Abstract
Capelin Mallotus villosus is one of the most abundant fish species in the Barents Sea and is a critical link between zooplankton and commercial species such as Atlantic cod. Climatic condi- tions influence the population structure, feeding, and biological condition of capelin by affecting their distribution and that of their zooplankton prey. We sampled more than 1500 stomachs of capelin from 1978, 2002, 2003, 2006, and 2007 spanning years with cold, moderate, and warm climatic conditions, and examined the distribution of their major prey items: euphausiids and Calanus copepods. Capelin distribution is broader during warmer years, especially in the north and northeast. Copepods and euphausiids dominated the diets of capelin, but hyperiid amphipods and chaetognaths were also important. Diet and stomach fullness showed significant geographic variability within the Barents Sea, and varied among years depending on whether the climatic conditions were warmer or colder than the long-term average. Abundance of inter- and intraspecific competitors appears to affect diet, feeding intensity, and fat content. Fat content is an important indicator of capelin reproductive po- tential and their food value for predators, and was highest in northeastern regions and strongly influenced by capelin diet. Analyses of these 5 years of data plus 10 more years from previously pub- lished studies indicate the importance of climate drivers for determining fat content. Mechanisms are complex, however, and many factors directly and indirectly influence condition of this critical species in the Barents Sea ecosystem.
Highlights
The efficient transfer of energy from primary producers to higher trophic levels is responsible for the rich communities of seabirds and marine mammals supported by Arctic marine food webs
We asked: (1) How does climate variability affect feeding of capelin on zooplankton prey? (2) How is this reflected in lipid content and, the ability to transfer energy to higher trophic levels? (3) What are the general mechanisms by which climatic conditions may affect these processes?
Body condition of capelin was assessed at every sampling station by estimating the fat content in muscle tissue (%) from approximately 25 individual fish from a variety of size classes using the method of Lazarevsky (1955)
Summary
The efficient transfer of energy from primary producers to higher trophic levels is responsible for the rich communities of seabirds and marine mammals supported by Arctic marine food webs. The distribution and abundance of their zooplankton prey, can be strongly impacted by climatic variability (e.g. Orlova et al 2002a, Ellingsen et al 2008) and human activities in an increasingly ice-free Arctic, with important implications for the condition of planktivorous fish and energy transfer to higher trophic levels (Orlova et al 2005). Ellingsen et al (2008) used an ecosystem model driven by recent climate projections to predict that temperature of Atlantic water entering the Barents Sea over the 50 yr will increase and lead to altered phytoplankton and zooplankton production It is important, to understand how variation in heat content of the Barents Sea influences ecosystem functioning, to better predict impacts of projected climate warming. We asked: (1) How does climate variability affect feeding of capelin on zooplankton prey? (2) How is this reflected in lipid content and, the ability to transfer energy to higher trophic levels? (3) What are the general mechanisms by which climatic conditions may affect these processes?
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
