No, not necessarily. Firstly, you will enter as a permanent resident which does not affect your current citizenship status. After two years you can apply for Australian citizenship (but this is not obligatory). The Australian Government allows dual-nationality (i.e. the holding of two passports), so you could retain your current passport and obtain an Australian passport as well. Having said this, you must check that your own country of citizenship allows dual-nationality, as this right must be reciprocal. If not, you will need to surrender your other passport in order to become a citizen.