Tropical vagrants found to be bigger and stronger


Marine researchers in Sydney are closer to solving the mystery of how tropical fish are moving in response to rising sea temperatures and the impact of climate change.

These 'vagrants', numbering in the hundreds of species, are moving more often into the temperate waters of New South Wales, which may alter the sensitive marine ecosystems found there.

In the latest research - "Latitudinal shifts in coral reef fishes: why some species do and others do not shift" in Fish and Fisheries - Dr David Feary, UTC Chancellors Postdoctoral Fellow and lead author of the study, found that just 360 species of tropical fish show seasonal shifts into temperate waters without much known reason as to why.

The study showed that larger adults, eggs that are spawned into the oceanic current, a relatively large larval body and larvae that are strong swimmers are features that stand out in tropical vagrants.

Dr Feary said he and his colleagues had expected some biological and ecological factors would stand out as aiding the vagrants survival in warmer regions, but they did not expect that these traits would be so strongly associated with success.

He said: "Although there is exceptionally strong evidence to show that animal populations are undergoing substantial shifts in their latitudinal distribution, this is the first time that we have been able to show that there are certain measurable traits that may help to predict successful range shifts.

"The findings of this work can now be shared with other marine researchers within Australia and globally and contribute to our understanding of how climate change is rapidly re-structuring our biological communities around the world.

"Marine scientists internationally can use our findings to determine which species in their regions may have the capacity to move and adapt in the face of climate change and those that will perish.

"This work will be vital in Australia as our fish stocks rapidly change in their latitudinal distributions.

"We can now start to understand the traits, and therefore the species, which will make successful latitudinal shifts within Australian waters."

It is important to understand the significance of these changes in structuring the fish communities, as well as future repercussions, as the eastern Australian environment is changing more rapidly than any other place in the world.