Butterfly fish may face extinction

February 25th, 2008 - 12:36 pm ICT by admin  

Sydney, Feb 25 (IANS) A starkly beautiful black, white and yellow fish, the Chevroned Butterfly fish, may be close to extinction. The fate of the fish - long admired by eco-tourists, divers and aquarium keepers alike - is a grim reminder of human pressure on coral reefs, forcing certain species into “blind alleys” from which escape is unthinkable, said Morgan Pratchett, who led a study on the butterfly fish.

“Seventy percent of the world’s coral reefs are now badly degraded, which usually involves the loss of this particular coral and, when it goes, the C. Trifascialis (scientific name of the species) also disappears from the reef, Pratchett explained.

A study published in the journal Behavioural Ecology and Sociobiology, quoting Pratchett and Michael Berumen of Woods Hole Oceanographic Institution in the US, warned that the specialised nature of the fish’s feeding habits is pushing it to the brink of extinction.

“The irony is that these butterfly-fish are widespread around the world, and you’d have thought their chances of survival were pretty good,” Pratchett said.

“But they only eat one sort of coral - Acropora hyacinthus - and when that runs out, the fish just disappears from the reef.”

The fish grew well when its favourite coral was available - but when this was removed and other sorts of corals offered, it grew thin, failed to thrive and some died.

“It indicates strong dietary preference for one kind of food and we still don’t have a satisfactory scientific explanation,” Pratchett said.

A. hyacinthus coral, a staple of the butterfly-fish, is itself highly vulnerable to attacks by plagues of crown-of-thorns starfish.

These attacks are believed to be triggered by humans releasing excess nutrients onto the reef as sediment, fertiliser or sewage, to storms and to the coral bleaching caused by the heating of ocean surface linked to global warming.

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