Sammendrag
1. Climate change is commonly associated with many species redistributions and the
influence of other factors may be marginalized, especially in the rapidly warming
Arctic.
2. The Barents Sea, a high latitude large marine ecosystem in the Northeast Atlantic
has experienced above-average temperatures since the mid-2000s with divergent
bottom temperature trends at subregional scales.
3. Concurrently, the Barents Sea stock of Atlantic cod Gadus morhua, one of the most
important commercial fish stocks in the world, increased following a large reduction in fishing pressure and expanded north of 80°N.
4. We examined the influence of food availability and temperature on cod expansion
using a comprehensive data set on cod stomach fullness stratified by subregions
characterized by divergent temperature trends. We then tested whether food
availability, as indexed by cod stomach fullness, played a role in cod expansion in
subregions that were warming, cooling, or showed no trend.
5. The greatest increase in cod occupancy occurred in three northern subregions
with contrasting temperature trends. Cod apparently benefited from initial
high food availability in these regions that previously had few large-bodied fish
predators.
6. The stomach fullness in the northern subregions declined rapidly after a few years
of high cod abundance, suggesting that the arrival of cod caused a top-down effect on the prey base. Prolonged cod residency in the northern Barents Sea is,
therefore, not a certainty.
abiotic, Barents Sea, biotic, hierarchical design, marine food webs, range expansion, spatial
distribution, stomach data
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