The past and present status of the southern elephant seal (Mirounga leonina Linn.) in Greater Antarctica

Mammalia ◽  
1989 ◽  
Vol 53 (1) ◽  
Author(s):  
Nicholas J. GALES ◽  
Harry R. BURTON
Keyword(s):  
Present Status ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
The Past

scholarly journals Bottom-up regulation of a pole-ward migratory predator population

2014 ◽  
Vol 281 (1782) ◽  
pp. 20132842 ◽  
Author(s):  
John van den Hoff ◽  
Clive R. McMahon ◽  
Graham R. Simpkins ◽  
Mark A. Hindell ◽  
Rachael Alderman ◽  
...  
Keyword(s):  
Sea Ice ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Island Population ◽  
Predator Population ◽  
Mirounga Leonina ◽  
Atmospheric Variability ◽  
Macquarie Island ◽  
The Past ◽  
Foraging Range

As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal ( Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change ( r ) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from −0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced ( R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals’ foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.

scholarly journals The northernmost haulout site of South American sea lions and fur seals in the western South Atlantic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Natália Procksch ◽  
M. Florencia Grandi ◽  
Paulo Henrique Ott ◽  
Karina Groch ◽  
Paulo A. C. Flores ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
South American ◽  
Mirounga Leonina ◽  
Sea Lions ◽  
Significant Difference ◽  
Northern Portion ◽  
Kernel Density Analysis

AbstractWe present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months.

A histochemical examination of the epidermis of the southern elephant seal (Mirounga leonina L.) during the telogen stage of hair growth

1968 ◽  
Vol 16 (1) ◽  
pp. 17 ◽  
Author(s):  
RIC Spearman
Keyword(s):  
Hair Growth ◽  
Outer Part ◽  
Elephant Seal ◽  
Basal Part ◽  
Southern Elephant Seal ◽  
Horny Layer ◽  
Mirounga Leonina ◽  
Disulphide Bonds ◽  
Sulphydryl Groups ◽  
Hair Shafts

The epidermal horny layer in the elephant seal, Mirounga leonina, is formed of dead, flattened, solidly keratinized cells without basophilic nuclear remnants. The basal part is more compacted than the outer part which is loosely arranged and has wide dorsoventral intercellular spaces, but the cornified cells appear firmly stuck together along their lateral junctions. Sloughing of the horny layer at the end of a season's growth appears to take place without the development of a specialized fission zone. This is in contrast to the sloughing mechanism in lizards and snakes. Keratin disulphide bonds are uniformly distributed in the horny layer but bound sulphydryl groups, calcium, and phospholipids are more concentrated in the basal part. At the telogen hair growth stage the epidermal horny layer was found to be closely united with the hair shafts within the insunken follicle necks. In these regions the compact junctional horny layer reacted for disulphide bonds, bound sulphydryl groups, phospholipids, and calcium. These substances also occurred in the hook-like keratinized cells which attached the resting club hair to the base of the follicle, but the hair keratin itself only reacted strongly for disulphide bonds. The possible significance of bound phospholipid in the horny layer in waterproofing the skin is discussed.

Studies on the ectoparasites of seals and penguins. 1. The ecology of the louse Lepidophthirus macrorhini Enderlein on the southern elephant seal, Mirounga leonina (L)

1965 ◽  
Vol 13 (3) ◽  
pp. 437 ◽  
Author(s):  
MD Murray ◽  
DG Nicholls
Keyword(s):  
Stratum Corneum ◽  
Skin Temperature ◽  
Elephant Seal ◽  
The Body ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Prolonged Stay ◽  
Blood Sucking ◽  
Southern Elephant Seals ◽  
Causes Of Mortality

Although the southern elephant seals, Mirounga leonina, that breed on Macquarie I., come ashore for only 3-5 weeks twice a year, the hind flippers of most of them are infested with the blood-sucking louse Lepidophthirus macrorhini. L. macrorhini does not oviposit, and eggs do not hatch, in water. Reproduction occurs when the elephant seal is ashore on the beach or in the adjacent tussock. The life cycle can be completed in c. 3 weeks and, because 6-9 eggs are laid daily, multiplication can be rapid. Temperatures greater than 25�C are required for rapid multiplication, and these temperatures occur more frequently on the hind flippers than elsewhere on the body. The number of L. macrorhini on a hind flipper however rarely exceeds 100. The principal causes of mortality of the lice are failure to survive the seal's prolonged stay at sea, the moult of the seal, and transmission to unfavourable sites on the seal. When an elephant seal goes to sea its skin temperature falls to nearly that of the sea. The reduction in the metabolic rate of the louse at low temperatures results in the amount of oxygen obtained from the sea by cutaneous respiration being sufficient for survival. The lice do not enter into a state of complete suspended animation, and a blood meal is required at least once a week to enable sufficient to survive to repopulate the seal. The skin temperature of a seal at sea rises more frequently on the flippers than elsewhere on the body because of the increased rate of blood flow to the flippers after diving and whenever it is necessary to dissipate heat. Consequently, there are more opportunities for the lice on the hind flippers to feed. L. macrorhini burrows into the stratum corneum, thus reducing losses to the population when the elephant seal annually sheds the outer layers of the stratum corneum attached to the hair, because only the roof of the burrow is lost. Lice do not reproduce on the older seals that moult in muddy wallows, and consequently fewer lice are found on these animals. Pups are infested within a few days of birth, and the gregarious habits of the elephant seal spread infestations through the seal population. Lice transfer to all parts of the bodies of seals but it is the multiplication of those on the flippers that maintains the louse population. The abundance of L. macrorhini is determined largely by the frequency and duration of opportunities to reproduce when the elephant seal is ashore, and to feed when the elephant seal is at sea.

The skin and hair of the southern elephant seal, (Mirounga Leonina (L.) II. pre-natal and early post-natal development and moulting

1967 ◽  
Vol 15 (2) ◽  
pp. 349 ◽  
Author(s):  
JK Ling ◽  
CDB Thomas
Keyword(s):  
Cellular Proliferation ◽  
Elephant Seal ◽  
Hair Follicles ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Adult Type ◽  
Root Sheath ◽  
Stratum Lucidum ◽  
Near Term ◽  
Post Implantation

The embryological development of hair follicles and the emergence and growth of the foetal pelage of the southern elephant seal, Mirounga leonina (L.), are described in terms of 10 recognizable stages. Follicle primordia appear at a post-implantation age of about 8 weeks and growth of the first definitive hairs takes approximately 14 weeks. Sebaceous glands develop after the sweat gland anlagen, but their ontogeny is more rapid and they function earlier in the formation of the hair canals. The latter are formed by epidermal cellular accretion from without and sebaceous cellular activity within the developing pilosebaceous unit. Development of three epidermal layers is also described and the absence of a stratum granulosum and stratum lucidum noted. The formation of muscle, collagen, and elastic fibres, and blood vessels in the dermis has been observed and described. The histological development of the first adult-type hair generation has been followed in near-term foetuses and young pups until the latter go to sea. The post-natal moult usually commences about 1 week after birth and takes 3 weeks for its completion. Whereas the foetal hairs are not connected to the stratum corneum lining the pilary canal, with a result that they are shed individually, the epidermis and all subsequent hair generations are united. This union is established after the post-natal moult at the end of the active follicular phase by a process of epidermal and external root sheath cellular proliferation around the bottom of the hair canal.

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