Software Open Access
K. A. S. Mislan; Dunne, John P.; Sarmiento, Jorge L.
The P50 Depth Analysis v1.0 calculates blood-oxygen binding, which is a mechanism determining hypoxia tolerance in the ocean. Blood-oxygen binding is measured as the oxygen pressure in the blood at which whole blood is 50% oxygenated, called P50. A low P50 means that respiratory pigments in the blood of an organism equilibrate to 100% oxygenation at lower oxygen pressures, and the organism is more hypoxia tolerant. Temperature alters hypoxia tolerance by shifting the P50 of organisms. The effect of temperature is measured as the heat of oxygenation (ΔH) which is the amount of heat energy released (negative ΔH) or absorbed (positive ΔH) when oxygen binds to respiratory pigments. Marine organisms swim between warmer, well-oxygenated waters near the surface of the ocean and colder, less-oxygenated waters in the deeper ocean.
This analysis assumes P50 acclimation to temperatures at 10 m depth in the mixed layer. P50 in the water column can be determined relative to P50 at 10 m depth using the Van't Hoff equation and oxygen pressure and temperature data. The P50 depth is defined as the shallowest depth in the ocean where pO2 = P50. This code calculates P50 depths for the global ocean.
Please cite the following paper if you use this code:
Mislan, K. A. S., J. P. Dunne, and J. L. Sarmiento. (2015) The fundamental niche of blood-oxygen binding in the pelagic ocean. Oikos. http://dx.doi.org/10.1111/oik.02650