An Australian study reveals that survival isn’t easy for young fish living on the Great Barrier Reef (GBR) - and may be even harder under climate change.

Environmental differences experienced early in life not only have immediate consequences for survival of baby fish, but also profoundly influence their chances of success later in life.

This is the finding of research by Dr Monica Gagliano and Dr Mark McCormick of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and James Cook University (JCU), and colleague Dr Mark Meekan from the Australian Institute of Marine Science (AIMS).

The team have studied hundreds of Ambon damselfish from egg to adulthood to establish the extent to which parental quality and environmental rearing conditions shape the survival of these fishes.

"Even long before spawning, mothers mould the quality of their babies, thereby influencing their chances of survival," Dr Gagliano says, "however, the mother’s effort isn’t the only thing that influences their survival."

The team’s research at Lizard Island on the northern GBR showed that elevated temperatures experienced during development of the young fish have devastating consequences for the future survival of baby fish.

"Survival of fish embryos was dramatically compromised at 31°C, which is not uncommon at this location during summer" Dr Gagliano says.

"There is no doubt that the quality of parents and the early environment experienced by fish as they develop have major effects on who will survive."

"For the first time, we have been able to establish the fate of young fishes in their natural environment by following them through time, from leaving their parents up to months after settling back on the reef," she says.

The team’s findings, recently published in prestigious science journals including Oecologia, Journal of Animal Ecology and Proceedings of the Royal Society: Biological Science, showed that the effects mothers have on young fish and the environment encountered during their early life, have long-lasting consequences in determining who survives to repopulate the reef into the future.

The team’s detailed look at the struggles of growing up on the GBR and their findings help us understand how these, and other reef fish, can be managed and protected so that they can survive through the threats of climate change.　

"While a privileged upbringing of good quality parents and a high quality environment can significantly define an individual’s success in life, the major environmental changes taking place today may well undermine these prerequisites for survival"

Our ability to understand what shapes the life of these fish is pivotal to our success in predicting their responses to today’s rapidly changing environment," Dr Gagliano says.

As reef environments may experience dramatic shifts in the face of climate change, understanding the complex lives of reef fish becomes essential to ensuring they survive into the future, since the colourful damselfish, along with the many other species of reef fish on the GBR, are all of vital importance to the area’s environment – and part of the attraction that drawn $4.5 billion’s worth of tourism to the region.

Together with her colleagues from CoECRS, JCU and the AIMS, Dr Gagliano now aims to investigate how the impact of environmental changes occurring today will be translated in the future.

"The possibility that stressful conditions experienced by today’s fish may be transmitted on through successive generations of offspring remains largely unexplored, but it seems very likely in light of our recent findings," says Dr Gagliano.

More information:
www.coralcoe.org.au
AIMS - reef monitoring