Big fish shelters could be under threat


The architectural preferences of large coral-reef fishes such as coral trout and grouper may affect their long-term survival under global climate change, according to a study to be published in a forthcoming issue of the journal Coral Reefs.

Carrying out their study at Lizard Island in Australia's Great Barrier Reef, James Kerry and David Bellwood used stationary underwater digital video cameras to record the fishes visiting three different types of coral structures (tabular, branching and massive).

They also constructed artificial shelters using PVC pipes, plastic bases and lids in one of three forms: (i) roofless structure; (ii) with a clear roof and (iii) with a black roof, which they used to test the preferences of the fishes.

They found that large coral reef fishes showed a marked (more than three times) preference for sheltering under large, flat table corals over branching or massive structures.

The authors hypothesised that tabular corals provide the most concealment for many large reef fishes that are ambush predators to enable them to hunt the most effectively.

The fishes also preferred hiding under artificial structures with a black roof, demonstrating that shelter from sunlight (so that less energy is expended to produce protection from it) seems to be a key consideration.

However, tabular corals are the most susceptible to bleaching and ocean acidification, all of which are expected to increase as a result of climate change. This would lead to a reduction in shelter options for large coral reef fish, and severely compromise the abundance of reef fishes.

For more information, see the paper: Kerry, JT and DR. Bellwood (2012) The effect of coral morphology on shelter selection by coral reef fishes. Coral Reefs doi:10.1007/s00338-011-0859-7

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