The Mummified Seals of the Dry Valleys : A literature review
Degree GrantorUniversity of Canterbury
Degree LevelPostgraduate Certificate
Degree NamePostgraduate Certificate in Antarctic Studies
By the accounts of most who visit them the Dry Valleys of southern Victoria Land, on the shores of the Ross Sea, exert a strange fascination. Left literally high and dry by receding glaciers, these “oases in the ice” (Clarke) are starkly beautiful. They are of unusual scientific interest too: stripped of the ice mantle up to 4km deep which covers most of Antarctica, they provide a rare opportunity to study the continent’s geology, flora and fauna. But not all of the secrets of the Dry Valleys are readily revealed. From the first years of Antarctic exploration observers were puzzled to find the contorted and mummified carcases of seals many kilometres up the valleys and in surrounding areas, often at considerable heights above sea level. What drove the seals to trek doggedly away from their colonies and food sources until they apparently starved to death remained a mystery: theories from tidal waves to climate change, glacial retreat or suicide were put forward, but none seemed satisfactlory. Also mysterious was the age of the carcases. Early efforts at carbon dating suggested some of the seal remains were up to 2600 years old, but the inaccuracy of carbon-dating marine creatures in Antarctica makes these results unreliable. A more recent theory is that the harsh conditions prevailing in the Dry Valleys obliterate bone and tissue quickly, and that even the most weathered of the carcases are only a few decades old (Dort 1981). Other questions abound. Most of the seal carcases are Crabeater seals (Lobodon carcinophaguis), yet the dominant seal in McMurdo Sound, where they appear to have come from, is the Weddell (Leptonychotes weddellii). The seals demonstrate a puzzling determination to march to their deaths: faint tracks from one seal found dead on the surface of Lake Bonney (Dort 1981) ran for several kilometres in an almost straight line, and a live animal heading inland across the McMurdo Ice Shelf resisted all attempts to point it back towards the sea (Stirling and Kooyman). This has led to speculation that these unfortunate animals are following some sort of internal guidance system which has gone wrong (Dort 1981). After a flurry of activity studying the seals in the sixties and seventies, little work appears to have been done since. Some study is currently focused on the microbial colonies beneath the dead seals, which apparently differ greatly from one carcase to another. Dr Craig Cary of Waikato University is shortly to publish on this topic. This paper will attempt to follow the trail of the seals, as it were, from the earliest observations by Scott and Shackleton’s parties to the most recent – and still inconclusive - theories about how and why they met their strange deaths.
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