344 research outputs found
Greenland whales and walruses in the Svalbard food web before and after exploitation
Between 1600 and 1900 two numerous and ecologically important large marine mammals were extirpated in the Svalbard archipelago. These were the pelagic-feeding Greenland whale (Balaena mysticetus) and the benthic-feeding walrus (Odobaenus rosmarus rosmarus), the initial stocks of which prior to exploitation are estimated to have numbered approximately 46 000 and 25 000 animals respectively. Their annual food consumption at that time is estimated to have been some 4 million tons of plankton and 0.4 million tons of benthic organisms. Assuming that the primary and secondary production of the shelf/coastal ecosystem in the 16th century (before the peak of the Little Ice Age) was similar to that of the present day, the authors have concluded that a major shift in the food web must have occurred after the Greenland whales and walruses were eliminated. Planktonivorous seabirds and polar cod (Boreogadus saida) very probably took advantage of the extirpation of the Greenland whales, while eiders (Somateria mollissima) and bearded seals (Erignathus barbatus) benefited from the walrus's extinction. In turn, the increased amount of pelagic fish provided food for piscivorous alcids and gulls, and may have given rise to the huge present-day seabird colonies on Svalbard
Greenland whales and walruses in the Svalbard food web before and after exploitation
Between 1600 and 1900 two numerous and ecologically important large marine mammals were extirpated in the Svalbard archipelago. These were the pelagic-feeding Greenland whale (Balaena mysticetus) and the benthic-feeding walrus (Odobaenus rosmarus rosmarus), the initial stocks of which prior to exploitation are estimated to have numbered approximately 46 000 and 25 000 animals respectively. Their annual food consumption at that time is estimated to have been some 4 million tons of plankton and 0.4 million tons of benthic organisms. Assuming that the primary and secondary production of the shelf/coastal ecosystem in the 16th century (before the peak of the Little Ice Age) was similar to that of the present day, the authors have concluded that a major shift in the food web must have occurred after the Greenland whales and walruses were eliminated. Planktonivorous seabirds and polar cod (Boreogadus saida) very probably took advantage of the extirpation of the Greenland whales, while eiders (Somateria mollissima) and bearded seals (Erignathus barbatus) benefited from the walrus's extinction. In turn, the increased amount of pelagic fish provided food for piscivorous alcids and gulls, and may have given rise to the huge present-day seabird colonies on Svalbard
The hunting of the Greenland right whale in Svalbard, its interaction with climate and its impact on the marine ecosystem
During the 17th and 18th centuries, tens of thousands of Greenland right whales were killed as a result of extensive European whaling in the coastal waters of the Svalbard archipelago. The author reconstructed these whaling activities, examined how the changing climate affected whaling productivity, and considered the consequences of climate and whaling on the species and on the North Atlantic ecosystem. Annual catch records made it possible to calculate the original size of the whale population; its natural migration pattern in the Greenland Sea could be reconstructed using shipping logs and itineraries. Other written sources revealed that besides human hunting activities, climate change played an important role in the elimination of the Greenland right whale from the Arctic marine ecosystem. This elimination made millions of plankton available for other marine mammals, polar cod and planktonfeeding birds. This has caused a major shift in the food web. changing the marine ecosystem in Svalbard
Life in the Polar Winter - Strategies of Survival
The perception of the polar winter as a period in which organisms have to struggle for survival is common among people living almost exclusively outside the polar regions, even if sometimes in areas with winter resembling the polar winter. ... For arctic organisms, endemic to and wintering in the far North, the polar winter possibly has a different significance. For these organisms it is often a period of rest, during which they conserve energy and prepare for reproduction in the coming feeding season. Until the last decades of this century, we knew little about the significance of the polar winter for organisms that live there year-round. For migratory species it is obviously a rather intolerable season, but how resident species survive and live through the winter was unknown. ... The series of eight papers presented here ... stem from a multidisciplinary symposium organized by the Arctic Centre of the University of Groningen on the occasion of the 375th anniversary of this university of 1989. ... The guiding question of this symposium was: How do humans and their living resources survive the polar winter? As the resources are both terrestrial and marine, both are discussed when presenting organisms from different trophic levels. ... This series of papers concludes with a study of the successes and misfortunes of western Europeans wintering in the High Arctic in the 16th and 17th centuries and an article about Russian trappers during the 18th and 19th centuries wintering in Spitsburgen. ..
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