A mass bleaching of more than 50 million sponges in Fiordland was the largest event of its kind ever recorded and is estimated to have cut the population by close to half, a new study reports. A mass bleaching of more than 50 million sponges in Fiordland was the largest event of its kind ever recorded and is estimated to have cut the population by close to half, a new study reports. Plants & Animals Ecology Phys.org – latest science and technology news stories