Where the big fish hang …
Researchers have found that big reef fish – like coral trout, snappers and sweetlips – show a marked preference for sheltering under large, flat table corals, as opposed to branching corals or massive corals.
In a study that covered 17 separate locations around Lizard Island in far North Queensland, researchers from the ARC Centre of Excellence for Coral Reef Studies at James Cook University used reefcams to video the behavior of large reef fish in order to identify the kind of habitat the fish most preferred.
James Kerry is co-author of the study, published the journal Coral Reefs in February 2012. He said:
Like human beings, fish have strong preferences on where they like to hang out – and it appears that they much prefer to shelter under overhanging tablecorals. This tells us quite a bit about how important these corals are to the overall structure of the reef and the large reef fish that live there.
The researchers deployed artificial shelters made from plastic in the lagoon and discovered that it isn’t the coral, so much as the shelter that is important to big fish. And the fish even had preferences about roof color. James said:
We made one sort with no roof, one with a translucent roof and one with a roof painted black. Far and away the fish preferred to shelter under the black roof, which suggests they either want to hide or else to avoid direct sunlight.
The reason for the fishes’ preference is not yet clear – but possibilities include hiding from predators such as sharks, shading themselves from ultraviolet sunlight, or lying in ambush for prey.
The research was aimed at understanding the process of fish population decline when coral reefs sustain major damage.
Professor David Bellwood, co-author of the study, explained:
The importance of this finding is that table corals are among the types most vulnerable to climate change. In shallow waters and on the tops of reefs, they are often the main source of cover for these big fish.
If they die back as a result of bleaching or disease, or are destroyed by storm surges, this would strip the reef of one of its main attractions, from a coral trout’s viewpoint.
Bottom line: Big reef fish – like coral trout, snappers and sweetlips – show a marked preference for sheltering under large, flat table corals, as opposed to branching corals or massive corals. That’s according to a Feburary 2012 paper in the journal Coral Reefs.