Überwinterungsstrategien polarer Copepoden: Physiologische Kontrollmechanismen und Auftriebsregulation durch Ammonium

• Antragsteller: Holger Auel, Ph.D.; Dr. Franz Josef Sartoris
• Fachliche Zuordnung: Physik, Chemie und Biologie des Meeres
• Förderung: Förderung von 2010 bis 2016
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 172475510

Ontogenetic seasonal migration associated with a diapause is known as an adaptation to escape temporally from an unfavourable environment in several calanoid copepod species in Polar Seas. Diapausing copepods reside for several months in greater depths where they are presumably neutrally buoyant. Ammonium buoyancy as been observed in several marine invertebrates has never been studied in diapausing copepods. Dependent on the pH, ammonia exists in solutions as both NH3 and NH4 +). Due to the toxicity and the higher diffusibility of NH3 a low haemolymph pH is required to favour the formation of ammonium (NH4 +). The trigger (onset, duration, termination) of diapause is yet unknown. In a recent study we detected ammonium values as high as 500 mmol L-1 in the haemolymph of the diapausing Antarctic copepods Calanoides acutus and Rhincalanus gigas, as well as in the diapausing calanoid copepods Calanoides carinatus and Eucalanus sp. in the Benguela Current upwelling system, indicating ammonia buoyancy in these species. In diapausing copepods metabolic depression is evident by reduced metabolic rate and reduced swim activity. We hypothesize that a low extracellular pH in the haemolymph of diapausing copepods necessary to form NH4 + and to prevent it from diffusive loss could play a fundamental role in the regulation of metabolic depression and thus in the control of diapause. This would lead to a seasonality of ammonia buoyancy with high ammonium and low pHe during diapause and high pHe and low ammonium in the active periods.

• DFG-Verfahren: Infrastruktur-Schwerpunktprogramme
• Teilprojekt zu: SPP 1158: Bereich Infrastruktur - Antarktisforschung mit vergleichenden Untersuchungen in arktischen Eisgebieten
• Beteiligte Person: Professorin Dr. Sigrid Schiel