Evolutionary ecology

New publication

Oxygen availability has large influences on guppy life history

The new study published in Conservation Physiology shows that maturation in guppies is highly plastic with respect to ambient oxygen levels.

Guppies with an air stone

Mikko Heino

In contrast to the terrestrial environments, oxygen is often in short supply in aquatic environments. This is a natural phenomenon, but human influences such as eutrophication and warming climate is making the challenge more acute. How do fish cope with reduced oxygen availability? In an experiment, we exposed newly born guppies to either normal or reduced oxygen conditions. The results show that the guppy life history is highly plastic: guppies exposed to reduced oxygen matured earlier, grew initially faster, and allocated more energy to reproduction compared to guppies under normoxia.

Curiously, the plastic changes induced by reduced oxygen were similar to what sustained size-selective fishing did. This finding highlights that reduced oxygen is one of the environmental factors that should be considered when trying to identify drivers of ubiquitous life-history trends in exploited fish stocks. 

The publication stems from the experiment that Geetha Jeyakanth carried out as her master's project.

The Norwegian Broadcasting Corporation has interviewed Jeppe Kolding to discuss the possible implications of our findings under the title "Less oxygen in the ocean can make fish to shrink" (in Norwegian).

This open access article also highlights a dark side of UiB's open access policy. For the university to cover the open access fee, the corresponding author must be a university employee. The assignment of correspondence to the last instead of the first author is in this case an unwanted side effect of an otherwise good initiative, instead of a sign of changing practice, as discussed in this blog post


Díaz Pauli, B., Kolding, J., Jeyakanth, G. & Heino, M. 2017. Effects of ambient oxygen and size-selective mortality on maturation and growth in guppies. Conservation Physiology 5(1): cox010. doi: 10.1093/conphys/cox010. Open access!