Marine organisms and entire ecosystems are influenced by increasing temperatures and increasing CO2 partial pressure (hypercapnia). The experimental organism of this thesis, the marine teleost Gadus morhua, inhabits regions that are supposed to experience some of the largest climatic changes on the globe. The aim of this study was to investigate the effects of ocean acidification and increasing temperature on the physiological mechanisms in the heart of Gadus morhua in order to draw conclusions for the whole organism. The fish were divided into two groups, one was incubated under ambient pCO2 (390 μatm) and the other group under future pCO2 levels (1170 μatm; scenario after IPCC: RCP 8.5). Both groups were split into four different temperature levels (3, 8, 12 and 16 °C) with 12 animals in each treatment. The main focus was on the metabolic products of glycolysis, citric acid cycle, lactic acid cycle, amino acid metabolism and amino acid derivatives. Results show that environmental hypercapnia led to a significant decrease of glucose-6- phosphate (glycolysis), on amino acids and their derivatives alanine, glutamine,isoleucine, creatine phosphate, glucarate and taurine. The elevation of temperature led to a significant increase of creatine (amino acid derivatives) and lactate in the treatment groups with 390 μatm CO2. Hypercapnic accumulation did not significantly influence the metabolites of the citric acid cycle. Furthermore, similar ATP concentrations through all treatments indicated that Gadus morhua is able to cope with environmental changes and to maintain its supply of energy.