Activity,milk intake and energy consumption in free-living ringed seal (Phoca hispida) pups

Measurements of growth, activity and energy consumption and estimates of milk intake were made in free-living, nursing ringed seal (Phoca hispida) pups. This was accomplished through the simultaneous use of time-depth recorders and the doubly labelled water technique. The pups spent an average of 52±7% of their time hauled out on the ice, 37±5% of the time in the water at the surface, and 11±5% of the time diving. Average daily mass gain of the pups (n=3) throughout the duration of the study period was 0.35±0.08 kg. The composition of the mass gain was 76% fat, 6% protein and 18% water. The total water flux was measured to be 52±10 ml·kg^-1·day^-1. Average CO₂ production was 0.85±0.16 ml·g^-1·h^-1, corresponding to a field metabolic rate of 0.55±0.10 MJ·kg^-1·day^-1, or 3.8±0.6 times the predicted basal metabolic rate based on body size (Kleiber 1975). Average daily milk intake was estimated to be 1379±390 ml. The field metabolic rate for the different components of seal pup activity budgets were calculated to be FMR_{haul out}=1.34 BMR, FMR_surface=6.44 BMR, and FMR_diving=5.88 BMR.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - HTO tritiated water - HT¹⁸O doubly labelled water - RQ respiration quotient - SDA specific dynamic action - TDR time-depth recorder     

Avian predation on ringed seal Phoca hispida pups

Summary Ringed seals, Phoca hispida, born in exposed situations are killed by glaucous gulls, Larus hyperboreus. The small size of ringed seals adapted to giving birth in snow shelters makes them especially vulnerable to avian predators when born outside the lair. This might be one of the important factors in limiting the southern range of breeding in this seal species.     

Hypoxia-Inducible Factor in ringed seal (Phoca hispida) tissues

Tissue hypoxia and ischemia-reperfusion pose a dangerous situation for oxidative stress. However, diving mammals and birds show pronounced resistance to oxidative injury under such conditions, which are a consequence of selective vasoconstriction during a dive. As the function of Hypoxia-Inducible Factor-1alpha (HIF-1alpha) in protection against and adaptation to hypoxia has been recognized in terrestrial animals, we have investigated the genomics and expression of this protein in ringed seal (Phoca hispida) in order to determine if it may play a protective role in this diving mammal. PCR studies using primers based on sequences from mouse HIF-1alpha exons 3, 4, 5, 6, 9, 10, 11, 12 and 15 showed that DNA from seal lung generated PCR products similar to those from mouse DNA. These studies have established that a putative HIF-1alpha gene exists in the seal genome that appears to have a similar but not identical sequence to the mouse gene. Seal lung and skeletal muscle tissues showed the highest relative levels of HIF-1alpha protein expression, with heart muscle showing significantly lower levels, and levels of HIF-1beta protein expression paralleled this situation. Analysis of oxidized cellular protein levels indicated that seal lung and heart muscle had the lowest levels of oxidized proteins. Thus, as seal lung tissue had the highest level of HIF-1alpha protein expression and the second lowest level of protein oxidation, this suggests that HIF-1alpha expression may have an important protective effect in this tissue in diving mammals. Our results support the hypothesis that HIF-1alpha expression is dependent on both tissue-specific energy requirements and adequate metabolic supply-to-demand ratio. Combined, the evidence available suggests that diving mammals have an overall anticipatory response to avoid the ill effects of dive-associated ischemia-reperfusion which may involve the HIF-1 system.     

Mass transfer efficiency between harp seal (Phoca groenlandica) mothers and their pups during lactation

We investigated the efficiency of mass transfer in lactating harp seals through serial measurements on individual mother-pup pairs during the whelping seasons of 1988 and 1989. We also compared the influence of longitudinal versus cross-sectional sampling on estimates of the efficiency of mass transfer. Among longitudinally sampled pairs, pups grew at an average rate of 2·3 ± 0·5 (mean ± S.D.) kg/d (N = 20). The concomitant mass loss by females averaged 3·1 ± 0·8 kg/d (N = 19). The mean efficiency of mass transfer was 77·0 ± 13·6% (N= 19 pairs).
Estimates of pup growth and female mass loss from regressions of cross-sectional data were 2·0 kg/d and 3·1 kg/d, respectively. These values produce an estimate of 65% for the efficiency of mass transfer.
Consistent with the high efficiency of mass transfer, harp seal females contribute less of their total body mass to nursing ( c. 28%) than most other phocids examined. The resulting energy savings may be important for females of an ice-breeding species, which migrate a long distance shortly after weaning their pups     

Diving in darkness: whiskers as sense organs of the ringed seal (Phoca hispida saimensis)

Underwater vocalization and the functional structure of different vibrissae of the ringed seal ( Phoca hispida saimensis ) of Lake Saimaa, Eastern Finland, were studied. These seals live in darkness under the ice cover for several months during the year. It is known that blind seals are managing well in the lake. Visibility under water in some parts of the area where the seals live is only 2 m. It is suggested that echolocation is used in orientation and feeding. The Saimaa seal has click and click trial underwater vocalizations. However, both the frequency and intensity of the vocalization are low compared with, for example, those of dolphins. The structural adaptations for underwater sound localization are also not well developed.
The ringed seal has, however, extremely well-developed vibrissae. The innervation of one vibrissa is more than 10 times greater than normally found in mammals. The main structural deviations from normal mammalian vibrissae are: (1) an upper cavernous sinus, (2) a groove in the wall of the capsule at the level of the lower cavernous sinus, (3) elasticity of the connective tissue bands fixing the hair root to the capsule in the lower cavernous sinus and especially (4) the structure and innervation of the ring sinus area. Sensory elements are situated upon the glassy membrane on the surface of the outer rootsheath and in the basal cell layer of the outer rootsheath which is like a sensory epithelium. Below this epithelium a layer of liquid or gelatinous material and large amounts of glycogen are found. This sensory epithelium is especially well developed in the superciliary vibrissae. These vibrissae are protruded some millimetres when the seals are attentive. It is suggested that the vibrissae also sense sounds, which are transmitted to the sensory elements by tissue conduction through the capsule wall and via the blood sinuses. The seals may possibly detect compressional waves with the vibrissae.     

The scent of rutting male ringed seals (Phoca hispida)

Odorous substances of rutting male ringed seals (Phoca hispida) were studied by extracting facial skin, which contains hypertrophied sebaceous and apocrine sweat glands, with methanol/hexane, and analysing the extracts with gas chromatography and combined gas chromatography/mass spectrometry. The extract contained high concentrations of a tertiary amine, three aminoalcohols, several organosulphur compounds, and two hydrocarbons. We suggest that the ringed seal males use scent to mark the breathing holes and subnivean lairs within their territories. Some of the lipids in the extract were not found in extracts from sexually immature males, and these lipids may be important as vehicles for scent deposition.     

Breeding habitat and lair structure of the ringed seal (Phoca hispida ladogensis) in northern Lake Ladoga in Russia

The breeding habitat and lair structures of the ringed seal (Phoca hispida ladogensis) were studied by snowmobile expeditions in northern Lake Ladoga, Russia, during 1996 to 1999. Mostly flat ice and no large pack ice existed in northern Lake Ladoga during this study. All birth lairs and 88% of haul-out lairs were located in snowdrifts in the shorelines of islands or islets and 12% of the haul-out lairs occurred in pressured ice ridges. Some large haul-out lairs had been used communally by the seals. A total of 15% of the lairs observed had been attacked or marked by red fox (Vulpes vulpes), wolf (Canis lupus) or unidentified canines. The colour of the lanugo fur of the Ladoga ringed seal pup appeared to be dark grey. We conclude that the northern part of Lake Ladoga is an active breeding area for the ringed seal, which attests conservation needs for this area. Accepted: 18 September 2000     

Movements and diving of adult ringed seals (Phoca hispida) in Svalbard

Seven post-moulting adult ringed seals (Phoca hispida) were equipped with Satellite Linked Dive Recorders in Svalbard in July 1996 to determine if ringed seals conduct long-distance post-moulting feeding excursions, and to obtain details of their diving behaviour. The mean duration of tags was 206 days (range 103–325). Two seals swam 400 km north to the drifting pack ice (82°N). The rest undertook more local movements. Forty-eight percent of all dives were shallower than 20 m and 90% were shallower than 100 m. Ninety-five percent of all dive durations were shorter than 10 min, and 99.5% were shorter than 15 min. This study has shown that adult ringed seals undertake varying patterns of post-moulting excursions. Accepted: 1 April 2000     

The intrarenal and pericapsular venous systems of kidneys of the ringed seal, Phoca hispida

The kidneys of Phoca hispida are comprised of many closely adherent renculi, each of which is a small kidney, functionally independent of its neighbours except with respect to venous drainage. Venous blood from the rencular parenchyma drains to the periphery through interlobular veins. These interlobular veins empty into a perirencular plexus comprised of subcapsular veins on the free surface of the renculus, interrencular veins on adjoined surfaces, and marginal subcapsular veins lying in the furrows between adjoined renculi. A pericapsular plexus of large veins overlies the marginal subcapsular veins and has frequent connections with them. Blood drains from the pericapsular plexus into large superficial collecting veins that converge over the surface of the kidney toward the divided hilum and connect directly to the paired trunks of the posterior vena cava. There are also connections to other major venous systems of the region. There is no arcuate venous system, no major vein at the rencular hilum, and no vein of consequence emerging from the renal hilum. Venous outflow is virtually entirely directed to the peripheral plexuses. The venous pattern differs from that of most mammals in which blood drains from the renal parenchyma to arcuate veins and leaves the kidney through a renal vein, or veins, emerging from the hilum. The walls of veins in the kidney are remarkably thin in comparison to their size. Subcapsular veins up to 0.5 mm wide have walls on the parenchymal side that in places consist only of a thin, fenestrated endothelium and a basal lamina.     

The fibromuscular basket (Sporta perimedullaris musculosa) in renculi of kidneys from the ringed seal, Phoca hispida (Pinnipedia)

The medulla of renculi from kidneys of Ringed seals (Phoca hispida) is completely enclosed by cortex except at the hilum. Within the renculus, the fibromuscular coat of the calyx separates from the transitional epithelium at the level of the corticomedullary junction, where the intrarencular arteries also diverge into the parenchyma. Flat ribbons of this stromal tissue form an arborized framework near the medullary side of the intrarencular arteries and the larger of the arcuate arteries derived from them. The ribbons, which are clearly distinct from periarterial connective tissue, are composed of coarse collagenous fibers, elastic fibers, and smooth muscle cells, all oriented in the direction of the long axes of the ribbons, and myofibroblasts. The proportion of smooth muscle cells decreases and that of myofibroblasts increases with increasing distance from the calyx. At the base of the medullary pyramid, the elements of the framework diminish in width and ultimately blend with the surrounding interstitial tissue. The stromal framework, or basket, is homologous with the Sporta perimedullaris musculosa of cetacean kidneys.     

Respiratory chemosensitivity during wake and sleep in harbour seal pups (Phoca vitulina richardsii)

In this study, we examined the cardiorespiratory patterns of harbour seal pups under normoxic/normocarbic (air), hypoxic/normocarbic (15%, 12%, and 9% O2 in air), and normoxic/hypercarbic (2%, 4%, and 6% CO2 in air) conditions while awake and sleeping on land. Animals were chronically instrumented to record electroencephalogram (EEG), electromyogram (EMG), and electrocardiogram (EKG) signals, which, along with respiration (whole-body plethysmography) and oxygen consumption (VO2), were recorded from animals breathing each gas mixture for 2-4 h on separate days. Our results show that for animals breathing air, VO2 was not significantly lower during slow-wave sleep (SWS; 7.71 +/- 0.39 mL O2 min(-1) kg(-1); all measurements are mean +/- SEM) than during wakefulness (WAKE; 8.80 +/- 0.25 mL O2 min(-1) kg(-1)) and was unaffected by changes in respiratory drive. Although there was no significant fall in VO2 associated with a decrease in arousal state, breathing frequency (f(R)) did decrease (from 18.80 +/- 1.50 breaths min(-1) in WAKE to 10.40 +/- 0.49 breaths min(-1) in SWS), while the incidence of long apneas (>20 s) increased (12.76 +/- 4.06 apneas h(-1) in WAKE and 31.95 +/- 2.37 apneas h(-1) in SWS). Breathing was rarely seen during rapid eye movement (REM) sleep. Tachypnea was present at all levels of increased respiratory drive; however, hypoxia induced a dramatic bradycardia regardless of arousal state, while hypercarbia produced a tachycardia in SWS only. The hypoxic and hypercarbic chemosensitivities of harbour seal pups were similar to those of terrestrial mammals; however, unlike terrestrial mammals, where hypoxic and hypercarbic sensitivities are often reduced during SWS, the sensitivity of harbour seal pups to hypoxia and hypercarbia remained unchanged during the decrease in arousal state from WAKE to SWS.     

Assimilation efficiency of captive ringed seals (Phoca hispida) fed different diets

Food type or quality can influence assimilation efficiency (AE). AE (digestibility of dry matter) of two captive adult ringed seals (Phoca hispida; one male, one female) was estimated for five prey types. In trials, each of >8 days duration, the seals were fed redfish (Sebastes spp.), capelin (Mallotus villosus), Arctic cod (Boreogadus saida), Atlantic herring (Clupea harengus) and a mixture of herring and shrimp (Pandalus borealis). Prey were marked so that faecal samples could be matched to individual seals, and AE was estimated by the relative concentration of Mn²⁺ in food and faeces. AE was high but varied among the prey species (redfish 83%; capelin 87%; Arctic cod 88%; herring 94%; herring/Pandalus mixture 92%). There was a weak, positive relationship between AE and prey lipid content or energy density, but a negative relationship with inorganic content. AE was lower than expected for cape lin with high fat content. AE was not correlated with meal mass, number of fish in a meal, or seal mass. AE did not differ between the two seals. Received: 30 September 1996 / Accepted: 28 December 1996     

The Ladoga seal (Phoca hispida ladogensis Nordq.)

Oligochaetes are the dominant group of macrofauna in a river reach (1–450 m) below the Dobczyce dam on the River Raba. The Oligochaeta made up from 60.2% to 78.7% of the community. The next most abundant group were the Chironomidae comprising 20.5%–38.8% of the fauna. Upstream-downstream movements of the macrofauna were studied at one station, with an oligochaete density of 50 000 ind. m^–2, and a chironomid density about 20 000 ind. m^–2. In the drift the proportions of these two groups were reversed—Chironomidae represented 59% of the drift fauna, and the oligochaetes — about 40%. On the river bottom and in the drift a similar number of species (12–13) of Naididae were identified.In order to compare the intensity of the movement of the various taxonomic groups, the percentage of animals moving upstream and downstream over 24 h was calculated. The highest percentage of the population migrating were dipterans (7.3%). The Chironomidae and Ephemeroptera had similar proportions migrating (3.2% and 2.6% respectively). The Oligochaeta had the lowest value — only 0.6% of animals were displaced in a 24 h period.The Naididae appear to be strongly attached to the substratum and, under normal environmental conditions, their reproduction sufficiently compensated for the decrease in their number associated with the drift or predation.     

Escape responses of hauled out ringed seals (Phoca hispida) to aircraft disturbance

Arctic marine mammals may be subject to human-induced disturbance from various air traffic, mostly in connection with exploration and exploitation of non-renewable resources. The escape responses (i.e. leaving the ice) of hauled out ringed seals (Phoca hispida) to a low-flying (150 m) fixed-wing twin-engine aircraft (Partenavia PN68 Observer) during strip censuses in eastern Greenland (June 1984) and to a low-flying (150 m) helicopter (Bell 206 III) during reconnaissance in northwestern Greenland (May 1992) were recorded. Overall, 6.0% of the seals (N _tot = 5040) escaped as a reaction to the fixed-wing aircraft. Seals escaped less than about 600 m in front of the aircraft. The overall probability of escaping was 0.21 within a 200-m-wide centre zone, 0.06 on the side of the aircraft (100–300 m from the flight track), and 0.02 between 300 and 500 m from the track. The probability of escaping was found to be influenced by the time of day, relative wind direction and wind chill. Overall, about 49% of all seals (N _tot = 227 cases) escaped as a response to the helicopter. Seals entered the water a maximum of about 1250 m in front of the aircraft. At wind chill values below 1100 kcal/m² h, the probability of escaping was 0.79 in the 200-m-wide centre zone. On the sides the probability of escaping decreased up to about 500 m from the flight track whereafter it remained constant at about 0.30 up to about 1450 m. During the helicopter surveys wind chill was the only environmental factor found to have an additional effect on the probability of escaping. The study indicated that the risk of scaring ringed seals into the water can be substantially reduced if small-type helicopters do not approach them closer than about 1500 m, and small fixed-winged aircraft not closer than about 500 m. Accepted: 27 August 1998     

Energy gain and loss during lactation and postweaning in southern elephant seal pups (Mirounga leonina) at King George Island

Deuterium-labeled water was used to measure changes in the proximate body composition during the lactation period and after weaning in southern elephant seal pups at King George Island, South Shetland Islands, Antarctica. During the lactation period (23.0 ± 1.4 days) pups gained a mean of 4.9 ± 0.5 kg/day (n=7). Of the total mass gain (112 ± 8 kg), 38% was water, 48% was fat, and 11% was protein. This represented an increase in total body gross energy of 2437 ± 145 MJ. The proportion of body mass represented by fat was less than 2% at birth, increasing to 35 ± 2% at weaning. We followed the pups during a mean period of 36 ± 3 days after weaning. During this period, pups had a mean loss of 1.21 ± 0.10 kg/day (n=7) comprising 39% water, 48% fat, and 12% protein. The energy cost over this period was 952 ± 168 MJ, which represented, on average, 39% of the total energy gained during the suckling period. Accepted: 3 January 2000     

Antibodies to human-related H3 influenza A virus in Baikal seals (Phoca sibirica) and ringed seals (Phoca hispida) in Russia

Antibodies to influenza A virus were detected using enzyme-linked immunosorbent assay (ELISA) in the sera from two of seven Baikal seals (Phoca sibrica) and from five of six ringed seals (Phoca hispida) in Russia. In a hemagglutination-inhibition test using H1-H15 reference influenza A viruses, ELISA-positive sera from one Baikal seal and four ringed seals reacted to A/Aichi/2/68 (H3N2) and A/Bangkok/1/79 (H3N2) strains. One ringed seal serum sample reacted to A/seal/Massachusetts/1/80 (H7N7). The present results suggested that human-related H3 viruses were prevalent in Baikal seals and ringed seals inhabiting the central Russian Arctic.