Metabolism and life-cycle and thus geographic distribution of marine species are primarily influenced by temperature. By recognizing the effects of climate change, and particularly the increase of sea water temperature, knowledge about the response of marine organisms to temperature changes is essential for understanding and modelling ecosystem processes related to climate change. With the present objective of monitoring the effect of temperature on the metabolic performance of calanoid copepods, two incubation experiments were performed, one with Metridia longa and the other with Temora longicornis. While changing the temperature from ambient temperature to 5C, 10C, 15C and 20C, parameters including body mass (dry mass, carbon and nitrogen content), metabolic activity (respiration and citrate synthase activity), digestive activity (proteinase and lipase/esterase activity), reproduction (egg production) and mortality rate were determined. A change to 20C led in both species to a strong response of their metabolic performance including a high mortality rate. M. longa died at 20 C within 20 hours. Respiration rates were affected significantly by temperature, having the highest rate at 15C for M. longa and at 15 and 20C for T. longicornis. The Q10 value of M. longa (3.2) was higher than the value of T. longicornis (2.0), assuming a higher sensibility to changes in temperature. Further results of somatic growth and digestive activity suggest a higher temperature tolerance of T. longicornis compared to M. longa, hence different responses to climate change are expected. |
