I've found the article (Z Magazine Autumn 2006 Issue 27). It just states the issues that amphibians are dealing with (chytridiomycosis - a fungal disease, and other problems) and that it is important for zoos to build Assurance Populations which will keep species alive until methods are found to prevent chytridiomycosis. Chester has been constructing Amphibian Arks and are gradually building the collection.
London's amphibian house will be called "Frog World", I believe.
Great thanks for that... To google...