Global climate change will affect fish sizes in unpredictable ways and, consequently, impact complex food webs in our oceans, a new IMAS-led study has shown.
Led by IMAS and Centre for Marine Socioecology scientist Dr Asta Audzijonyte and published in the journal Nature Ecology and Evolution, the study analysed three decades of data from 30,000 surveys of rocky and coral reefs around Australia.
Dr Audzijonyte said the study confirmed that changes in water temperature were responsible for driving changes in average sizes of fish species across time and spatial scales.
“Cold blooded animals, especially fish, have long been noted to grow to a smaller size when raised in warmer temperatures in an aquarium,” Dr Audzijonyte said.
“If fish grow to smaller sizes in warmer aquaria, it is only natural to expect that global warming will also lead to shrinkage of adult fish size.
“However, average fish body size in wild populations are affected by growth, mortality, recruitment as well as interactions with other organisms and their environment simultaneously and it is unclear how all of these factors are affected by temperature.”
The researchers were surprised to find that while temperature has a significant impact, it caused different fish species to react differently.
In some the average fish body size got smaller as predicted (around 55% of species) but in others it increased (around 45%).
In general — but not universally — larger species tended to get even bigger in warmer waters, while smaller species tended to get smaller.
Read more at University of Tasmania