Leo, Elettra

Mark, Felix C.

Pörtner, Hans-Otto

Storch, Daniela

OceanRep

Elettra LeoAWI, GermanyIntegrative Ecophysiologyelettra.leo@awi.deHeart metabolism of two gadoid fish species at their distribution boundary under elevated temperature and PCO2Elettra Leo, Daniela Storch, Hans-Otto Pörtner, Felix C MarkSEB Annual MeetingPrague 2015A9.23Due to rising ocean temperature, Atlantic cod (Gadus morhua) have entered the waters around Svalbard, populated by the resident Polar cod (Boreogadus saida)[1].Polar cod are cold stenotherm and the waters around Svalbard define their southern and warmest limit, while for Atlantic cod these waters represent the northern and coldest distribution limit.IntroductionElevated PCO2 in the ocean affects biological and physiological processes and influences the animals‘ thermal tolerance by decreasing the aerobic performance and narrowing the thermal range[2].Cardiocirculatory capacity has a key role in defining the thermal tolerance of fish and heart failure is considered to set the limits of thethermal window[3].Heart failure at elevated temperature may be caused by extrinsic factors like deficient oxygen supply or by intrinsic factors like mismatch in energy demand/supply.Cardiac mitochondria provide 90% of requested energy (ATP), therefore the study of their function can help to understand a species‘thermal tolerance[3].OXPHOSContribution of Complex I & IINo changes with temp.No changes with PCO2Increasing with tempDecreased capacity at 16°C under high PCO2 levelsPolar cod Atlantic codComplex I capacity is lower under high PCO2Complex I capacitydecreases at 16°CComplex II capacityincreases at 16°C Which is the role of heart mitochondria in shaping the thermal tolerance of these two fish species?Do high PCO2 levels impact mitochondrial physiology and by this the thermal tolerance of the fish species?Can different physiology be related to environmentaladaptations?ObjectivesConclusionsT (°C) CO2 (µatm)03903903903901170117011701170368T (°C)3812163903903903901170117011701170CO2 (µatm)   4 months   4 Temp.    2 PCO2AcclimationHigh Resolution Respirometry (O-2k)Permeabilized heart fibersSubstrate-Inhibitor-TitrationMaximum Oxidative Phosphorylation capacityContribution of the single complexes to the Electron Transport SystemMethod* p<0.05References:[1]  Drinkwater 2009, Deep Sea Res. Part II: Topical Studies in Oceanogr. 56, 2087-2095[2]  Pörtner and Farrell 2008, Science 322, 690-692[3] Pörtner and Knust 2007, Science 315, 95-97    No effects of high PCO2 in both complexesComplex II capacitydecreases at 8°CPolar codAtlantic codCardiac mitochondria are affected by temperature close to the animals‘ upper thermal limits indicating a role in thermal tolerancePolar cod mitochondria are not sensitive to elevated PCO2In Atlantic cod, the lower OXPHOS under elevated PCO2 suggests a narrowing of the thermal tolerance at the upperthermal limitThe limited plasticity shown by Polar cod mitochondria is consistent with the adaptation to the cold and stable Arctic watersAtlantic cod are able to adjust their mitochondrial metabolism with rising temperature indicating higher thermal acclimationcapacity

Heart metabolism of two gadoid fish species at their distribution boundary under elevated temperature and PCO2

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