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Reconciling differences in trophic control in mid‐latitude marine ecosystems
Author(s) -
Frank Kenneth T.,
Petrie Brian,
Shackell Nancy L.,
Choi Jae S.
Publication year - 2006
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2006.00961.x
Subject(s) - trophic level , ecology , ecosystem , mesopredator release hypothesis , population , environmental science , marine ecosystem , trophic cascade , oceanography , apex predator , geography , biology , food web , geology , demography , sociology
The dependence of long‐term fishery yields on primary productivity, largely based on cross‐system comparisons and without reference to the potential dynamic character of this relationship, has long been considered strong evidence for bottom‐up control in marine systems. We examined time series of intensive empirical observations from nine heavily exploited regions in the western North Atlantic and find evidence of spatial variance of trophic control. Top‐down control dominated in northern areas, the dynamics evolved from bottom‐up to top‐down in an intermediate region, and bottom‐up control governed the southern areas. A simplified, trophic control diagram was developed accounting for top‐down and bottom‐up forcing within a larger region whose base state dynamics are bottom‐up and can accommodate time‐varying dynamics. Species diversity and ocean temperature co‐varied, being relatively high in southern areas and lower in the north, mirroring the shifting pattern of trophic control. A combination of compensatory population dynamics and accelerated demographic rates in southern areas seems to account for the greater stability of the predator species complex in this region.