CIV dominated the overwintering population, which resulted in the presence of very few CV and females during spring 2008. Spawning began at the peak of the ice algal bloom that preceded the precocious May ice break-up. Although the main recruitment may have occurred later in the season, low abundance of females combined with a potential mismatch between egg production/development to the first feeding stage and phytoplankton bloom resulted in low recruitment of C. glacialis in the early summer of 2008.     

Metazoan meiofauna dynamics and pelagic–benthic coupling in the Southeastern Beaufort Sea,Arctic Ocean

Pelagic–benthic coupling is relatively well studied in the marginal seas of the Arctic Ocean. Responses of meiofauna with regard to seasonal pulses of particulate organic matter are, however, rarely investigated. We examined the dynamics of metazoan meiofauna and assessed the strength of pelagic–benthic coupling in the Southeastern Beaufort Sea, during autumn 2003 and spring–summer 2004. Meiofauna abundance varied largely (range: 2.3 × 10⁵ to 5 × 10⁶ ind m⁻²), both spatially and temporally, and decreased with increasing depth (range: 24–549 m). Total meiofauna biomass exhibited similar temporal as well as spatial patterns as abundance and varied from 25 to 914 mg C m⁻². Significant relationships between sediment photopigments and various representatives of meiofauna in summer and autumn likely indicate the use of sediment phytodetritus as food source for meiofauna. A carbon-based grazing model provided estimates of potential daily ingestion rates ranging from 32 to 723 mg C m⁻². Estimated potential ingestion rates showed that meiofauna consumed from 11 to 477% of the sediment phytodetritus and that meiofauna were likely not food-restricted during spring and autumn. These results show that factors governing the distribution and abundance of metazoan meiofauna need to be better elucidated if we are to estimate the benthic carbon fluxes in marginal seas of the Arctic Ocean. This paper is dedicated to the memory of our dear friend and colleague Gaston Desrosiers who contributed so much to benthic ecology. We will continue in his spirit.     

Distribution of beluga whales (Delphinapterus leucas) in the Russian Arctic seas according to the results of expedition aboard RV Mikhail Somov, September–November 2010

Data on the distribution of marine mammals, including beluga whales (Delphinapterus leucas Pallas, 1766), in the Arctic are scarce because of various causes and conditions, including the vast expanses of the region, its poor accessibility, severe climate, long polar night, and high cost of research. Nevertheless, the results of aerial observations during ice reconnaissance and onboard observations during sea voyages (Kleinenberg et al., 1964; Geptner et al., 1976; Belikov, Boltunov, and Gorbunov, 2002; Belikov and Boltunov, 2002; Ezhov, 2005; Matishov and Ognetov, 2006; Biologiya i okeanografiya??, 2007; Lukin and Ognetov, 2009) have provided a general idea of the distribution pattern of beluga whales in the Russian Arctic seas. More detailed data concern the distribution of these whales in the White Sea, where aerial surveys of the water area were performed previously and have been resumed in recent years (Nazarenko et al., 2008; Glazov et al., 2010, 2011). The relevant data on the Barents, Kara, Laptev, and East Siberian seas are much poorer. In the summer (ice-free) period, beluga whales concentrate in coastal waters. They have been recorded most frequently off Franz Josef Land, Novaya Zemlya, Vaygach Island, and in Czech Bay in the Barents Sea; in Baydaratskaya Bay, Gulf of Ob, and Yenisei Gulf in the Kara Sea; off the northeastern coast of Taimyr and in estuaries of the Anabar, Olenyok, and Lena rivers in the Laptev Sea; and in the estuaries of the Indigirka (where the whales come from the west) and the Kolyma and Ked??ma rivers (where they come from the east) in the East Siberian Sea. The amount of information obtained in other seasons is very limited. In autumn, mass migration of beluga whales from the Kara Sea to the Barents Sea have been recorded in the Karskie Vorota Strait and off Cape Zhelaniya in the north of Novaya Zemlya. In winter, almost no records of these whales have been made in the Kara, Laptev, and East Siberian seas. These data are based on previous observations and have practically not been complemented in recent years.     

Year-round acoustic detection of bearded seals (Erignathus barbatus) in the Beaufort Sea relative to changing environmental conditions, 2008–2010

Bearded seals (Erignathus barbatus) are pan-Arctic pinnipeds that are often seen in association with pack ice, and are known for their long, loud trills, produced underwater primarily in the spring. Acoustic recordings were collected from August 2008 to August 2010 at two locations and a single year (2008–2009) at a third location, in the western Beaufort Sea. Three recorders in 2008–2009 had a 30 % duty cycle and a bandwidth of 10–4,096 Hz. One recorder in 2009–2010 had a 45 % duty cycle and a bandwidth of 10–4,096 Hz and the second had a 20 % duty cycle and bandwidth of 10–8,192 Hz. Spectrograms of acoustic data were examined for characteristic patterns of bearded seal vocalizations. For each recorder, the number of hours per day with vocalizations was compared with in situ water temperature and satellite-derived daily sea ice concentrations. At all sites, bearded seals were vocally active year-round. Call activity escalated with the formation of pack ice in the winter and the peak occurred in the spring, coinciding with mating season and preceding breakup of the sea ice. There was a change in the timing of seasonal sea ice formation and retreat between the two consecutive years that was reflected in the timing of peak bearded seal call activity. This study provides new information on fall and winter bearded seal vocal behavior and the relationship between year-round vocal activity and changes in annual sea ice coverage and in situ water temperature.     

Ringed and bearded seal densities in the eastern Chukchi Sea, 1999–2000

Aerial surveys were conducted in 1999 and 2000 to estimate the densities of ringed (Phoca hispida) and bearded (Erignathus barbatus) seals in the eastern Chukchi Sea. Survey lines were focused mainly on the coastal zone within 37 km of the shoreline, with additional lines flown 148–185 km offshore to assess how densities of seals changed as a function of distance from shore. Satellite-linked time-depth recorders were attached to ringed seals in both years to evaluate the time spent basking on the ice surface. Haulout patterns indicated that ringed seals transitioned to basking behavior in late May and early June, and that the largest proportion of seals (60–68%) was hauled out between 0830 and 1530 local solar time. Ringed seals were relatively common in nearshore fast ice and pack ice, with lower densities in offshore pack ice. The average density of ringed seals was 1.91 seals km⁻² in 1999 (range 0.37–16.32) and 1.62 seals km⁻² in 2000 (range 0.42–19.4), with the highest densities of ringed seals found in coastal waters south of Kivalina and near Kotzebue Sound. The estimated abundance of ringed seals for the entire study area was similar in 1999 (252,488 seals, SE=47,204) and 2000 (208,857 seals, SE=25,502). Bearded seals were generally more common in offshore pack ice, with the exception of high bearded seal numbers observed near the shore south of Kivalina. Bearded seal densities were not adjusted for haulout behavior, and therefore, abundance was not estimated. Unadjusted average bearded seal density was 0.07 seals km⁻² in 1999 (range 0.011–0.393) and 0.14 seals km⁻² in 2000 (range 0.009–0.652). Levels of primary productivity, benthic biomass, and fast ice distribution may influence the distributions of ringed and bearded seals in the Chukchi Sea. Information on movement and haulout behavior of ringed and bearded seals would be very useful for designing future surveys.     

Winter–spring feeding and metabolism of Arctic copepods: insights from faecal pellet production and respiration measurements in the southeastern Beaufort Sea

Faecal pellet production (FPP) and respiration rates of Calanus glacialis, C. hyperboreus and Metridia longa were measured under land-fast ice in the southeastern Beaufort Sea during the winter–spring transition (March–May 2004) prior to the phytoplankton spring bloom. Despite different overwintering and life cycle strategies and remaining low concentrations of suspended chlorophyll a and particulate organic matter, all species showed increasing FPP rates in spring. A corresponding increase in respiration was only observed in C. glacialis, while respiration remained constant in C. hyperboreus and M. longa. In C. glacialis and C. hyperboreus calculated ingestion covered respiratory expenditures. The constancy of the oil sac volume in M. longa suggests that the animals fed during winter-spring. Pre-bloom grazing as shown here seems to acclimate the copepod populations physiologically for the upcoming high feeding season, so that they are able to resume maximum grazing and reproduction as soon as the phytoplankton bloom is initiated.     

The extensive bloom of alternate-stage Prymnesium polylepis (Haptophyta) in the Baltic Sea during autumn–spring 2007–2008

During autumn 2007, an unusual increase in an algal species belonging to the order Prymnesiales was observed throughout the Baltic Sea Proper during routine national monitoring. Electron microscopical examination of the blooming species showed two types of flat scales – small and large – that resembled those of the alternate stage of Prymnesium polylepis. No spine-bearing scales were found. The 18S rDNA sequence data (n?=?20, c. 1500?bp) verified the species identification as P. polylepis. There was up to 0.5% (7?bp) variability in the P. polylepis partial 18?S rDNA sequences from the Baltic Sea. These environmental sequences differed by 0–0.35% (0–4?bp) from cultured P. polylepis (isolate UIO036), and by 1.0–3.7% from other available Prymnesium sequences. The number of cells assumed to be P. polylepis began to increase in October 2007 coincidently with significantly calm and dry weather, and at their maximum the cells accounted for over 80% of the total phytoplankton biovolume in December–January. During February–April 2008, 95% of the Prymnesiales cells were in the size class of P. polylepis (>6?µm). The species attained bloom concentrations (>1?×?10⁶?cells?l^–1) from March to May 2008. The species was observed throughout the Baltic Sea, except the Bothnian Bay, Gulf of Riga and the Kattegat. No toxic effects of the bloom were observed.     

Production and retention of biogenic matter in the southeast Beaufort Sea during 2003�C2004: insights from annual vertical particle fluxes of organic carbon and biogenic silica

Regional variability in the annual fluxes of particulate organic carbon (POC) and biogenic silica (Si) at the periphery of the Mackenzie Shelf (Beaufort Sea) was investigated using eight long-term sediment traps moored at ~100-m depth. Relatively high autochthonous POC and Si fluxes were recorded in the Mackenzie Trough (4.1 and 8.9 g m⁻² year⁻¹ respectively) and off Cape Bathurst (6.6 and 79 g m⁻² year⁻¹), two areas where upwelling events are frequently observed. Diatomaceous new production was minimum on the mid-slope of the Mackenzie Shelf (2.8 g C m⁻² year⁻¹), moderate in the Mackenzie Trough (14.5 g C m⁻² year⁻¹), and highest off Cape Bathurst (128.7 g C m⁻² year⁻¹). High annual autochthonous POC flux corresponded to high diatom production. Among sites, the vertical attenuation of the POC flux increased with diatomaceous new production. Hence, the retention of autochthonous POC in the surface layer (<100 m) was highest (95%) at the highly productive site off Cape Bathurst, intermediate (72%) in the moderately productive Mackenzie Trough, and low (4%) at the unproductive mid-slope of the shelf. Our results indicate that, on Arctic shelves, upwelling and the production of diatoms increase the fraction of the POC which is retained in the surface layer and diverted to the pelagic food web. In the relatively unproductive waters of the Arctic Ocean, biological hot spots such as the one identified off Cape Bathurst where the food web promotes retention rather than vertical export could be disproportionately important as feeding grounds for higher trophic levels.     

Marine primary production in the Canadian Arctic, 1956, 1961�C1963

Marine primary productivity studies pursued in the Canadian Arctic in 1961–1963, using standard techniques (oxygen and carbon-14) of the time, showed that maximum production developed rapidly in July at 5-m depth under very low light intensities and under intact but melting sea ice. The time of maximum production was correlated with depths of snow in spring. Low production levels were found in August in those years and estimated in 1956. Nitrate exhaustion occurred before maximum production and was followed by rapid sinking of chlorophyll and productivity and reduction of assimilation numbers. Gross production values greatly exceeded net production values in 1961–1963, and gross production in 2 years was about double that of a third year, which may be due to different initial conditions of nutrient concentrations in the euphotic zone. Interannual variability in primary production may be the result of changes in water masses in the surface layer, as driven by atmospheric pressure patterns.     

Sexual dimorphism in the otolith shape of shi drum,Umbrina cirrosa (L.), in the eastern Mediterranean Sea: Fish size–otolith size relationships

Little is known about possible differences in sagitta otolith size and shape between sexes of the shi drum, Umbrina cirrosa, and relationships between their body and otolith size. Thus, this study aimed to fill this knowledge gap via examination of 414 sagittal otoliths from 108 male (total length 13.8–26.8 cm) and 99 female (13.5–26.7 cm) U. cirrosa caught between May 2017 and April 2018 in gillnets set at a depth of ~15 m in Mersin Bay, Eastern Mediterranean Sea. No statistical differences were observed between the shape indices of the left-sided and right-sided sagitta. However, there were significant differences in the size and shape of otoliths between males and females. The slopes of allometric power functions from otolith width × fish sizes gave significant differences between males and females (ANCOVA, P < 0.05). The relationship for length × weight of otoliths from both males and females showed isometric growth, whereas the relationship of otolith width × otolith weight showed positive allometry. Negative allometric growth was observed for the relationship otolith length × otolith width. In summary, this study revealed the presence of sexual dimorphism in the otolith shape of U. cirrosa, and the data on regression relationships of fish-otolith sizes can be used to estimate fish size from U. cirrosa otolith sizes.     

Development of on‐shore behavior among polar bears (Ursus maritimus) in the southern Beaufort Sea: inherited or learned?

Polar bears (Ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. Polar bears of the southern Beaufort Sea (SB) have historically spent most of the year on the sea ice. However, recent reports from Alaska indicate that the proportion of the SB subpopulation observed on‐shore during late summer and early fall has increased. Our objective was to investigate whether this on‐shore behavior has developed through genetic inheritance, asocial learning, or through social learning. From 2010 to 2013, genetic data were collected from SB polar bears in the fall via hair snags and remote biopsy darting on‐shore and in the spring from captures and remote biopsy darting on the sea ice. Bears were categorized as either on‐shore or off‐shore individuals based on their presence on‐shore during the fall. Levels of genetic relatedness, first‐order relatives, mother–offspring pairs, and father–offspring pairs were determined and compared within and between the two categories: on‐shore versus off‐shore. Results suggested transmission of on‐shore behavior through either genetic inheritance or social learning as there was a higher than expected number of first‐order relatives exhibiting on‐shore behavior. Genetic relatedness and parentage data analyses were in concurrence with this finding, but further revealed mother–offspring social learning as the primary mechanism responsible for the development of on‐shore behavior. Recognizing that on‐shore behavior among polar bears was predominantly transmitted via social learning from mothers to their offspring has implications for future management and conservation as sea ice continues to decline.     

Organic solutes in the deepest phylogenetic branches of the Bacteria: identification of ��(1�C6)glucosyl-��(1�C2)glucosylglycerate in Persephonella marina

The accumulation of organic solutes was investigated in the thermophilic bacteria Persephonella marina and Marinitoga piezophila, two representatives of the deepest lineages in the domain Bacteria. These organisms grow optimally at around 70 °C in medium containing 3 % NaCl. A new disaccharide, accumulating in Persephonella marina, was identified as ??(1?C6)glucosyl-??(1?C2)glucosylglycerate (GGG), by nuclear magnetic resonance. This identification was validated by comparison with the spectra of the compound obtained by chemical synthesis. Besides GGG, the solute pool of Persephonella marina comprised ??-glutamate, di-myo-inositol-1,3??-phosphate and 2-O-??-glucosylglycerate. In contrast, amino acids such as ??-glutamate, proline and alanine were the dominant components of the solute pool of Marinitoga piezophila and sugar derivatives were absent. The ability of GGG to protect protein structure against heat denaturation was assessed using model proteins. A genomic search for the biosynthetic pathways of known ionic solutes in Aquificales and Thermotogales shows the inability of this analysis to predict the nature of compatible solutes and underlines the need for efficient cultivation techniques.