Temperature-Dependent Lipid Storage of Juvenile Arctic cod (Boreogadus saida) and Co-Occurring North Pacific Gadids
Ben Laurel1, Louise Copeman2,3, Mara L. Spencer4, Paul Iseri4 and Angie L. Sremba3, (1)NOAA Fisheries, Alaska Fisheries Science Center, Fisheries Behavioral Ecology Program, Newport, OR, United States, (2)Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Oregon, United States, (3)Oregon State University, Cooperative Institute for Marine Resources Studies, Newport, OR, United States, (4)National Oceanic and Atmospheric Administration, Fisheries Behavioral Ecology Program, Alaska Fisheries Science Center, Newport, OR, United States
Abstract:
Climate change impacts on Arctic ecosystems will largely be determined by temperature-dependent bioenergetics of resident and invading forage fish species. In this study, we experimentally measured total lipids and lipid class storage in the liver and muscle of juvenile Arctic gadids (Arctic cod, Boreogadus saida and saffron cod, Eleginus gracilis) and two North Pacific gadids (walleye pollock, Gadus chalcogrammus and Pacific cod, Gadus macrocephalus). Experiments were conducted over a 6-wk period across five temperatures (0, 5, 9, 16 and 20 °C) at the Hatfield Marine Science Center in Newport, OR, USA. Results indicated clear physiological differences among species in terms of temperature-dependent growth and lipid storage. Arctic cod exhibited highest growth and lipid storage (27 mg/g WW) at the coldest temperature (0 °C) compared to the other gadids, with near maximum growth at 5 °C and onset of mortality above 9 °C. In contrast, saffron cod growth rates steadily increased at temperatures beyond 16 °C, but lipid storage was low overall with only slightly higher lipid storage at warm temperatures (10 to 17 mg/g WW). Both walleye pollock and Pacific cod showed a domed response with increased lipid storage and growth at intermediate temperatures (9 - 12°C) and reduced growth and lipid storage at cold and warm maxima. We did not observe a trade-off between growth rate and lipid accumulation in any species. These results suggest that saffron cod can thrive in a warming Arctic but will be energetically inferior as a prey item to the more temperature-sensitive Arctic cod. Alternatively, North Pacific gadids can energetically resemble Arctic cod at warmer temperatures and could theoretically be an important prey item if their range extends northward with continued climate change.
