Resource-driven colonization by cod in a high Arctic food web
Edda Johannesen1, Nigel G Yoccoz2,3, Torkild Tveraa3
1Institute of Marine Research Nordnes Norway.
Ecology and Evolution
|January 4, 2021
Summary
Atlantic cod (Gadus morhua) expanded into the Arctic Barents Sea due to warming and high food availability. However, their long-term residency is uncertain as cod abundance impacted prey availability.
Area of Science:
- Marine Biology
- Climate Change Ecology
- Fisheries Science
Background:
- Arctic marine ecosystems are experiencing rapid warming and associated species redistributions.
- The Barents Sea, a key Arctic ecosystem, has seen above-average temperatures and a significant increase in Atlantic cod (Gadus morhua) populations.
- Divergent bottom temperature trends exist across Barents Sea subregions.
Purpose of the Study:
- To investigate the influence of food availability and temperature on the northward expansion of Atlantic cod in the Barents Sea.
- To determine if food availability, indicated by stomach fullness, played a role in cod expansion across areas with different temperature trends.
Main Methods:
- Utilized a comprehensive dataset on cod stomach fullness, stratified by Barents Sea subregions.
- Analyzed cod expansion in relation to subregional temperature trends (warming, cooling, no trend).
- Assessed the role of food availability (stomach fullness) in cod expansion patterns.
Main Results:
- Greatest cod occupancy increases were observed in three northern subregions with varied temperature trends.
- Initial high food availability in these northern areas, previously lacking large predators, supported cod expansion.
- Cod stomach fullness declined rapidly after a few years, indicating a top-down effect on the prey base.
Conclusions:
- Cod expansion into the Barents Sea is influenced by both temperature and prey availability.
- The arrival of cod can lead to a rapid depletion of local prey resources.
- The long-term persistence of cod in the northern Barents Sea is not guaranteed due to these top-down effects.
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