Why is support for multiculturalism declining?

This week's Lowy Institute poll showed the largest drop in support for cultural diversity in Australia on record. Multiculturalism has long been hailed as an Australian success story, a global exemplar in integrating migrant communities, the envy of Europe and the US. It follows so soon after Pauline Hanson's rallying cry for monoculturalism to replace multiculturalism. So what's driving this feeling?