Reduced oxygen availability in water causes aquatic animals to reduce their body size much more with warming than those on land.

This new information could be significant in analysing the impact of climate change on animal species, as changes in body size with warming could affect many aspects of an animal's health, as well as alter the composition of ecologically and economically important ecosystems.
Curtis Horne, author of the research said, "Increasing our understanding of what influences how big animals grow will mean we can start to make better predictions about how different groups of species will cope with climate change. We see a really close match between lab experiments and patterns observed in nature, which suggests that the same factors are at play. It brings us a significant step closer to solving a problem that has long puzzled biologists."
Source-Medindia