News: News, Research, WA

Listening to past environments

Our climate is changing fast and water temperatures in the ocean have been rising over the past few decades.

Being able to predict how such changes in climate and the ocean environment will affect the growth of marine species is crucial, but has not been fully explored due to the lack of long term growth datasets.

Ms Joyce Ong, a postgraduate student at the University of Western Australia (UWA), with local and international collaborators, has published a study in Scientific Reports, examining how historical climate changes over the past few decades have affected the growth of the mangrove jack snapper in tropical north-western Australia.

They focused on the tiny ear stones (otoliths) of this fish, which contain rings very similar to those seen in a tree trunk. These rings enable researchers to determine both the age and the growth rate of these fish. By using light microscopy in the AMMRF at UWA to image these tiny structures, the researchers found that over the past few decades these fish grew faster when the waters along the north-west coast were warmer and less salty.

By understanding how fish have responded in the past to climate changes and which environmental factors are crucial for their growth, researchers can now predict how fish might respond in the future. This knowledge will help us to better conserve the ocean ecosystem and the sustainability of our fisheries.

Ong, J. J. L. et al. Sci. Rep. 5, 10859; doi: 10.1038/srep10859, 2015.

Light micrograph of a Lutjanus argentimaculatus (mangrove jack) otolith section with a close up image of the rings labelled with corresponding calendar years.