Benthopelagic mysids play an important role in coastal ecosystems. The mysids can experience high thermal variability on short time scales particularly in shallow waters, forcing them to permanently adjust their metabolism. Respiration rates are directly influenced by temperature, whereas ingestion rates might additionally be influenced by behavioral aspects. We aim to understand how respiration and ingestion rates respond to temperature changes during a diurnal thermal fluctuation cycle and how both processes are linked. Neomysis integer was collected in a littoral zone of the Baltic Sea. After laboratory acclimation, mysids were exposed to either a constant temperature of 15°C or a daily temperature fluctuation of 15±5°C. Short-term respiration and ingestion rates were measured at four equidistant time points within 24 hours. Under constant temperature, respiration and ingestion rates of mysids did not differ among time points. However, in the fluctuating treatment both rates showed significant differences among time points. Respiration was highest at the thermal maximum and lowest at the thermal minimum. Ingestion rates showed the opposite pattern. When temperature transited the average, the direction of temperature change was crucial for the animals‘ response in respiration and ingestion rates. Our results suggest that even though respiration is instantaneously affected by temperature, it is additionally influenced by the previously experienced direction of thermal change. Ingestion appears to be decoupled from respiratory performance in likely stressful conditions.

Primary Presenter: Konstanze Bergunder, University of Greifswald (konstanze.bergunder@uni-greifswald.de)

Authors:

Konstanze Bergunder, University of Greifswald  (konstanze.bergunder@uni-greifswald.de)

Laura Wienhausen, University of Greifswald  (laura.hennigs@uni-greifswald.de)

Erik Sperfeld, University of Greifswald  (erik.sperfeld@uni-greifswald.de)

Alexander Wacker, University of Greifswald  (alexander.wacker@uni-greifswald.de)