Meeting Abstract
P2.114 Wednesday, Jan. 5 Vertical migration in oxygen minimum zones: the physiological consequences for the hyperiid amphipod Phronima . ELDER, LE*; SEIBEL, BA; University of Rhode Island, Kingston leab83@hotmail.com
As global temperatures and carbon dioxide levels increase, oceanic oxygen levels are predicted to decrease. As a result oxygen minimum zones (OMZ) will expand vertically. OMZ’s are regions in the world’s oceans where oxygen consumption is greater than oxygen supply. The expansion of OMZ’s may affect the ecology and vertical distribution of diel migrating organisms. This study focuses on the respiratory physiology of the hyperiid amphipod, Phronima sedentaria, in the pronounced OMZ of the Eastern Tropical Pacific. Hyperiid amphipods are the third most abundant type of marine zooplankton in the crustacean family and an important food source for fish. Live specimens were collected using a Tucker Trawl. Respiration experiments were performed under hypoxic (1% O2) and normoxic (21% O2) conditions, equivalent to the night and daytime exposures during migration. The Q10 (a measure of temperature dependence of metabolism) is approximately 2 between 10 and 20°C. L-lactate concentrations in whole organism homogenate, an index of anaerobic ATP production, was significantly higher, (T(13)= -3.65; p=0.0027), in hypoxic (6.0527 ± 1.0417mmol/L Lactate), compared to normoxic, (2.031 ±0.3598 mmol/L lactate) specimens. Oxygen consumption was 2.090 µM O2/g*h under hypoxic conditions and 3.802 µM O2/g*h under normoxic conditions. This demonstrates a 55% reduction in oxygen consumption under hypoxic conditions. These results indicate that Phronima is using anaerobic glycolysis to partially compensate for reduced aerobic ATP production while in the hypoxic conditions of the OMZ, but total metabolism is also suppressed. As global warming continues OMZ’s are predicted to expand and Phronima will have to migrate shallower at night to burn off the oxygen debt accumulated in the OMZ.
