Oxygen consumption in single eggs of a desert pupfish

Abstract

Pupfish of the genus Cyprinodon live in environments that may be very warm (>35 °C) and hypoxic. In order to address how these conditions might affect the metabolism of fish eggs, we developed an approach that allowed for the measurement of oxygen consumption of a single egg. Eggs were classified into one of 4 groups depending on the stage of development and reared at either 28 or 33 °C. Expected increases in oxygen consumption as the result of development were found for the first three stages of development. However in well developed embryos, exposure to 33 °C resulted in an unexpected decrease in oxygen consumption. Interestingly, oxygen consumption spiked when eggs hatched during the assay suggesting that eggs are oxygen‐limited by the end of development. Critical partial pressures of oxygen were relatively high (~112 to 125 torr). These data call into question what role oxygen might have in the development of pupfish eggs in the wild.