As the climate changes worldwide the aquaculture industry suffers several stressors, such as altered ocean chemistry due to warming temperatures, increases in CO2 “ocean acidification”, and reductions in dissolved oxygen (DO) (i.e., hypoxia). In addition to occurring naturally, we know that hypoxic events are associated with upwelling, which are surges of deep water that are rich in nutrients but low in oxygen. This phenomenon can increase with climate change, for example along the U.S. West Coast and Chile. The aims of this study were to determine the effect of hypoxia on several osmoregulatory organs including gills, kidney, intestine (foregut-midgut, and hindgut), muscle, red blood cells and brain of Onchorynchus kisutch. The fish were challenged by 4 hypoxic conditions (60, 50, 35 and 25% DO) and a normoxic “control”. After days of exposure, NKA and H+ activities decreased in gills and kidney in hypoxic conditions and ions at 25% DO were increased. Meanwhile in the peripheral tissue such as muscle and red blood cells NKA activity levels were increased, which was consistent with several portions of the intestine. In conclusion, our data suggest that the osmotic response is altered by hypoxia, and prolonged exposure leads to deactivation of the primary pump. Although it appears that the required energy is potentially for oxygen transport rather than the osmotic process. Furthermore, while peripheral systems may strive to maintain homeostasis, the ionic balance is progressively lost.

This dataset contains the ATPasa, H+ and NKA activity messured on Oncorhynchus kisutch under hypoxic stress.