The Bering Sea Ecosystem (1996) / Chapter Skim
Currently Skimming:
2 Marine Ecosystems: A Conceptual Framework
2 Marine Ecosystems: A Conceptual Framework
Pages 11-27
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 11... ...
The chapter then discusses ecosystem management and explores whether it can be seen as a solution to perceived problems in the Bering Sea. Finally, it describes the Bering Sea ecosystem and its analogs.
|
From page 12... ...
For example, Sherman and Alexander (1986) identified several separate large marine ecosystems (LMEs)
|
From page 13... ...
Because of the significance of processes on multiple spatial and temporal scales to the generation of ecological pattern, and especially the unknown contributions of historical events, scientists studying ecosystems are always faced with incomplete and imperfect information. As a result, ecosystem processes reside in what Magnuson (1990)
|
From page 14... ...
Because the exploitation history affects the organization of a marine ecosystem, it should be taken into account in attempting to develop ecosystem management policy. Cascading Trophic Interactions in Ecosystems Development of the science necessary to support ecosystem management probably will require a new synthesis of previously separate approaches to the study of ecology -- a melding of relevant aspects of population ecology, community ecology, and traditional ecosystem ecology.
|
From page 15... ...
Summary Marine ecosystems are complex structures in which significant (re-) ordering occurs in both top-down and bottom-up directions.
|
From page 16... ...
. Important differences include the following: • Random environmental forcing of terrestrial ecosystems shows constant variance per unit frequency out to about 50 years, while that of oceanic ecosystems shows increasing variance with decreasing frequency from hours to millennia.
|
From page 17... ...
. ENVIRONMENTAL AND ANTHROPOGENIC EFFECTS Oceanic ecosystems are affected by environmental change as well as by human activities such as fishing.
|
From page 18... ...
(1993) stated, "After several decades of intense fishing in the Eastern Bering Sea, the Aleutian Islands, and the Gulf of Alaska, a number of fish stocks have been overfished, with signs of depletion and ecosystem disturbance apparent in associated marine populations." Although the meaning of the term is ambiguous, overfishing in the context of fishery management is generally defined as "a [fishing]
|
From page 19... ...
In most cases where overfishing and mismanagement have been blamed for declines of nontarget species, as for the pollock fishery and Steller sea lions in the eastern North Pacific, the effects (alleged or actual) have been indirect, and ecosystem (or ecological)
|
From page 20... ...
Apart from this, there appear to be few, if any, objective criteria that can be used to determine if an oceanic ecosystem has been adversely affected by humans. ECOSYSTEM MANAGEMENT Ecosystem management in the marine environment lags substantially behind the record of terrestrial progress both in conceptual development and in application.
|
From page 21... ...
The National Marine Fisheries Service has developed and employed multispecies models and has expressed commitment to the principles of ecosystem management. Although ecosystem management is widely perceived as the goal of modern fishery management, it is not clearly defined in an operational sense.
|
From page 22... ...
States take responsibility for management of fisheries resources within this coastal fringe, although regional management councils play an increasing role in integrating state programs on migratory stocks shared among several states. The National Marine Fisheries Service of the National Oceanic and Atmospheric Administration has responsibility for management of fishery resources from 3 to 200 miles offshore.
|
From page 23... ...
Ecosystem management as applied to pelagic marine ecosystems demands a fundamental change in our management institutions and integration among them. Transition from commodity to ecosystem management in the sea also will require public involvement to be successful.
|
From page 24... ...
Public opinion must play a vital role in resolving these conflicts and in setting limits to the application of ecosystem management in the seas. THE BERING SEA ECOSYSTEM AND ITS ANALOGS The Bering Sea ecosystem is not unique among oceanic ecosystems in its response to environmental and anthropogenic forcing.
|
From page 25... ...
. While Bering Sea fur seals and sea lions have declined during the last several decades, in the North Sea, grey seal populations have been stable or increased.
|
From page 26... ...
The principal exchanges of water take place through Bering Strait into the Chukchi Sea, and in the western Bering Sea where the Kamchatka Current flows south into the Oyashio mixing region; this water is supplied by diffuse flow through the Aleutians. Atmospheric systems that control surface ocean conditions in the region, such as the Aleutian Low, extend well beyond these domains and are influenced by events at much greater distances, such as El Niño Southern Oscillation events in the equatorial Pacific.
|
From page 27... ...
Aleutian Basin, (3) Aleutian Islands, and (4)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.