Fishy future written in the genes(is the key to whether or not a species m...)

The spiny damselfish is significant because, unlike many other reef fish it does not release its eggs into the sea currents, but broods them on the home reef, meaning that a much higher percentage of its young 'stay home' rather that settle on distant reefs.

"Our work clearly indicates that this damselfish is a homebody that rarely moves far from its natal reef. When these fish do move, they don't go far and tend to relocate to neighbouring reefs and this can be seen in their genes. What is also clear is that not all populations are equal and that some populations may be more vulnerable to natural population size fluctuations and local extinctions compared to others. These population dynamics have probably been going on for a long time before humans started impacting on the reef."

However the research has immediate relevance to successful management of the GBR in times of extreme change, she adds. "If we can understand how reefs are connected, in terms of their fish populations, we can make sure we take steps to protect the ones which supply the pioneers who resettle devastated or maybe new coral areas if corals move in response to warmer water and changed conditions.

A particular area of interest is the southern end of the GBR, off Gladstone, where scientists expect that corals which have less tolerance for the very high water temperatures likely to occur further north will settle, bringing with them populations of reef fish.

Dr Bay says that the spiny damselfish population at the southern end of the GBR displays this unstable, ebb-and-flow pattern in its genes.

"If populations on the edge of the distribution are the ones that we rely on to colonise new habitats, then we need to make sure they are adequately protected," she says

"Our data indicate that they are potentially more vulnerable than more centrally located popula
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