Effects of interdecadal climate variability on the
oceanic ecosystems of the NE Pacific
DRAFT: DO NOT CITE WITHOUT
PERMISSION OF AUTHORS
by Robert C. Francis1, Steven
R. Hare2, Anne B. Hollowed3, and Warren S. Wooster4
This page last updated
1 School of Fisheries Box 357980, University of Washington, Seattle,
WA 98195
2 International Pacific Halibut Commission, P. O. Box 95009, University
of Washington, Seattle, WA 98145-2009
3 Alaska Fisheries Science Center, National Marine Fisheries Service,
7600 Sand Point Way NE, Seattle, WA 98115
4 School of Marine Affairs, University of Washington, 3707 Brooklyn
Ave NE, Seattle, WA 98105-6715
Talk presented at 1995 PACLIM Workshop
Paper accepted by Fisheries Oceanography
Final Submission January 1997
Abstract
A major reorganization of the North-east Pacific biota transpired
following a climatic "regime shift" in the mid 1970s. In this paper, we
characterize the effects of interdecadal climate forcing on the oceanic
ecosystems of the NE Pacific Ocean. We consider the concept of scale in
terms of both time and space within the North Pacific ecosystem and develop
a conceptual model to illustrate how climate variability is linked to ecosystem
change. Next we describe a number of recent studies relating climate to
marine ecosystem dynamics in the NE Pacific Ocean. These studies have focused
on most major components of marine ecosystems - primary and secondary producers,
forage species, and several levels of predators. They have been undertaken
at different time and space scales. However, taken together they reveal
a more coherent picture of how decadal scale climate forcing may affect
the large oceanic ecosystems of the NE Pacific. Finally, we synthesize
the insight gained from interpreting these studies. Several general conclusions
can be drawn:
1 There are large-scale, low-frequency, and
sometimes very rapid changes in the distribution of atmospheric pressure
over the North Pacific which are, in turn, reflected in ocean properties
and circulation.
2 Oceanic ecosystems respond on similar
time and space scales to variations in physical conditions.
3 Linkages between the atmosphere/ocean
physics and biological responses are often different across time and space
scales.
4 While the cases presented here demonstrate
oceanic ecosystem response to climate forcing, they provide only hints
of the mechanisms of interaction.
5 A model whereby ecosystem response to
specified climate variation can be successfully predicted will be difficult
to achieve because of scale mismatches and non-linearities in the atmosphere-ocean-biosphere
system.
Copyright © Steven R. Hare