Ontogenetic and Spatial Variation in the Trophic Roles of Chukchi Sea Fishes

Climate warming and potential anthropogenic disturbances (e.g., shipping, coastal development, oil extraction) are expected to alter the Chukchi Sea ecosystem, including its fish communities. As a component of the Arctic Ecosystem Integrated Survey, we assessed the ontogenetic and spatial variability in the trophic roles (trophic level and source) of key fish species in the Chukchi Sea using C and N stable isotopes. During August and September of 2012, sixteen fish species and two baseline invertebrate species were collected from surface, midwater and bottom trawls within the eastern Chukchi Sea. Linear mixed-effects models were used to detect possible variation in the relationship between body length and either δ¹³C or δ¹⁵N among water masses. Additionally, we examined the community isotopic niche space, trophic redundancy, and trophic separation in each water mass as measures of resiliency of the food web. We present results on the ontogenetic and temporal variability in the trophic roles of sixteen fish species, including Arctic cod (Boreogadus saida), and saffron cod (Eliginus gracilis), as well as community-wide measures of isotopic niche space. Examining how spatial gradients in trophic roles are linked to environmental drivers can provide insight into potential community shifts with a changing climate.