Isolated reef fish at greater risk of extinction

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Living the life of a hermit may spell doom for the future of some coral reefs, according to research by Australian scientists to be published in a forthcoming issue of the journal Ecology.

Camille Mellin and colleagues reported that fishes living in isolated reefs are in greater danger of going extinct after studying data for 43 reefs located in Australia’s Great Barrier Reef over a period of 15 years. 

The authors tested the relationships between reef area and isolation and temporal stability of fish communities using statistical methodsapplied to their data. 

The results support the notion that fishes living in small and isolated reefs are thought to be more extinction-prone because of a tendency of the populations to fluctuate more over time. 

According to the authors, this fluctuation arises because there is reduced immigration for smaller and more isolated reefs. 

A reduction of immigrants would lead to isolated reefs recovering more slowly from climate change-driven degradation (e.g. bleaching) than in continental reef systems, where larval replenishment from less-impacted reefs is more likely. 

Smaller reefs also intrinsically support fewer species, which have stronger interactions (e.g. competition, predation) with each other than species in larger reefs. This also makes the populations more prone to large fluctuations over time.

The results support the idea that conservation resources would be better allocated to the protection of large, connected habitats or some combination of habitats that optimise area and connectivity in a given landscape.

For more information, see the paper: Mellin, C, C Huchery, M Caley, M Meekan and C Bradhsaw (2010) Reef size and isolation determine the temporal stability of coral reef fish populations. Ecology doi:10.1890/10-0267.1