194
Land-Ocean SYstems in the Siberian Arctic: Dynamics and History
Impact on the bottom fauna
Stomachs in King Eiders coming from the Polynya contain remains of Gastropoda and Bivalvia
shells. Two mollusc species were identified from the remains as Leonucula bellotii and
Cryptonatica clausa. Biocoenoses, been dominated by Leonucula bellotii with average biomass
in 111-188g/m2 (Sirenko et aI., 1995), was found directly beneath the place where Polynya
was situated in spring 1996. We used the average between sexes ME, calculated from average
BMR, for the purpose of impact estimation. Average ME in bird is 1973 KJ/day. So intake by
one bird in 782g of shell food was calculated from ME using metabolic efficiency coefficient
and value of caloric density of food. Number of diving acts during daily feeding is 271,
therefore 2.9g of shell food must be taken by each dive. Intake of entire Eider population (Table
I) during 31 days springing is 480961 kg of shells, or 0.183g per m 2 of bottom fauna, situated
beneath the ice-free area of the Polynya. So the impact on benthic fauna is 0.10-0.17% of its
biomass.
Discussion
All bird species we found on the Polynya, except the Snow Bunting, are marine birds. Absence
of the birds such as Brunnich's Guillemot (Uria lomvia) and Black Guillemot (Cepphus grylle)
was in a good accord with early spring migration of these species to breeding colonies situated
westward of our study area (Uspensky, 1969). Kittiwakes, breeding in the same colonies,
usually migrate later than auks. The Kittiwakes observed migrating westward in this study,
might breed along the Eastern Taimyr coast. Ducks and Pomarine Skua widespread breeding in
the maritime tundra, migrate to the breeding grounds close to Polynya.
Our study of King Eider bioenergetics shows that the value of metabolised energy in 3.17
BMR (males) and 3.44 BMR (females) doesn't enlarge maximal permissible level for this value
in 4 BMR. Living on the Polynya Eiders take 2.8g of shell food by one dive, but the average
body mass in Leonucula bellotii here is 0.12g (Petriashov, pers. com.). This allows us to
conclude, that Eiders feed by selecting the large prey, which doesn't dominate in biocoenoses.
The selective feeding may be the main reason for King Eiders to leave relatively warm waters of
the Bering Sea, where many species of sea-ducks winter, reducing the source of large prey,
occur on the Great Siberian Polynya for overspringing.
Acknowledgements
I am cordially thankful to Dr. H. Kassens (GEOMAR, Kiel) for the possibility of field work
this study is based on. The stomach contents were identified by Prof. Ya. 1. Starobogatov and
Dr. B. 1. Sirenko, Dr. V. V. Petriashov consulted on bottom fauna. Dr. 1. A. Dmitrenko and
V. Yu. Karpiy provided technical support. Special thanks are due to Prof. V. R. Dolnik for his
invaluable expertise on bioenergetics approaches to birds ecology. He also reviewed the
preliminary draft.
References
Alimov, A.F. (198\) Functional ecology of freshwater Bivalves (in Russian). Nauka, Leningrad, 248 pp.
Birulya, A.A. (1907) Notes on the life of birds along the polar coast of Siberia (in Russian). Zapiski
Imperatorskoy Academii Nauk po fiz.-mat. sekcii 18(2), 1-157.
Dolnik, V.R. (1995) Energy and time resources in free-living birds (in Russian). Nauka, St.Petersburg, 360pp.
Jenssen, B.M., M. Ekker and C. Bech (1989) Thermoregulation in winter-acclimatized common eiders
(Somateria mollissima) in air and water. Can. J. Zoo!., 67, 669-673.
Land-Ocean SYstems in the Siberian Arctic: Dynamics and History
Impact on the bottom fauna
Stomachs in King Eiders coming from the Polynya contain remains of Gastropoda and Bivalvia
shells. Two mollusc species were identified from the remains as Leonucula bellotii and
Cryptonatica clausa. Biocoenoses, been dominated by Leonucula bellotii with average biomass
in 111-188g/m2 (Sirenko et aI., 1995), was found directly beneath the place where Polynya
was situated in spring 1996. We used the average between sexes ME, calculated from average
BMR, for the purpose of impact estimation. Average ME in bird is 1973 KJ/day. So intake by
one bird in 782g of shell food was calculated from ME using metabolic efficiency coefficient
and value of caloric density of food. Number of diving acts during daily feeding is 271,
therefore 2.9g of shell food must be taken by each dive. Intake of entire Eider population (Table
I) during 31 days springing is 480961 kg of shells, or 0.183g per m 2 of bottom fauna, situated
beneath the ice-free area of the Polynya. So the impact on benthic fauna is 0.10-0.17% of its
biomass.
Discussion
All bird species we found on the Polynya, except the Snow Bunting, are marine birds. Absence
of the birds such as Brunnich's Guillemot (Uria lomvia) and Black Guillemot (Cepphus grylle)
was in a good accord with early spring migration of these species to breeding colonies situated
westward of our study area (Uspensky, 1969). Kittiwakes, breeding in the same colonies,
usually migrate later than auks. The Kittiwakes observed migrating westward in this study,
might breed along the Eastern Taimyr coast. Ducks and Pomarine Skua widespread breeding in
the maritime tundra, migrate to the breeding grounds close to Polynya.
Our study of King Eider bioenergetics shows that the value of metabolised energy in 3.17
BMR (males) and 3.44 BMR (females) doesn't enlarge maximal permissible level for this value
in 4 BMR. Living on the Polynya Eiders take 2.8g of shell food by one dive, but the average
body mass in Leonucula bellotii here is 0.12g (Petriashov, pers. com.). This allows us to
conclude, that Eiders feed by selecting the large prey, which doesn't dominate in biocoenoses.
The selective feeding may be the main reason for King Eiders to leave relatively warm waters of
the Bering Sea, where many species of sea-ducks winter, reducing the source of large prey,
occur on the Great Siberian Polynya for overspringing.
Acknowledgements
I am cordially thankful to Dr. H. Kassens (GEOMAR, Kiel) for the possibility of field work
this study is based on. The stomach contents were identified by Prof. Ya. 1. Starobogatov and
Dr. B. 1. Sirenko, Dr. V. V. Petriashov consulted on bottom fauna. Dr. 1. A. Dmitrenko and
V. Yu. Karpiy provided technical support. Special thanks are due to Prof. V. R. Dolnik for his
invaluable expertise on bioenergetics approaches to birds ecology. He also reviewed the
preliminary draft.
References
Alimov, A.F. (198\) Functional ecology of freshwater Bivalves (in Russian). Nauka, Leningrad, 248 pp.
Birulya, A.A. (1907) Notes on the life of birds along the polar coast of Siberia (in Russian). Zapiski
Imperatorskoy Academii Nauk po fiz.-mat. sekcii 18(2), 1-157.
Dolnik, V.R. (1995) Energy and time resources in free-living birds (in Russian). Nauka, St.Petersburg, 360pp.
Jenssen, B.M., M. Ekker and C. Bech (1989) Thermoregulation in winter-acclimatized common eiders
(Somateria mollissima) in air and water. Can. J. Zoo!., 67, 669-673.