P29-4 Sat Jan 2 The influence of different oxygen regimes on bioenergetics of a soft shell clam Mya arenaria Ouillon, N*; Sokolov, EP; Jarret, A; Sokolova, IM; University of Rostock, Germany ; Leibniz-Institute for Baltic Research, Warnemuende, Germany; University of Rostock, Germany ; University of Rostock, Germany natascha.ouillon@uni-rostock.de
Hypoxia is common in the coastal zone requiring physiological adaptations in the benthic sessile organisms to cope with this condition. A lack in oxygen could affect mitochondrial function that accounts for 90% of ATP production and impair energy-dependent functions such as locomotion and bioturbation. We exposed the soft shell clams Mya arenaria for 21 days to chronic (1.78 O2 mg/mL), fluctuating (5.46-0.82 O2 mg/L) hypoxia, or normoxia (9.16 O2 mg/mL). To mimic conditions occurring in coastal hypoxic zones, CO2 and pH levels varied with the oxygen. We assessed their digging performance, bioirrigation capacity and bioenergetics. Clams acclimated to chronic or fluctuating hypoxia dug slower and/or shallower than their normoxic counterparts. Furthermore, bioirrigation capacity decreased in clams acclimated to chronic hypoxia. Chronic hypoxia led to a decrease in the lipid content of the clam tissues whereas acclimation to the fluctuating hypoxia resulted to accumulation of proteins and carbohydrates compared to the normoxic clams. Exposure to the fluctuating (but not chronic) hypoxia led to an increase in the mitochondrial proton leak and reactive oxygen species production resulting in a higher maintenance cost of the mitochondria. Our results indicate that chronic and fluctuating hypoxia impair digging performance of clams and might negatively affect predator escape and bioturbation activity. Fluctuating oxygen conditions also appear to be more damaging to the clams’ mitochondria than the chronic oxygen deficiency.
