Grey Seal Pups Research Articles

Infection, haematology and biochemistry in grey seal pups exposed to chlorinated biphenyls

Grey seal ( Halichoerus grypus) pups can receive substantial doses of organochlorine contaminants during lactation. This exposure may cause immunosuppression. We studied the effect of exposure to individual chlorobiphenyl (CB) congeners on grey seal pups at the Isle of May in the Firth of Forth, Scotland, by monitoring the prevalence of non-specific infection in pups, and by measuring perturbations in various haematological and biochemical blood parameters. There was no relationship between the prevalence of infection in pups, as a sign of immunosuppression, and the cumulative lactational dose of CB congeners. There was also no relationship between age at diagnosis of infection and CB dose, thus pups receiving relatively higher doses of contaminants early in life were no more likely to succumb to infection than those receiving lower doses. There was also no relationship between age-related changes in haematological and biochemical blood parameters and exposure to CB contaminants. Although pups which became infected with non-specific pathogens had received higher cumulative doses of CB on a toxicity equivalence basis than those which did not, this effect disappeared when results were corrected for the effect of pup age.

Chromosome survey of seals in the Baltic Sea in 1988-1992.

The populations of grey seals (Halichoerus grypus) and ringed seals (Phoca hispida botnica) in the Baltic Sea have decreased very much, especially during the last decades. Environmental pollution has been seen as an important cause. As top predators, the seals accumulate pollutants from their environment. High concentrations of chlorinated hydrocarbons and heavy metals have been found in seals from the Baltic Sea. In the present study the possible mutagenic effects of environmental pollutants on the seals have been studied by screening cultured lymphocytes for chromosome aberrations. Blood samples were taken from grey seal pups before weaning in March-April, and from adult ringed seals at the end of April during 1988-1992. Blood cells were cultured for 48 h for screening for chromosome aberrations, and for 61 h with bromodeoxyuridine for the study of sister chromatid exchange (SCE). The types of aberrations found were chromosome and chromatid breaks, gaps, and fragmentations. More complicated rearrangements were rare. Blood samples from a total of 47 grey seal pups and from ten adult ringed seals were analysed. The mean frequency of cells with chromosome aberrations from the grey seals was 5.7% (SD +/-5.3). The median was 4, because the distribution was skewed with some animals having a considerably higher frequency of aberrations than the average. Some cells with several aberrations and fragmentation of the chromosomes were observed among the lymphocytes from these animals. The frequencies of SCEs were not markedly higher than those normally found in humans. The frequencies of aberrations found in the adult ringed seals were lower than those found in the grey seal pups. The chromosome aberrations are probably caused by chemical pollutants.

An overview of exposure to, and effects of, petroleum oil and organochlorine pollution in grey seals (Halichoerus grypus).

Most incidences involving oil pollution of grey seals (Halichoerus grypus) seem to have occurred at the breeding sites. Because of the high concentration of animals at this time, even small oil spills will pollute many animals. As a result of chronic low-level pollution from coastal ship traffic and discharges from offshore petroleum activity in the North Sea, approximately 50% of the grey seal pups at the largest breeding colony in Norway are polluted each year by oil. In this case, as well as in other similar cases of spills at breeding colonies, oil has produced little visible disturbance to the seals behaviour and there has been little mortality. The effects and mortality may, however, be more serious following a spill of crude oil, where animals may be affected by inhalation of toxic volatile compounds. High body burdens of PCBs and DDTs seem to have caused skull-bone lesions and occlusions of the uteri in grey seals in the Baltic Sea. Exposure to these persistent compounds has also been suspected to be the cause of reduction in the population of Baltic grey seals. There are indications that thyroid hormone and vitamin A status of grey seal pups are affected by the low exposure concentrations experienced at the Norwegian coast (approximately 1/20 of the concentration detected in grey seal pups from the Baltic Sea). This gives serious cause for concern about the effects that chronic low-level exposure to persistent organochlorine pollutants may have on individuals and on populations of grey seals.

Congener-specific exposure of grey seal (Halichoerus grypus) pups to chlorinated biphenyls during lactation

Nous avons mesure l'exposition totale et quotidienne de jeunes phoques gris (Halichoerus grypus) a 25 congeneres de biphenyle chlore (BC) presents dans le lait des meres a l'ile de May (Ecosse) en 1990, 1991 et 1992. L'exposition totale de 36 petits nes de 13 femelles differentes variait entre 8,8 et 58,9 mg; les congeneres UICPA CB-153 et CB-138 etaient les composantes principales dans le lait, ou ils representaient 42,1% de l'exposition totale aux BC. La quantite de lait consommee chaque jour par les petits et la teneur en lipides de ce lait augmentaient pendant la lactation. En consequence, l'exposition quotidienne aux BC a augmente fortement pendant la premiere moitie de la periode d'allaitement de 18 jours. Il y avait des differences significatives entre les femelles dans les concentrations de BC dans le lait et dans la contribution relative des differents congeneres a l'exposition totale aux BC. Lorsqu'on eliminait les effets des variations entre femelles, on observait des changements significatifs dans les concentrations de BC moins chlores pendant la lactation et d'une annee a l'autre. On peut estimer de facon precise l'exposition d'un petit phoque gris aux BC si l'on connait l'identite de sa mere, sa masse au moment du sevrage et la concentration de BC dans un echantillon de lait preleve vers la fin de l'allaitement.

Organochlorine compounds in blubber, liver and brain in neonatal grey seal pups

The present study focuses on the distribution and accumulation of persistent organochlorine compounds in different tissues and organs of grey seal ( Halichoerus grypus) pups. Thus, levels of drins (aldrin, dieldrin, endrin), chlordanes (heptachlor, heptachlorepoxide, oxychlordane, transnonachlor), DDTs ( p,p′-DDE, o,p′-DDD, p,p′-DDD, o,p′-DDT, p,p′-DDT) and 22 PCB congeners were determined in samples of brain, fat, and liver of 0–10 days old grey seal pups from the species' main breeding site in Norway. Whereas 10 different compounds were detected in the blubber, 8 compounds were detected in the liver. The concentrations of the two major classes of OCs (PCBs and DDTs) in liver were both about 75% of that in blubber. In cerebral tissue, only two PCB congeners were detected, and ϵPCB was only about 1% of that measured in the blubber. The distribution pattern of PCB-congeners in liver and brain differed significantly from that in blood and blubber tissue, indicating that the physico-chemical properties of the individual congeners and the lipid composition of the tissues are decisive for the tissue-specific pattern of congener distribution. A significant increase of the ϵDDT/ϵPCB-ratio as a function of blubber thickness indicates that DDT compounds are more readily accumulated in older pups.

Congener-specific e×posure of grey seal (<I>Halichoerus grypus</I>) pups to chlorinated biphenyls during lactation

Congener-specific e×posure of grey seal (<I>Halichoerus grypus</I>) pups to chlorinated biphenyls during lactation

Tag loss in grey seals (Halichoerus grypus) and potential effects on population estimates

Cumulative tag loss among 4064 grey seal (Halichoerus grypus) pups observed on Sable Island was less than 1% during the first 5 months of life, 13% by the end of the first year, and continued to increase with age. Cumulative tag loss among grey seals aged 6 and older was over 40.0%. A double-tagging study indicated that pre-punching of flippers, the colour of tags applied, and application to the left or right flipper significantly affected tag loss. The addition of a flag to the tag had no significant effect. A comparison of scientific observations of tag loss with commercial bounty return data indicated that casual observers probably missed tags on double-tagged animals. Overlooked tags in single-tagging experiments result in population overestimates. In double-tagging experiments, overlooked tags result in correction factor overestimates and population underestimates. Age-specific tag loss correction factors should be used if population estimates include more than one age group.

Blood sampling as a non-destructive method for monitoring levels and effects of organochlorines (PCB and DDT) in seals

The aim of the present study was to examine the possibilities of using blood as a matrix for determining exposure to organochlorine compounds in seal pups, and to elucidate the possible correlations between pollutant load and biological variables. The mean values of ∑PCB and ∑DDT in blood cells of 17 live grey seal ( Halichoerus grypus ) pups from Froan, Norway, were 4.59 (SD = 7.61, n = 17), and 3.38 ng/g wet weight (SD = 4.74, n = 17), respectively. If calculated on lipid weight basis, the contents of ∑PCB and ∑DDT were 2819.6 (SD = 2956.7, n = 17) and 1982.3 ng/g l.w. (SD = 2013.7, n = 17), respectively, and similar to mean values reported in blubber tissue of dead seal pups from the same area. The data indicate that the concentrations of ∑PCB and ∑DDT in neonatal pups at Froan are lower as compared to concentrations reported in blood of grey seal pups from the Northwest Atlantic. Although the two pups that had the highest ∑PCB concentrations also had the lowest plasma concentrations of thyroxine, there was no significant correlation between the ∑PCB concentration in blood cells and the corresponding plasma concentrations of any of the thyroid hormones. We conclude that blood-sampling is a suitable non-destructive method for monitoring organochlorine residues in seals.

Organochlorine residue concentrations and burdens in grey seal (Halichoerus grypus) blubber during the first year of life

Between 1988 and 1991 grey seal (Halichoerus grypus) pups at various developmental stages were sampled at Sable Is., NS, and blubber samples were analysed for lipid content and organochlorine (OC) residue concentrations. Blubber lipid content increased significantly between birth and 12 d, and then stayed relatively constant. Blubber OC residue concentrations were fairly constant during the first 12–16 d of life. From weaning (approx. 16 d) until four months, the pups are learning to feed but are relying on blubber fat reserves; thus, during this period blubber weight declined to minimum levels, and OC residue concentrations in blubber lipid increased significantly. Blubber lipid OC concentrations then declined slightly as the pups gained weight, until at the end of one year they were about twice those immediately post‐weaning. Blubber lipid residue burdens calculated from these data showed that at weaning, about 98% of the seal's residues were accumulated from maternal milk. After weaning, there were no significant changes in the burdens of any residue until the end of the first year of the pup's life, and the organochlorine concentration changes reflected a fairly constant organochlorine burden around which lipid contents varied. These data suggest that the capacity of the seal to degrade the residue inherited from its mother is very limited. Furthermore, the absence of any significant accumulation of organochlorines during the second six months of the seal's life suggests that the juvenile seal must feed at a low trophic level which is not highly contaminated with organochlorines.

Mass changes of grey seal Halichoerus grypus pups on Sable Island: differential maternal investment reconsidered

Theory predicts that where variance in reproductive success differs between sexes, as in many sexually dimorphic species, mothers should invest more in male than in female offspring. In pinnipeds, parental investment is the sole responsibility of the mother. Both size at birth and subsequent mass gain during lactation are measures of that investment. We studied mass gain of grey seal pups, a sexually dimorphic species, during lactation and mass loss during the first 13 days of the postweaning fast using longitudinal data obtained on Sable Island, Canada. A mixed‐effects repeated measures model was used to account for the serial correlation in these longitudinal data. We found no significant difference in the birth mass of male (16.6 ± 0.45 kg) and female (15.6 ±0.74 kg) pups. Rate of mass gain by males (3.0 ± 0.13 kg/d) and females (2.7 ± 0.12 kg/d) also did not differ significantly during the lactation period. Grey seal pups on Sable Island tended to be larger at birth and gain mass more rapidly (70%–100%) during lactation than those in the United Kingdom. Mass loss of weaned pups was curvilinear over time. Over the first 10 days of the fast, pups lost 22% of their weaning mass. In both males and females, large pups lost mass more slowly than small ones during the postweaning fast. Based on our results and a review of previous studies, we found little evidence of differential maternal investment in male and female grey seal pups.

Water flux and early signs of entrance into phase III of fasting in grey seal pups.

Body water loss and turnover rate were measured in fasting newly weaned grey seal (Halichoerus grypus) pups without access to water for 52 days, by use of bolus injections of deuterated water. Total body water (N) was 41.8 +/- 2.3 (SD)% of total body weight at day 3 and 44.5 +/- 5.9 (SD)% at day 51 of fasting (P greater than 0.05), while the water content of body core decreased from 73 to 61% over the same period. The average water efflux rate in the same period was 362 +/- 17 (SD) ml d-1, the reduction in N over the same period contributing 35% to this end. The biological half-time of deuterated water was 38.2 +/- 3.3 (SD) d. Plasma osmolality increased from a stable level of 329 +/- 11 (SD) mosmol kg-1 to 445 +/- 11 (SD) mosmol kg-1 after day 38 of fasting. Plasma urea was the major contributor to this increase, in spite of a steadily decreasing urine urea concentration (Nordøy et al. 1990) throughout the entire experimental period. It is concluded that grey seal pups endure 52 d of fasting without intake of water with a minor dehydration of body core, while they become hyperosmotic due to increased catabolism of protein after 38 d when sparing of the insulating blubber layer in preparation for life in cold water seems to occur.

Chronic oil-fouling of grey seal pups at the Froan breeding ground, Norway

Frequent oil contamination of grey seal Halichoerus grypus pups is shown to be a severe problem within the Froan breeding area off central Norway. Since 1985, annual surveys have revealed that 30–60% of all pups born become oil-fouled during their first month of life. The location of the Froan archipelago within the coastal current serve to accumulate petroleum residues, and the main source of contamination of the pups is beached oil spots that melt when pups lay upon them. The proportion of oil contamined pups therefore increases with time spent ashore.

Observations on seals on Surtsey in the period 1980-1989

In this paper are presented records of sighting~ of seals in Surtsey from 1980 to 1989. Seals in Surtsey have been couilted regularly, as part of a bigger project of aerial censusing of seals around the coast of Iceland (Erlingur Hauksson 1985 and 1986). Earlier accounts of seals in Surtsey are rather sporadic and only based 011 occasional observations. Some of them are mentioned, but many may have been omitted whicl~ the author has not been aware of, since observers of seals in Surtsey have not published their records. INTRODUCTlON Fig. I. Grey seal pups on the northel-11 sallcly spit of the islanrl of Surtsey. Tlle picture is takc~~ by the :~uthor from an aircraft 011 October l!Ith 1986.

Glucose and ketone body turnover in fasting grey seal pups

Concentration and metabolic replacement (turnover) rate of glucose and ketone bodies were determined at intervals during a 52 day postweaning fast in five grey seal (Halichoerus grypus) pups, using bolus injections of radiotracers. Blood glucose was maintained at a high level throughout the fast, while beta-hydroxybutyrate increased 26 times from day 3 to day 37, whereafter it by and large was maintained. Glucose replacement rate decreased to 56% of the day 9 value at day 37 and dropped further to only 32% of the day 9 level at day 52 in two seals, while in another 2 seals it increased at this late stage. The average ketone body replacement rate ranged between 8.6 and 13.8 mumols min-1 kg-1, but did not change significantly (P greater than 0.05) during the fasting period. These results suggest a reduced gluconeogenesis from protein and increased production of ketone bodies, which may in part replace glucose as energy source during fasting.

Adaptations to prolonged fasting in free-living weaned gray seal pups

The water and energy metabolism of 12 free-living gray seal pups during their postweaning fast was investigated using tritiated water for determination of rates of energy expenditure and water turnover and changes in body composition. Changes in serum composition and urinary output were also measured. The duration of the postweaning fast ranged from 10 to greater than 28 days. The mean daily energy expenditure of pups was 12.0 +/- 1.0 (SE) MJ, equivalent to 2.7 times the basal metabolic rate predicted from M. Kleiber (The Fire of Life. Huntington, NY: Krieger, 1975). On average, lipid catabolism provided 94% of the energy used. Water-turnover rates were lower than predicted from C. R. Richmond, W. H. Langham, and T. T. Trujillo (J. Cell. Comp. Physiol. 59: 45-55, 1962). Urinary output of water and solute were also low, and these declined as the fast progressed. Although pups were in negative water balance, there was no evidence that they experience dehydration during the post-weaning fast. The principal adaptations to prolonged fasting in weaned gray seals are, therefore, lowering of field metabolic and water-turnover rate and reliance on stored lipid as fuel.

Insulation and thermal balance of fasting harp and grey seal pups

1. 1. Harp and grey seal pups were examined during the post-weaning period to quantify their thermoregulatory abilities and thermal limits. 2. 2. Deep body temperatures of harp seals (37.8 ± 0.8°C) were not significantly different from those of grey seals (38.9 ± 0.4°C). 3. 3. As blubber depth declined during the fast, temperature gradients extended increasingly deeper into the muscle layer potentially decreasing heat loss. 4. 4. Blubber conductivity (≈0.18 W/m/°C) did not vary regionally within an animal, or between animals or species. 5. 5. Calculated lethal cold limits in air were between — 85.4°C and — 116.1°C, suggesting that fasting, weaned pups can easily cope with temperatures they would normally experience.

Depressed metabolism and low protein catabolism in fasting grey seal pups

Grey seal pups (Halichoerus grypus) were collected at the time of weaning (mid-October) and fasted for 52 days at thermoneutrality in separate cages. Body weight decreased exponentially, while metabolic rate dropped 45% from an average of 2.95 +/- 0.15 (SEM) W kg-1 at day 2 of fasting to a stable level of 1.62 +/- 0.06 (SEM) W kg-1 from day 10 to day 47 of fasting. Respiratory quotient was low, indicating extensive catabolism of triglycerides, while plasma cortisol was fairly stable at 110 +/- 8 (SEM) nmol l-1 throughout the fasting period. Daily urinary output decreased from 236 +/- 20 (SEM) ml day-1 at day 2 to a stable value of 87 +/- 6 (SEM) ml day-1 between days 8 and 50 of fasting. The urine was analysed for urea, uric acid, creatinine, ammonia, total nitrogen and osmolality. Urea was always the principal excretory end-product, amounting to between 70 and 80% of the total excreted nitrogen. The urine was moderately concentrated (range 770-1300 mosmol kg-1). Total excreted urinary nitrogen decreased by 68% from 3.7 +/- 0.7 (SEM) g day-1 to 1.2 +/- 0.4 (SEM) g day-1 between days 2 and 50. The urinary nitrogen was used to calculate the daily amount of protein being oxidized and its energy content was compared with the measured basal metabolic rate of individual animals. Approximately 6% of the energy expended by grey seal pups during the post-weaning fast is derived from oxidation of protein. It is concluded that a rapid depression of basal metabolic rate and extensive blubber catabolism enable grey seal pups to endure prolonged periods of fasting without any apparent signs of discomfort or stress.

Characterization and measurement of immunoglobulins in the grey seal ( Halichoerus grypus)

Immunoglobulin concentrations were measured in the serum and colostrum of adult and pup Grey seals from North Rona in the outer Hebrides and the Isle of May in the Firth of Forth. IgG was shown to be the main immunoglobulin and two subclasses were identified. Serum immunoglobulin content was low in the week-old pups and increased up to 5 weeks, although it remained substantially lower than in the adults. Colostral immunoglobulins were high and cannot explain the low values in the pup serum. It is considered that the increased opportunistic infections seen in Grey seal pups may be related to this low immunoglobulin status.

Effects of environment on grey seal (Halichoerus grypus) pup mortality. Studies on the Isle of May

Breeding sites, including beach environment and topography, play a significant role in the causes of death of grey seal (Halichoerus grypus) pups, in particular the incidence of starvation, peritonitis/navel ill, other infectious diseases and injuries as a result of adult‐pup interactions. The bacteria involved are opportunistic invaders. A wide and differing sex ratio in dead pups was found on different beaches and this has not been satisfactorily explained.

Erratum: Mass Loss, Metabolic Rate, and Energy Utilization by Harp and Gray Seal Pups during the Postweaning Fast

Previous articleNext article No AccessErratum: Mass Loss, Metabolic Rate, and Energy Utilization by Harp and Gray Seal Pups during the Postweaning FastPDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 61, Number 3May - Jun., 1988 Article DOIhttps://doi.org/10.1086/physzool.61.3.30161242 Views: 1Total views on this site Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). Copyright 1988 The University of ChicagoPDF download Crossref reports no articles citing this article.